JP2010157988A - Color evaluation method and color evaluation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color evaluation method for easily recognizing an actual color difference from an ideal color. <P>SOLUTION: A color evaluation method of one embodiment includes the steps of: (a) measuring wavelength strength distribution of light from an object or three stimulus values based on the light; and (b) obtaining an XYZ value or an RGB value from the measured wavelength strength distribution, searching for a hue and a saturation on the basis of the XYZ value or RGB value, and creating a distribution figure indicating positions of the searched hue and saturation, the distribution figure expressing the hue in a direction of a deviation angle and expressing the saturation in a direction of a moving radius. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a color evaluation method and a color evaluation system for evaluating the color of an object and the color displayed on a display device.

  Conventionally, a color system such as an XYZ color system or a UCS color system defined by CIE has been used for evaluating colors displayed on a display device. The color evaluation methods disclosed in the following Patent Document 1 and Patent Document 2 evaluate colors displayed on a display device using such a color system.

JP 2002-209230 A JP 2002-218261 A

  A chromaticity diagram used for conventional color evaluation is a diagram in which the color space is distorted. Further, in the conventional chromaticity diagram, the symmetry of the positions of the primary color and the secondary color is poor, and white is not located at the origin. Therefore, in the conventional chromaticity diagram, it is difficult to grasp an actual color difference with respect to an ideal color of an object or an ideal color to be displayed by a display device on a color space.

  An object of the present invention is to provide a color evaluation method and a color evaluation system that make it easy to grasp the difference between actual colors and ideal colors.

  The color evaluation method of the present invention includes (a) a step of measuring a wavelength intensity distribution of light from an object or a tristimulus value based on the light, and (b) obtaining an XYZ value or an RGB value from the measured wavelength intensity distribution. The hue and saturation are obtained based on the XYZ value or RGB value, the hue is taken in the declination direction, and the saturation is taken in the radial direction, showing the obtained hue and the position of the saturation. Creating the distribution map.

  The color evaluation system of the present invention includes (a) a wavelength intensity distribution of light from an object or a tristimulus value based on the light, and (b) a wavelength intensity measured by a means of measuring the wavelength intensity distribution. An XYZ value or RGB value is obtained from the distribution, hue and saturation are obtained based on the XYZ value or RGB value, and the hue is set in the declination direction and the saturation is taken in the radial direction. And means for creating the distribution map showing the hue and the position of the saturation.

  In the present color evaluation method and color evaluation system, the wavelength intensity distribution of light output from a display device as an object or the tristimulus value based on the light may be measured.

  The distribution chart created by the present color evaluation method and color evaluation system has hue (H) in the declination direction and saturation (S) in the radial direction, and distortion in the declination direction and radial direction is Absent. Therefore, according to this distribution diagram, when the object is, for example, a printed material or a dyed object, the actual color of the object in a specific environment is cyan, magenta, It becomes easy to grasp an actual color difference with respect to an ideal color, such as which direction of yellow is shifted. Further, according to the distribution diagram, when the object is a display device, the actual color with respect to the ideal color, such as in which direction the color output from the display device is shifted in red, green, or blue, etc. It becomes easy to grasp the difference between the two.

  The distribution diagram is equivalent to a display format of a vector scope that measures the distortion of an electrical color signal. Therefore, the output of the vector scope can be used together with the distribution map in the present invention such as superimposing on the distribution map. This makes it possible to compare the ideal color value, the color signal measured by the vector scope, and the color value obtained by this color evaluation method. As a result, the difference between the actual color value and the ideal color value can be separated into an electrical factor and a factor specific to the display device.

  In the present invention, as a means for measuring, a colorimeter using a color filter having a transmission spectrum corresponding to the XYZ color matching function, or a spectrophotometer that obtains light intensity for each wavelength component by splitting input light. A color meter may be used. A colorimeter using a color filter has the advantage of being a simple device. In addition, since the spectrocolorimeter can output the wavelength intensity distribution, it can provide the wavelength intensity distribution together with the above distribution diagram, and the color value of the color value due to the difference in the wavelength intensity distribution of the display devices with different coloring methods can be provided. It is also possible to provide information such as subtle differences.

