JP7679650B2 - Display device primary color design system, display device primary color design method and program - Google Patents

Description

The present invention relates to a display device primary color design system, a display device primary color design method, and a program for designing the spectral radiance of the primary colors used in a display device.

Depending on the spectral characteristics of a display device such as a monitor, even when the same display screen is being observed, different display colors may be perceived due to individual differences in color matching functions between different observers.
As a result, when multiple observers evaluate the colors of a design displayed on the display screen of a display device, the same displayed color may be observed as different displayed colors by the different observers, making it difficult for the observers to communicate their understanding of the color evaluation.

Furthermore, as shown in Patent Document 1, in order to improve the image quality of displayed colors, the spectral characteristics of the primary colors of the display device are narrowed, thereby expanding the display color gamut, but on the other hand, individual differences in perception become more pronounced.
Patent Document 1 discloses a software method for performing color conversion of an image so as to reduce individual differences in color perception by adjusting the display color of the image based on a color matching function that differs for each observer.

Furthermore, Japanese Patent Laid-Open No. 2003-233663 discloses, as a hardware method, a method for designing the spectral characteristics of the primary colors of a display device so as to reduce individual differences in color based on color matching functions that differ for each observer.
In designing the primary colors of the display device, colorimetric values for each observer are obtained from the spectral reflectance of the object to be displayed and the spectral radiance of the light source, and the spectral distribution of the primary colors of the display device is optimized so that the color difference between the colorimetric values of the display device for each observer is small.

JP 2014-120796 A JP 2019-62285 A

However, in the technique disclosed in Japanese Patent Laid-Open No. 2003-233699, when each observer observes an image, it is necessary to carry out color conversion processing on the display colors based on the color matching function of each observer for each observed image.
Furthermore, in Patent Document 2, since the objects to be displayed are indefinite in fields such as digital cinema, the spectral distribution of the display device is designed based on the spectral reflectance of various objects, and the suppression effect against individual differences is incomplete for each object.
Furthermore, in Patent Document 2, since the light source in the object observation environment is indefinite, it cannot necessarily be said that the effect of suppressing individual differences can be obtained under a light source that was not used in the design.

The present invention has been made in consideration of such circumstances, and provides a display device primary color design system, a display device primary color design method, and a program for designing the spectral distribution (sometimes simply referred to as the spectral distribution) of the spectral radiance of the primary colors of a display device such that the displayed colors are observed similarly by multiple observers, without the need to correct the displayed colors for each observer.

In order to solve the above-mentioned problems, the display device primary color design system of the present invention is characterized by comprising: an object color calculation unit that calculates, as object colors, each of colors perceived by an object belonging to a predetermined material classification by each of color matching functions of different observers under a light source in an environment in which the object is observed ; a display color calculation unit that calculates an approximate composite spectral distribution of the display device that approximates each of the object colors and corresponds to each of the object colors, from the spectral distributions of candidate primary colors that are candidates for the primary colors of the display device and each of the color matching functions, and calculates, from the approximate composite spectral distribution, a display color when observed with the color matching function of one observer selected from observer candidates including each of the different observers; and a display device primary color optimization unit that calculates a color difference between the display color of the one observer and a reference that is determined based on the display colors of each of the observer candidates , and determines, based on the color difference , a spectral distribution of the primary colors of the display device that brings the color difference within a color difference range corresponding to the object, from the spectral distributions of the candidate primary colors.

The display device primary color design system of the present invention is characterized in that the classification includes at least one of the following: printed matter, painted matter, painting, skin, and fabric.

The display device primary color design system of the present invention is characterized in that, when the classification is the printed matter, the object is set in sub-classifications based on at least each combination of the substrate and ink to be printed.

The display device primary color design system of the present invention is characterized in that, when the classification is skin, the object is set at least in subclassifications according to body parts.

The display device primary color design system of the present invention is characterized in that , when calculating the object color, the object color calculation unit calculates the object color by integrating the product of the color matching functions of the different observers, the spectral reflectance of the object, and the spectral distribution of the environment over wavelength.

The display device primary color design system of the present invention is characterized in that the reference is the display color of a reference observer selected from the observer candidates, or an average of the display colors of each of the observer candidates .

