KR20030074967A - optical measuring method - Google Patents

Abstract

The present invention relates to a method for measuring the brightness, luminance, chromaticity, color temperature, illuminance, and light emission angle (direction angle) of an object, which can be easily obtained using a personal computer (PC) and an image camera using a dedicated program. It is about a method.

To this end, the present invention separates the light source into three primary colors of light, red, blue, and green, in order to be received from an image camera and displayed on a computer monitor, and each value thereof is stored in a video memory. The brightness, luminance, chromaticity, color temperature, emission angle, and illuminance can be measured by the calculation formula. In addition, the shape of the light source can also measure the shape of special light sources such as triangular, rectangular, and ellipse.

The present invention is equipped with a computer and a Mars camera, and then by installing a measurement program on the computer can perform the various measurements described above relating to light.

Description

Optical measuring method using a computer image camera {optical measuring method}

According to the present invention, the conventional measuring equipment is composed of a luminance, luminance meter, chromaticity meter, color temperature meter, and luminous angle meter separately according to the measurement item. Because it is possible to measure, it is impossible to measure the whole light source, it is difficult to obtain accurate measurement value, and it is fixed type, which limits the size and distance of the light source. In addition, when the light emission angle (direction angle) measurement changes the light source in the left and right directions, the sensor in the fixed position converts the sensor in the left and right directions after fixing the light source as opposed to the method of measuring the change of light according to the conversion angle. Since the measuring method is used, when measuring an ellipse or a rectangular light source, rotate the light source by 90˚ after measuring the vertical direction. This will take a long time to turn on the way that must be measured, there is a problem in the larger measurement error due to the measurement source movement.

The present invention is to solve the above problems, the light is composed of a combination of red, blue, green (three primary colors) by using an image camera and an optical measurement program, the three primary colors received from the camera It is stored in the video memory and displayed on the monitor. When the three primary colors of the measurement range are read from the video memory by the measurement program and the values of each of the three primary colors are 256 steps, 256 * 256 * 256 = 16,777,216 color values are obtained. If the separation step is changed by the setting value of the program, the color to be decomposed can be increased or decreased.If the resolution and the area of the light source and the measurement distance are combined and converted and adjusted by the program, the brightness, luminance, It is possible to measure chromaticity, color temperature, illuminance, light emission angle (direction angle), and light source measurement in the form of triangle, square, rectangle, ellipse or special light source By setting the range of the desired shape to measure the shape of the light source input from the camera, the data value of the desired light source shape can be calculated by taking the video memory data value of the portion corresponding to the range.

In addition, the zoom in and zoom out functions of computers and video cameras can be used to overcome the limitations of the size and distance of the light source. It can be obtained automatically by using the angle correction filter on the front of the image camera for precise distance measurement.

The area of the light source can be automatically calculated by the sum of the pixel areas within the set measurement range by applying the proportion of the pixel area of the monitor and the area of the measured light source.

The angle of light emission (orientation) is measured by measuring the shape of the light source from the camera to the left and right lengths and the top and bottom lengths, and measuring the distance from the light source to obtain an angle by a trigonometric function. Can be obtained.

It is an object of the present invention to provide a measuring method capable of performing various optical measurements using a single device using the above method.

9 is a light measurement program full screen

10 is a luminance value measurement screen diagram

11 is a chromaticity value measurement screen diagram

12 is a color temperature measurement screen

13 is an illuminance measurement screen diagram

14 is a light emission angle measurement screen

The optical measuring method according to the present invention will be described in detail as follows.

(1) photometric measurement

In general, luminance is used when comparing different light sources or measuring their intensity.

Luminous Intensity (l) refers to the force by which a light source or an illuminated surface emits light in a particular direction. 1

The unit is candela (cd).

1 candela = average spherical brightness of 100W bulb

Luminance (L) = Luminous flux / direction angle emitted in one direction

The intensity of light is received from the image camera and the light source displayed on the computer monitor is reduced and enlarged according to the size of the light source and the distance from the light source. It reads all video memory values of three primary colors (Red, Green, Blue), and the sum of those memory values is the basic value of brightness, and the program displays the correct value on the computer monitor through the standard sample value and contrast adjustment conversion step. .

(2) luminance measurement

The brightness of the surface that emits or reflects. The brightness indicates how bright the light from the light source enters the eyes or enters the eyes after being reflected on the surface of the object.

The appearance of an object is affected by the amount of light the object emits or reflects relative to its surface area. The concept of brightness on this surface is called luminance.

