JPS62189871A - Picture information reader - Google Patents

Abstract

PURPOSE:To eliminate the influence of dusts and to accurately measure the irregularity of illuminance by measuring shading data for plural times, and using the maximum value of the said measurement as shading data for each picture element, to determine a shading correction value. CONSTITUTION:During the detection of correction value, rays of light are repeatedly emitted for plural times from an illumination optical system (a). The rays of light transmit through an IR filter (b) inserted in a light path during the detection of correction value, an original (c), and a projection optical system (d), and received by a photoelectric conversion element (e). The output of the photoelectric conversion by the element (e) is transferred to a correction value detecting means (f), where a correction value chiefly based on the illuminance distribution of infrared rays included in the illuminating light is detected by arithmetic operation. In the picture reading of an original (c), a shading correction based on the above said correction value is applied on the output signal of the element (e) by a picture processing means (g).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image information reading device that obtains image information from a document by a charge conversion means, and more particularly to an image information reading device having a special F shading correction function.

[Prior Art] Conventionally, a transmitted light image of a transparent color original is converted into three primary colors, for example, R.
The colors are separated into (red), G (green), and B (blue), and a 3fiII image signal corresponding to each color separation image is obtained from the image sensor, and these three types of images are converted into digital image information. Image information reading devices that convert image information are generally known.

[Problems to be Solved by the Invention] However, in conventional image information reading devices of this type, " There is a problem in that the read image data becomes uneven due to vignetting and the like, making it impossible to obtain high-quality image data.

On the other hand, it is known that the scanned image data is corrected using a predetermined correction value that corresponds to the uneven illuminance. It changes depending on the magnification, so
The previous correction value cannot be applied as is.

Therefore, when determining the projection magnification, we measure the illuminance unevenness,
It is conceivable to determine the correction value each time.

However, in the case of this conventional method, the document holder,
Another problem is that accurate measurement of illuminance unevenness is not possible due to dust adhering to the optical system.

SUMMARY OF THE INVENTION An object of the present invention has been made in view of the above-mentioned problems.It is an object of the present invention to obtain accurate image reading data for enlargement and reduction, and to obtain uneven illuminance data corresponding to the enlarged/reduced screen. Another object of the present invention is to provide an image information reading device that can obtain high quality image data even if there is dust attached to the optical system.

[Means for solving the problem] In order to achieve this purpose, in an image information reading device that converts image information of a document into an electrical signal using a photoelectric conversion element,
a correction value detection means for measuring the illuminance distribution of the illumination light from the document reading optical system multiple times to determine the maximum value of each pixel as the illuminance distribution, and determining a shading correction value based on the illuminance distribution of the maximum value; The present invention is characterized by comprising an image processing means for performing shading correction on image information read by the photoelectric conversion element using the shading correction value detected by the detection means.

[Function] In the present invention, the illuminance distribution of the illumination light from the illumination optical system and the projection optical system is measured multiple times by the correction value detection means, the maximum value of each pixel is determined as the illuminance distribution, and the illuminance distribution of the maximum value is A shading correction value is determined based on this. Using the detected correction value, the image processing means performs shading correction on the image information read by the photoelectric conversion element. As mentioned above, since multiple measurements are taken and the maximum value of each pixel is used as the illuminance distribution, the influence of dust adhering to the document holder or optical system is eliminated, and accurate illuminance unevenness can be measured, resulting in high image quality. Image reading image data is obtained.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the basic configuration of an embodiment of the present invention.

In Fig. 1, a is an illumination optical system, b is an IR filter inserted into the optical path when detecting a correction value, C is an original, d is a projection optical system, e is a photoelectric conversion element, and f is a correction value detection means. . When detecting a correction value, the light is emitted from the illumination optical system a multiple times and passes through the IR filter b, the document C1, the projection optical system d, and is received by the photoelectric conversion element e.
The output is sent to the correction value detection means f, where a correction value based on the illumination intensity distribution of mainly infrared light of the illumination light is calculated and detected. Next, when reading the image of the original C, the image processing means g performs shading correction on the output signal of the photoelectric conversion element e based on the above-mentioned correction value.