  Further, the spectrocolorimeter includes an optical fiber having an end surface for receiving light, an adapter for defining a distance between the end surface of the optical fiber and an object, a spectroscopic element for splitting light output from the optical fiber, And a plurality of light receiving elements that receive light separated by the spectral element for each wavelength component. According to such a spectrocolorimeter, the distance between the end face of the optical fiber and the display device can be kept substantially constant by the adapter, so that a stable spectral distribution can be obtained.

なお、ａ及びｂは定数である。また、ＭＩＮ、ＭＡＸはそれぞれ、ＲＧＢ値のうちの最大値、最小値である。 In the present invention, using the RGB values obtained by converting the RGB values or the XYZ values, the hue H and the following formulas (1a) and (1b) or the following formulas (1a) and (1c) are used. It is preferable to obtain the saturation S.

Note that a and b are constants. MIN and MAX are the maximum value and the minimum value of the RGB values, respectively.

  By displaying the hue and saturation obtained by (1a) and (1b) or the following expressions (1a) and (1c) on the distribution map, when a = b = 1, The positional relationship between red, green, and blue can be an equilateral triangle, and the positional relationship between cyan, magenta, and yellow can be an equilateral triangle. The origin is white. Therefore, a distribution map that is very easy to understand can be obtained. Further, the distribution diagram is equivalent to a vector scope. Further, by selecting the values of a and b, a desired color area can be enlarged. That is, when it is desired to enlarge a color region such as a skin color, | a | <1 may be set.

ここで、ａ及びｂは定数である。 In the present invention, it is also preferable to obtain the hue H and saturation S based on the following equation (2) using RGB values obtained by converting RGB values or XYZ values.

Here, a and b are constants.

  In the first quadrant of the distribution map obtained by equation (2), the secondary color is located in the positive direction of the coordinate axis, and the primary color is located in the 45 degree direction. Further, in the distribution diagram, the negative direction of each coordinate axis is a direction representing a primary color which is a complementary color of the secondary color. Therefore, by using this distribution chart, it becomes easy to determine the primary color to be corrected to approximate the ideal color and the correction amount of the primary color. The distribution map obtained by the equation (2) is suitable for a device that spontaneously emits light, such as a display device. However, a reflected light or a transmitted light with a printed material or a dyed object as an object. When light is to be measured, the same effect as when the object is a display device is obtained by switching the primary color and the secondary color with respect to the display device and shifting the phase of the hue by 45 degrees. Can do.

  As described above, according to the present invention, a color evaluation method and a color evaluation system that make it easy to grasp the difference between actual colors and ideal colors are provided.

It is a figure which shows the color evaluation system which concerns on one Embodiment of this invention. It is a figure which shows an XYZ color matching function. It is a flowchart which shows the color evaluation method which concerns on one Embodiment of this invention. It is a figure which shows an example of the distribution map displayed by the color evaluation system which concerns on one Embodiment of this invention. It is a figure which shows an example of the distribution map displayed by the color evaluation system which concerns on one Embodiment of this invention. It is a figure which shows the chromaticity diagram of the XYZ color system corresponding to FIG. It is a figure which shows the chromaticity diagram of the UCS color system corresponding to FIG. It is a figure which shows the chromaticity diagram of the UCS color system corresponding to FIG. It is a figure which shows the color evaluation system which concerns on another one Embodiment of this invention. It is a perspective view which shows the measurement unit in FIG. It is a figure which shows an example of the distribution map obtained by the color evaluation system which concerns on another embodiment of this invention. It is a figure which shows an example of the wavelength intensity distribution obtained by the color evaluation system shown in FIG. It is a figure which shows an example of the wavelength intensity distribution obtained by the color evaluation system shown in FIG. It is a figure which shows an example of the wavelength intensity distribution obtained by the color evaluation system shown in FIG. It is a figure which shows an example of the wavelength intensity distribution obtained by the color evaluation system shown in FIG. It is a figure which shows the color evaluation system which concerns on another one Embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a color evaluation system according to an embodiment of the present invention. A color evaluation system 10 illustrated in FIG. 1 includes a measurement unit 12, a calculation unit 14, and a display 16. Although the color evaluation system of the present embodiment includes the display 16, the color evaluation system of the present invention may not include a display and may output a signal supplied to a general-purpose display. Hereinafter, each component of the color evaluation system 10 will be described in detail.