The display device primary color design method of the present invention includes an object color calculation step in which an object color calculation unit calculates, as object colors, each of colors perceived by an object belonging to a predetermined material classification by each of color matching functions of different observers under a light source in an environment in which the object is observed ; a display color calculation step in which a display color calculation unit calculates an approximate composite spectral distribution of the display device that approximates each of the object colors and corresponds to each of the object colors, from each of the color matching functions and spectral distributions of candidate primary colors that are candidates for a light source of the primary colors of the display device , and calculates, from the approximate composite spectral distribution, a display color when observed with the color matching function of one observer selected from observer candidates including each of the different observers; and a display device primary color optimization step in which a display device primary color optimization unit calculates a color difference between the display color of the one observer and a reference that is determined based on the display color of each of the observer candidates, and determines , based on the color difference, from the spectral distributions of the candidate primary colors, a spectral distribution of the primary colors of the display device that brings the color difference within a color difference range corresponding to the object.

The program of the present invention is a program for causing a computer to function as: object color calculation means for calculating, as object colors, each of the colors perceived by an object belonging to a predetermined material classification using each of the color matching functions of different observers under a light source in an environment in which the object is observed; display color calculation means for calculating, from each of the color matching functions and the spectral distributions of candidate primary colors that are candidates for the light source of the primary colors of the display device, an approximate composite spectral distribution of the display device that approximates each of the object colors and corresponds to the object colors , and calculating, from the approximate composite spectral distribution , a display color when observed using the color matching function of one observer selected from observer candidates including each of the different observers ; and display device primary color optimization means for calculating a color difference between the display color of the one observer and a reference that is determined based on the display colors of each of the observer candidates, and determining, based on the color difference, from the spectral distributions of the candidate primary colors, a spectral distribution of the primary colors of the display device that brings the color difference within a color difference range corresponding to the object.

As described above, the present invention can provide a display device primary color design system, a display device primary color design method, and a program for designing the spectral radiance of the primary colors of a display device such that the display colors are observed similarly by multiple observers, without the need to correct the display colors for each observer.

1 is a block diagram showing an example of the configuration of a display device primary color design system according to a first embodiment of the present invention. 13 is a diagram showing an example of an observer selection screen that the color matching function selection unit 102 displays on the display screen of the display unit 109. FIG. 11 is a diagram showing an example of a selection screen for selecting an object category that the object category selection unit 103 displays on the display screen of the display unit 109. FIG. FIG. 11 is a diagram showing an example of selection items that the object classification selection unit 103 displays on the display screen of the display unit 109 in order to further classify printed matter. FIG. 11 is a diagram showing an example of selection items that the object classification selection unit 103 displays on the display screen of the display unit 109 in order to further classify skin. 11 is a diagram showing an example of a selection screen for selecting a light source category when observing an object displayed on a display screen of a display unit 109 by an ambient light selection unit 104 according to the first embodiment. FIG. FIG. 13 is a diagram showing an example of a screen for setting the shape and selecting the type of the primary colors of the display device, which is displayed on the display screen of the display unit 109 by the primary color spectral distribution setting unit 106. FIG. 2 is a diagram showing an example of the distribution shape of primary color spectral radiance (r(λ), g(λ), b(λ)) in the present embodiment. FIG. 13 is a conceptual diagram showing an example of a diagram in which the display device primary color optimization unit 108 compares average values of color differences of the primary colors observed; FIG. 13 shows a collection of color difference maps in which the display primary color optimizer 108 selects printed matter as an object classification and compares the average color difference values for each of the observed primaries. 1 is a diagram showing the spectral radiance of a light source used when a display device primary color optimization unit 108 calculates color differences of the primary colors of the display device in the first embodiment. FIG. 10 is a diagram showing the spectral reflectance of a substrate of a printed matter used when a display device primary color optimization unit 108 calculates color differences of the primary colors of the display device in the first embodiment. FIG. FIG. 13 shows a collection of color difference maps in which the display primary color optimizer 108 selects skin as the object classification and compares the average color difference of each of the observed primary colors. FIG. 13 shows a collection of color difference maps in which the display primary color optimizer 108 selects paintings (eg, oil paintings) as an object classification and compares the average color difference values for each of the observed primary colors. FIG. 13 shows a collection of color difference maps in which the display primary color optimizer 108 selects paintings (eg, watercolors) as an object classification and compares the average color difference values for each of the observed primary colors. FIG. 13 shows a collection of color difference maps in which the display primary color optimizer 108 selects printed matter as an object classification and compares the average color difference values for each of the observed primaries. FIG. 13 shows a collection of color difference maps in which the display primary color optimizer 108 selects skin as the object classification and compares the average color difference of each of the observed primary colors. 10 is a flowchart showing an example of the operation of a process for calculating a central wavelength and a half width of a primary color of a display device by the display device primary color design system of the present embodiment. FIG. 11 is a diagram showing an example of a selection screen for selecting a light source category when observing an object displayed on the display screen of the display unit 109 by the ambient light selection unit 104 in the second embodiment.

