JP6548879B2 - Color headlight tester and test method of headlight by color image processing - Google Patents

Description

  The present invention relates to a headlight tester for testing headlights of vehicles such as automobiles, and more particularly to a color headlight tester for performing color image processing on a received light image of the headlights to test the headlights. It is a thing.

  Conventionally, most commercialized headlight testers that use image processing use monochrome cameras. Under such circumstances, the applicants have previously proposed a color headlight tester capable of performing color image processing of the projection light of the headlight using a color camera (Japanese Patent Application Laid-Open No. 2013-2969). By using a color camera (color image sensor), it is possible to perform color image analysis of the projection light from the headlight, and the amount of information is rich compared to the case of using a monochrome camera, It is possible to perform various analyzes that were not possible with a headlight tester using a conventional monochrome camera.

  The headlight test is originally conducted in a state where it is projected on an external screen (also referred to as a 10 m screen) positioned 10 m forward, but in the headlight tester, the optical system and the inside of the light receiving unit The screen is disposed and projected onto the inner screen through the optical system. Since the projection light from the headlight is thus projected onto the inner screen through the optical system, in particular, when color image processing is performed, the error due to the influence of the chromatic aberration of the optical system can be corrected. It becomes important.

  For example, although there are halogen, HID, LED, etc. as the light source type of the headlight, it is impossible in the prior art to automatically determine the light source type using the projection light from the headlight. Furthermore, there has not been provided a practical technique for performing color image processing of the projection light from the headlight to measure the luminous intensity of the headlight, the optical axis (irradiation direction), and the detection of the elbow point.

JP, 2013-2969, A

  The present invention has been made in view of the above points, and a color head light tester capable of performing a test with high accuracy, and a method of testing a head light by color image processing, which overcome the drawbacks of the prior art as described above. Intended to provide. Furthermore, another object of the present invention is a color headlight capable of performing a test with high speed and high accuracy by receiving projected light from a headlight through an optical system and performing color image processing. It aims to provide a test method of a tester and a headlight.

I. According to one aspect of the present invention, an optical system for receiving projection light from a headlight, a screen on which a light distribution pattern of the projection light is projected through the optical system, the light distribution on the screen A measuring color camera for imaging a pattern; a light source type determining unit that receives RGB data from the measuring color camera and determines a light source type of the headlight based on a relationship between at least two of the RGB data; A color headlight tester is provided.

  According to one preferred embodiment, the light source type is determined based on the ratio between two selected ones of the RGB data. According to yet another preferred embodiment, the determination of the light source type is performed based on the difference between the two data. According to yet another embodiment, the light source type is determined based on both the ratio and the difference between the two data. According to one embodiment, the two data are G and R data, the ratio is G / R, and the difference is | G-R |.

  According to one preferred embodiment, the determination of the light source type is a determination of a warm color light source (halogen as a representative example) and a cold color light source (HID as a representative example).

II. Determination of the Optical Axis According to another aspect of the present invention, an optical system for receiving projection light from a headlight, a screen on which a light distribution pattern of the projection light is projected through the optical system, the distribution on the screen A color camera for measuring a light pattern, rgb coefficient determining means for determining an rgb coefficient for each of a plurality of selected pixels of the color camera for measurement, RGB data received from the color camera for measurement and the rgb The luminance determining means for applying the rgb coefficient to the corresponding pixel determined by the coefficient determining means to determine the luminance for the corresponding pixel, determining the highest luminance among the luminances, and determining the position of the highest luminance in the upper, lower, left, and right directions A color headlight tester is provided, comprising optical axis determination means determined as the optical axis of the headlight.

  According to one preferred embodiment, the optical system comprises a main lens. More preferably, the main lens is a Fresnel lens. In one preferred embodiment, the measuring color camera includes a color image sensor having a predetermined number of pixels, and RGB data for each pixel of the color image sensor is output. Preferably, the color image sensor is a single-plate type, and its RGB color filter has a so-called Bayer array, and the color camera for measurement performs interpolation processing to calculate each RGB data for each pixel. Output. In another preferred embodiment, the color image sensor is multi-plate and the measuring color camera outputs RGB data directly from each pixel. In one embodiment, the color image sensor is a CCD color image sensor.

  According to one preferred embodiment, the luminance is determined as the Y coordinate in the XYZ coordinate system defined by the tristimulus values X, Y, Z in the CIE XYZ color system, ie Y = r × R + g × G + b × B Here, R, G, B are RGB data output from the color camera for measurement, and r, g, b are coefficients as weightings of the RGB data.

  When determining the rgb coefficients, it is necessary to determine the color space to which it applies. There are several color spaces (so-called color triangles) such as sRGB, adobe RGB, NTSC_RGB in the xy chromaticity diagram, but in one embodiment the NTSC_RGB color space is used.

  The rgb coefficient (also abbreviated as Y coefficient) changes depending on the color temperature (K: Kelvin) of the headlight as the light source. The color temperature is a numerical value representing the color of light, which is different from the light intensity (cd), and the color tone of the light source changes sequentially from yellow to white to blue as the color temperature becomes higher. That is, when the color temperature changes, the spectral distribution of light also changes, and as a result, the rgb coefficient also changes. Therefore, the rgb coefficient used when determining the luminance Y needs to correspond to the color temperature of the headlight. If the color temperature is known (such as measurement with a color temperature meter), it is possible to use the rgb coefficient corresponding to the measured color temperature, but if the color temperature is unknown, the head It is necessary to estimate and approximate the color temperature of the light.

  More preferably, the rgb coefficient is determined by correcting the variation in each pixel of the color image sensor due to the influence of chromatic aberration or the like through the optical system. In general, the variation tends to be noticeable as the color image sensor moves away from near the center of the color image sensor. In one embodiment, the rgb coefficients include at least one reference rgb coefficient determined based on the color temperature of the CIE standard light source and at least one correction rgb coefficient that is a modification of the reference rgb coefficient. ing. In one embodiment, to absorb this variation, the rgb coefficient is determined for each pixel of the color image sensor. In another embodiment, all pixels of the color image sensor are divided into zones of a predetermined number of pixels, and a common rgb coefficient is applied to the pixels in each zone.

  In the case of determining the maximum luminance, it is possible to apply a balance method or a binarized center of gravity method. In the balance method, in one embodiment, the three times 30 minutes method is applied.

  In one embodiment, the optical axis determination means includes a maximum brightness (e.g., balance point) position correction table, and the maximum brightness position correction determined in advance with respect to the position of the pixel extracted as the maximum brightness. Apply the hv position correction data to determine the final highest intensity position. Here, h is position correction data in the horizontal (left and right) direction, and v is position correction data in the vertical (upper and lower) direction.

  In one preferred embodiment, a light source type determination unit is further provided to determine an rgb coefficient to be applied according to the determined light source type.

  In one preferred embodiment, the rgb coefficient determination means has a plurality of tables in which rgb coefficients are calculated for predetermined light intensity or color temperature, and the table is selected and used according to the measured or calculated light intensity or color temperature. Determine the rgb factor to be done.

  Preferably, the rgb coefficient determination means, the luminance determination means, and the optical axis determination means are provided in the image processing apparatus connected to the color camera for measurement in the color headlight tester. In one embodiment, the image processing apparatus comprises a computer system having at least a CPU and a memory, and the rgb coefficient determination means, the luminance determination means, and the optical axis determination means is the present color head light tester Stored as part of a program that controls the operation of

III. Determination of luminous intensity (part 1)
According to still another aspect of the present invention, there is provided an optical system for receiving projection light from a headlight, a screen on which a light distribution pattern of the projection light is projected via the optical system, the light distribution pattern on the screen Measurement color camera for imaging, rgb coefficient determination means for determining an rgb coefficient for each of a plurality of selected pixels of the measurement color camera, RGB data is received from the measurement color camera, and the rgb coefficient determination means Means for determining the luminance for the corresponding pixel by applying the rgb coefficient for the corresponding pixel determined by the step of determining the highest luminance among the plurality of luminances respectively corresponding to the plurality of pixels. A color headlight tester is provided, comprising: first light intensity determining means for determining the light intensity of the headlights from the highest brightness.

  According to one preferred embodiment, the optical system comprises a main lens. More preferably, the main lens is a Fresnel lens. In one preferred embodiment, the measuring color camera includes a color image sensor having a predetermined number of pixels, and RGB data for each pixel of the color image sensor is output. Preferably, the color image sensor is a single-plate type, and its RGB color filter has a so-called Bayer array, and the color camera for measurement performs interpolation processing to calculate each RGB data for each pixel. Output. In another preferred embodiment, the color image sensor is multi-plate and the measuring color camera outputs RGB data directly from each pixel. In one embodiment, the color image sensor is a CCD color image sensor.

  According to one preferred embodiment, the luminance is determined as the Y coordinate in the XYZ coordinate system defined by the tristimulus values X, Y, Z in the CIE XYZ color system, ie Y = r × R + g × G + b × B Here, R, G, B are RGB data output from the color camera for measurement, and r, g, b are coefficients as weightings of the RGB data.

  When determining the rgb coefficients, it is necessary to determine the color space to which it applies. There are several color spaces (so-called color triangles) such as sRGB, adobe RGB, NTSC_RGB in the xy chromaticity diagram, but in one embodiment the NTSC_RGB color space is used.

  The rgb coefficient (also abbreviated as Y coefficient) changes depending on the color temperature (K: Kelvin) of the headlight as the light source. The color temperature is a numerical value representing the color of light, which is different from the light intensity (cd), and the color tone of the light source changes sequentially from yellow to white to blue as the color temperature becomes higher. That is, when the color temperature changes, the spectral distribution of light also changes, and as a result, the rgb coefficient also changes. Therefore, the rgb coefficient used when determining the luminance Y needs to correspond to the color temperature of the headlight. If the color temperature is known (such as measurement with a color temperature meter), it is possible to use the rgb coefficient corresponding to the measured color temperature, but if the color temperature is unknown, the head It is necessary to estimate and approximate the color temperature of the light.

  More preferably, the rgb coefficient is determined by correcting the variation in each pixel of the color image sensor due to the influence of chromatic aberration or the like through the optical system. In general, the variation tends to be noticeable as the color image sensor moves away from near the center of the color image sensor. In one embodiment, the rgb coefficients include at least one reference rgb coefficient determined based on the color temperature of the CIE standard light source and at least one correction rgb coefficient that is a modification of the reference rgb coefficient. ing. In one embodiment, to absorb this variation, the rgb coefficient is determined for each pixel of the color image sensor. In another embodiment, all pixels of the color image sensor are divided into zones of a predetermined number of pixels, and a common rgb coefficient is applied to the pixels in each zone.

  In one embodiment, when determining a pixel having the highest luminance, it is possible to apply a balance method or a binarized center of gravity method. In the balance method, in one embodiment, the three times 30 minutes method is applied.

  In one embodiment, the first light intensity determining means is predetermined between the light intensity of a reference light source (eg, a standard headlight or a reference sphere) having a known light intensity and the brightness determined by the brightness determining means. Determine the light intensity based on the conditions. In one embodiment, the intensity of the projected light of the reference light source (e.g., a standard headlight or reference sphere) is measured using a reference light source (e.g., a standard headlight or reference sphere) having a known light intensity. Measure and set in advance the relationship between the light intensity and the brightness.

  In one preferred embodiment, a light source type determination unit is further provided to determine an rgb coefficient to be applied according to the determined light source type.

  In one preferred embodiment, the rgb coefficient determination means has a plurality of tables in which rgb coefficients are calculated for predetermined light intensity or color temperature, and the table is selected and used according to the measured or calculated light intensity or color temperature. Determine the rgb factor to be done.

  Preferably, the rgb coefficient determination means, the luminance determination means, and the first light intensity determination means are provided in the image processing apparatus connected to the color camera for measurement in the color headlight tester. In one embodiment, the image processing apparatus comprises a computer system having at least a CPU and a memory, and the rgb coefficient determination means, the luminance determination means, and the first light intensity determination means are the present color headlights. It is stored in the memory as part of a program that controls the operation of the tester.

IV. Determination of luminous intensity (part 2)
According to still another aspect of the present invention, there is provided an optical system for receiving projection light from a headlight, a screen on which a light distribution pattern of the projection light is projected via the optical system, the light distribution pattern on the screen A measurement color camera for imaging, rgb coefficient determination means for determining an rgb coefficient for each of a plurality of selected pixels of the measurement color camera, RGB data is received from the measurement camera, and the rgb coefficient determination means Luminance determination means for applying the rgb coefficient to the determined corresponding pixel to determine the luminance for the corresponding pixel, determining the luminance at a predetermined position from the center of the headlight in the light distribution pattern and determining the luminance A color headlight tester is provided, comprising: second light intensity determining means for determining the light intensity of the headlight.

  According to one preferred embodiment, the optical system comprises a main lens. More preferably, the main lens is a Fresnel lens. In one preferred embodiment, the measuring color camera includes a color image sensor having a predetermined number of pixels, and RGB data for each pixel of the color image sensor is output. Preferably, the color image sensor is a single-plate type, and its RGB color filter has a so-called Bayer array, and the color camera for measurement performs interpolation processing to calculate each RGB data for each pixel. Output. In another preferred embodiment, the color image sensor is multi-plate and the measuring color camera outputs RGB data directly from each pixel. In one embodiment, the color image sensor is a CCD color image sensor.

  According to one preferred embodiment, the luminance is determined as the Y coordinate in the XYZ coordinate system defined by the tristimulus values X, Y, Z in the CIE XYZ color system, ie Y = r × R + g × G + b × B Here, R, G, B are RGB data output from the color camera for measurement, and r, g, b are coefficients as weightings of the RGB data.

  When determining the rgb coefficients, it is necessary to determine the color space to which it applies. There are several color spaces (so-called color triangles) such as sRGB, adobe RGB, NTSC_RGB in the xy chromaticity diagram, but in one embodiment the NTSC_RGB color space is used.

  The rgb coefficient (also abbreviated as Y coefficient) changes depending on the color temperature (K: Kelvin) of the headlight as the light source. The color temperature is a numerical value representing the color of light, which is different from the light intensity (cd), and the color tone of the light source changes sequentially from yellow to white to blue as the color temperature becomes higher. That is, when the color temperature changes, the spectral distribution of light also changes, and as a result, the rgb coefficient also changes. Therefore, the rgb coefficient used when determining the luminance Y needs to correspond to the color temperature of the headlight. If the color temperature is known (such as measurement with a color temperature meter), it is possible to use the rgb coefficient corresponding to the measured color temperature, but if the color temperature is unknown, the head It is necessary to estimate and approximate the color temperature of the light.

  More preferably, the rgb coefficient is determined by correcting the variation in each pixel of the color image sensor due to the influence of chromatic aberration or the like through the optical system. In general, the variation tends to be noticeable as the color image sensor moves away from near the center of the color image sensor. In one embodiment, the rgb coefficients include at least one reference rgb coefficient determined based on the color temperature of the CIE standard light source and at least one correction rgb coefficient that is a modification of the reference rgb coefficient. ing. In one embodiment, to absorb this variation, the rgb coefficient is determined for each pixel of the color image sensor. In another embodiment, all pixels of the color image sensor are divided into zones of a predetermined number of pixels, and a common rgb coefficient is applied to the pixels in each zone.