Luminance is a measure of how much light or reflecting surface area can give a bright feeling. 2

The unit of luminance is the candela per unit area, the luminance of the displayed light source (L) = the luminance in a given direction / the area of the light source seen in that direction (unit: cd / m²)

The area of the light source is calculated by calculating the proportion of one pixel area on the monitor and the actual area corresponding to one monitor pixel of the measurement light source, and automatically calculating the number of pixels within the set range by the program. The luminance value is obtained by substituting the measured luminance value into the formula.

3

For example, if you want the luminance measured value of the arrow in Fig. 3, grab the arrow screen to obtain the brightness by the method of photometric measurement, and automatically calculate the number of computer monitor pixels in the arrow. The area is matched by a proportional formula, the area of the measured light source is calculated, and the brightness value is obtained by the application program to the brightness formula.

In the same way, any particular type of light source can be measured.

(3) chromaticity measurement

It is called the Munsell symbol and is a visualized system of color.

This labeling standardizes the method of marking colors by a mathematical method determined by the CIE method.

The xyz color space, represented by replacing all spectral curves with x, y, and z coordinate values, was established in 1931.

This is a graph of the chromaticity diagram of the CIE.

The saturation of the color is higher toward the edge, and the saturation is lower toward the center.

The perimeter of this graph is the visual range of the human eye and encompasses the presentation area according to all devices.

Chromaticity coordinate calculation

Calculate the x, y, z coordinates of the measured wavelength distribution.

X =

Y =

Z =

P ( ): Intensity according to wavelength

: Orange, red, green, blue

Since color depends on relative values, the three values of X, Y, and Z are normalized to X + Y + Z as follows:

Each can be referred to as x, y, z, and can be used as a coordinate value representing a color.

Here x + y + z is kept at 1 by normalization, so one color is represented by two values of x, y, and z.

When the color of the light is expressed by x, y, z values, the absolute brightness information of the light disappears.

However, since the X, Y, and Z values can represent the brightness of light, the colors are named as x, y, and y, which is called CIE chromaticity.

The part of the horseshoe that appears in chromaticity coordinates corresponds to monochromatic light, and the spectral distribution of the sun

It will be a white area in the center.

The measured data obtained by substituting the three primary color intensity values measured in the photoluminescence process into the above formulas are applied to the chromaticity coordinate values and the CIE chromaticity diagram to express the measured data.

(4) color temperature measurement

The most convenient way to define the color of a light source is to quote the color temperature.

Based on the property that all materials have a constant radiation pattern as the temperature increases

By analyzing the radiation distribution of the light source and calculating the temperature of the light source inversely, the color temperature can be known.

Radiation distribution of the light source means the color of the light source, so the temperature of the light source is calculated by looking at the color of the light source.

Black-> Red-> Orange-> Yellow-> White-> Yeoncheong-> Jincheong

If it is less than 5000K, it is red, and if it is as high as 7000K, it is blue.

The color temperature of the light source is the temperature of the black body when the colors of the light source are the same.

, Unit of color temperature is Kelvin (k))

Kelvin = Absolute Temperature = Celsius + 273

The value of the three primary colors calculated in the photometric process is matched with the color temperature of the x and y coordinates to the color temperature on the color coordinates to obtain data values through the program.

Find the color temperature by looking at the absolute temperature table. 5

Spectral spectrum of color temperature Figure 6

For reference, typical color temperatures of sunlight are as follows.

Clear Blue Day Sky --- 10000 ~ 20000K

Cloudy blue sky --- 8000 to 10100k

Cloudy sky --- 7000K

Sunlight through the cloud (noon) --- 6500K

Summer and Average Sun (10 am~3pm) --- 5500K

Morning and afternoon late hours sunshine --- 4000 ~ 5000K

Sunlight at sunrise and sunset --- 2000 ~ 3000K

(5) Light emission angle measurement (direction angle measurement)

In the method of measuring the light emission angle, the light emission angle can be obtained by a trigonometric function by measuring the left and right lengths and the top and bottom lengths of the shape of the light source and measuring the distance from the light source.

The program allows you to obtain angle measurements in chart form or numerical values at once.

7

Example of measurement of emission angle of elliptical light source

8

The shape of the light source to be measured is divided by x, y (line shown in red) of the light source shown in the installed image camera, and then the screen pixel values of each light source are sequentially read. By substituting the values, the data values may be displayed on the graph of FIG. 14 to calculate the light emission angle of the light source.

College official

Right angle = Upward angle tan =

Left angle = Downward angle tan =

(6) roughness measurement

When the speed of light reaches a surface, the surface becomes bright, which is the effect of illumination.