The present invention relates to a display device primary color design system that designs primary colors (color component R (Red), color component G (Green), and color component B (Blue)) of a display device that minimizes individual differences in colors perceived in an image when a plurality of different observers observe the same image in a general display device that displays an object.
In order to minimize the individual differences between multiple observers, the display device primary color design system of the present invention is configured to limit the objects to be observed by a predetermined classification and to specify the spectral radiance of the primary colors of the display device in accordance with the individual color characteristics of each object.

In addition, since the light source in the environment in which the object to be displayed is captured is generally indefinite, the device is configured to evaluate individual differences in the display device using multiple light sources, thereby improving the effect of suppressing individual differences without relying on a specific light source (corresponding to the first embodiment described below).
On the other hand, although the environment in which each of the objects to be displayed is generally indefinite, the present invention is configured to limit each of the objects, identify the light source to be irradiated onto each of the objects, and use that light source to improve the effect of suppressing individual differences (corresponding to the second embodiment described later).

First Embodiment
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an example of the configuration of a display device primary color design system according to a first embodiment of the present invention.
In FIG. 1 , the display device primary color design system 1 includes a data input unit 101, a color matching function selection unit 102, an object classification selection unit 103, an ambient light selection unit 104, an object color calculation unit 105, a primary color spectral distribution setting unit 106, a display color calculation unit 107, a display device primary color optimization unit 108, a display unit 109, a color matching function storage unit 110, an object spectral reflectance storage unit 111, an ambient light spectral radiance storage unit 112, a primary color spectral radiance storage unit 113, and an optimized primary color spectral radiance storage unit 114.

The data input unit 101 reads data such as the color matching functions of each human observer, the classification of objects and the spectral reflectance and spectral radiance of the ambient light of each object, and the spectral radiance of the primary colors of the display device from an external device, and writes and stores the data in the color matching function memory unit 110, the object spectral reflectance memory unit 111, the ambient light spectral radiance memory unit 112, and the primary color spectral radiance memory unit 113, respectively.

The color matching function selection unit 102 displays on the display unit 109 a group of color matching functions used when an object color calculation unit 105 (described later) calculates object colors (i.e., tristimulus values of object colors).
Then, the color matching function selection unit 102 reads out the color matching functions of the observer selected by the operator from each of the observers displayed on the display unit 109 from the color matching function storage unit 110 , and outputs the color matching functions to the object color calculation unit 105 .

FIG. 2 is a diagram showing an example of an observer selection screen that the color matching function selection unit 102 displays on the display screen of the display unit 109. As shown in FIG.
In FIG. 2, the CIE standard observer, the CIE supplementary standard observer, Publication data #1, Publication data #2, and Observer #1 are each shown as selected observers.
Each of the CIE standard observer and the CIE auxiliary standard observer is a common human being defined by the CIE, and color matching functions corresponding to these standard observers are provided by the CIE.

Paper data #1 is a group of many observers included in a paper on color matching functions, and color matching functions for each observer are shown.
The paper data #2 is a group of many observers included in a paper on color matching functions different from the paper data #1, and color matching functions for each observer are shown.
Observer #1 is a group of observers previously gathered by an operator or the like, and is, for example, a group of people with known color matching functions who belong to a group that determines colors in a design by observing the same image on the same display device (or the same type of display device), or a single observer.

Then, the color matching function selection unit 102 reads out the color matching functions of the observer selected by the operator from the color matching function storage unit 110 .
For example, when the operator selects each of the CIE standard observer, the CIE auxiliary standard observer, and observer #1, the color matching function selection unit 102 reads out the color matching functions of the CIE standard observer, the CIE auxiliary standard observer, and observer #1, respectively (color matching functions x _i (λ), y _i (λ), and z _i (λ), which will be described later), from the color matching function storage unit 110.