  The measurement unit 12 receives reflected light or transmitted light from the object 100 whose color is to be evaluated, or light based on light emission, and generates a wavelength intensity distribution of the light.

  A spectrocolorimeter can be used as the measurement unit 12. The spectrocolorimeter includes, for example, a diffraction grating or a prism, and a light receiving element array (a one-dimensional line sensor or a one-dimensional photodiode array). In this case, light from the object 100 passes through the diffraction grating or prism, and light of different wavelengths is received by different light receiving elements of the light receiving element array. As a result, a wavelength intensity distribution of light is obtained from the light receiving element array.

  Note that the measurement unit 12 may generate tristimulus values (XYZ values) based on light from the object 100. In this case, a colorimeter can be used as the measurement unit 12. As the colorimeter, for example, a color meter including three color filters having XYZ color matching function transparency and three light receiving elements can be used.

ここで、S（λ）は、波長強度分布であり、x（λ）、ｙ（λ）、ｚ（λ）はそれぞれ、図２に示すようなｘ、ｙ、ｚの等色関数であり、Ｋは、任意の定数である。なお、測定部１２が上述した測色計の場合には、演算部１４は、測定部１２によって生成されるデータの三刺激値をＸＹＺ値として用いることができる。 The calculation unit 14 is a part that creates a distribution map indicating the position of the color of the object 100 using the data generated by the measurement unit 12. Specifically, when the measurement unit 12 generates a wavelength intensity distribution of light as data, the calculation unit 14 calculates an XYZ value from the wavelength intensity distribution based on the following equation (3).

Here, S (λ) is a wavelength intensity distribution, and x (λ), y (λ), and z (λ) are x, y, and z color matching functions as shown in FIG. K is an arbitrary constant. When the measurement unit 12 is the colorimeter described above, the calculation unit 14 can use tristimulus values of data generated by the measurement unit 12 as XYZ values.

Moreover, the calculating part 14 calculates an RGB value by applying the calculated XYZ value to the following formula (4).

  When the wavelength intensity distribution is obtained from the measurement unit 12, the calculation unit 14 uses the RGB color matching functions r (λ), g (λ), and b (λ) to calculate RGB values from the wavelength intensity distribution. It is also possible to calculate directly. In this case, x (λ), y (λ), and z (λ) in Equation (3) may be replaced with r (λ), g (λ), and b (λ).

  The calculation unit 14 obtains the hue H and the saturation S based on the formulas (1a) and (1b) using the calculated RGB values. Here, arbitrary constants can be used for a and b in the expressions (1a) and (1b). In the following description, it is assumed that a and b are “1”. Note that the expression (1c) may be used instead of the expression (1b).

  Further, the calculation unit 14 is a distribution diagram in which the hue is in the declination direction and the saturation is in the radial direction, and the distribution of the calculated hue H and saturation S, that is, the position of the colorimetric value (hereinafter referred to as the colorimetric value). "First distribution map") is created.

  Further, the calculation unit 14 obtains the hue H and the saturation S based on the equation (2) using the calculated RGB values, and the distribution chart in which the hue is set in the declination direction and the saturation is set in the radial direction. Then, a distribution map (hereinafter referred to as “second distribution map”) indicating the positions of the obtained hue H and saturation S, that is, the position of the colorimetric value may be created. Here, arbitrary constants can be used for a and b in the equation (2). In the following description, it is assumed that a and b are “1”. If a <0, the hue turns in the opposite direction.

  In the present system 10, the distribution map created by the calculation unit 14 is displayed on the display 16. The distribution map displayed on the display 16 may be either the first distribution map or the second distribution map, or one of them.