  In one embodiment, the second light intensity determination means determines the light intensity based on a predetermined condition between the light intensity of the headlight and the brightness determined by the brightness determination means. In one embodiment, the intensity of the projected light of the reference light source (e.g., a standard headlight or reference sphere) is measured using a reference light source (e.g., a standard headlight or reference sphere) having a known light intensity. Measure and set in advance the relationship between the light intensity and the brightness. The predetermined position from the center of the headlight is, in one embodiment, a so-called road surface illumination point when the headlight is in the low pass mode, and is 1.3 degrees left and 0.6 degrees below the center of the lamp Point (if the headlight height is 1 m or less) or a point of 1.3 degrees on the left and a lower 0.9 degree (if the headlight height exceeds 1 m).

  In one preferred embodiment, a light source type determination unit is further provided to determine an rgb coefficient to be applied according to the determined light source type.

  In one preferred embodiment, the rgb coefficient determination means has a plurality of tables in which rgb coefficients are calculated for predetermined light intensity or color temperature, and the table is selected and used according to the measured or calculated light intensity or color temperature. Determine the rgb factor to be done.

  Preferably, the rgb coefficient determination means, the luminance determination means, and the second light intensity determination means are provided in the image processing apparatus connected to the color camera for measurement in the color headlight tester. In one embodiment, the image processing apparatus comprises a computer system having at least a CPU and a memory, and the rgb coefficient determination means, the luminance determination means, and the second light intensity determination means are the present color headlights. It is stored in the memory as part of a program that controls the operation of the tester.

V. Elbow Point Determination According to still another aspect of the present invention, an optical system for receiving projection light from a headlight, a screen on which a light distribution pattern of the projection light is projected through the optical system, the screen on the screen A color camera for measuring a light distribution pattern; rgb coefficient determining means for determining an rgb coefficient for each of a plurality of selected pixels of the color camera for measurement; RGB data received from the color camera for measurement; luminance determination means for applying the rgb coefficient to the corresponding pixel determined by the rgb coefficient determination means to determine the luminance for the corresponding pixel, at least one horizontal cut line comparing the luminances for the plurality of pixels with each other And at least one oblique cut line having a predetermined angle with respect to the horizontal cut line, and A color headlight tester is provided having elbow point determination means for determining an elbow point as an intersection point.

  According to one preferred embodiment, the optical system comprises a main lens. More preferably, the main lens is a Fresnel lens. In one preferred embodiment, the measuring color camera includes a color image sensor having a predetermined number of pixels, and RGB data for each pixel of the color image sensor is output. Preferably, the color image sensor is a single-plate type, and its RGB color filter has a so-called Bayer array, and the color camera for measurement performs interpolation processing to calculate each RGB data for each pixel. Output. In another preferred embodiment, the color image sensor is multi-plate and the measuring color camera outputs RGB data directly from each pixel. In one embodiment, the color image sensor is a CCD color image sensor.

  According to one preferred embodiment, the luminance is determined as the Y coordinate in the XYZ coordinate system defined by the tristimulus values X, Y, Z in the CIE XYZ color system, ie Y = r × R + g × G + b × B Here, R, G, B are RGB data output from the color camera for measurement, and r, g, b are coefficients as weightings of the RGB data.

  When determining the rgb coefficients, it is necessary to determine the color space to which it applies. There are several color spaces (so-called color triangles) such as sRGB, adobe RGB, NTSC_RGB in the xy chromaticity diagram, but in one embodiment the NTSC_RGB color space is used.

  The rgb coefficient (also abbreviated as Y coefficient) changes depending on the color temperature (K: Kelvin) of the headlight as the light source. The color temperature is a numerical value representing the color of light, which is different from the light intensity (cd), and the color tone of the light source changes sequentially from yellow to white to blue as the color temperature becomes higher. That is, when the color temperature changes, the spectral distribution of light also changes, and as a result, the rgb coefficient also changes. Therefore, the rgb coefficient used when determining the luminance Y needs to correspond to the color temperature of the headlight. If the color temperature is known (such as measurement with a color temperature meter), it is possible to use the rgb coefficient corresponding to the measured color temperature, but if the color temperature is unknown, the head It is necessary to estimate and approximate the color temperature of the light.

  More preferably, the rgb coefficient is determined by correcting the variation in each pixel of the color image sensor due to the influence of chromatic aberration or the like through the optical system. In general, the variation tends to be noticeable as the color image sensor moves away from near the center of the color image sensor. In one embodiment, the rgb coefficients include at least one reference rgb coefficient determined based on the color temperature of the CIE standard light source and at least one correction rgb coefficient that is a modification of the reference rgb coefficient. ing. In one embodiment, to absorb this variation, the rgb coefficient is determined for each pixel of the color image sensor. In another embodiment, all pixels of the color image sensor are divided into zones of a predetermined number of pixels, and a common rgb coefficient is applied to the pixels in each zone.

  In one embodiment, the elbow point determination means comprises an hv position correction table for elbow point correction to selected pixels of the color image sensor, for the horizontal and oblique cut lines or as their intersection point Apply hv position correction to the determined elbow point position. Preferably, the hv position correction data is commonly applied to each zone of the color image sensor. Here, h is position correction data in the horizontal (left and right) direction, and v is position correction data in the vertical (upper and lower) direction.

  In one preferred embodiment, a light source type determination unit is further provided to determine an rgb coefficient to be applied according to the determined light source type.

  In one preferred embodiment, the rgb coefficient determination means has a plurality of tables in which rgb coefficients are calculated for predetermined light intensity or color temperature, and the table is selected and used according to the measured or calculated light intensity or color temperature. Determine the rgb factor to be done.

  Preferably, the rgb coefficient determination means, the luminance determination means, and the elbow point determination means are provided in the image processing apparatus connected to the color camera for measurement in the color headlight tester. In one embodiment, the image processing apparatus comprises a computer system having at least a CPU and a memory, the rgb coefficient determination means, the luminance determination means, and the elbow point determination means is the present color head light tester Stored as part of a program that controls the operation of

  According to the present invention, it is possible to accurately and quickly determine at least one of the light axis (illumination direction), the luminous intensity, and the elbow point position of the headlight by performing color image processing on the projection light of the headlight.

FIG. 1 is a schematic front view of a color headlight tester configured in accordance with one embodiment of the present invention. (A) thru | or (D) is the schematic which respectively showed the example of arrangement | positioning of the optical system in the light-receiving part which comprises a part of color headlight tester of FIG. 1, and some cameras. FIG. 2 is a schematic view showing a configuration for performing data processing in the color headlight tester of FIG. 1; FIG. 7 is a schematic view showing a relationship in which an external screen (10 m screen) at a distance of 10 m from the headlight is reproduced on the internal screen in the light receiving unit of the color headlight tester of FIG. 1. FIG. 2 is a schematic view showing a relationship between an inner screen of the color headlight tester of FIG. 1 and a color camera for measuring a light distribution pattern of the projection light of the headlight received on the inner screen. The schematic which showed the relationship between an external screen (10 m screen), the internal screen of the color headlight tester of FIG. 1, and the image sensor in the color camera for measurement. The table which showed an example of the RGB relative intensity ratio used, when carrying out color image processing of the projection light from a headlight, and determining it as halogen and HID as the light source classification. A table of chromaticity coordinates of white points of various standard illuminants published by CIE described in Wikipedia. A table of the primary color RGB chromaticity coordinates in the NTSC_RGB color space. A table showing rgb coefficients calculated using the chromaticity coordinates of the white point of the CIE standard light source and the chromaticity coordinates of the primary color RGB of the NTSC_RGB color space. The graph which showed an example of the approximation formula of the rgb coefficient in the table | surface of FIG. (A) And (B) is each schematic which showed the position of the highest brightness Y _MAX in the light distribution pattern 33 on a screen. (A) and (B) are each schematic which showed the principle which searches the position of the highest brightness | luminance by a balance system. (A) is a flowchart showing one example of a procedure for searching for the position of the highest luminance by the balance method, (B) shows the processing situation for the light distribution pattern 33 on the screen 19 in each step of the flowchart of (A) Explanatory drawing. The schematic which showed the principle which searches the position of the highest brightness | luminance by the binarization gravity center method. The graph which showed the value of the effective brightness | luminance Y obtained when changing shutter speed (SP) with respect to each setting luminous intensity (hcd) of a reference sphere. (A) shows the shutter speed (SP) in FIG. 16 and the corresponding gradient of the brightness value, and the A coefficient determined for each gradient by fitting the gradient to the approximate expression shown in (B) Shown table. For each shutter speed SP in FIG. 16, the value of the coefficient B corresponding to the coefficient A is determined by the linear expression Y = A × light intensity + B in which the relationship between the brightness Y and the light intensity is defined using the gradient A and the coefficient B Table. Schematic which showed the position of the orientation pattern of a passing light, its cut line and elbow point, and a road surface irradiation point. (A) A schematic diagram showing the scanning state of the pixels of the image sensor for applying the difference method to determine the cut line of the passing light, (B) searching the horizontal cut line by the difference method FIG. 6C is a schematic diagram showing the pixel array used for the (C) is a schematic diagram showing the pixel array used to search diagonal cut lines in a difference-difference system. FIG. 16 is a graph showing RGB data distributions in the horizontal direction (horizontal axis) and the vertical direction (vertical axis) near the center of the lamp when the luminous intensity of the traveling light reference sphere is set to 50, 400 and 1200 hcd, respectively. FIG. 16 is a graph showing RGB data distributions in the horizontal direction (horizontal axis) and the vertical direction (vertical axis) near the center of the lamp when the luminous intensity of the passing lamp reference sphere is set to 50, 100, and 120 hcd, respectively. (A) A plan view of a system for measuring the luminous intensity of the projection light from a reference sphere with a luminometer on a 10 m screen, and (B) is a side view of the system. Explanatory drawing which showed the aspect which measures light intensity using the system of FIG. The schematic which showed the aspect which divided equally the measurement range which consists of 640x480 pixels of an image sensor into the zone which consists of 20x20 pixels. Explanatory drawing of the table which showed the correspondence of a block number and a rgb coefficient. (A) and (B) show the relationship between the luminous intensity (hcd) and the corresponding color temperature (K) when using a reference sphere as a light source, respectively, a correspondence table and a graph of an approximate expression. A measurement range consisting of 640 × 480 pixels of the image sensor is equally divided into a zone consisting of 20 × 20 pixels, an effective range is set within the measurement range, and a light source of 400 hcd in each zone within the effective range Explanatory drawing at the time of allocating the suitable block number with respect to light intensity. FIG. 29 is a correspondence table showing each block number of FIG. 28 and the value of the corresponding rgb coefficient. FIG. 24 is an explanatory view showing an aspect in which longitudinal scanning is sequentially performed at respective lateral positions using the system shown in FIG. 23 to obtain a longitudinal direction point sequence; 6 is a table showing an example (500 hcd) of a balance point position correction correction table showing the correspondence between block numbers and corresponding horizontal (left and right) position correction data h and vertical (vertical) position correction data v; FIG. 14 is a schematic view showing a state in which block numbers for correcting balance point position for a 400 hcd traveling light are assigned to each zone 41 of the image sensor 20 b. FIG. 35 is a correspondence table showing correspondences between block numbers assigned to respective zones 41 of FIG. 32 and horizontal position correction amounts h and vertical position correction amounts v corresponding thereto. In the system shown in FIG. 23, a passing light reference ball is mounted as a reference ball 51 and set at a horizontally selected position, and the position of the elbow point is angularly displaced over a predetermined range in the vertical direction. A graph showing the variation when measured at 10. 34 shows horizontal variation and vertical variation of the measurement position of the elbow point when the selected position in the horizontal direction in the graph of FIG. 34 is set to 10 cm left (10 m screen conversion) and angular displacement is performed in the vertical direction The graph which also shows each approximation formula. (A) to (C) show the correspondence tables between block numbers and horizontal corrections, and correspondences between block numbers and cut line corrections, respectively, for correcting variations in measurement positions of elbow points shown in FIGS. 34 and 35. Table showing correspondence between block numbers and height corrections. Schematic which respectively demonstrates "horizontal correction | amendment" in FIG. 36, "cutline correction | amendment", and "height correction | amendment."

  FIG. 1 shows a schematic front view of a color headlight tester 10 configured in accordance with one embodiment of the present invention. The color headlight tester 10 roughly includes a light receiving unit 11 for receiving light projected from a headlight of a vehicle such as an automobile to be inspected, and a base 12 supporting the light receiving unit 11 so as to be movable vertically and horizontally. And a stand unit 14 erected on the base 12 and a display unit (monitor) 15 disposed on the top of the stand unit 14. A plurality of rolling elements 12 a are provided at the bottom of the base 12, and these rolling elements 12 a are provided on the floor surface 13 and extend in the left and right in FIG. ) It is movable along the top. In the illustrated example, the stand portion 14 is attached with a vertically extending guide rod 14b, and further, a bracket 14c is provided so as to be vertically movable along the guide rod 14b. Also, the bracket 14c is provided so as to be manually rotatable around the guide rod 14b, and can be fixed to the guide rod 14b at a desired rotational position. Since the light receiving unit 11 is mounted on the bracket 14c, the light receiving unit 11 can be controlled to move up and down along the guide rod 14b and around the central axis of the guide rod 14b. A finder (telescope) 11a is attached to the light receiving unit 11, and it is possible to rotate the light receiving unit 11 around the guide rod 14b in order to align with the direction of the headlight to be inspected. Further, a first drive control unit for controlling the vertical movement of the light receiving unit 11 and a second drive control unit for controlling the horizontal movement of the base 12 are provided in the stand unit 14. The stand unit 14 is further provided with a console panel 14a including a plurality of switches, and the operator controls the operation of the color headlight tester 10 by inputting data through the console panel 14a. It is possible. The display unit 15 has an LCD display or the like capable of displaying various inspection states and inspection results.

  In the illustrated example, the data processing device 21 is provided on the light receiving unit 11, and as described later, various circuits for image processing the projection light from the headlight to be inspected received by the light receiving unit 11 Elements are provided in the data processing device 21. Although the data processing device 21 is provided on the light receiving unit 11 in the illustrated example, the data processing device 21 is not necessarily provided on the light receiving unit 11 and a color It can be provided in other places of the headlight tester 10, for example, in the stand part 14, and furthermore, in the case of using a wireless connection, it can also be provided at a distance from the color headlight tester 10. is there. The data processing device 21 only needs to be connected so as to be able to receive data from an imaging device (camera), which will be described later, provided in the light receiving unit 11 by wire or wireless or the like. .

  FIGS. 2A to 2D schematically show some embodiments of the internal configuration of the light receiving unit 11. As is apparent from the embodiment shown in FIG. 2A, the light receiving unit 11 has a function as a housing, and the main lens 17 is provided on the front surface thereof. It is positioned to receive the projection light from the headlight L which should be. That is, when a headlight test is performed, it is necessary to set the distance between the headlight L to be inspected and the main lens 17 to a predetermined test distance D (usually 1 m). Therefore, normally, a vehicle such as an automobile equipped with the headlight L to be inspected is made to travel and the headlight L is positioned in front of the main lens 17 of the color headlight tester 10 at the test distance D. On the other hand, the color headlight tester 10 may be provided so as to be movable in the front-rear direction, and the color headlight tester 10 may be set at a predetermined test distance D with respect to the headlight L to be tested. Of course there is one.