Then, the color matching function selection unit 102 outputs the read (i.e., selected by the operator) observer's color matching function to the object color calculation unit 105 .
Here, the observer can arbitrarily select one or more observer groups on the selection screen (multiple selections possible).

Returning to FIG. 1, the object category selection unit 103 displays on the display unit 109 the classification (object category) of the spectral reflectance of the object (substance) used when the object color calculation unit 105 described later calculates the object color.
Then, the object classification selection unit 103 reads out the spectral reflectance (object spectral reflectance) of the material of the object classification of the object selected by the operator from each of the object classifications, which are classifications of objects displayed on the display unit 109, from the object spectral reflectance memory unit 111, and outputs it to the object color calculation unit 105.

FIG. 3 is a diagram showing an example of a selection screen for selecting an object category that the object category selection unit 103 displays on the display screen of the display unit 109. As shown in FIG.
In FIG. 3, prints, paints, paintings, skin, textures, etc. are each shown as object classes that may be selected.
Printed matter includes photographic images, posters, building materials, etc., and refers to objects printed with ink on a print medium (substrate). Painted objects refer to objects painted with paint or the like on a substrate (including substrates with a base coat). Paintings refer to objects such as oil paintings using oil paints and watercolor paintings using watercolor paints. Skin refers to objects of various parts of the human body. Fabrics are fabrics such as cloth, and are further classified (subcategorised) by the material (type, product number) of the thread used to create them, the weaving method (or sewing method), the colour of the thread, etc.

For example, when the operator selects a print on the display screen of FIG. 3, the color matching function selection unit 102 displays a selection screen for classifying the print in more detail.
FIG. 4 is a diagram showing an example of selection items that the color matching function selection unit 102 displays on the display screen of the display unit 109 in order to further classify printed materials.
4(a) shows the type of substrate (printing medium) used for printing, which is one of the selection items as a minor classification in the classification of printed matter. Paper #1 to Paper #3 each show a standard paper that is generally used, or a paper used for printing. Metal #1 and Metal #2 each show a standard metal that is generally used, or a metal used for printing. Wood #1 and Wood #2 each show a standard wood that is generally used, or a wood used for printing.

4B shows the type of printing method used for printing, which is one of the selection items as a minor classification in the classification of printed matter. Here, the printing method shows offset, gravure, silk, inkjet, etc. as printing techniques of the minor classification.
4C shows the type of ink used for printing (ink set), which is one of the selection items. Each of inks #1 to #5 shows a commonly used ink set or an ink set used for printing (in the case of an ink set, each ink color is printed monochromatically on a substrate).

When the operator selects paper #1 and paper #3 as the substrate, offset and gravure as the printing method, and ink #1 and ink #3 as the offset printing ink on the selection screens of FIG. 4(a), FIG. 4(b), and FIG. 4(c), the object classification selection unit 103 reads out the spectral reflectance (object spectral reflectance) for each combination of paper #1, paper #3, offset, ink #1, and ink #3 (an ink set used for offset printing, for single color printing or multi-color printing) from the object spectral reflectance storage unit 111. In the offset printing method, when ink #1 is composed of three types and ink #3 is composed of five types of ink, 2 (number of types of paper) x 3 (number of types of ink for ink #1) + 2 (number of types of paper) x 5 (number of types of ink for ink #3) = 16 types of spectral reflectance are read out.

Returning to FIG. 3, when the operator selects skin on the display screen of FIG. 3, the color matching function selection unit 102 displays a selection screen for classifying skin in more detail.
FIG. 5 is a diagram showing an example of selection items that the object classification selection unit 103 displays on the display screen of the display unit 109 in order to further classify skin.

5A shows the types of body parts, which are one of the selection items, for identifying the part of the body the skin is from, including sub-categories such as the palm, the back of the hand, the arm, the back, the abdomen, and the face.
5B shows the skin color type for the race and skin part, which is one of the selection items. As the type, skin color is classified into subcategories, such as skin color #1 to skin color #7.

In addition, when the display device primary color design system 1 is operated for a specific race, such as Caucasoid, Mongoloid, Negroid, Austroloid, etc., which is a biological classification of race, the type of skin color is specified to be one type, so there is no need to make skin color an option. In this case, the display device primary color design system 1 may be configured without having a function for selecting the type of skin color.