  Hereinafter, the operation of the color evaluation system 10 will be described with reference to FIG. FIG. 3 is a flowchart showing a color evaluation method according to an embodiment of the present invention. As shown in FIG. 3, in the present embodiment, first, in step S <b> 2, the measurement unit 12 of FIG. 1 measures the wavelength intensity distribution of light from the object 100. In step S2, tristimulus values based on light from the object 100 may be measured instead of the wavelength intensity distribution.

  Next, in step S4, the calculation unit 14 calculates the XYZ value by applying the wavelength intensity distribution measured by the measurement unit 12 to the above equation (3). When the measurement unit 12 measures tristimulus values, the tristimulus values may be used as they are as XYZ values. Next, in step S4, the calculation unit 14 calculates the RGB values by applying the calculated XYZ values to the above equation (4). Note that the RGB value may be directly obtained from the wavelength intensity distribution measured by the measurement unit 12.

  Next, in step S6, the calculation unit 14 applies the RGB values to the above formulas (1a) and (1b), or (1a) and (1c) to calculate the hue H and the saturation S. . Next, in step S8, the calculation unit 14 creates the first distribution map described above using the hue H and saturation S calculated in step S6.

  In step S6, the calculation unit 14 calculates the hue H and the saturation S by applying the RGB values to the above equation (2). In step S8, the calculation unit 14 uses the calculated hue H and the saturation S. The second distribution map may be created.

  Hereinafter, a distribution map created by the color evaluation system 10 will be described. 4 and 5 are diagrams illustrating examples of distribution maps created by the color evaluation system according to the embodiment of the present invention.

  The distribution diagram shown in FIG. 4 is obtained by measuring the light output from the display device when the display device as the object 100 is colored with a plurality of different colors, and measuring the light with the spectrocolorimeter. The XYZ values are calculated from the obtained wavelength intensity distribution, converted into RGB values, and the hue H and the saturation S are obtained from the RGB values. In FIG. 4, the distribution map shown on the left side is the first distribution map, and the three distribution maps shown on the right side are the second distribution maps.

  The distribution chart shown in FIG. 5 shows a plurality of colors obtained by gradually adding the other two primary colors in units of 1/8 of the maximum saturation to one of the three primary colors (RGB) given the maximum saturation. FIG. 2 shows a first distribution chart and a second distribution chart created by the color evaluation system 10 when the image is displayed on the display device. That is, the distribution chart shown in FIG. 5 shows the colorimetric values when a certain change in saturation is gradually applied to each primary color.

  For comparison, FIG. 6 and FIG. 7 show the chromaticity diagram of the XYZ color system and the chromaticity diagram of the UCS color system based on the measurement data obtained by the measurement unit 12 used to create the distribution chart of FIG. . Further, FIG. 8 shows a chromaticity diagram of the UCS color system based on the measurement data obtained by the measurement unit 12 used to create the distribution diagram of FIG.

  4 to 8, reference numerals R, G, B, C, M, Y, and W are red, green, blue, cyan, magenta, yellow, and white, respectively, displayed on the display device. The position of the colorimetric value is shown. Also, in FIGS. 4, 6, and 7, a smaller black circle than the others indicates an ideal position of the color value when an intermediate color is displayed on the display device. 4, 6, and 7, black squares indicate the colorimetric values when an intermediate color is displayed on the display device. In FIGS. 5 and 8, the black squares indicate the positions of the colorimetric values of the colors displayed on the display device as described above.

  As shown in FIGS. 6 and 7, in the conventional chromaticity diagram, the distance from white is different for each of the primary color and the secondary color. Also, the angle between the primary colors, the angle between the secondary colors, and the angle between the primary colors and the secondary colors are not constant. Therefore, the conventional chromaticity diagram includes distortion in the angular direction. Furthermore, as shown in FIG. 8, the conventional chromaticity diagram is a chromaticity diagram in which the amount of change in saturation increases as the saturation increases even if there is a certain change in saturation. Yes. Therefore, in the conventional chromaticity diagram, it is not easy to grasp the difference between the actual color and the ideal color, such as the direction in which the actual color deviates from the ideal color and the amount of the deviation.