FIGS. 2(A) and 2(B) show the respective spectral transmittances of typical negative films and reversal films. This figure (^) shows the unexposed spectral transmittance characteristics of a negative film, and this figure (B) shows the unexposed spectral transmittance characteristics of a universal film. Here, the horizontal axis represents wavelength, and the vertical axis represents transmittance. This figure (A).

As shown in (B), it is understood that both the negative film and the reversal film have high transmittance in the infrared region, for example, at wavelengths of 800 nm or more. Furthermore, it has been experimentally confirmed that the transmittance in the infrared region remains high and does not change depending on the transmittance in the visible region (approximately 350 to 700 nm). That is, 800n
It can be seen that by focusing on wavelengths in the infrared region of m or more, it is possible to measure illuminance unevenness on the light-receiving surface regardless of film image information. The embodiment of the present invention utilizes this principle to perform shave correction as detailed below.

FIG. 3 shows a schematic configuration of a film scanner according to an embodiment of the present invention.

In this figure, 1 is an illumination lamp that illuminates the film original;
2 is a condenser lens for condensing illumination light, and 3 is a heat shielding filter. These lamps 1, condenser lens 2, and heat shielding filter 3 constitute an illumination system. 4 is the filter exchange mechanism described later in FIG. 6, and 5 is the fifth
This is a shutter mechanism that will be described later in the figure. Reference numeral 6 denotes a sub-scanning system, which will be described later in FIG. 4, which scans the film original, and sequentially scans the film original in the vertical direction (sub-scanning direction) of the drawing, which is approximately perpendicular to the optical axis. 7 is the sensor 1 that detects the transmitted light of the film original.
It is a projection lens that forms an image on a single image, and has a zoom function that allows variable projection magnification.

Reference numeral 8 denotes a total reflection mirror that is rotatable around a pivot, and is located in the optical path (solid line position in the figure) during viewfinder observation. During film scanning, a known drive mechanism, such as a rotary It is driven by a plunger or the like and retreats. Reference numeral 9 denotes a focus plate of the finder, which is used by the user to observe the film original. 10
is a photometric sensor patterned on a transparent glass substrate.

The sensor 11 is a self-scanning type line sensor such as a CCD, and is perpendicular to the optical axis and in the scanning direction of the sub-scanning system 6 (
The numbers are written in the direction perpendicular to the drawing (main scanning direction) at a 90° shift from the sub-scanning direction. Reference numeral 12 denotes a light amount adjusting mechanism such as an aperture mechanism or an ND filter, which controls (adjusts) the illuminance of the light receiving surface of the line sensor 11 based on the photometric output of the photometric sensor IO. It is arranged.

Note that β-1 indicates the optical axis.

FIG. 4 shows a detailed configuration example of the sub-scanning system 6 of FIG. 3. In this figure, 21 is a scanning unit (carriage) that is supported movably in the direction of the arrow (sub-scanning direction) in the figure, and 22 is a guide that supports the scanning unit 21 in the moving direction of the arrow (sub-scanning direction). The rail 23 is a feed screw 24 and 2 which is rotated by a drive motor (26) to be described later to drive the scanning unit 21.
Reference numeral 5 denotes a support portion that supports the rail 22 and the feed screw 23 at both ends with respect to a base (not shown).

26 is a drive motor that rotates a feed screw to drive the scanning unit 21 in the direction of the arrow in the figure, and is a step motor that drives in steps according to the reading pitch of the sensor 11. A film document holder 27 is fixed on the scanning section 21 and moves together with the scanning section 21. 27
A and 27b are a pair of glasses of the holder 27, which sandwich the film original between them to improve the flatness of the film original. In particular, dust on the surfaces of the glasses 27a and 27b and on the surface of the film original sandwiched between the glasses 27a and 27b is located at a position approximately equivalent to the sensor light receiving surface due to the projection lens, so there is a problem that image information is lost due to dust. big.

28. 29 and 30 are switches for detecting the scanning start position, center position, and scanning end position of the scanning section 21, respectively, and corresponding projections 21a, 21b, which are integrally provided at three locations on the side surface of the scanning section 21, ON by 21c,
0FF (open/close). That is, the first switch 30
is ON, the scanning unit 21 is at the start position, and the second
When the third switch 29 is on, the scanning section 21 is at the center position, and when the third switch 28 is on, the scanning section 21 is at the scanning end position. Detection of the center position using the switch 29 is used when observing the entire screen using the finder 9.