Illuminance refers to the density of the light beam reaching the plane.

The unit is lux (lx). (1 lux = 1 lumen / square meter of 1cd total luminous flux is 4 lumen)

Roughness (E) = F / A

E = brightness 4 / Area of camera (㎡)

F: Sum of the beams reaching the plane (lumen lm)

A: The measured value can be obtained by using the formula of the area (square meter m²).

For reference, the illuminance we feel in our daily lives ranges from 0.2 lux (moonlight) to about 100,000 lux (daylight).

The luminance value calculated in the "(2) Luminance Measurement" process is changed to lumens (lm), and the illuminance measurement value is obtained by dividing the area (lens area of the image camera) on which the light is incident.

<Description of operating program>

Program operating environment

Program Name: BRIGHTNESS VER1.0

Operating program minimum operating environment

-CPU Pentium III 800MHz or higher

Operating system: Windows 95, 98, ME

-REM: more than 125MB

-HDD: 500MB or more

VGA: 32MB or more of video memory

-USB Port Ver2.0 or higher

Image camera

<Program Overview>

This program uses video information of a general video camera.

The total luminance value of the video screen displayed by the image camera and each of red, green, and blue

It is an operation program that displays data values of advertisement, luminance, illuminance, chromaticity, color temperature, and emission angle (directed angle) in real time using average values.

<Key features>

-Real-time display of luminance, luminance, chromaticity, color temperature, emission angle (directed angle) and illuminance data

-AVI video file creation function

-BMP file creation function

<Program Menu Diagram>

File capture file Save as: Rename "cature.avi"

Exit Exit the operating program

Edit copy ctrl + c: Copy the camera screen.

Paste: Can be inserted into any program.

Properties: Set the first screen of program and avi format.

Format Screen Size (Format): Set the image camera screen.

PC camera (Source): Provided by the video camera company.

Display

Compress: Sets the video compression codec.

Preview

Overlay

<none>

Capture Capture one frame (single freame): Save the "* .bmp" screen.

Frames: "capture.avi" Save the screen you want.

Video: Save as “capture.avi” file in real time.

Measurement Brightness: Displays the window to measure the brightness value.

Colorimetry: Displays the window for chromaticity measurement.

Color temp: Displays the chart which shows the color temperature.

Illumination: Displays a window to measure illuminance values.

Luminous Angle Measurement: Displays the chart that can measure the range of the direct angle

Help System Info: Displays the information of the operating PC.

Dong Kwang Electronics Co., Ltd. (About): Company Information

<Description of the operating program main screen>

Main Screen and Luminance Measurement

9

Display of each measured value

① luminance measurement

10

② chromaticity measurement

11

③ Color temperature measurement

Figure 12

④ roughness measurement

13

⑤ Measurement of emission angle

14

As described above, the present invention is a computer camera and the present development program, which measures the brightness, luminance, chromaticity, color temperature, emission temperature (direction angle) and illuminance without any equipment, and reads the video memory of the computer by the program. Since the measured value is calculated and displayed by adjusting and converting, it is possible to measure according to the setting of the measurement range regardless of the shape of the light source. Of course, you can do the measurement you want with one measurement.

Claims (4)

In the optical measuring method using a computer camera, the light source input from the image camera and displayed on the computer monitor is reduced or enlarged according to the size of the light source and the distance from the light source. How to read and adjust the brightness of the three primary colors of the video memory to find the brightness. Luminance is determined by photometric method, but the shape of the light source is triangle, rectangle, ellipse or unusual light source type, the range is set as desired on the monitor, and the pixel area within the set range is calculated by calculating the proportional relationship between the pixel area of the monitor and the measurement object A method of calculating the luminance of a light source by substituting the luminance value and the area of the light source obtained by the photometric method by automatically processing the real area by calculating the number of. A method of displaying chromaticity and color temperature on color coordinate values and chromaticity diagrams as values of three primary colors measured by photometric method. A method of obtaining illuminance applied to a formula by a program by measuring the lens area of an image camera and measuring it by photometric method. Roughness (E) = (luminosity / 4 ) / Lens area of the camera (㎡) (Lux) [ Claim 5 ] In the center of the light source, the values of the horizontal side and the vertical side are taken in the form of lines in sequence, the size of the pixel and the number of pixels are calculated as the length, and the distance from the light source is applied to the trigonometric function. The method of automatically calculating the light emission angle on the vertical side and displaying it in numerical values and graphs. [ Claim 6 ] How to measure regardless of size or distance using the zoom in / out function of the camera