  The main lens 17 is usually a Fresnel lens, and is used to minimize the size of the light receiving unit 11, in particular, the length thereof. That is, although the test of the headlight is originally performed by visually projecting the projection light from the headlight on the external screen (10 m screen) positioned 10 m ahead of the headlight, in the headlight tester Is configured to reproduce the light distribution pattern on the 10 m screen on the screen 19 inside the light receiving unit 11 by using an optical system including a Fresnel lens. The reproduction of this 10 m screen will be described in more detail later. As shown in FIG. 2A, in the light receiving unit 11, a pair of first and second half mirrors 22 and 18 are provided on the optical axis of the main lens 17. Therefore, after passing the projection light from the headlight L through the main lens 17, a part thereof is transmitted by the first half mirror 22 and the remaining part is reflected upward. The transmitted light from the first half mirror 22 is transmitted through the second half mirror 18 to form a light distribution image of the projection light on the measurement screen 19 as an internal screen. As described later, the distance between the measurement screen 19 and the main lens 17 is determined based on the 10 m reproduction described above.

  A measuring camera 20 as an imaging device for measuring a color image is provided vertically above the second half mirror 18, and the measuring camera 20 is projected light on the measuring screen 19 reflected by the second half mirror 18 Capture a light distribution image of The measurement camera 20 is a color camera, and images a light distribution image on the measurement screen 19 as a color image. The measuring camera 20 is connected to a data processing device 21 provided above the light receiving unit 11, and data from the measuring camera 20 is supplied to the data processing device 21. On the other hand, a third mirror 23 is provided vertically above the first half mirror 22 so as to reflect the light reflected from the first half mirror and to input it to the normal-pairing camera 24 as a normal-pairing imaging device. The facing camera 24 may be a color camera, but may also be a monochrome camera. The facing camera 24 is also attached to the light receiving unit 11 and is further connected to the data processing device 21, and data from the facing camera 24 is also supplied to the data processing device 21. It is to be noted that the camera 24 for facing is used to make the color headlight tester 10, more specifically, the center 17a of the main lens 17 of the light receiving unit 11 face the headlight L. The facing camera 24 is disposed in a positional relationship for capturing the image of the headlight L itself, and the arrangement conditions are different from the measuring camera 20 for capturing the light distribution image of the projection light, as described in detail later. ing.

  FIG. 2B shows the configuration of another embodiment of the light receiving unit 11. The configuration of the embodiment of FIG. 2 (B) is basically the same as the configuration of the embodiment of FIG. 2 (A), but from the configuration of the embodiment of FIG. 2 (A), the first half mirror 22 and the third It is the same as that in which the mirror 23 and the facing camera 24 are removed. Therefore, the light receiving unit 11 in FIG. 2B processes only the light distribution image from the headlight L projected on the screen 19, and the light receiving unit 11 does not control the facing function. The facing operation needs to be performed using an element other than the light receiving unit 11.

  FIG. 2C shows the configuration of still another embodiment of the light receiving section 11. In this case, from the configuration of the embodiment of FIG. 2A, the measuring camera 20 and the second half mirror related thereto are shown. 18 and screen 19 are deleted. Therefore, the light receiving unit 11 in FIG. 2C only controls the facing operation to the headlight L by the facing camera 24 and does not image the light distribution pattern of the projection light of the headlight L. FIG. 2D shows the construction of still another embodiment of the light receiving section 11, which is the longitudinal axis of the light receiving section of the camera 24 for the front facing and the third mirror 23 in the construction of the embodiment of FIG. 2C. The arrangement relationship in the direction is inverted. Accordingly, the angular arrangement of the third mirror is also changed to a state in which the reflected light from the first half mirror 22 can be reflected to the facing camera 24. Also in this case, the light receiving unit 11 controls only the facing operation to the headlight L by the facing camera 24.

  FIG. 3 is a block diagram showing the connection between the data processor 21 and the related parts. The data processing device 21 has an image processing device 30 and a control unit 31, and the image processing device 30 receives RGB data as color image data from the measurement camera 20 for capturing a color light distribution image, The imaging data of the headlight L from the companion camera 24 is received. The image processing apparatus 30 is composed of, for example, a computer system including a CPU, a memory and the like, and the memory is processed according to the ROM storing a program for controlling the operation of the color head light tester 10 and the like, It includes a RAM etc. for temporarily storing various data in it. The image processing apparatus 30 is connected to the display unit (monitor) 15, and causes the display unit 15 to display the results processed according to the program and / or various setting conditions and the like. Furthermore, the image processing apparatus 30 is connected to the control unit 31, and the control unit 31 is connected to a console (control unit) 14a including various switches and the like that receive an operator's input. It is connected to an up-and-down, left-right drive and detector 14d which includes a drive for moving up and down, left and right, and a limiter for restricting position control of the light receiving unit 11 in up, down, left, and right directions.

  FIG. 4 shows a relational expression in the case of performing 10 m reproduction in the light receiving unit 11, which is published by the Traffic Safety and Pollution Research Institute (current Traffic Safety and Environment Research Institute). That is, in the headlight test, the projection light is originally irradiated on an external screen (10 m screen) located 10 m in front of the headlight, and visually observed based on the light distribution pattern on the 10 m screen It is supposed to be done. The headlight tester adopts a 10 m reproduction configuration to effectively test such headlights. That is, as shown in FIG. 4, an external screen (10 m screen) is disposed at a position A 10 m in front of the headlight L, and the projection light from the headlight L is irradiated there and the external screen (10 m) The light distribution pattern of the projection light of the headlight L can be visually confirmed on the screen. Therefore, when the headlight tester performs 10 m reproduction, the main lens 17 of the light receiving unit 11 is disposed 1 m ahead of the headlight L, and the headlight is incident on the main lens 17 by the focal distance f of the main lens 17 A light distribution pattern of the projection light is projected on the internal screen 19 disposed at a position B at a distance x from the main lens 17. At this time, the size a on the outer screen (10 m screen) A becomes the size y on the inner screen B. By appropriately selecting the focal length of the main lens 17 in this manner, it is possible to appropriately determine the distance x between the main lens 17 and the inner screen 19 at the position B. That is, it becomes possible to arrange the main lens 17 and the internal screen 19 in the light receiving section 11, and it becomes possible to realize 10 m reproduction in the headlight tester.

  Referring also to FIG. 5 with reference to FIG. 4, the measuring camera 20 captures a color light distribution pattern of the projection light from the headlight L projected on the internal screen 19 at the position B in the light receiving unit 11. It is a thing. The measuring camera 20 has a lens 20 a and a semiconductor image sensor 20 b, and the lens 20 a is located at a distance z (work distance) from the internal screen 19. Therefore, the light distribution pattern of the projection light on the internal screen 19 is imaged on the semiconductor image sensor 20b through the lens 20a, whereby the color distribution image on the internal screen 19 is measured by the measuring camera 20. It is possible to image. As the semiconductor image sensor 20b, a CCD or a CMOS can be used.

  The relationship between FIG. 4 and FIG. 5 is summarized in FIG. That is, as shown in FIG. 6, the large 10 m screen 25 originally scheduled in the headlight test is reproduced on the small internal screen 19 in the light receiving unit 11 by the focal length f of the main lens 17. The color light distribution image on the inner screen 19 is imaged on the semiconductor image sensor 20 b through the lens 20 a of the measuring camera 20. Here, x is a 10 m correlation distance (the distance between the main lens 17 and the inner screen 19), and z is a working distance between the inner screen 19 and the measuring camera 20 or its image sensor 20b.

  The semiconductor image sensor 20b in the measuring camera 20 is preferably composed of a CCD, and has a two-dimensional array of a plurality of pixels, as is well known. The image sensor 20b may be a single-plate type or multi-plate type, and in the case of the single-plate type, R (red) which is three primary colors on each of a plurality of pixels arranged in the shape of a two-dimensional matrix. , G (green) and B (blue) are disposed. Although the arrangement of the color filters in this case is generally a so-called Bayer arrangement, the present invention should not be limited to only such a specific arrangement. In the case of such an array of color filters, charges corresponding to the amount of light of color components according to the corresponding filters are only obtained as pixel data from each pixel. Therefore, in the measuring camera 20, after A / D conversion of the obtained pixel data, color interpolation processing is performed based on data of a predetermined number of peripheral pixels, and the remaining two other pixels missing in each pixel Generate data of primary color components. When the single-plate type is used as the semiconductor image sensor 20b in this way, the measurement camera 20 performs digital interpolation processing as described above to obtain digital RGB data (levels 0 to 255) for each pixel. Digital data or analog data) within the range of On the other hand, when the semiconductor image sensor 20b is a multi-plate type, each data of RGB is obtained directly from each pixel, so the measuring camera 20 performs A / D conversion of each RGB data and then RGB data. It outputs as (digital data or analog data whose level is in the range of 0 to 255).

  In one embodiment, as the image sensor 20b, a CCD image sensor having a measurement area consisting of pixels of a two-dimensional array of 640 (horizontal) × 480 (vertical) is used.

  Next, a configuration for automatically performing the light source type determination of the headlight by performing color image processing based on the present invention will be described with reference to FIG. 7 in particular. FIG. 7 summarizes the results of measuring the relative intensity ratio of RGB for a large number of halogen lamps and HID lamps obtained as a result of intensive research conducted by the present inventors. If this result is plotted, for example, G / R on the horizontal axis and | G-R | on the vertical axis, it is clear that the regions of the halogen lamp and the HID lamp are clearly distinguished. Therefore, if the relative intensity ratio of RGB shown in FIG. 7 is stored in the image processing apparatus 30 in the form of a table or the like, whether the headlight L to be inspected is a halogen lamp (warm color lamp), The color headlight tester 10 can automatically determine whether the lamp is an HID lamp (cold color lamp).

  When the conditions shown in FIG. 7 are stored as a table in the memory of the image processing apparatus 30, many forms can be taken, and at least the following three examples of tables can be configured. It is.

(1) When only G / R is used as a parameter 0.0 ≦ G / R ≦ 1.19 → Halogen lamp 1.20 ≦ G / R ≦ 1.79 → HID lamp (2) | In case of parameter 1.0 ≦ | G−R | <30 → Halogen lamp 30 ≦ | G−R | ≦ 80 → in case of using both HID lamp (3) G / R and | G−R | 0.0 ≦ G / R ≦ 1.19 and 1.0 ≦ | GR 1 <30 → halogen lamp 1.20 ≦ G / R ≦ 1.79 and 1.0 ≦ | GR 1 ≦ 80 → HID Lamp In the color headlight tester 10, the operation of determining the type of the headlight L to be inspected will be described. First, the projection light from the headlight L to be inspected is projected on the internal screen 19 of the light receiving unit 11. . The light distribution pattern on the internal screen 19 is imaged on the image sensor 20b of the measurement camera 20, and RGB data is generated from the measurement camera 20 according to the light distribution pattern for each pixel of the image sensor 20b. Then, the highest luminance value Y in the light distribution pattern is extracted, and it is ensured that the highest luminance value Y falls within a predetermined range (for example, a range of 195 or more and 220 or less).

  The relationship between the luminance value and the RGB data for each pixel is expressed by the following equation.

Y = r × R + g × G + b × B
Note that RGB is each digital data (0 to 255) of RGB of each pixel, and rgb is a coefficient as a weighting of RGB (the rgb coefficients are collectively referred to as Y coefficient).

  In one embodiment, the measuring camera 20 has the following rgb coefficient values at a color temperature of 3170 K as a default value.

r = 0.4111
g = 0.5461
b = 0.0428
Therefore, it is possible to calculate the luminance value Y of each pixel using these rgb coefficient values and RGB data. And in that case, to ensure that the extracted maximum luminance value Y falls within the predetermined range, the measurement camera 20 can adjust the shutter speed, and the shutter speed is appropriately adjusted. To set the value to That is, when the shutter speed is first set to the lower limit value, the RGB data from many pixels becomes the saturated value (255), so the shutter speed is sequentially increased so that the RGB data from each pixel becomes 255 or less. In this case, the process is initially rough, that is, the process is performed while skipping a predetermined number of pixels, and the process is performed more finely as the target value is approached. Then, it is ensured that the extracted maximum luminance value Y falls within the predetermined range.

  It is possible to calculate the relative intensity ratio such as G / R and | G−R | based on the RGB data in the pixel corresponding to the highest luminance value Y extracted by the above processing. In another embodiment, calculating the relative intensity ratio based on a predetermined number of pixels (for example, 10 × 10 pixels) around the pixel corresponding to the highest luminance value Y extracted in this manner. Is also possible.

  Furthermore, as described above, when calculating the luminance value Y of each pixel, it is possible to calculate using RGB data of each pixel, but in another embodiment, it is calculated as such. Based on the luminance value Y of each pixel, it is also possible to replace the average value of the peripheral pixels (for example, 3 × 3 pixels) with each luminance value Y as the luminance value Y of the central pixel.

  Based on the relative intensity ratio calculated as described above, it is automatically determined whether the headlight L under test is a halogen lamp (warm color lamp) or a HID lamp (cold color system lamp) It is possible to

  By the way, in the embodiment described above, two parameters of G / R and | G-R | are used as parameters of the headlight light source type determination, but three data of RGB from the measurement camera 20 Is selected, any two of these three RGB data may be selected to configure parameters such as a ratio and / or a difference to be used as parameters for determining the type of headlight light source. Of course it is possible. Furthermore, although the halogen lamp and the HID lamp are adopted as the light source type in the embodiment described above, the LED lamp is also available as the other light source, so the present invention can be applied to the LED lamp as well. Of course there is one. Furthermore, the color temperature of the headlight L when it is a halogen lamp is said to be about 2500-4000 K, while the color temperature when it is a HID lamp is said to be about 4000-6000, so the color of the headlight L It is also possible to determine the type of these light sources by measuring the temperature.

Next, based on another aspect of the present invention, measurement of an optical axis, luminous intensity, or elbow point by the color headlight tester will be described. In any measurement, first, the light distribution pattern of the projection light from the headlight L is imaged by the measurement camera 20 which is a color imaging device for measurement of the color headlight tester 10, and the light distribution pattern is taken according to the light distribution pattern. It is necessary for the measurement camera 20 to supply RGB data for each pixel to the image processing apparatus 30 and calculate the luminance Y. In one embodiment, the measuring camera supplies RGB data to the image processor 30 as digital values from 0-255. In another embodiment, when the RGB data output from the measuring camera is an analog value, the image processing device 30 has 256 gradations (8 bits) of 0 (minimum luminance) 255 in the analog RGB data. Convert to (maximum brightness) digital RGB data. Then, the image processing device 30 processes the digital RGB data to calculate the luminance Y for each pixel of the color image sensor 20 b of the measuring camera 20. In this case, the luminance Y corresponds to the Y coordinate in XYZ coordinates defined by tristimulus values X, Y, Z in the CIE · XYZ color system, and in the present specification,
Y = r × R + g × G + b × B (1)
Shall be defined by The respective coefficients of r, g and b are Y values in the case where R, G and B each have an intensity of 100%, that is, a value of 1.