FIG. 5 shows a detailed configuration of the shutter mechanism 5 of FIG. 3. As shown in FIG.

In this figure, 31 and 32 are the rotating shafts 31a, respectively.
, 32a are rotary plungers that rotate the light shielding plates 31 and 32 via rotating shafts 31a and 32a, respectively. Further, the range shown by the two-dot chain line in this figure is the screen range of the film original.

During viewfinder observation, the light shielding plates 31 and 32 are driven outward by the rotary plungers 33 and 34, and are in the open position shown by the broken line in this figure.When reading film original data, the rotary plungers 33 and 34 Accordingly, the light shielding plates 31 and 32 are driven inward and are in the light shielding position shown by the solid line. When the light-shielding plates 31 and 32 are in this light-shielding position, they are closed leaving a slit portion 31b with a width a so that only a portion of the film document facing the light-receiving portion of the sensor 11 is illuminated, and the remaining film is illuminated. The document portion is shielded from light by the shielding plates 31 and 32, thereby minimizing deterioration of the image quality of the read image data due to ghost flare and the like. It-11 is the optical axis similar to that in FIG.

FIG. 6 shows a detailed configuration of the filter exchange mechanism 4 shown in FIG. 3. In this figure, 35 is a filter holder that holds color filters etc. inserted into the optical path unit 1.
It is rotatably supported by a support shaft 35g. The filter holder 35 is provided with a transparent section 35b for viewfinder observation, and color separation filters 35c, 35d, and 35e for R (red), G (green), and B (blue), respectively, and further includes shading correction. An IR filter (infrared rays filter) 35f having a visible light cut characteristic is provided for measuring values and detecting dust and scratches on film originals or optical systems.

35a is a gear formed around the circumference of the semicircular filter holder 35. The filter holder 35 is rotated by the drive of the motor 37 via the small-diameter gear 36 and the above-mentioned large-diameter gear 35a that meshes with this gear 36, and the transparent portion 35b and the It, G, B, Ill filter part 35c are rotated. , 35d, 35e, and 35f are selectively inserted into the optical path it-1.

Further, on the side surface of the filter holder 35, the optical path A-
Pattern electrodes 38a, 39a, 40a, 41a, 42a, 4 for detecting the position of the filter inserted in J2
3a is installed. That is, the electrode 43a is placed corresponding to the position of the transparent portion 35b, the electrode 39a is placed corresponding to the position of the R filter 35c, the electrode 40a is placed corresponding to the position of the G filter 35d, and the electrode 40a is placed corresponding to the position of the B filter 35e. An electrode 41a and an electrode 42a are arranged corresponding to the position of the IR filter 35f, and each of these pattern electrodes is electrically connected.

Furthermore, the above-mentioned electrodes 38a, 39a, 40a, 41a,
Brushes 38b and 3 correspond to brushes 42a and 43a, respectively.
9b, 40b, 41b.

42b and 43b are arranged. Now, if the electrode 38a
Assuming that the brush 38b that always follows is at ground level (earth potential), if the transparent section 35b is inserted in the optical path as shown in FIG. 6, the brush 43b becomes low level, and the R filter 35c is inserted, the brush 39b becomes low level and the G filter 35
When B filter 35e is inserted, the brush 40b becomes low level, and when the B filter 35e is inserted, the brush 41b becomes low level, and! R filter 35f
When the brush 42b is inserted, the brush 42b becomes low level. 1-1 is an optical axis similar to that in FIG.

FIG. 7 shows the overall spectral sensitivity including the spectral sensitivity of the linear sensor 11 with respect to the spectra of the R, G, B, and IR filters 35G, 35d, 35e, and 36f of the filter holder 35. Here, the horizontal axis is the wavelength.

The vertical axis represents sensitivity. As shown in this figure, IR filter 3
While using 5f, the linear sensor 11 performs photoelectric conversion especially at wavelengths in the infrared region of 80 Qnm or more.