  On the other hand, as shown in FIG. 4, on the first distribution chart obtained by the color evaluation system 10, the angles between the primary colors of red, green, and blue are constant, and cyan, magenta, and yellow The angle between the secondary colors is also constant, and the angle between the primary color and the secondary color is also constant. On the first distribution map, the white position is the origin of the distribution map. Further, in the first distribution diagram, the distance between white and each primary color is constant, and the distance between white and each secondary color is constant. Further, as shown in FIG. 5, on the distribution chart obtained by the color evaluation system 10, the amount of change in the saturation of the distribution chart is substantially constant with respect to the constant change of saturation. In FIG. 4, there is a difference between the ideal position of the color and the position of the measurement value when an intermediate color is displayed on the display device. This difference is due to a correction result such as gamma correction of the display device. It is.

  According to the first distribution diagram having the characteristics described above, it is possible to easily understand the direction in which the actual color deviates from the ideal color, and the correction amount for correcting the deviation in hue and saturation.

  Further, as shown in FIG. 4, in the second distribution diagram based on the equation (2), the secondary colors cyan, magenta, and yellow are distributed in the positive direction of the coordinate axis and are complementary colors of the secondary color (that is, Primary colors) are distributed in the negative direction of each axis. Therefore, according to the second distribution chart, it is possible to more easily grasp the primary color to be corrected when correcting a certain color and the correction amount of the primary color. The correction amount can be easily calculated because the conversion method is known.

  Since the color evaluation system 10 described above uses the measuring unit 12, unlike a color camera or the like, it can acquire data that does not depend on electrical characteristics, filter characteristics, or the like. Therefore, under a certain environment (daylight, fluorescent light, etc.), the hue and saturation inherent in the object can be measured, and the hue and saturation measured on a display device with good color reproducibility can be measured. The brightness (maximum intensity of RGB) is displayed, and the appearance and the measured value can be compared. It is also possible to measure the amount of color change when the environment is changed.

  In the above description, “a” and “b” in the expressions (1a), (1b), and (2) are “1”, but the color region is enlarged by appropriately adjusting a and b. It is also possible. That is, by setting | a | <1, it is possible to enlarge the difference in hue. Further, by setting b> 1, it becomes possible to enlarge the difference in saturation. Thus, by adjusting a and b, it is possible to capture a subtle color change.

  The above description relates to the evaluation of the color displayed by the display device, but the evaluation object of the color evaluation system 10 may be a printed material or a dyed object. The printed matter or the dyed object is obtained by subtractive color mixture using CMY as a primary color, and is different from a display device using additive color mixture using RGB as a primary color. Therefore, when a printed matter or a dyed object is used as an object, the axis of the second distribution map is corrected by performing a phase transformation of 45 degrees on the hue H calculated by the equation (2). RGB can be distributed in the direction, and CMY can be distributed in the negative direction.

  Here, an example of application of the color evaluation system when a printed material or a dyed object is used as an object will be shown below. For example, in clothing, printing, or dyeing, it may be desirable for a color to appear similar in various environments. In such a case, when an object made of the same material is placed in various lighting environments and the hue and saturation are acquired by the color evaluation system 10, how the hue and saturation change occur, It is possible to obtain information on whether the influence of the three primary color values in the direction is large with high accuracy. By using this result for material development and ink development, it becomes possible to develop a material that is resistant to environmental changes.

  Hereinafter, a color evaluation system according to another embodiment of the present invention will be described. FIG. 9 is a diagram showing a color evaluation system according to another embodiment of the present invention. The color evaluation system 20 illustrated in FIG. 9 includes a measurement unit 22, a first calculation unit 24, a second calculation unit 26, and a display 28. The display 28 may not be a component of the color evaluation system 20.

  The color evaluation system 20 is a system for evaluating the color displayed on the display device 120 based on signals (for example, RGB signal, YPbPr signal, etc.) generated by the color image generation device 110. For this purpose, the measurement unit 22 of the color evaluation system 20 acquires the wavelength intensity distribution of the light generated by the display device 120.