  Therefore, in order to calculate the luminance Y, the values of the coefficients r, g and b as the respective weightings of the RGB data must be determined. In order to determine the values of these coefficients r, g, b, it is necessary to derive a conversion equation from RGB to XYZ.

  Here, it is assumed that the conversion equation from RGB to XYZ is represented by the following equation.

  This transformation matrix M is set as follows.

Here, x _R , y _R , z _R are the chromaticity coordinates of the primary color R (such as x _R = X _R / (X _R + Y _R + Z _R )), x _G , y _G , z _G are the primary colors G The chromaticity coordinates x _B , y _B and z _B are the chromaticity coordinates of the primary color B, and C _R , C _G and C _B are undetermined constants.

Then, RGB values are normalized to [0,1] and white _{X W,} Y _W, When represented by _{Z W} above equation (2) becomes the following as.

Since white Y _W = 1 and X _W = x _W Y _W / y _W = x _W / y _W and Z _W = z _W Y _W / y _W = z _W / y _W , the above equation ( 4) becomes the following three simultaneous equations.

x _W / y _W = C _R x _R + C _G x _G + C _B x _B
1 = C _B y _R + C _G y _G + C _B y _B (5)
z _W / y _W = C _R z _R + C _G z _G + C _B z _B
In the three simultaneous equations of equation (5), the chromaticity coordinates (x _R , y _R , x _G , y _G , x _B ) of the primary color RGB are specified by specifying the RGB color space (for example, sRGB, adobe RGB, NTSC_RGB, etc.) , Y _B ) are determined (by definition, z _R = 1-(x _R + y _R ), z _G = 1-(x _G + y _G ), z _B = 1-(x _B + y _B )) Furthermore, by specifying the light source, the chromaticity coordinates (x _w , y _w ) of the white point are specified (though, by definition, z _w = 1- (x _w + y _w )), It is possible to solve for indefinite constants C _R , C _G , C _B.

And from the above equation (3), Y is
Y = C _R y _R x R + C _G y _G x G + C _B y _B x B (6)
Therefore, the coefficients r, g, b in the definition equation (1) of the luminance Y described above are determined as follows.

r = C _R y _R , g = C _G y _G , b = C _B y _B (7)
As described above, the chromaticity coordinates of the primary color RGB are identified by specifying the RGB color space (for example, sRGB, adobe RGB, NTSC_RGB, etc.), and the chromaticity coordinates of the white point are specified by specifying the light source. The r, g and b coefficients in the definition equation (1) of the luminance Y are specified.

On the other hand, as shown in FIG. 8, the CIE (International Commission on Illumination) defines a large number of standard light sources as standard illuminants (A, B, C, D, E, F, etc.). A white point (white point) is defined as chromaticity coordinates (x, y). In FIG. 8, those of 2 ° visual field defined in 1931 and those of 10 ° visual field defined in 1964 are described for these white points. In the following example, the chromaticity coordinates (x ₂ , y ₂ ) of the 2 ° field of view white point specified in 1931 are used. Furthermore, in the following embodiment, assuming that NTSC_RGB is specified as the RGB color space, the chromaticity coordinates of each of the primary colors R, G and B in the NTSC_RGB color space have the values shown in FIG.

  Therefore, the x and y chromaticity coordinates of the NTSC_RGB color space shown in FIG. 9 and the x and y chromaticity coordinates of the respective white points of the respective standard light sources A to F12 shown in FIG. 8 are used. The r, g, b coefficients for each standard light source are calculated as shown in the table of FIG. In the table of FIG. 10, the color temperature (K) for each standard light source is also described, but this is a copy of CCT (K) in the table of FIG. 8, that is, the correlated color temperature. In the present specification, the correlated color temperature will be described conceptually as simply the color temperature.

  Since the table in FIG. 10 shows that the r, g, b coefficients change as a function of color temperature (K), it is possible to fit an approximation equation and use a quadratic equation An example of the case is shown in FIG. Such an approximate expression is not limited to the quadratic expression shown in FIG. 11 but may be a polynomial or linear expression of a higher order, or may be fitted with another appropriate type of approximate expression. Of course it is possible. In one embodiment, the color temperature is changed using such an approximation to determine the values of the r, g, and b coefficients, and the relationship between the color temperature and the rgb coefficient is used as a table in the image processing apparatus 30. It is possible to store. From the above results, if the color temperature of the light source is known, it is possible to specify the rgb coefficient corresponding to the color temperature, and based on digital RGB data obtained by image processing the projection light from the light source It is possible to determine the luminance Y for each pixel according to the above equation (1).

  Therefore, in the present color headlight tester 10 shown in FIG. 1, an apparatus capable of measuring the color temperature of the projection light from the headlight L as a light source to be measured is provided to process the measured color temperature If it is possible to supply directly to the device 30, it is possible to determine the values of the r, g, b coefficients directly on the basis of the color temperature so measured. Or, as another example, the color temperature measurement of the projection light from the headlight L to be measured by the operator using an apparatus capable of measuring the color temperature of a separate body is measured. It is also possible for the operator to input via the operation unit 14a. In this case, additional labor is required for the operator to separately measure and input the color temperature, but without using a configuration in which the color temperature measuring device is mounted on the color headlight tester 10, it is popularized It has the advantage of being able to be addressed using a color temperature meter. On the other hand, if the color temperature measured by the color temperature measuring device is not used, the color temperature is first estimated and processed, and then it is ensured that the estimated color temperature is within the required tolerance. It is necessary to take measures.

  As described above, since the brightness Y is calculated for each pixel of the color image sensor 20b of the measurement camera 20, the light of the headlight L is found by finding the highest brightness among these calculated brightness Y. The axis (irradiation direction) can be determined, and then the luminous intensity (hcd) corresponding to its maximum intensity can be determined. On the other hand, it is also possible to use these calculated luminances Y to determine the luminous intensity at so-called road surface illumination points which are at predetermined positions in the light distribution pattern. It is also possible to search for horizontal cut lines and diagonal cut lines in the light distribution pattern by comparing these calculated luminances Y with each other, and to determine the position of the elbow point as the intersection of those cut lines. is there. Each of these processes will be described in detail below.

1. Determination of the optical axis (irradiation direction) of the traveling light As described above, if the color temperature of the headlight L as a light source is known, it is possible to determine the corresponding rgb coefficient by the rgb coefficient determination means. The brightness Y for Y can be calculated by the brightness determination means. As a result, in the memory of the image processing device 30, the calculated luminance Y for each pixel is temporarily stored, for example, in the RAM. The rgb coefficient determination means and the luminance determination means are stored in the image processing apparatus 30 of the headlight tester 10 as part of an image processing program, for example, in a ROM. The image processing program further includes, as a part thereof, an optical axis determination means, the optical axis determination means having the highest luminance Y of each pixel temporarily stored in the RAM. The brightness of the maximum) is found, and the position of the maximum brightness in the vertical and horizontal directions is determined as the optical axis (irradiation direction) of the projection light from the headlight L.

When the optical axis determination means finds the highest luminance Y _MAX , a plurality of luminances Y temporarily stored in the RAM are scanned in a predetermined direction, for example, between adjacent pairs of pixels. It is possible to do things such as ones with higher luminance Y to survive sequentially, etc. It is also possible to apply any known algorithm for finding other maxima. FIG. 12A schematically shows the light distribution pattern 33 projected on the measurement screen 19 in the light receiving unit 11 as a plurality of equal-intensity ellipses, and the measurement camera 20 captures an image of the light distribution pattern 33. Then, the RGB data is output, and the image processing device 30 processes these RGB data in accordance with the image processing program. In the light distribution pattern 33 of FIG. 12A, the maximum luminance Y _MAX exists substantially at the center thereof, and it is possible to determine the position where the maximum luminance Y _MAX exists as the optical axis (illumination direction). On the other hand, FIG. 12B shows that a plurality of maximum luminances Y _MAX exist near the center of the light distribution pattern 33, or the maximum luminance Y _MAX is one, but it is constantly fluctuating in position near the center The case is shown. In the case as shown in FIG. 12B, for example, it is possible to determine a position obtained by averaging the positions of the plurality of maximum luminous intensities Y _MAX as an optical axis (irradiation direction).

FIG. 13 shows the principle of the balance method, which is another approach for determining the position of the maximum luminance Y _MAX of the light distribution pattern 33 of the traveling light. The embodiment shown in FIG. 13 is a case where the 3 times 30 minutes system is applied as the balance system. By the way, as the light distribution pattern 33 of FIG. 12 shows, the luminance distribution of the light distribution pattern 33 of the traveling light changes almost gently in the vertical and horizontal directions. Therefore, according to the balance method, as shown in FIG. 13A, the center of each position where the luminances of two points separated by 3 degrees to the left and right are the same Y _H is taken as the center O _H of the left and right and brightness of two points spaced increments 30 minutes to the center position of each is the same Y _V and the upper and lower center O _V on. Then, the luminance at the center position determined by the center O _H of the left and right and above and below the center O _V and the maximum brightness Y _MAX.

Next, with reference to FIG. 14, a specific procedure in the case where the 3 degrees and 30 minutes method is applied as the balance method will be described in detail. FIG. 14A shows a flowchart 35 of the balance method, and FIG. 14B shows a light distribution pattern 33 on the measurement screen 19 in the step corresponding to the flowchart 35. That is, in the flowchart 35 of FIG. 14A, when the balance point measurement procedure is started, the position of the maximum luminance Y _MAX of the light distribution pattern 33 is extracted and the position is extracted in step 35a of FIG. 14A and step 36a of FIG. Set as the position of interest. Next, in step 35b of FIG. 14A and steps 36b1 to 36b2 of FIG. 14B, the respective luminances Y at positions of 3 degrees left and right from the current position of interest are compared (step 36b1), and the luminances Y at these left and right positions are balanced. The current position is updated as the left and right current target positions (step 36b2). Next, in step 35c of FIG. 14A and step 36c1 to 36c2 of FIG. 14B, the respective luminances Y at positions 30 minutes above and below the updated current position of interest are compared (step 36c1). The position where the luminance Y balances is updated as a new upper and lower attention position (step 36c2). Next, in step 35d, 1 is added to the count which is the number of repetitions, and then, in step 35e, it is determined whether the count exceeds a predetermined maximum number of repetitions (for example, 50). In this case, the process returns to step 35b again to continue the balance process. On the other hand, if the count exceeds the predetermined repetition maximum number, the process proceeds to step 35f, and the current target position in the updated horizontal and vertical directions is the optical axis of the projection light of the headlight L (irradiation direction) Decide as. Furthermore, in another embodiment, the process is repeatedly terminated when the difference between the updated focused position and the focused position before updating falls within a predetermined allowable range.

FIG. 15 shows another method of extracting the maximum luminance Y _MAX , which is a binarized centroid method. According to the binarization centroid method, as shown in FIG. 15, there is a certain value with respect to the luminance Y (0 to 255) for each pixel obtained for the light distribution pattern 33 on the measurement screen 19. The threshold luminance Y _T is set to perform binarization processing to cut out only the luminance higher than Y _T. In this case, as one example, as shown in FIG. 15, Y _T is set to Y _T (= 127) which is 50% of Y _MAX (= 255), and only the luminance higher than that is cut out . By the way, when 50% binarization is performed, the left and right pixel positions 33d1 for obtaining balance in each of the left and right direction in the balance method in which the 50% of the boundary 33a applies the 3 degrees and 30 minutes method. , 33 d 2 will almost match. Next, the first moment of area is calculated with respect to the sectional figure of the cut-off boundary 33a, and the position of the center of gravity 33b 'as the center of the figure is determined. In the example of FIG. 15, the cross section of the luminance level in the vertical direction is assumed to be symmetrical with respect to the horizontal axis H, so the position of the center of gravity 33b 'is on the horizontal axis H. If the cross section of the luminance level in the vertical direction is not symmetrical with respect to the horizontal axis H, the moment of the first cross section is calculated for the cross sectional figure of the boundary 33a also in the vertical direction V to determine the position of the gravity center 33b 'in the vertical direction. It is necessary to. In the illustrated example of FIG. 15, the position 33b of the determined center of gravity 33b 'is slightly shifted to the left compared to the position 33e of the true maximum luminance Y _MAX , but each of the left and right 3 degrees by the balance method As compared with the position 33c determined as the center of the light intensity, it is closer to the position 33e of the true maximum luminous intensity Y _MAX . This is because, when the light distribution pattern 33 as shown in FIG. 15 is asymmetrical in the left-right direction, the binarized center of gravity method is closer to the true maximum light intensity Y _MAX position than the balance method. It indicates that the position can be obtained.

2. Determination of Light Intensity of Running Light Next, a procedure for determining the light intensity of the headlight L from the maximum brightness Y _MAX determined as described above will be described. In addition, although candelas (cd) are generally used as a unit of the luminosity of headlight L, in the headlight tester industry, the hectode candelas (hcd) (ie, 1 hcd = which multiplied it 100 times). Since it is usual to use 100 cd) as a unit of luminous intensity, also in this specification, unless otherwise noted, hcd or HCD is used as a unit of luminous intensity of the headlight.

  By the way, the luminance Y is merely a dimensionless numerical value obtained by the image processing device 30 performing color image processing on RGB data obtained from the projection light of the headlight L, and it is usually between the luminance and the light intensity. Since there is no special relationship with H, when determining the light intensity (hcd) from the brightness Y, the brightness and the light intensity must be related in some way. In one embodiment of the present invention, the relationship between the light intensity and the brightness is established in advance using a reference light source (for example, a standard headlight or a reference sphere) whose light intensity is known. It will be described in detail below. In the industry, there are reference balls used to calibrate or test headlight testers. A reference ball is a lamp manufactured by the general association of Japan Automotive Machinery and Tools Association with a request from a lamp manufacturer for reference conformity test, and in particular, a high precision manufactured for testing the headlight tester itself. It is a lamp of The reference sphere is a glass lamp, the light distribution is a lens cut, the light source is a halogen lamp, and there are two types, one for traveling lights and one for passing lights. The reference sphere can generate a luminous intensity in the range of 50 to 12,000 hcd to be checked according to the regulations.

  FIG. 16 uses such a reference sphere, receives the projection light from the reference sphere by the color image sensor 20b of the measurement camera 20, and sends RGB data from the measurement camera 20 to the image processing device 30, A part of the result of outputting the luminance Y from the image processing device 30 is shown. As shown in FIG. 16, the reference sphere used changes its luminous intensity (hcd) from 10 to 1250 first, every 5 hcd and then every 10 hcd. The measurement camera 20 can change its shutter speed (SP), and here it is changed between SP = 0-64. As shown in FIG. 16, as the light intensity of the reference sphere increases, when the shutter speed SP is slow, the brightness Y is 255, which indicates that the brightness is equal to or higher than the maximum brightness (that is, an overflow state). As the shutter speed SP is increased, an effective luminance value starts to be obtained. In this example, the luminance values below the threshold are cut to 0 in order to avoid setting a certain threshold to calculate the luminance value more than necessary. In FIG. 16, numerical values enclosed by squares are effective luminances Y obtained at each shutter speed SP with respect to the set luminous intensity (hcd) of the reference sphere. The table shown in the lower part of FIG. 16 is an enlarged part of the upper table.