5(a) and 5(b), when the operator selects the palm and face as body parts and skin color #1, skin color #3, and skin color #6 as skin color classifications, the object classification selection unit 103 reads out the spectral reflectance (object spectral reflectance, spectral reflectance r _j (λ) described later) for each combination of the palm and face, skin color #1, skin color #3, and skin color #6 from the object spectral reflectance storage unit 111. In this case, 2 (number of body part types)×3 (number of skin color types)=6 types of spectral reflectance are read out.
In addition, multiple selection items are displayed for each of the other painted objects, paintings, and textures, and the object classification selection unit 103 reads out the object spectral reflectance (spectral reflectance r _j (λ) described later) from the object spectral reflectance memory unit 111 in response to each selected combination of selection items.

Returning to Figure 1, the ambient light selection unit 104 displays on the display unit 109 the classification of the spectral radiance of the light source (ambient light spectral radiance) in the environment in which the object is observed, which is used when the object color calculation unit 105 described later calculates the object color.
Then, the ambient light selection unit 104 reads out the spectral radiance (ambient light spectral radiance) of the light source selected by the operator from each of the light source classifications displayed on the display unit 109 from the ambient light spectral radiance memory unit 112, and outputs it to the object color calculation unit 105.

Figure 6 is a diagram showing an example of a selection screen for the classification of light sources when observing an object displayed on the display screen of the display unit 109 by the ambient light selection unit 104 in the first embodiment. Figure 6 shows a screen for selecting, for example, LED lighting #1, LED lighting #2 (with ultraviolet light), fluorescent lamp #1, fluorescent lamp #2, outdoors, etc. as classifications of light sources.

6, LED lighting #1, LED lighting #2 (with ultraviolet light), fluorescent lamp #1, fluorescent lamp #2, outdoors, etc. are shown as classifications of light sources in the environment (ambient light spectral radiance). Here, LED lighting #1 indicates data on spectral radiance in the wavelength range that humans can recognize, and LED lighting #2 indicates data on spectral radiance including the wavelength range of ultraviolet light that humans cannot recognize.
For example, the device names for which the manufacturers provide specifications are listed for LED lighting #1, LED lighting #2, fluorescent lamp #1, and fluorescent lamp #2. Outdoors indicates, for example, a state under sunlight on a clear day.

Then, the ambient light selection unit 104 reads out the ambient light spectral radiance corresponding to the light source selected by the operator from the ambient light spectral radiance storage unit 112 .
For example, when the operator selects LED lighting #1, LED lighting #2, and outdoors, the ambient light selection unit 104 reads out the ambient light spectral radiance of each of the light sources, LED lighting #1, LED lighting #2, and outdoors, from the ambient light spectral radiance storage unit 112.
Here, the viewer can arbitrarily select one or more light sources on the selection screen (multiple selections possible).

Returning to FIG. 1 , the object color calculation unit 105 calculates the object color from the color matching functions, object spectral reflectance, and ambient light spectral radiance supplied from the color matching function selection unit 102, the object classification selection unit 103, and the ambient light selection unit 104, respectively.
At this time, the object color calculation unit 105 receives the color matching functions x _i (λ), y _i (λ), and z _i (λ) of the observer selected by the operator from the color matching function selection unit 102. Here, i represents the observer index.

Furthermore, the object color calculation unit 105 receives the object spectral reflectance r _j (λ) corresponding to the object classification selected by the operator from the object classification selection unit 103. Here, j represents the index of the object.
Furthermore, the object color calculation unit 105 receives the ambient light spectral radiance (spectral distribution) l _k (λ) corresponding to each of the ambient light sources selected by the operator from the ambient light selection unit 104. Here, k represents the index of the light source.

Then, the object color calculation unit 105 calculates the tristimulus values Xp i,j,k , Yp i,j,k , _Zp i,j,k of the object color viewed by the i-th observer from the spectral reflectance r _j (λ) of the j-th object, the spectral distribution l _k (λ) of the k-th light source, and the color matching functions x _{i (} λ), y _{i (λ)} , and z _i (λ) of the i-th observer, using the following equation ₍₁₎ :

The primary color spectral distribution setting unit 106 reads out spectral radiance data (r(λ), g(λ), b(λ) described below) of the primary colors (e.g., color component R, color component G, color component B) of the display device selected by the operator.
At this time, the primary color spectral distribution setting unit 106 causes the display unit 109 to display a display screen for selecting a spectral radiance, and prompts the operator to select the type of primary color.