In FIG. 8, B is a visible light filter (for example, B 7
47L'ta 358), IR is In74 router 35f
(7) An example of output at the same position on the film is shown. That is, B and In in FIG. 8 are 1 of the linear sensor 11, respectively.
This shows the output of the line, and in B of this figure, the shading of the image on the transparent color film original ■-1 is
It is clearly reproduced as the size of the output. On the other hand, the output of the sensor 11 at the IR filter 35f shown in IR in this figure is a nearly constant output regardless of the magnitude of the image output of the sensor 11 at the B filter 35e shown in B, and the change in this waveform is Since it is considered to be due to uneven illuminance, it is possible to measure the uneven illuminance on the light receiving surface of the sensor 11 using the output of the sensor 11 when using the IR filter 35f, but dust attached to the optical system etc., scratches on the film etc. The signal level is output only at a low level.

FIG. 9 shows the circuit configuration of the film scanner according to the embodiment of the present invention shown in FIG. In this figure, lot is a control unit that controls each motor and sensor according to the control procedure shown in FIGS. 1O to 12. 102 is a mirror drive unit that drives and controls the rotary plunger 8a that opens and closes the mirror 8; 103 is a shutter control unit that drives and controls the rotary plungers 33 and 34 of the shutter mechanism 5;
Reference numeral 104 denotes a filter control section that drives and controls the motor 37 of the filter exchange mechanism 4, and 105 indicates a scan control section that drives and controls the motor 26 of the sub-scanning system 6. IH is a sensor driver that drives and controls the linear sensor 11. 108 sequentially converts the output of the self-scanning type linear sensor 11 such as CCD into analog and digital.
It is a D (analog-digital) converter.

109 is a calculation memory for calculating a correction value for shading correction as described later from the illuminance unevenness data measured by the linear sensor 11 by inserting the IR filter 35f into the optical path, and storing the calculated correction value; This is a correction processing unit that applies shading correction to the image output of the A/D converter 10B based on the correction values stored in the memory 109.

Next, the operation of the embodiment of the present invention will be described in detail with reference to the flowcharts of FIG. 1O, FIG. 11, and FIG. 12.

Now, when observing a film original through the finder with the naked eye, the mirror 8 is in the optical path 1-J2, the center of the film original holder 27 of the sub-scanning system 6 is in the center of the optical path, and the shutter mechanism 5 Light shielding plate 31.
32 is in an open state, and the transparent portion 35b of the filter exchange mechanism 4 is further inserted into the optical path. User (operator)
In this state, the image condition of the film original is confirmed by the image on the focus plate 9 of the finder.

Next, when the start button 112 is pressed and a scanning start signal (start signal) 211 is generated (step Sl),
The control section 101 first outputs a mirror drive signal 201 to the mirror drive section 102 to retract the mirror 8 from the optical path using the rotary plunger 8a (step S2), and then outputs a shutter drive signal 202 to the shutter control section 103. , the pair of rotary plungers 33, 34 drive the light blocking plates 31, 32 of the shutter mechanism 5 to the light blocking position, thereby blocking harmful light such as ghost flare (
Step S3).

At the same time, the control unit 101 outputs a filter control signal 203 to the filter control unit 104 to selectively insert a color separation filter into the optical path.

First, the filter control unit 104 outputs the filter control signal 20
3, the filter 37 is driven until the IR filter 35f is inserted into the optical path, that is, until the brush 42b becomes low level (step S4).

When the brush 42b becomes low level, the filter control unit 104 returns a filter replacement completion signal 204 to the control unit 101, which means that the filter replacement is completed.

In the subroutine shown in FIG. 11 in step S5,
When the control unit 101 receives the filter replacement completion signal 204 (step 5101), the sensor driver 10
The reading start signal 207 is output to the driver 10.
6 drives the sensor 11 in response to this start signal 207 (step 5102). The output signal (image signal) 209 of the sensor 11 is sequentially converted into a digital signal by the A/D converter 108, sent to the calculation memory 109 and stored (step 5103), and the sensor 11 outputs the output signal 209 for a predetermined number of pixels. After that, reading of one line is finished (step 5104).