  As apparent from the lower table of FIG. 16, the luminance Y obtained for each shutter speed SP increases as the light intensity hcd of the reference sphere increases. Therefore, the values of luminance Y shown in FIG. 16 represent the slopes for each shutter speed SP, and it is possible to calculate the slope defined by the values of these luminances Y for each shutter speed SP It is. FIG. 17A is a table showing the values of the gradient calculated for the range of shutter speeds SP = 0 to SP = 34 shown in the enlarged display portion shown in the lower part of FIG. . Next, values of these gradients are regarded as a function of the shutter speed SP to obtain an approximate expression, which is shown in FIG. Although the approximate expression shown in FIG. 17B is an example exponential function, it is of course possible to fit any other appropriate type of function. The value calculated for each shutter speed SP from the approximate expression obtained in this manner is shown in the table of FIG. 17A as a coefficient A. The coefficient A can be said to be a smoothed gradient.

  Next, FIG. 18 is a copy of a part of the enlarged table in the lower part of FIG. 16 (a range from 0 to 10 for the shutter speed SP and from 10 to 60 for the luminous intensity hcd of the reference sphere). The shutter speed SP shown to FIG. 17 (A) has shown the value of the coefficient A obtained with respect to 0-10. By the way, in the table of FIG. 18, the coefficient A represents the slope for each shutter speed SP, and further, for each shutter speed SP, the value of the luminance defining the slope is shown over the corresponding light intensity hcd There is. Therefore, the relationship between the brightness and the light intensity at each shutter speed SP can be approximated by a linear equation using the corresponding gradient (coefficient A) as in the following equation.

Y = A × light intensity + B (8)
Therefore, for each shutter speed SP, for example, the effective maximum luminance value shown in the table of FIG. 18 (for example, “242” in the case of SP = 1) is used as an example. It is possible to calculate the coefficient B of the first order approximation. The values of the B factor so calculated are shown in the table of FIG.

  From the above, if the shutter speed SP of the measuring camera 20 when the luminance Y is obtained is known, the corresponding A coefficient and B coefficient can be obtained from the table of FIG. For the luminance Y thus obtained, it is possible to calculate the corresponding luminous intensity hcd according to the following equation.

Intensity = (Y-B) / A (9)
As described above, it is possible to determine the luminous intensity (hcd) as the traveling light of the headlight L corresponding to the maximum luminance Y _MAX of the traveling light. Note that the aspect of establishing the relationship between the luminance and the light intensity is not limited to the above-described embodiment, and it is needless to say that the association can be appropriately performed by other methods.

3. Determining the Light Intensity of the Passing Light As described above, if the headlight L is a traveling light, calculate the luminance Y for each of the selected pixels using RGB data obtained from the measuring camera 20, then It was necessary to search for the highest luminance Y _MAX among those luminances Y and to convert the highest luminance Y _MAX into a luminous intensity (hcd). On the other hand, in the case of a passing lamp, the position at which the light intensity should be measured is determined in advance as a "road surface irradiation point" by a rule (the Road Transportation Vehicle Act etc.). That is, as shown in FIG. 19, the road surface illumination point 36 where the luminous intensity of the passing light is to be measured is 1.3 degrees leftward from the vertical line V passing through the center of the headlight L and below the horizontal line H passing through the center The point 36a is 0.6 degrees (the height of the headlight L is 1 m or less) or the point 36b is 0.9 degrees (the height of the headlight L is more than 1 m). Vertical lines V and horizontal lines H in FIG. 19 indicate vertical lines and horizontal lines 10 m ahead of the centers of the left and right headlights L on the central axis extension of the vehicle. These angles represent angles when projected 10 m forward of the headlight L. Cut lines 37 (horizontal cut lines 37 a and oblique cut lines 37 b) and elbow points 38 exist in the light distribution pattern 33 of the passing light shown in FIG. 19.

  Thus, in the measurement of the luminous intensity of the passing light, since the position to be measured is defined in an invariable manner, the light distribution pattern 33 of FIG. 19 is imaged by the measuring camera 20, and the RGB data is processed by the image processing device 30. When supplied to the road surface, it is possible to determine the light intensity (hcd) of the headlight L from the brightness Y of the pixel corresponding to the position of the road surface illumination point 36 using the above-mentioned equation (9).

4. Detection of Elbow Point of Passing Light As described above, since the luminance Y is calculated for each pixel of the color image sensor 20b of the measuring camera 20, as shown in FIG. 19, these calculated luminances It is possible to search the horizontal cut line 37a and the oblique cut line 37b in the light distribution pattern 33 by comparing Y with each other, and determine the position of the elbow point 38 as the intersection point of these cut lines. In one embodiment of the present invention, the cut line is extracted using the difference method, and the principle of the difference method will be described below with reference to FIGS. 20 (A) to (C).

  FIG. 20A shows a light distribution pattern 33 of projection light from the headlight L as a passing light imaged on the CCD color image sensor 20b. A light distribution pattern 33 schematically shown by a plurality of equal light intensity lines is a bright part, and a horizontal cut line 37 a is shown on the upper right side of the light distribution pattern 33, and the upper left side of the light distribution pattern 33. The diagonal cut line 37b is shown in FIG. An intersection of the horizontal cut line 37 a and the oblique cut line 37 b constitutes an elbow point 38. The cut line 37 is a light and dark branch line which forms a boundary between the bright part of the light distribution pattern 33 on the lower side thereof and the dark part on the upper side thereof. The right side of FIG. 20A shows a cross section of the luminance (light intensity) distribution of the light distribution pattern 33 including the cut line 37, and the cut line 37 is steep from the bright light distribution pattern 33 to the dark part Within the gradient part, it exists at the maximum brightness gradient point of the brightness gradient line. The difference-difference method is, in principle, a technique for finding the maximum luminance gradient point of this luminance gradient line by image processing.

That is, FIG. 20 (B) are mutually predetermined distance apart from the three that have been provided and vertically arranged is (0.44 ° pitch in the illustrated example) measurement points e ₁ to e ₃ is shown. Each measurement point corresponds to each pixel of the image sensor 20b. Assuming that the luminance values at the respective measurement points e ₁ , e ₂ and e ₃ are Y ₁ , Y ₂ and Y ₃ respectively, in the difference method,
_{(Y 1 + Y 3) -2Y} 2 = 0 (10)
It is determined that the position of the measurement point e2 that satisfies the condition of ( _{1) is} the position of the cut line 37. The equation of the difference system of this difference can be rewritten as Y ₁ -Y ₂ = Y ₂ -Y ₃ , which is the maximum gradient constituting the inflection point in the luminance gradient line in FIG. It means that it is a point. When measurement points are arranged at a pitch of 0.44 ° as shown in the example shown, the horizontal cut line is moved by sequentially moving downward about every 0.1 ° across the pixels 40 of the image sensor 20b to perform a vertical scan 39a. It is possible to find out the position of 37a. Then, when scanning for one pixel row is completed, vertical scanning 39a is similarly performed for another pixel row with a predetermined distance shift in the horizontal direction to determine the position of the horizontal cut line 37a in that pixel row, and so on. It is possible to determine the position of the horizontal cut line 37a by performing all the scans over a preset range. That is, the horizontal cut line 37a as a point sequence by connecting multiple points locates the point of their measurement point e ₂ that satisfy the equation of the difference method of the difference by repeating the vertical scan 39a.

On the other hand, in order to find the oblique cut line 37b, as shown in FIG. 20C, these three measurement points e _{1 to} e ₃ are arranged mutually offset in the horizontal direction. In the case of the illustrated example, the four pixels are disposed at the lower side and shifted to the left by one pixel, but it is fundamental that the oblique cut line 37b is inclined 15 degrees with respect to the horizontal cut line 37a. It is an arrangement that takes into account the In this case, the scan direction is the oblique scan 39b, and scanning is performed in a direction substantially orthogonal to the oblique cut line 37b. Also in the case of the oblique scan 39b, the equation of the difference system between the _three measurement points e _{1 to} e ₃ is applied, and the position of the pixel 40 at which the equation of the difference system is satisfied is oblique scan It determines as the position of the diagonal cut line 37b in 39b.

  As described above, when the horizontal cut line 37a and the oblique cut line 37b are determined, it is possible to find the intersection of these cut lines, and such an intersection can be determined as the elbow point 38. It is.

  In the embodiment described above, the pitch between the three measurement points is 0.44 °, but this is merely an example, and for example, the 0.23 ° pitch (corresponding to UTAC) or the color image sensor 20b used Of course, it is possible to select any other pitch depending on the pixel arrangement of. As described above, the horizontal cut line 37a and the oblique cut line 37b in the projection light from the headlight L are searched by performing image processing to compare the respective luminances Y of the plurality of pixels 40 of the color image sensor 20b with one another. It is possible to determine the elbow point 38 as the intersection of the cut lines of.

  As described above, the projection light from the headlight L is processed using the measurement camera 20 having the CCD color image sensor 20b to output RGB data, and these RGB data are output to the image processing apparatus 30 as the color of the light source By image processing based on temperature, it is possible to determine the optical axis, luminous intensity, elbow point etc. However, the projection light of the headlight L is not irradiated on the 10 m screen 10 m ahead, but is irradiated on the internal measurement screen 19 via the optical system including the lens 17 in the headlight tester 10 Therefore, depending on the design conditions of the headlight tester 10, the optical system may be adversely affected, such as chromatic aberration. The present invention is characterized in that it includes a technique for removing the adverse effect of the optical system caused by such a chromatic aberration or the like.

  By using the above-mentioned reference sphere as a light source, the luminous intensity is set to 50 hcd, 400 hcd, and 1200 hcd sequentially in stages, and the irradiation direction is set to 0-0 (horizontal angle 0-vertical angle 0). The light distribution pattern is imaged by the measurement camera 20 of the color headlight tester 10 to obtain bit map data, and respective data values of RGB are collected from the bit map data and plotted as shown in FIG. FIG. 22 (in the case of a passing reference sphere) and FIG. 22 (in the case of a passing reference sphere). In these figures, the horizontal axis position is the position in the horizontal direction near the center of the light distribution pattern, and the vertical axis position is the position in the vertical direction near the center of the light distribution pattern. Furthermore, in these figures, a level is a data value of each of RGB and takes a value within the range of 0 to 255, respectively. It should be noted that in these figures, although the light intensity of the reference sphere is increased from 50 hcd to 1200 hcd, the respective data values (levels) of RGB are almost the same level. However, this is because, due to display limitations, the shutter speed of the measurement camera is increased as the light intensity is increased. Therefore, the absolute evaluation of the RGB data values themselves is meaningless.

  In the case of the traveling light reference sphere of FIG. 21, the luminous intensity is relatively low at 50 hcd, and the light distribution is reddish, and the G and B data values are lower than the R data value. At 400 hcd, the respective data values of RGB are substantially the same, and show an average light distribution as a headlight. At 1200 hcd, since the light intensity is high, the light distribution becomes whitish, and the G and B data values are reversed and further increased compared to the R data value. Also in the case of the passing-light reference sphere of FIG. 22, as the light intensity is increased in order from 50 hcd to 100 hcd and 120 hcd, a tendency is observed that the magnitudes of the respective data values of RGB are reversed though relatively. In the case of the passing light reference sphere, the difference between the respective RGB data values is not so noticeable because the width for changing the light intensity is narrower. The reversal phenomenon of the respective sizes of the RGB data is more pronounced in the peripheral portion than in the central portion of the image sensor 20b, which is considered to be caused by measuring the projection light through the optical system. Therefore, when the influence of the optical system to be used is large, it may be appropriate to make some correction, particularly in the peripheral area.

5. Correction of rgb Coefficient As described above, according to one aspect of the present invention, it is possible to determine (select) respective values of the rgb coefficient based on the color temperature of the headlight L as a light source, and as a result, Equation (1) can be used to determine the luminance Y and the corresponding luminous intensity. However, in the color headlight tester 10, in order to realize 10 m reproduction, the projection light from the headlight L is imaged by the measurement camera 20, which is a color camera, through the optical system including the main lens 17. Therefore, the projection light is affected by chromatic aberration and the like by passing through the optical system, and the influence may not be neglected depending on the configuration of the optical system. In particular, in the case where a Fresnel lens is used as the main lens 17, the influence of such a chromatic aberration or the like may be more remarkable.

  In order to cope with such a situation, according to one aspect of the present invention, the reference rgb coefficient determined based on the color temperature of the headlight L (ie determined based on the CIE standard light source) The rgb coefficient is not commonly applied to all the pixels of the image sensor, but a corrected rgb coefficient in which at least one coefficient is corrected is applied to at least one pixel. For example, as described above, since the variation of the respective RGB data is relatively small in the central part of the image sensor but becomes more pronounced in the peripheral part, in one embodiment of the present invention, the central part of the image sensor A reference rgb coefficient determined (selected) based on the color temperature of the headlight L is applied to each pixel, and a corrected rgb coefficient obtained by appropriately correcting the reference rgb coefficient is applied to each pixel in the peripheral portion. Apply However, as in the case of particularly using a Fresnel lens, the influence of the optical system is particularly large, and the influence of chromatic aberration and the like may not be neglected even in the central part. Therefore, in another embodiment of the present invention, Apply the corrected rgb coefficients to at least one pixel or most pixels regardless of position. Furthermore, in another embodiment of the present invention, instead of applying the rgb coefficient to each individual pixel, all pixels within the measurement range of the image sensor are divided into zones composed of a plurality of pixels, and the rgb coefficient is Applies commonly to a plurality of pixels in each zone. Thus, for example, the reference rgb coefficient is applied to one or more zones in the central part of the image sensor, and the correction rgb coefficient is applied to the other zones. In this case, it is possible to prepare a plurality of correction rgb coefficients different from one another and to apply one correction rgb coefficient among them to a plurality of pixels in one zone in common. In this case, it is desirable to store the reference rgb coefficient and the plurality of corrected rgb coefficients in the form of a table in the image processing apparatus 30. Furthermore, since the reference rgb coefficient changes depending on the color temperature of the headlight L as a light source, the table of the reference rgb coefficient and the plurality of rgb correction coefficients is for each preselected color temperature or for each corresponding light intensity. It is desirable that the image processing apparatus 30 be prepared and stored.

  Next, a method of creating the rgb correction coefficient described above will be described.

  FIGS. 23A and 23B show a system for measuring the luminous intensity (hcd) of the projection light from the reference sphere 51 described above, and the system basically comprises the reference sphere attaching device 50 and 10 m from it. And a 10 m screen 25 located forward and equipped with a light meter 58. The reference ball mounting device 50 has a mounting bracket 52 a to which the reference ball 51 can be detachably mounted, and the mounting bracket 52 a is fixed to the turntable table 52. The turntable table 52 is rotatably supported by the turntable 54, and the turntable table 54 is provided on the turntable longitudinal movement base 56. Further, the left and right rotation handle and the angle scale 53 are attached to the turntable table 52, and the up and down rotation handle and the angle scale 55 are attached to the rotation platform 54. Although the specific configuration is not shown in FIG. 23, it is possible to move the turntable table 52 up and down and fix it at a desired height.