FIG. 7 is a diagram showing an example of a screen for setting the shape and selecting the type of the primary colors of the display device, which is displayed on the display screen of the display unit 109 by the primary color spectral distribution setting unit 106.
7A shows a setting screen for setting the shape of each of the spectral distributions of the spectral radiance r(λ) of the R primary color of color component R, the spectral radiance g(λ) of the G primary color of color component G, and the spectral radiance b(λ) of the B primary color of color component B, as primary color spectral radiance data of the display device. In this embodiment, the shape of the spectral distribution uses a distribution shape that is approximated by a symmetrical bell-shaped curve (a shape corresponding to a normal distribution), the wavelength of the median of the distribution shape is the central wavelength, and the left and right width of the distribution is set as the half-value width.

Fig. 8 is a diagram showing an example of the distribution shape of primary color spectral radiance (r(λ), g(λ), b(λ)) in this embodiment. In the graph of Fig. 8, the horizontal axis indicates wavelength, and the vertical axis indicates intensity value of radiated light (normalized value obtained by dividing the intensity value of the wavelength of radiated light in each color component by the maximum value of the radiated light in each color component).
In FIG. 8, the shape of the spectral distribution is a symmetrical bell-shaped curve, with wavelengths λ0 and λp indicating the central wavelengths.
The half-width L1 of the spectral distribution of each of the wavelengths λ0 and λp is set to an arbitrary value, as described later.

Returning to FIG. 7, a method for setting the shape of the spectral distribution will be described by taking the spectral distribution of the B primary color in FIG. 7(a) as an example.
The minimum central wavelength is the minimum value of the wavelength λ used when setting the display color in a display device, which will be described later, and corresponds to the wavelength λ0 in FIG.
The maximum central wavelength is the maximum value of the wavelength λ used when setting the above-mentioned display color, and corresponds to the wavelength λp in FIG.
The central wavelength increment indicates the increment width for generating wavelengths that become central wavelengths in the wavelength range from the minimum central wavelength value λ0 to the maximum central wavelength value λp.

For example, when the central wavelength increment width is 10 nm, it indicates that a spectral distribution is generated having central wavelengths that are increased by 10 nm from the central wavelength minimum value λ0.
That is, when the minimum central wavelength is 400 nm, the maximum central wavelength is 500 nm, and the central wavelength increment is 10 nm, eleven (0≦p≦10) spectral distributions are generated: 400 nm (λ0), 410 nm (λ1), 420 nm (λ2), 430 nm (λ3), 440 nm (λ4), 450 nm (λ5), 460 nm (λ6), 470 nm (λ7), 480 nm (λ8), 490 nm (λ9), and 500 nm (λ10).

The half-width minimum value is the minimum value (L0) of the half-width of the spectral distribution used when setting the display color in the display device described later.
The maximum half-width value is the maximum half-width value (Lq) of the spectral distribution used when setting the display color in a display device, which will be described later.
The half-width increment indicates the increment width for generating wavelengths that are the half-width of the spectral distribution in the wavelength range from the half-width minimum value to the half-width maximum value.
For example, when the half-width increment is 10 nm, it indicates that a spectral distribution is generated having center wavelengths that are increased by 5 nm from the half-width minimum value L0.

For example, when the half-width increment is 5 nm, this indicates that a spectral distribution is generated in which the half-width is set to wavelengths increased by 5 nm from the minimum half-width value.
That is, when the minimum half-width is 10 nm, the maximum half-width is 50 nm, and the half-width increment is 5 nm, nine (0≦q≦8) spectral distributions are generated: 10 nm (L0), 15 nm (L1), 20 nm (L2), 25 nm (L3), 30 nm (L4), 35 nm (L5), 40 nm (L6), 45 nm (L7), and 50 nm (L8).
As a result, a spectral distribution of the primary colors with 99 combinations for the B primary color is generated, with 11 combinations of center wavelengths and 9 combinations of half-widths.