The control unit 101 generates a scan control signal 205 to the scan control unit 105, and upon receiving the scan signal 205, the scan control unit 105 drives the pulse motor 26 by a predetermined pitch.
The line sub-scanning ends (step 5105).

Thereafter, the process returns to step 5103, and the sensor 11 is driven in the same manner as described above to read one line, which is sequentially output to the memory 109 and stored. At this time, memory 1
09 compares the magnitude with the corresponding pixel output of already stored shading data, and stores the larger one as new shading data.

The processing of steps 5103 to 5105 is repeated a predetermined cycle (for example, 16 times), and reading of the shading data is completed (step 5106).

In this way, since the larger data read multiple times is always stored as shading data, it is possible to eliminate missing image data due to dust or scratches.

Then, the maximum number of shading data for each pixel (
M) max is calculated (step 5107), and then for each pixel, the maximum value (
M) Ratio of illuminance unevenness data in of each pixel to max,
That is, the following equation (1) is calculated to obtain and store the correction value Hn for each pixel (step 5108).

+In=(TA)max/Mn-=
(1) Correction value of Hn:n pixel (i) max: Maximum value of illuminance unevenness data Mn:n
The illuminance unevenness data of the pixel is then processed to the subroutine of FIG. 12 in step S6.
When the control unit 101 receives the filter replacement end signal 204 (step 5201), it transmits a scan start signal 205 to the scan control unit 105. Upon receiving the scan start signal 205, the scan control unit 105 first drives the step motor 26 until the sub-scanning system (carriage) 6 reaches the scan start position, that is, until the switch 30 is turned on (step 5202). The scan control unit 105 uses this switch 3
When 0 turns ON, it is determined that scanning has ended and the scanning end signal 2 is output.
06 is returned to the control unit 101. At this point, the preparatory operations for scanning the film document are completed.

After receiving the scan end signal 206 (step 5203), the control unit 101 outputs a reading start signal 207 to the sensor driver 106, and the driver 106 drives the sensor 11 in response to this start signal 207. sensor 1
1 output signal (image signal) 209 is sequentially converted into a digital signal by the A/D converter 108, outputted by a predetermined number of pixels, and sequentially input to the correction processing section 110. The processing unit 110 sequentially processes the output signal from the ^/D converter 108 into a correction value I of the corresponding pixel stored in the memory 109.
n is read out, multiplied, and sequentially outputted to the outside as image read data (step 5204).

゛After the sensor 11 outputs the output signal 209 for a predetermined number of pixels,
Finish reading one line. Upon completion of reading this one line (step 5205), the control unit 101
outputs a scan control signal 205 to the scan control unit 105, and the scan control unit 105 drives the pulse motor 26 by a predetermined pitch in response to the scan control signal 205 to scan one line of sub-scanning system 6. End the scan (step 5206
).

After that, the process returns to step 5204, and the sensor 107 is driven in the same manner as described above, and one line of image signal (IR multiplied signal) is read out.The above reading processing operation of steps 5204 to 5206 is repeated for a predetermined cycle (for one screen). (Step 5207), reading of the IR image data ends.

Next, returning to the main routine and proceeding to step S7, the control unit 101 operates the filter control unit 104 using the filter control signal 203 for filter replacement until the R filter 35c is located in the optical path 11, -11. , that is, until the brush 39b becomes low level,
The motor 37 is driven.

After the R filter 35c is selected in this way, the process proceeds to step S8, and the processing cycle is similar to the above-mentioned In screen reading (steps 5201 to 5208 in FIG. 12).
By repeating , the R screen data is read.

Step 59: GIlii surface data and 8-screen data are also read from the linear sensor 11 in the same manner as described above.
510, 511, 512), one screen reading of the film original is completed.

After this screen reading is completed, the control unit 101 operates the scan control unit 105 using the scan control signal 205 to control the motor 2.
6 moves the sub-scanning system 6 to the center position of the sub-scanning (step 513), and after the drive is completed, that is, after the switch 29 is turned on, the motor 37 is operated by the filter control signal 203 via the filter control unit 104. to insert the transparent portion 35b into the optical path (step 514), operate the mirror drive unit 102 according to the mirror drive signal 201 to return the mirror 8 to the optical path (step 515), and at the same time operate the shutter control unit 1 according to the shutter drive signal 202.
03 to operate the rotary plungers 33.34 to open the light shielding plates 31.32 (step 51G
). With the above processing, a series of processing operations for screen reading of film originals is completed.