  FIG. 10 is a perspective view showing the measurement unit in FIG. The measurement unit 22 includes an optical fiber 22a, a spectroscope 22b, and an adapter 22c. The spectroscope 22b includes a reflective diffraction grating 22d and a line sensor 22e. In the measurement unit 22, light from the display device 120 enters one end surface of the optical fiber 22a, and the light exits from the other end surface of the optical fiber 22a and enters the reflective diffraction grating 22d. The reflective diffraction grating 22d reflects incident light in different directions depending on the wavelength, and the line sensor 22e receives light of each wavelength component. The line sensor 22e outputs a signal corresponding to the intensity of the received light. As described above, the measurement unit 22 measures the wavelength intensity distribution of the light from the display device 120.

  The adapter 22c in the measurement unit 22 is a component that keeps the distance between the surface of the display device 120 and one end face of the optical fiber 22a constant. The adapter 22c has a cylindrical shape or a cone-like cylindrical shape, and holds an optical fiber therein. The inner surface of the adapter 22c has a function of preventing intrusion of light from the outside by black coating or the like. With this adapter 22c, the measurement unit 22 can stably measure the wavelength intensity distribution of the light from the display device 120.

  Note that the measurement unit 22 may use a transmission diffraction grating element, a prism, or the like instead of the reflection diffraction grating. The line sensor 22e may be any device that can receive light, such as a device in which CCDs, CMOSs, or photodiodes are arranged in an array. The measurement unit 22 may be a colorimeter that measures tristimulus values instead of measuring the wavelength intensity distribution.

  The first computing unit 24 calculates the XYZ value by applying the wavelength intensity distribution measured by the measurement unit 22 to the above equation (3). When the measurement unit 22 is a colorimeter, the tristimulus values can be used as they are as XYZ values.

  The first calculation unit 24 applies the XYZ values obtained as described above to the above equation (4) to obtain RGB values. Note that the RGB value may be directly calculated from the wavelength intensity distribution.

  In addition, the first calculation unit 24 calculates the hue H and the saturation S from the RGB values as in the calculation unit 14 of the color evaluation system 10, and creates a first distribution map. The first calculation unit 24 may create a second distribution chart in the same manner as the calculation unit 14.

  The second calculation unit 26 receives the same signal as the signal that the color image generation device 110 gives to the display device 120, and obtains an RGB value from the signal. When the color image generator 110 outputs RGB signals, the RGB signals are used as they are as RGB values. If the color image generator 110 is a YPbPr signal, the YPbPr signal is converted into RGB values by a known conversion.

  The second calculation unit 26 uses the RGB values based on the signals received from the color image generation device 110 to calculate the hue H and the saturation according to the expressions (1a) and (1b), or (1a) and (1c). The degree S is calculated, and the positions of the hue H and the saturation S are displayed on the first distribution map. The second calculation unit 26 may further calculate the hue H and the saturation S by the expression (2) and display the positions of the hue H and the saturation S on the second distribution map.

  In the color evaluation system 20, the first distribution map and the second distribution map are displayed on the display 28. In the color evaluation system 20, the wavelength intensity distribution obtained by the measurement unit 22 may be further displayed on the display 28.

  Hereinafter, the distribution map created by the color evaluation system 20 will be described with reference to FIG. FIG. 11 is a diagram illustrating an example of a distribution diagram obtained by a color evaluation system according to another embodiment of the present invention. In FIG. 11, the left diagram is the first distribution diagram, the three diagrams at the center are the second distribution diagrams, and the right diagram displays the wavelength intensity distribution obtained by the measurement unit 22. .

  In the first distribution diagram of FIG. 11, smaller points around the origin indicate the hue and saturation obtained by the second computing unit 26, and the black squares around them are the first squares. The hue and saturation obtained by the calculation unit 24 are shown. As described above, the color evaluation system 20 can display the hue and saturation obtained by the first computation unit and the hue and saturation obtained by the second computation unit on the first distribution map. it can.