  The reference ball attaching device 50 is moved back and forth by the rotating table longitudinal movement base 56, and the position of the rotation center 51a of the reference ball 51 is set at a position of 10 m from the screen 25 and fixed at that position. An illuminance meter 58 is provided on the 10 m screen 25 in the same plane. This luminometer 58 is a special one and has the same structure and function as the luminometer 1 shown in FIG. 1 of Japanese Patent Application Laid-Open No. 2013-2969 mentioned above. However, in practice, in order to measure the light intensity of the headlights, a candelas (or hector candelas) value converted as the light intensity (hcd) of the headlights L is output as the measurement value. With such a system configuration, it is possible to receive the projected light from the reference sphere 51 by the illuminance meter 58 and measure the luminous intensity (hcd). In that case, the illuminance meter 58 is fixed to the 10 m screen 25. However, it is possible to change the projection direction of the reference sphere 51 in the left and right direction by operating the left and right rotation handle and the angle scale 53. Furthermore, by operating the vertical rotation handle and the angle scale 55, it is possible to change the projection direction of the reference ball 51 in the vertical direction. Since the reference ball attaching device 50 is manufactured with extremely high precision, it is possible to change the reference ball 51 in the vertical and horizontal directions with extremely high precision.

  Next, with reference to FIG. 24, an aspect of measuring the light intensity of the reference sphere 51 by the system shown in FIG. 23 will be described. The positional relationship between a selected position of the 10 m screen 25 and the corresponding position of the screen 19 in the light receiving portion 11 of the headlight tester 10 and the corresponding pixel of the image sensor 20b is unique as shown in FIG. It is possible to decide on Therefore, for example, as shown in FIG. 24, when the projection direction of the reference sphere 51 is directed to a specific position of the lower 20 and the left 35 cm / 10 m on the 10 m screen 25, an image corresponding to that position It is possible to identify the pixels of the sensor 20b. That is, basically, the position of each pixel of the image sensor 20b can specify the corresponding position on the 10 m screen 25. Thus, it is possible to determine the light intensity of the reference sphere 51 for each pixel of the image sensor 20b using the reference rgb coefficient corresponding to the color temperature of the reference sphere 51, while using the illuminometer 58 It is possible to determine the light intensity at a position on the 10 m screen 25 for the position of each pixel of the image sensor 20b. The light intensity values determined via these image sensors 20b are compared with the light intensity values determined by the illuminometer 58, and if they substantially match, the reference rgb coefficients are for those pixels. It applies, and if they do not substantially match, the light intensity values substantially corresponding to the light intensity values obtained by the illuminometer 58 are obtained for the corresponding pixels so as to be obtained from the image processing device 30. Then, the reference rgb coefficient is corrected to newly determine a corrected rgb coefficient.

  When determining such a correction rgb coefficient, in one embodiment, the correction rgb coefficient is determined finely for each individual pixel, and in another embodiment, all pixels within the measurement range of the image sensor 20b are specified. Divided into a plurality of zones, and a correction rgb coefficient is determined for each zone. In the zone division embodiment, the reference rgb coefficient or the corrected rgb coefficient determined for the zone is commonly applied to a plurality of pixels belonging to one zone. Then, when determining the correction rgb coefficient, the value of the reference rgb coefficient is adjusted so that the difference between the light intensity obtained using the reference rgb coefficient and the light intensity obtained through the illuminometer 51 is zero. However, the adjustment method has several aspects. That is, in one embodiment, all values of the reference rgb coefficient are adjusted to be a corrected rgb coefficient, and in another embodiment, at least one of the reference rgb coefficients is set to zero and the rest The values of these are appropriately adjusted to obtain corrected rgb coefficients. Then, when adjusting the value of the reference rgb coefficient, in one embodiment, the respective coefficients of all the reference rgb coefficients are adjusted independently of each other, and in another embodiment, the values of the reference rgb coefficients are adjusted. The respective values are adjusted by multiplying the same value in common. Furthermore, since the reference rgb coefficient changes depending on the color temperature of the headlight L, the predetermined color temperature or the corresponding light intensity (for example, 50, 75, 100, 150, 400, 500, 700, Reference rgb coefficients exist every 1000, 1100, and 1200 hcd), and the correction rgb coefficients are similarly determined for these reference rgb coefficients, and a table consisting of reference rgb coefficients and correction rgb coefficients for each light intensity Can be created and stored in the image processing apparatus 30. When such a table is created, the light intensity of the headlight L may not necessarily correspond to the light intensity of a particular table, but in that case, the distance between the two nearest light intensity tables is It is possible to interpolate to obtain the desired value.

6. Zone division In one embodiment, the correction rgb coefficient is determined for each individual pixel, but in another embodiment from the viewpoint of processing efficiency, all pixels of the image sensor are divided into zones of a predetermined number. It is also possible to determine a common corrected rgb coefficient for each zone. When performing zone division, there are cases where all zones have the same number of pixels and cases where at least one zone has different numbers of pixels. Although any zone division can be applied in the present invention, a case where all zones have the same number of pixels will be described here as one embodiment.

  In the embodiment shown in FIG. 25, the image sensor 20 b has a measurement area consisting of 640 × 480 pixels 40 in width × length. Then, the whole of these pixels are divided into zones 41 consisting of 20 × 20 pixels, and divided into zones of width × length 32 × 24. In each zone 41, respective RGB pixels 40 are arranged in a so-called buyer array. In FIG. 25, block numbers 3 to 6 are assigned to some zones 41 near the center (for example, block number 4 is assigned to the (12, 9) zone). Each block number points to a block in the table storing the corresponding rgb coefficient. FIG. 26 shows an example of such a table of rgb coefficients. For example, in FIG. 26, the rgb coefficient indicated by the block number 5 is r = 0.4315, g = 0.5369, b = 0.0317. Therefore, for example, since the zone (12, 11) in FIG. 25 is assigned the block number 5, for that zone, an rgb of r = 0.4315, g = 0.5369, b = 0.0317 The value of the coefficient is applied.

  Thus, as shown in FIG. 25, since a block number is assigned to each zone 41, a correspondence table between the zone 41 and the block number is stored in the image processing apparatus 30, Furthermore, a correspondence table of block numbers and rgb coefficients as shown in FIG. 26 is also stored in the image processing apparatus 30. Therefore, when calculating the luminance Y (light intensity) for a specific pixel 40, first, which zone 41 the pixel 40 belongs to is determined to determine the corresponding block number, and the block number The calculation is performed using the rgb coefficient indicated by. In FIG. 25, block numbers are assigned not to all zones 41 but only to the selected zone 41 near the center, but it is also possible to assign block numbers to all zones 41 in the same manner. As another example, it may not be necessary to use all of the measurement range of the image sensor 20b of FIG. 25, and in such a case, as shown in FIG. It is also possible to define a smaller effective range and to assign block numbers only to the zones 41 belonging to the effective range.

  By the way, the embodiment shown in FIGS. 25 and 26 corresponds to the rgb coefficient when the light intensity is 400 hcd, and the block number 5 corresponds to the reference rgb coefficient in the case of 400 hcd. Accordingly, block number 5 indicating the reference rgb coefficient is assigned to many zones 41 near the center of the image sensor 20b of FIG. As shown in FIG. 26, rgb coefficients indicated by block numbers other than block number 5 are different in value from the reference rgb coefficient, and it is understood that they are corrected rgb coefficients. These corrected rgb coefficients are appropriately determined by the above-described procedure of correcting the rgb coefficient. In block numbers 0 to 4 and 6 to 8, the corrected rgb coefficients have coefficient values other than 0, but in block numbers 9 to 11, the correction r coefficient and the correction b coefficient among the corrected rgb coefficients Are those whose values are 0, and only the correction g coefficient has a value other than 0. Then, in the block number 12-14, all the corrected rgb coefficients are set to 0, and the calculation of the luminance Y is not performed in the zone 41 to which the block number is assigned.

  As described above, the correspondence table between the block numbers and the rgb coefficients in FIG. 26 is one in which the light source luminous intensity is adjusted to 400 hcd. By the way, although the light intensity and the color temperature are not directly related, it can be generally said that the color temperature tends to increase as the light intensity increases. Therefore, using the system shown in FIG. 23, the luminous intensity of the reference sphere 51 is 50 hcd using a color temperature measuring device (a device capable of measuring the color temperature directly with a spectroradiometer etc.) instead of the illuminance meter 58. The color temperature of the projected light from the reference sphere 51 is measured in the case of gradually changing from 1,200 hcd to 1,200 hcd, and the result is shown in FIG. 27 (A). FIG. 27 (B) fits one example of the approximation formula to the result of FIG. 27 (A). From this result, it can be generally said that as the light intensity of the light source increases, the color temperature of the light emitted from the light source also increases. Therefore, the correspondence table between the zone 41 and the block number as shown in FIG. 25 and the correspondence table between the block number and the rgb coefficient as shown in FIG. It is necessary to prepare for each light intensity (color temperature) and store it in the image processing apparatus 30 over the period.

  FIG. 28 shows a configuration in which all the pixels 640.times.480 in the image sensor 20b similar to FIG. 25 are equally divided into zones 41 consisting of 20.times.20 pixels. In FIG. 28, a rectangular effective area 42 is defined inside the measurement area consisting of a 640 × 480 image of the image sensor 20b, and the block number 0 is applied to all zones 41 outside the effective area 42. Assigned On the other hand, block numbers 2 to 7 are assigned to zones 41 within the effective range 42, respectively. The correspondence table of the block numbers and the rgb coefficients is shown in FIG. 29, but the correspondence table of FIG. 29 is the same as the correspondence table of FIG. The block number 0 assigned to the zone 41 in FIG. 28 is, as shown in FIG. 29, the values of their rgb coefficients are r = 0.4111, g = 0.5461, b = 0.0428 . In FIG. 29, the value of the rgb coefficient indicated by the block No. 5 is the reference rgb coefficient when the light source luminous intensity is 400 hcd, therefore the block number vs. rgb coefficient correspondence table of FIG. 29 is for the luminous intensity of the light source 400 hcd. It is understood. Furthermore, as shown in FIG. 29, the rgb coefficients indicated by block numbers other than block number 5 are corrected rgb coefficients, and in particular, the values of the corrected rgb coefficients indicated by block numbers 2 to 4 and 6 to 8 are standard. It is understood that each value of the rgb coefficient is determined by multiplying it by a predetermined constant. Since the correspondence table of FIG. 29 is to be applied to each zone 41 of FIG. 28, the correspondence table of the zone 41 and the block number of FIG. 29 is also for the light source luminous intensity of 400 hcd.

  As described above, by applying the correction rgb coefficient, the variation due to the chromatic aberration or the like due to the optical system (in particular, the Fresnel lens as the main lens) in the color headlight tester 10 is corrected and the light intensity of the headlight L is appropriately determined. It is possible to determine with high accuracy. Furthermore, it is possible to speed up processing by applying zone division processing.

7. Correction of Maximum Luminance Position It has been described above that the position (h, v) of the maximum luminance Y _MAX in the light distribution pattern 33 of the traveling light can be determined by, for example, the 3 ° 30 minutes balance method or the like. Note that h and v are horizontal and vertical position coordinates on the screen 19, respectively. By the way, in the system shown in FIG. 23, a reference ball for traveling light is used as the reference ball 51, and the projection direction is stepwise displaced in the vertical direction by setting the reference ball 51 to the selected horizontal angle position. When the position of the maximum luminance Y _MAX was determined by the color headlight tester 10 positioned 1 m ahead of the reference sphere 51 in place of the 10 m screen 25 in the system of FIG. 23, it was found that variation may occur. As shown in FIG. 30, for example, the reference sphere 51 is set at an angular position of 35 cm left (that is, h = -35), and the reference sphere 51 is uniformly spaced from the top 10 cm (that is, v = 10). The angle is displaced downward in the downward direction (i.e. every 1 cm in the example shown) down to 35 cm (i.e. v = -35), using the color headlight tester 10 at each angular position for maximum brightness Y _MAX The position was measured. In that case, since the reference sphere 51 is only angularly displaced from the top to the bottom at the same horizontal angular position, the (h, v) position coordinates of Y _MAX obtained at each angular position in the vertical direction v are the same. It is planned to exist on the h coordinate. However, it has been found that in the color headlight tester 10, there may be a slight but slight variation in the Y coordinate of such Y _MAX . Not only the h coordinate but also the v coordinate may vary. This is also considered to be due to the influence of the chromatic aberration and the like by the optical system (in particular, the Fresnel lens) in the color headlight tester 10.

Therefore, in order to correct such variations, as described above in the system of FIG. 23, the reference sphere for the traveling light is used as the reference sphere 51, and the reference sphere 51 is set to each horizontal angle position to vertically The position of the maximum luminance Y _MAX is measured by the color headlight tester 10 positioned at 1 m ahead of the reference sphere 51 in place of the 10 m screen 25 in the system of FIG. It was checked whether there was significant variation. As a result, for the color headlight tester 10 that needs such correction of the maximum luminance position, the correspondence table between the block numbers and the position correction values shown in FIG. It is stored. The correspondence table of FIG. 31 is to be applied to the correspondence table of the zone 41 and the block number shown in FIG. In the embodiment shown in FIG. 31, although the height position correction is zero (v = 0), it can be seen that there are several horizontal position corrections. In another embodiment, not only horizontal position correction but also vertical position correction may be required.

  FIG. 32 shows an example of the same zone-block number correspondence table as FIG. 28, but for correcting the position (h, v) of the balance point of the traveling light of 400 hcd. FIG. 33 is a table indicating the horizontal position offset value h (cm) and the vertical position offset value v (cm) assigned to each block number in FIG. Therefore, for example, the block number 5 is assigned to the zones of the horizontal pixel range (300-319) and the vertical pixel range (120-139) in FIG. 32, and the position correction corresponding to the block number 5 is performed. The quantities are the horizontal position offset value h = 0 and the vertical position offset v = 0. That is, when the block number 5 is assigned to the zone of FIG. 32, the position correction is not performed on 20 × 20 pixels belonging to the zone. In the embodiment of FIG. 32, since most of the zones in the effective range are assigned the block number 5 and only 4 and 6 are assigned to the remaining zones, position correction is performed. It is understood that the amount of is relatively small.

8. Correction of Elbow Point Position In the system shown in FIG. 23, using the reference ball for the passing light as the reference ball 51, as shown in FIGS. 24 and 30, the horizontal (left and right) angles at which the reference ball 51 is selected. Set the position (shown as the corresponding horizontal position h (cm) on the 10m screen in Figures 24 and 30) and keep the reference sphere 51 vertical (up and down) while maintaining its selected horizontal angular position The angles in the angular direction (shown in FIGS. 24 and 30 as the corresponding vertical position v (cm) on a 10 m screen) are varied stepwise (every 1 cm in FIG. 30) and are shown in FIG. Measure the position of the elbow point at each vertical position v using this color headlight tester 10 located 1 m in front of the reference sphere 51 instead of the 10 m screen did. As the selected horizontal position h, left 35 cm, left 20 cm, left 10 cm, center (left and right 0), right 10 cm, right 20 cm, and right 35 cm were used. The results so obtained are shown graphically in FIG.

  By the way, the reference ball attaching device 50 in the system shown in FIG. 23 is configured with extremely high accuracy, and it is possible to perform angular displacement of the reference sphere 51 in the horizontal direction and the vertical direction with extremely high accuracy. A reference ball for passing lights projects a light distribution pattern having horizontal cut lines and oblique cut lines and elbow points as intersections of those cut lines. Therefore, when the reference ball for passing light is attached to the reference ball mounting device 50 as the reference ball 51 and the angle is changed stepwise in the vertical direction at the selected horizontal angle position, the horizontal angle position A point series of elbow points that change positions in a straight line in the vertical direction should be obtained.