In this embodiment, °C shading data is measured based on the characteristics of infrared light, and the correction value is determined based on that data. It goes without saying that a similar effect can be obtained by measuring shading data using light.

Further, the same effect can be obtained even if the shading data is created from a part of the IR data.

[Effects of the Invention] As explained above, according to the present invention, the shading data is measured multiple times, and the maximum value of the multiple measurements for each pixel is used as the shading data, and the correction value is determined based on that. ,■ It is possible to correct for changes over time in the lighting system, especially the lighting lamps, ■ Even if there is dust in the shading data, it is possible to obtain accurate shading data, and ■ Each of the image sensors It is also possible to correct unevenness in pixel sensitivity; ■ Even if unevenness in illuminance changes due to a change in projection magnification, it can be accurately corrected. Furthermore, shading data can be measured in the same way using infrared light. By doing so, remarkable effects such as (1) being possible to measure illuminance unevenness even if there is a document in the optical path can be obtained.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the basic configuration of an embodiment of the present invention, Fig. 2 (^) and (B) are characteristic curve diagrams showing the spectral transmission characteristics of the film in an unexposed state, and Fig. 3 is an embodiment of the present invention. 4 is a perspective view showing an example of the configuration of the sub-scanning system 6 in FIG. 3; FIG. 5 is a perspective view showing an example of the configuration of the shutter mechanism 5 in FIG. 3; FIG. 6 is a perspective view showing an example of the configuration of the filter exchange mechanism 4 shown in FIG. 3, FIG. 7 is a characteristic diagram showing the spectral sensitivity of each R, G, B, and IR filter, and FIG. An output waveform diagram showing an example of the output of the sensor 11 at the same position as the film of the IR filter, FIG. 9 is a block diagram showing the circuit configuration of the color scanner of FIG. 3, FIGS. 10, 11, and 12 are 8 is a flowchart showing a control procedure of the control unit 101 in FIG. 7. FIG. DESCRIPTION OF SYMBOLS 1... Lamp, 2... Condenser lens, 3... Heat protection filter, 4... Filter exchange mechanism, 5... Shutter mechanism, 6... Sub-scanning system, 7... Projection lens, 8... Total reflection mirror, 9... Focusing plate, 10... Photometry sensor, ]1... Sensor, 12... Light amount adjustment mechanism, 26.37... Motor, 27... Film original holder, 31.32--Light shielding plate, 35--Filter holder, 101--Control unit, 102-Mirror drive unit, 103-Shutter control unit, 104-Filter control unit, 105... Scanning control section, 106-: Sensor driver, 108... ^10 converter, 109... Arithmetic memory, 110... Correction processing section. Negafu 4 Lum/I tL-I: Spectrum of ・U U Ubo ・ Potato Fang ・ 1 To 1 Diagram Bas' - Sal Large Lum Power 11 1 ・ 1 Minute 1
Bamboo showing 41 tsubo folds) ji Fig. 2 (B) Fig. 4 Risei Ike J/l Shima ivy 4J! 5th grade of the 5th year of the 5th year of the 5th year of the 5th year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year of the year 1 1 , asking for firewood 6
Figure 6 Speed envy (nm) R, G, BJRf) @ - S) Lter's division 1
Blue, Figure 11, Figure 7, Figure 8, Example of projection a - Tatto beak, 1 Zoroku, Figure 9, Flownayat of the subroutine of the real Puhii, Figure 11.

Claims (1)

[Scope of Claims] 1) a) An image information reading device that converts image information of a document into an electrical signal using a photoelectric conversion element, and b) measuring the illuminance distribution of illumination light from a reading optical system of the document multiple times. c) correction value detection means for determining a shading correction value based on the illuminance distribution of the maximum value; 1. An image information reading device comprising: image processing means for applying shading correction to image information read by a conversion element.