  The output of the first calculation unit 24 is hue and saturation information expressing the color of the display device 120 itself, and the output of the second calculation unit 26 is a signal output from the color image generation device 110 itself. Hue and saturation information. Here, the second calculation unit 26 has a function similar to that of a vector scope often used in broadcasting and editing.

  Therefore, according to the first distribution chart provided by the color evaluation system 20, it is possible to compare the output from the first calculation unit 24 and the output from the second calculation unit (that is, the output of the vector scope). it can. As a result, it is possible to extract the color misregistration factor specific to the display device.

  As shown in FIG. 11, the color evaluation system 20 can also provide a wavelength intensity distribution. Therefore, according to the color evaluation system 20, it is possible to grasp the deviation of the hue and saturation of light from the display device 120 with respect to the desired hue and saturation by the input signal to the display device 120, and further, the display device. It is possible to simultaneously observe the influence caused by the 120-specific spectral distribution. Note that the output display of the first calculation unit 24 and the output display from the second calculation unit 26 are not shown on the same distribution chart but may be shown separately.

  Hereinafter, examples of wavelength intensity distributions obtained by the color evaluation system 20 are shown in FIGS. 12 to 14 show the wavelength intensity distribution of a certain liquid crystal display. The wavelength intensity distribution when the display device 120 displays red (R), and the display device 120 displays green (G). 2 shows the wavelength intensity distribution when the display device 120 displays blue (B).

  As shown in FIGS. 12 to 14, a relatively sharp set of bright lines and a spectrum of the phosphor are observed, and it can be seen that the light emission pattern of the backlight is provided as color information substantially as it is. The measured values of hue and saturation at this time are (0.009, 0.8192), (2.1482, 0.8514), (−2.2686, 0.8204) in full display of R, G, B. )Met. The hue and saturation of the corresponding signal given to the liquid crystal display when obtaining this measured value are (0, 0.8165), (2.0944, 0.8165), (−2.0943, 0.8165), respectively. )Met.

  FIG. 15 shows the wavelength intensity distribution when red (RED) is displayed on the organic EL display. It can be seen that there is no bright line in the wavelength intensity distribution of FIG. 15, and the wavelength intensity distribution of the phosphor is obtained. The hue and saturation at this time were (−0.0144, 0.8356).

  Thus, it can be seen that the actual chromaticity of the light from the display device measured by the color evaluation system 20 deviates from the chromaticity of the original signal applied to the display device. By comparing the chromaticity of the original signal with the chromaticity measured by the color evaluation system 20 and referring to the spectrum distribution, it is possible to display what kind of property the circuit is caused by the circuit. It is possible to efficiently analyze whether it is due to the nature of the device itself.

  Hereinafter, still another embodiment of the present invention will be described. FIG. 16 is a diagram showing a color evaluation system according to another embodiment of the present invention. A color evaluation system 10A illustrated in FIG. 16 is different from the color evaluation system 10 in that the camera 18 is provided and the processing content of the calculation unit 14A is different from the calculation unit 14.

  Hereinafter, it is assumed that the object 100 is a color sample chart, and this color sample chart is illuminated under appropriate illumination conditions. In such an environment, the color evaluation system 10A performs camera calibration.

  In the color evaluation system 10A, the camera 18 captures the color sample chart 100 and obtains RGB values. Similarly, the measurement unit 12 measures the wavelength intensity distribution or tristimulus value of the light reflected or transmitted from the color sample chart 100.

  The calculation unit 14A calculates the hue H and the saturation S from the data measured by the measurement unit 12 in the same manner as the calculation unit 14, and creates a distribution chart (first distribution chart and / or second distribution chart). . The computing unit 14A calculates the hue H and the saturation S by applying the RGB values from the camera 18 to the formulas (1a) and (1b) or the formulas (1a) and (1c), A first distribution map is created. Further, the calculation unit 14 may calculate the hue H and the saturation S by applying the RGB values from the camera 18 to the equation (2) to create the second distribution chart.