  However, as shown in the graph of FIG. 34, the measurement results were obtained when the reference sphere 51 was angularly displaced stepwise in the vertical (up and down) direction at any of the above horizontal positions h. The horizontal position h of the elbow point has left and right variations. In FIG. 35, the reference sphere 51 is set on the 10 m screen at a horizontal angular position h of 10 cm (ie, -10 cm) on the left, and the reference sphere 51 is positioned 20 cm below (i.e. This color headlight whose position (h, v) of the elbow point is located 1 m ahead of the reference ball 51 by shifting the angle stepwise and linearly down to 35 cm (that is, v = -35) in the direction It is the graph which showed the position shift of the perpendicular | vertical (upper and lower) direction at the time of measuring with the tester 10, and the position shift of the horizontal (left and right) direction. From this graph, it can be seen that the position of the elbow point measured by the present color headlight tester 10 varies not only in the horizontal (left and right) direction but also in the vertical (upper and lower) direction. The horizontal (left and right) position h of the measured elbow point should originally be kept constant at the position of h = −10 cm, but fluctuates between h = −10 and h = −20 doing. Furthermore, it is also shown that the vertical (upper and lower) position v of the measured elbow point is not aligned on one straight line, and that there is slight variation.

  As a cause of occurrence of such variations when the h, v position of the elbow point is measured using the color headlight tester 10, an optical system is used to establish a 10 m reproduction in the color headlight tester 10. It is considered to be due to the influence of chromatic aberration etc. In particular, in the case where a Fresnel lens is used as the main lens 17 of the optical system, it is considered that the influence thereof becomes more remarkable due to the structural peculiarity of the Fresnel lens.

  Therefore, in the case of measuring the positions h and v of the elbow point in the color headlight tester 10, it is important to correct the horizontal and vertical variations described above. Therefore, in the present invention, the reference ball for passing light is set as the reference ball 51 using the system shown in FIG. 23, and the reference ball 51 is set to the horizontally selected angular position h to obtain the reference ball. The angular position v is changed stepwise in the vertical direction 51 to determine the position (h, v) where the elbow point should be on the 10 m screen 25 from the angular memory of the reference ball mounting device 50, while in the same setting Compared with the position (h, v) of the elbow point measured by the color headlight tester 10, when there is a difference between them, the position correction amount is determined. The position correction tables determined as such are shown as (A) to (C) in FIG. In FIG. 36, (A) shows the correspondence between the block number and the horizontal correction, (B) shows the correspondence between the block number and the cutline correction, and (C) shows the block number and the height correction. It shows the correspondence with. Note that, as schematically shown in FIG. 37, the horizontal correction in (A) in FIG. 36 refers to the horizontal position correction h and the vertical position correction v with respect to the measurement position of the horizontal cut line, (B) The cutline correction of the horizontal position correction h and the vertical position correction v with respect to the measurement position of the oblique cutline, and the height correction of (C) is the second position above the horizontal cutline. These are horizontal position correction h and vertical position correction v with respect to the measurement position of the horizontal cut line. In addition, the height correction of (C) is a correction amount to be applied when the light distribution of the headlight L is actually a Z-beam light distribution. A correspondence table (not shown) showing, for example, which pixel 40 (or zone 41) of the image sensor 20b the block number indicated in each correction table shown in FIG. 36 is applied to, for example, is also shown in FIG. It is prepared and stored in the image processing apparatus 30 in the form of FIG.

9. Measurement Principle and Procedure According to the principle of the present invention, the rgb coefficient is determined based on the color temperature of the CIE standard light source, the projection light of the headlight is subjected to color image processing to determine RGB data, the RGB data and the rgb The luminance Y is determined using the coefficients. The color temperature represents the color of the light source, and utilizes the temperature of a black body that appears to be the same color as the color, and is not an index indicating the brightness of the light source. In the present invention, since the headlight is also a light source, the rgb coefficient used when imaging the projection light of the headlight with a color camera and subjecting the light distribution pattern to color image processing depends on the color temperature of the headlight Focus on what needs to be determined. Then, if it is possible to directly determine the color temperature of the headlight by some method, the rgb coefficient corresponding to the color temperature may be determined (selected). On the other hand, if the color temperature of the headlight can not be determined directly, the light intensity (color temperature) of the headlight is estimated, and the estimated light intensity (color temperature) can be brought closer to the true color temperature of the headlight Just do it. For example, temporary brightness (color temperature) is used to determine temporary rgb coefficients, and temporary brightness is determined using these temporary rgb coefficients, and temporary brightness (color temperature) is determined from the temporary brightness. And the temporary light intensity (color temperature) is closer to the true color temperature of the headlight than the estimated color temperature. Then, if the temporary light intensity (color temperature) exceeds the tolerance from the light intensity (color temperature) initially estimated, a new rgb coefficient corresponding to the temporary light intensity (color temperature) is determined, The same procedure may be followed.

Then, by finding the maximum luminance Y _MAX among the luminances Y determined as described above, it is possible to determine the position of the maximum luminance Y _MAX as the optical axis (illumination direction) of the headlight. This corresponds to determining the irradiation direction of the projection light when the headlight is in the traveling light mode. Furthermore, it is possible to convert this maximum luminance Y _MAX into a luminous intensity (hcd) according to a predetermined luminance-luminance conversion formula. This corresponds to determining the luminous intensity (hcd) of the headlight when the headlight is in the traveling light mode.

  On the other hand, it is also possible to determine the brightness Y corresponding to a predetermined position (road surface illumination point etc.) among the brightness Y determined as described above, and to convert the brightness Y into a light intensity. This corresponds to determining the light intensity at the road surface illumination point when the headlights are in the passing mode.

  Furthermore, it is possible to compare the luminance Y determined as described above with each other to find a horizontal cut line and a diagonal cut line as a light and dark dividing line, and to determine an elbow point as an intersection point of these horizontal and diagonal cut lines. It is.

  Next, several embodiments of the procedure for testing a headlight in the present invention will be described.

  First, the headlight and the headlight tester are relatively moved to a position where the light distribution pattern of the projection light from the headlight can be imaged by the measurement color camera of the headlight tester. The image processing device of the headlight tester extracts the maximum luminance in the light distribution pattern, and adjusts the shutter speed of the color camera for measurement to increase or decrease so that the maximum luminance falls within a predetermined range. When the shutter speed is set to an appropriate value, the image processing apparatus determines the type of light source of the headlight using the color camera for measurement. As a light source type, typically, there are a halogen lamp, an HID lamp, and an LED lamp. Halogen lamps are also referred to as warm-colored lamps, while HID lamps are also referred to as cold-colored lamps. In particular, the color temperature is different between the warm color lamp and the cold color lamp, and the basic rgb coefficient for the warm color lamp and the basic rgb coefficient for the cold color lamp are prepared. The basic rgb coefficients are representative and basic rgb coefficients in the light source type, and for example, in the case of a warm color light source type, they are rgb coefficients for a light intensity of 400 hcd. Therefore, even if the color temperature of the headlight can not be determined directly by determining the light source type, it is possible to use the basic rgb coefficient of the light source type as a temporary rgb coefficient. . For example, if the headlight to be tested is a warm lamp, the light intensity of the headlight is provisionally set to 400 hcd, which estimates the color temperature of the headlight to a color temperature corresponding to 400 hcd. Is the same as The basic rgb coefficients are also determined in advance for cold color lamps and LED lamps, and stored in the image processing apparatus.

  After determining the light source type, the lamp type of the headlight (projector, lens cut, multi-reflector) is performed, which is preferably performed by the facing camera. Further, using the facing camera, the image processor aligns the center of the headlight with the optical axis of the headlight tester. This operation is usually called facing operation.

  When the confrontation is completed, the processing is divided according to the difference in the measurement mode of the running light mode or the passing light mode. In the case of a traveling light mode, there are two embodiments, direct and iterative, as follows, depending on whether it is possible to directly determine the color temperature of the headlights.

A. Running Light Mode (1) Direct Method First, when it is possible to directly determine the color temperature of the headlight L, the direct method is adopted. This is because, once the color temperature of the headlight L is determined (selected), it is possible to directly determine the rgb coefficient to be applied to the projection light from the headlight L. For example, in one embodiment, the headlight tester 10 is provided with a color temperature measuring device, which detects the projection light from the headlight L to be tested to determine the color temperature of the headlight, which is determined The color temperature information is supplied to the image processing device 30. In another embodiment, an operator operates a commercially available color temperature measuring instrument of a popular type to measure the color temperature of the headlight, and the operator inputs the color temperature information to the headlight tester 10. The color camera for measurement 20 images the light distribution pattern 33 of the projection light from the headlight L and supplies RGB data to the image processing device 30, and the image processing device 30 uses the RGB data and the rgb coefficient to generate a color image The luminance Y for the pixel 40 of the sensor 20b is calculated.

  Incidentally, due to the influence of an optical system (in particular, a Fresnel lens) used by the headlight tester 10, it may not be possible to ignore the variation in light intensity based on the variation in RGB data within the measurement range of the color image sensor 20b. In such a case, the rgb coefficient determined based on the color temperature of the CIE standard light source is used as a reference rgb coefficient, and the position within the measurement range to which the reference rgb coefficient is applied is specified, while absorbing such variations The corrected rgb coefficient is determined so as to correct the reference rgb coefficient, and the position within the measurement range to which the corrected rgb coefficient is applied is specified. A table of correspondences between these reference rgb coefficients and the corrected rgb coefficients and the coefficients and the application position within the measurement range is stored in the image processing device 30. Furthermore, in one embodiment, such a correspondence table is generated for all the pixels 40 in the measurement range, but in another embodiment, a plurality of all pixels 40 in the measurement range is provided. It is divided into zones 41 composed of pixels 40, and a common correspondence table is applied to each zone 41. Each zone 41 may have the same number of pixels or may have a different number of pixels.

The image processing apparatus 30 finds the highest luminance Y _MAX among the luminances Y calculated as described above. Next, the image processing device 30 determines the position of the maximum luminance Y _MAX as the optical axis (illumination direction) of the headlight L. Furthermore, the image processing device 30 converts the maximum luminance Y _MAX into a light intensity (hcd) in accordance with a predetermined conversion equation between the brightness Y (dimensionless) and the light intensity (hcd). Thus, the optical axis (irradiation direction) of the headlight L and the light intensity (hcd) are determined by the direct method.

(2) Repeat Method Next, when it is impossible to directly determine the color temperature of the headlight L, the repeat method is adopted. In this case, the basic rgb coefficient specified in advance for each light source type is used as a temporary rgb coefficient using the determination result of the light source type described above. For example, when the determination of the light source type is a warm color system (halogen lamp), the image processing apparatus uses an rgb coefficient of 400 hcd as a temporary rgb coefficient as a temporary rgb coefficient. The color camera for measurement 20 images the light distribution pattern 33 of the projection light from the headlight L and supplies RGB data to the image processing device 30, and the image processing device 30 uses the RGB data and the temporary rgb coefficient. A provisional luminance Y for the pixel 40 of the color image sensor 20b is calculated.

  Incidentally, due to the influence of an optical system (in particular, a Fresnel lens) used by the headlight tester 10, it may not be possible to ignore the variation in light intensity based on the variation in RGB data within the measurement range of the color image sensor 20b. In such a case, the basic rgb coefficient is used as a reference rgb coefficient, and a position within the measurement range to which the reference rgb coefficient is applied is specified, while correction is performed by correcting the reference rgb coefficient to absorb such variations. The rgb coefficient is determined, and the position within the measurement range to which the corrected rgb coefficient is to be applied is specified. A table of correspondences between these reference rgb coefficients and the corrected rgb coefficients and the coefficients and the application position within the measurement range is stored in the image processing device 30. Furthermore, in one embodiment, such a correspondence table is generated for all the pixels 40 in the measurement range, but in another embodiment, a plurality of all pixels 40 in the measurement range is provided. It is divided into zones 41 composed of pixels 40, and a common correspondence table is applied to each zone 41. Each zone 41 may have the same number of pixels or may have a different number of pixels.

The image processing device 30 finds the temporary maximum brightness Y _MAX among the temporary brightness Y calculated as described above. Next, the image processing device 30 converts the provisional maximum luminance Y _MAX into a provisional luminous intensity (hcd) in accordance with a conversion formula between the luminance Y (dimensionless) and the luminous intensity (hcd) determined in advance.

Then, when the provisional light intensity obtained in this manner is different from the 400 hcd estimated based on the light source type determination result beyond the tolerance, the image processing device 30 is determined in this manner. A new rgb coefficient (preferably, a combination of a reference rgb coefficient and a corrected rgb coefficient) is selected based on the temporary light intensity (hcd), and RGB data of the light distribution pattern 33 supplied from the color camera 20 for measurement The new luminance Y for the pixel 40 of the color image sensor 20b is calculated using the new rgb coefficient. The image processing unit 30 detects the maximum new maximum luminance Y _MAX among these new luminances, and further, according to the conversion equation, the new maximum luminance Y _MAX is newly determined, preferably the final value Convert to (hcd). If necessary, it is also possible to select a new rgb coefficient again based on this new light intensity and repeat the processing until a final light intensity having a desired accuracy is obtained or until a predetermined number of repetitions. Then, the image processing device 30 applies the maximum luminance (e.g., balance point) position correction table to the position of the maximum luminance Y _MAX with respect to the final luminous intensity to determine the optical axis (irradiation direction) of the headlight L.

B. Passing light mode When passing light mode is selected, any of (1) direct method and (2) repetition method described above can be applied to determine the light intensity (hcd). It may not be necessary to use a corrected rgb coefficient since data variations are substantially negligible. Also, in the passing light mode, the point at which the light intensity is measured is not the highest luminance point but a point called road surface illumination point which is previously defined with respect to the lamp center. That is, when the lamp height is 1 m or less, the road surface irradiation point is 1.3 degrees left and 0.6 degrees down from the center of the lamp, and when the lamp height is more than 1 m, left from the lamp center It is a position of 0.9 degrees below at 1.3 degrees. Therefore, the luminance Y may be calculated from the RGB data and the rgb coefficient at these fixed positions, and converted to the luminous intensity (hcd) according to the above conversion formula.

  On the other hand, in the passing light mode, it is necessary to detect the position of the elbow point. Therefore, the image processing device 30 calculates the luminance Y for each pixel in the measurement range of the color image sensor 20b from the rgb coefficient and the RGB data, compares them with one another, and cuts the horizontal cut as a bright and dark branch line Find lines and diagonal cut lines. One embodiment for performing comparison processing is the difference method. Further, in the position detection of the elbow point, since the optical system (Fresnel lens 17) of the color headlight tester 10 has a relatively large influence, the position correction table is applied to correct the position of the detected elbow point.

  Although the specific embodiments of the present invention have been described above in detail, the present invention should not be limited to these specific embodiments, and various modifications may be made without departing from the technical scope of the present invention. Of course, changes are possible.

10: color headlight tester 11: light receiving unit 17: main lens (Fresnel lens)
19: internal (for measurement) screen 20: camera for measurement 20b: semiconductor color image sensor 21: data processor 24: camera for facing 25: 10 m screen 30: image processor 33: light distribution pattern (image)
37a: horizontal cut line 37b: oblique cut line 38: elbow point 40: pixel 41: zone 50: reference ball mounting device 51: reference ball 58: illuminance meter

Claims (61)

An optical system that receives the projection light from the headlights,
A screen on which a light distribution pattern of the projection light is projected via the optical system;
A color camera for measurement which captures the light distribution pattern on the screen;
An rgb coefficient determination unit that determines an rgb coefficient based on a color temperature of the projection light for each of a plurality of selected pixels of the measurement color camera;
Luminance determination means for receiving RGB data from the color camera for measurement and applying the rgb coefficient to the corresponding pixel determined by the rgb coefficient determination means to determine the luminance for the corresponding pixel;
Optical axis determination means for determining a pixel having the highest luminance among the plurality of pixels and determining the position of the pixel having the highest luminance in the vertical and horizontal directions as the optical axis of the headlight.
Color headlight tester with.   The color headlight tester according to claim 1, wherein the optical system has a main lens.   The color headlight tester according to claim 2, wherein the main lens is a Fresnel lens.   The color head light tester according to claim 1, wherein the color camera for measurement comprises a color image sensor having a plurality of pixels.   5. The color headlight tester according to claim 4, wherein the color image sensor is a CCD color image sensor.   The method according to claim 1, wherein the rgb coefficients include at least one reference rgb coefficient determined based on the color temperature of the CIE standard light source and at least one correction rgb coefficient obtained by modifying the reference rgb coefficient. Color headlight tester described.   The color head light tester according to claim 4 or 5, wherein the rgb coefficient determining means determines an rgb coefficient for each pixel of the color image sensor.   The plurality of pixels of the color image sensor are divided into a plurality of zones, and the rgb coefficient determination means determines an rgb coefficient commonly used for one of the zones. 5 color headlight tester.   The rgb coefficient determination means has a plurality of tables in which rgb coefficients are calculated for each predetermined light intensity or color temperature, and selects from among the plurality of tables and determines rgb coefficients to be used according to the table A color headlight tester according to any one of the preceding claims.   The color headlight according to claim 1, further comprising a light source type determination unit that determines a light source type of the headlight, wherein the rgb coefficient determination unit determines an rgb coefficient to be applied according to the determination of the light source type. tester.   The luminance corresponds to Y coordinates of XYZ coordinates defined by tristimulus values X, Y and Z in the CIE · XYZ color system, and the luminance determining unit calculates the luminance by the formula Y = r × R + g × G + b × B. The color headlight according to any one of claims 1 to 10, wherein the luminance is determined, RGB is RGB data outputted from the color camera for measurement, and rgb is a coefficient as a weighting of each of the RGB data. tester.   The color head light tester according to any one of claims 1 to 11, wherein the optical axis determination means determines the maximum luminance based on either a balance method or a binarization center of gravity method.   The optical axis determination means has a maximum luminance position correction table, and applies the position correction data from the maximum luminance position correction table to the determined position of the maximum luminance to determine the optical axis. A color headlight tester as claimed in any one of the preceding claims.   The image processing apparatus further comprises a computer system comprising at least a CPU and a memory, and the rgb coefficient determination means, the luminance determination means, and the optical axis determination means are the main color heads. The color head light tester according to any one of claims 1 to 13, which is stored in the image processing apparatus as part of a program for controlling the operation of a light tester. An optical system that receives the projection light from the headlights,
A screen on which a light distribution pattern of the projection light is projected via the optical system;
A color camera for measurement which captures the light distribution pattern on the screen;
An rgb coefficient determination unit that determines an rgb coefficient based on a color temperature of the projection light for each of a plurality of selected pixels of the measurement color camera;
Luminance determination means for receiving RGB data from the color camera for measurement and applying the rgb coefficient to the corresponding pixel determined by the rgb coefficient determination means to determine the luminance for the corresponding pixel;
First intensity determining means for determining the highest intensity among the plurality of intensities corresponding to each of the plurality of pixels and determining the intensity of the headlight from the highest intensity;
Color headlight tester with.   The color headlight tester according to claim 15, wherein the optical system has a main lens.   The color headlight tester according to claim 16, wherein the main lens is a Fresnel lens.   The color headlight tester according to claim 15, wherein the color camera for measurement comprises a color image sensor comprising a plurality of pixels.   The color head light tester according to claim 18, wherein the color image sensor is a CCD color image sensor.   15. The apparatus according to claim 15, wherein the rgb coefficients include at least one reference rgb coefficient determined based on the color temperature of the CIE standard light source and at least one correction rgb coefficient obtained by modifying the reference rgb coefficient. Color headlight tester described.   20. The color head light tester according to claim 18, wherein said rgb coefficient determining means determines an rgb coefficient for each pixel of said color image sensor.   The plurality of pixels of the color image sensor are divided into a plurality of zones, and the rgb coefficient determination means determines an rgb coefficient commonly used for one of the zones. 19 color headlight tester.   The rgb coefficient determination means has a plurality of tables in which rgb coefficients are calculated for each predetermined light intensity or color temperature, and selects from among the plurality of tables and determines rgb coefficients to be used according to the table The color headlight tester according to any one of claims 15 to 22.   The color headlight according to claim 15, further comprising a light source type determination unit that determines a light source type of the headlight, wherein the rgb coefficient determination unit determines an rgb coefficient to be applied according to the determination of the light source type. tester.   The luminance corresponds to Y coordinates of XYZ coordinates defined by tristimulus values X, Y and Z in the CIE · XYZ color system, and the luminance determining unit calculates the luminance by the formula Y = r × R + g × G + b × B. The color headlight according to any one of claims 15 to 24, wherein the luminance is determined, RGB is RGB data outputted from the color camera for measurement, and rgb is a coefficient as a weighting of each of the RGB data. tester.   The first light intensity determining means determines the light intensity of the headlight based on a condition predetermined between the light intensity of a reference light source having a known light intensity and the brightness determined by the brightness determining means. The color headlight tester according to any one of 15 to 25.   The image processing apparatus further comprises a computer system comprising at least a CPU and a memory, and the rgb coefficient determination means, the luminance determination means, and the first light intensity determination means are the main color. The color headlight tester according to any one of claims 15 to 26, stored in the image processing apparatus as part of a program for controlling the operation of a headlight tester. An optical system that receives the projection light from the headlights,
A screen on which a light distribution pattern of the projection light is projected via the optical system;
A color camera for measurement which captures the light distribution pattern on the screen;
An rgb coefficient determination unit that determines an rgb coefficient based on a color temperature of the projection light for each of a plurality of selected pixels of the measurement color camera;
Luminance determination means for receiving RGB data from the color camera for measurement and applying the rgb coefficient to the corresponding pixel determined by the rgb coefficient determination means to determine the luminance for the corresponding pixel;
A second light intensity determination unit that determines the brightness at a predetermined position from the center of the headlight in the light distribution pattern and determines the light intensity of the headlight from the brightness;
Color headlight tester with.   The color headlight tester according to claim 28, wherein the optical system comprises a main lens.   The color headlight tester according to claim 29, wherein the main lens is a Fresnel lens.   The color head light tester according to claim 28, wherein the color camera for measurement comprises a color image sensor comprising a plurality of pixels.   The color head light tester according to claim 31, wherein the color image sensor is a CCD color image sensor.   The method according to claim 28, wherein the rgb coefficients include at least one reference rgb coefficient determined based on the color temperature of the CIE standard light source, and at least one correction rgb coefficient that is a modification of the reference rgb coefficient. Color headlight tester described.   The color head light tester according to claim 31 or 32, wherein the rgb coefficient determination means determines an rgb coefficient for each pixel of the color image sensor.   The plurality of pixels of the color image sensor is divided into a plurality of zones, and the rgb coefficient determination means determines an rgb coefficient commonly used for one of the zones. 32. The color headlight tester according to 32.   The rgb coefficient determination means has a plurality of tables in which rgb coefficients are calculated for each predetermined light intensity or color temperature, and selects from among the plurality of tables and determines rgb coefficients to be used according to the table A color headlight tester as claimed in any of claims 28 to 35.   The color headlight according to claim 28, further comprising: a light source type determining unit that determines a light source type of the headlight, wherein the rgb coefficient determining unit determines an rgb coefficient to be applied according to the determination of the light source type. tester.   The luminance corresponds to Y coordinates of XYZ coordinates defined by tristimulus values X, Y and Z in the CIE · XYZ color system, and the luminance determining unit calculates the luminance by the formula Y = r × R + g × G + b × B. The color headlight according to any one of claims 28 to 37, wherein the luminance is determined, and RGB is RGB data outputted from the color camera for measurement, and rgb is a coefficient as a weighting of each of the RGB data. tester.   The second light intensity determination means determines the light intensity of the headlight based on a condition predetermined between the light intensity of a reference light source having a known light intensity and the brightness determined by the brightness determination means. 28. The color headlight tester according to any one of 28 to 38.   Further, the image processing apparatus comprises a computer system comprising at least a CPU and a memory, and the rgb coefficient determination means, the luminance determination means, and the second light intensity determination means are the main color. 40. A color headlight tester according to any one of claims 28 to 39 stored in the image processing device as part of a program for controlling the operation of a headlight tester. An optical system that receives the projection light from the headlights,
A screen on which a light distribution pattern of the projection light is projected via the optical system;
A color camera for measurement which captures the light distribution pattern on the screen;
An rgb coefficient determination unit that determines an rgb coefficient based on a color temperature of the projection light for each of a plurality of selected pixels of the measurement color camera;
Luminance determination means for receiving RGB data from the color camera for measurement and applying the rgb coefficient to the corresponding pixel determined by the rgb coefficient determination means to determine the luminance for the corresponding pixel;
The luminances for the plurality of pixels are compared with each other to determine at least one horizontal cut line and at least one oblique cut line having a predetermined angle with respect to the horizontal cut line, and as an intersection point of those cut lines Elbow point determination means for determining an elbow point,
Color headlight tester with.   42. The color headlight tester according to claim 41, wherein the optical system comprises a main lens.   43. The color headlight tester according to claim 42, wherein the main lens is a Fresnel lens.   42. A color headlight tester as claimed in claim 41, wherein the measuring color camera comprises a color image sensor comprising a plurality of pixels.   The color head light tester according to claim 44, wherein the color image sensor is a CCD color image sensor.   42. The method of claim 41, wherein the rgb coefficients include at least one reference rgb coefficient determined based on the color temperature of the CIE standard light source and at least one corrected rgb coefficient that is a modification of the reference rgb coefficient. Color headlight tester described.   46. The color head light tester according to claim 44, wherein said rgb coefficient determining means determines an rgb coefficient for each pixel of said color image sensor.   The plurality of pixels of the color image sensor are divided into a plurality of zones, and the rgb coefficient determination means determines an rgb coefficient commonly used for one of the zones. 45 color head light tester.   The rgb coefficient determination means has a plurality of tables in which rgb coefficients are calculated for each predetermined light intensity or color temperature, and selects from among the plurality of tables and determines rgb coefficients to be used according to the table 49. A color headlight tester as claimed in any of claims 41 to 48.   The color headlight according to claim 41, further comprising a light source type determination unit that determines a light source type of the headlight, wherein the rgb coefficient determination unit determines an rgb coefficient to be applied according to the determination of the light source type. tester.   The luminance corresponds to Y coordinates of XYZ coordinates defined by tristimulus values X, Y and Z in the CIE · XYZ color system, and the luminance determining unit calculates the luminance by the formula Y = r × R + g × G + b × B. The color headlight according to any of claims 41 to 50, wherein the luminance is determined, and RGB is RGB data output from the color camera for measurement, and rgb is a coefficient as a weighting of each of the RGB data. tester.   The image processing apparatus further comprises a computer system comprising at least a CPU and a memory, the rgb coefficient determination means, the luminance determination means, and the elbow point determination means being the main color head. 52. The color head light tester according to any one of claims 41 to 51, which is stored in the image processing apparatus as part of a program for controlling the operation of a light tester. Projecting light from the headlights onto the screen through the optical system,
The light distribution pattern on the screen of the projection light is imaged by a color camera for measurement,
The image processing apparatus receives a plurality of RGB data according to the light distribution pattern from the plurality of pixels of the color camera for measurement, and the color temperature of the projection light for each of the plurality of pixels selected by the camera for measurement. And determining a plurality of luminances Y for each of the plurality of pixels according to the equation Y = r × R + g × G + b × B based on
Determining at least one of an optical axis, a luminous intensity, and an elbow point for the headlight based on the plurality of luminances;
Test method of headlight by color image processing that includes.   54. The method of claim 53, wherein determining the rgb coefficient comprises measuring or estimating a color temperature of the headlight and determining the rgb coefficient based on the measured or estimated color temperature.   When determining the rgb coefficient, at least one reference rgb coefficient stored in the image processing device and determined based on the color temperature of the CIE standard light source, and at least one modified rgb coefficient 54. The method of claim 53, wherein the rgb coefficient is determined based on a corrected rgb coefficient of.   The light source type of the headlight is determined when the rgb coefficient is determined based on the estimation of the color temperature of the headlight, and a basic rgb coefficient determined in advance for each light source type is selected. Method. (A) selecting the basic rgb coefficients to determine a plurality of luminances Y;
(B) determining a provisional light intensity for the headlight based on the plurality of luminances Y;
(C) When the temporary light intensity exceeds the tolerance and is different from the light intensity of the determined light source type, a new rgb coefficient is selected based on the temporary light intensity,
(D) determining a plurality of new luminances Y using the new rgb coefficients;
(E) determining the provisional light intensity again for the headlight based on the plurality of new luminances Y,
(F) Repeat steps (c) to (e) until the provisional light intensity exceeds the tolerance and does not differ from the light intensity of the determined light source type to determine the final light intensity for the headlight. Do,
57. A method according to claim 56 comprising.   When determining an optical axis when the headlight is in the traveling light mode based on the plurality of luminances, the image processing device finds the highest luminance among the plurality of luminances and determines the highest luminance. 58. A method according to any one of claims 53 to 57, wherein the position is determined as the optical axis.   In the case of determining the light intensity when the headlight is in the traveling light mode based on the plurality of luminances, the image processing device finds the highest luminance among the plurality of luminances and is determined in advance. 59. A method according to any one of claims 53 to 58, wherein the corresponding light intensity is determined from the highest brightness according to the relationship between brightness and light intensity.   The image processing apparatus corresponds to a road surface illumination point of the headlight among the plurality of luminances when determining the light intensity when the headlight is in the low light mode based on the plurality of luminances. 58. A method according to any one of claims 53 to 57, wherein the intensity of the position is sought and the corresponding intensity is determined from the retrieved intensity according to a predetermined relationship between the intensity and the intensity.   When determining the elbow point when the headlight is in the low light mode based on the plurality of luminances, the image processing device compares the plurality of luminances with each other to form a horizontal cut line and the horizontal cut. 58. The method according to any one of claims 53 to 57, wherein an oblique cut line having a predetermined angle with respect to the line is searched, and an elbow point of the headlight is determined as a position of an intersection of the horizontal cut line and the oblique cut line. Method according to paragraph 1.

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