  If the hue and saturation based on the data obtained by the camera 18 and the hue and saturation based on the data obtained by the measurement unit 12 are different, the direction and magnitude of the color shift can be known. Therefore, the camera 18 can be calibrated by rewriting the look-up table related to the color conversion of the camera 18 using the direction and size of the color shift.

  In the present embodiment, the display 16 can also be used for checking the rewritten lookup table. Note that the measurement unit 12 in this embodiment is a spectroscope with a lens in which a diffraction grating or the like is arranged at a position where an object is imaged because it acquires reflection or transmission of light when the color sample chart is illuminated. Is desirable. The lookup table is preferably a lookup table obtained by appropriately dividing the RGB color gamut, a so-called 3D lookup table, and the 3D lookup table is preferably rewritten.

  DESCRIPTION OF SYMBOLS 10,10A, 20 ... Color evaluation system, 12 ... Measurement part, 14, 14A ... Calculation part, 16 ... Display, 18 ... Camera, 22 ... Measurement unit, 22a ... Optical fiber, 22b ... Spectroscope, 22c ... Adapter, 22d Reflective diffraction grating 22e Line sensor 24 First calculation unit 26 Second calculation unit 28 Display 100 Object 110 110 Color image generator 120 Display device

Claims (10)

Measuring the wavelength intensity distribution of light from the object or a tristimulus value based on the light;
An XYZ value or RGB value is obtained from the wavelength intensity distribution or the tristimulus value obtained by the measuring means, a hue and saturation are obtained based on the XYZ value or the RGB value, and the hue is colored in the declination direction. A distribution map in which the degree is taken in a radial direction, and creating the distribution map showing the obtained hue and the position of the saturation; and
Including color evaluation method. The object is a display device;
In the measuring step, the wavelength intensity distribution of the light output from the display device based on the input signal or the tristimulus value based on the light is measured.
The color evaluation method according to claim 1. In the step of creating the distribution map, using the RGB values obtained by converting the RGB values or the XYZ values, the following equations (1a) and (1b), or the following equations (1a) and (1c) The hue H and the saturation S are obtained based on the following: where a and b are constants, and MIN and MAX are a maximum value and a minimum value of RGB values, respectively. The described color evaluation method.

In the step of creating the distribution map, the hue H and the saturation S are obtained based on the following equation (2) using the RGB values obtained by converting the RGB values or the XYZ values, The color evaluation method according to claim 1, wherein a, b are constants.

Means for measuring a wavelength intensity distribution of light from an object or a tristimulus value based on the light;
An XYZ value or RGB value is obtained from the wavelength intensity distribution obtained by the measuring means or the tristimulus value, and a hue and saturation are obtained based on the XYZ value or the RGB value, and the hue is declination. A distribution map having a radius as a radius, and means for creating the distribution map showing the obtained hue and saturation position;
Including color evaluation system. The measuring means measures a wavelength intensity distribution of light output based on an input signal from a display device as the object or a tristimulus value based on the light,
The color evaluation system according to claim 5.   The means for measuring is a colorimeter using a color filter having a transmission spectrum corresponding to an XYZ color matching function, or a spectrocolorimeter that obtains the intensity of light for each wavelength component by splitting input light. The color evaluation system according to claim 5 or 6, wherein there is a color evaluation system. The spectrocolorimeter is
An optical fiber having an end face for receiving light;
An adapter for defining a distance between the end face of the optical fiber and the object;
A spectroscopic element for dispersing light output from the optical fiber;
A plurality of light receiving elements that receive light separated by the spectral element for each wavelength component;
The color evaluation system according to claim 7, comprising: The means for creating the distribution map uses the RGB values obtained by converting the RGB values or the XYZ values, and the following equations (1a) and (1b) or the following equations (1a) and (1c): The hue H and the saturation S are obtained based on the following: where a and b are constants, and MIN and MAX are a maximum value and a minimum value of RGB values, respectively. The color evaluation system as described in any one.

The means for creating the distribution map obtains the hue H and the saturation S based on the following formula (2) using the RGB values obtained by converting the RGB values or the XYZ values, The color evaluation system according to claim 5, wherein a and b are constants.

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