Furthermore, for each of the other G and R primary colors, similar to the above-mentioned B primary color, the primary color spectral distribution setting unit 106 determines the number of combinations for each of the G and R primary colors by setting the central wavelength minimum value, central wavelength maximum value, and central wavelength increment of the central wavelength, and the half-width minimum value, half-width maximum value, and half-width increment of the half-width.

The primary color spectral distribution setting unit 106 then obtains the distribution shape of the spectral distribution of the number of primary colors obtained by further combining each combination of the R primary color, G primary color, and B primary color, and outputs the distribution shape of the spectral distribution of the combinations, i.e., the intensity values (standardized values) for each wavelength of the R primary color, G primary color, and B primary color, to the display color calculation unit 107 in sequence.
Furthermore, in this embodiment, the shape of the spectral distribution has been described as a normal distribution, but it is not limited to the normal distribution shape and may be a distribution curve in which the left and right tails have different shapes.

FIG. 7B shows a selection screen for selecting data on the spectral distribution of radiant light luminance of the primary colors (R color component, G color component, and B color component) of a display device that is already in use.
In FIG. 7B, for example, primary color data set #1, primary color data set #2, primary color data set #3, primary color data set #4, and primary color data set #5 are displayed as primary color data sets of the display device.
In this embodiment, it is possible to select a plurality of primary color data sets, and in FIG. 7B, the operator selects primary color data set #1, primary color data set #2, and primary color data set #5 from the selection screen.

Then, the primary color spectral distribution setting unit 106 reads out data on the spectral distribution of radiant light luminance of each of the primary color data set #1, primary color data set #2, and primary color data set #5 selected by the operator from the primary color spectral radiance memory unit 113, and outputs it to the display color calculation unit 107.
In this embodiment, each of the primary color data sets is written and stored in advance as spectral distribution data, as intensity values for each wavelength (intensity values as standard values described in FIG. 7A), in the primary color spectral radiance storage unit 113. This spectral distribution data is data acquired by measuring the spectral radiance of primary colors that have already been manufactured.

In the present embodiment, the data is stored as data on the spectral distribution of the emitted light of each primary color, which is a combination of the backlight and the color filters of each primary color.
However, the spectral distribution of the spectral radiance of the light emitted from the backlight and the spectral distribution of the transmittance of the color filters of each primary color may be written and stored independently in the primary color spectral radiance storage unit 113 .
In this configuration, the display color calculation unit 107 combines the respective spectral distributions of the backlight and color filters selected by the operator and uses the combined spectral distribution as the primary color distribution.

Returning to FIG. 1 , when the display color calculation unit 107 receives the spectral distribution of the primary colors from the primary color spectral distribution setting unit 106, it uses the observer's color matching functions to calculate tristimulus values Xr,i _{, Yr,i, Zr,i} , Xg,i _{, Yg,i ,} Zg _, i, Xb, _i , Yb _,i , Zb _, i of the display colors in the color matching functions _xi (λ ₎ , yi( _{λ ), and zi} (λ ₎ of the i-th observer according to the following equation (2):

The display color calculation unit 107 calculates the spectral distribution d i,j,k (λ) of the display device that approximates the tristimulus values Xp _i,j,k , Yp _{i,j,k ,} Zp _i,j,k of the object color perceived by the _i-th observer when the observer observes the display device, using the following equations (3) and (4).

Here, in equation (3), the display color calculation unit 107 multiplies the vectors of tristimulus values Xp _i,j,k , Yp _i,j,k , Zp _i,j,k of the object colors perceived by each observer by the inverse matrix of tristimulus values Xr _,i , Yr, _{i , Zr,i , Xg,i , Yg ,i} , Zg _{,i ,} Xb, _i , Yb _,i , Zb _,i of the display colors of the primary colors perceived by each observer.
In this way, the display color calculation unit 107 calculates the ratios r _i,j,k , g _i, j,k , and b _i,j,k of the spectral radiance of each primary color perceived by each observer to the actual spectral radiance. The ratio r _i,j,k is a ratio corresponding to the spectral distribution of the R primary color. The ratio gi _,j,k is a ratio corresponding to the spectral distribution of the G primary color. The ratio b _i,j,k is a ratio corresponding to the spectral distribution of the B primary color.

The display color calculation unit 107 calculates a composite spectral distribution d _i,j,k (λ) obtained by combining the spectral distributions of the primary colors perceived by the observer i by multiplying the spectral distributions of the R primary color, the G primary color, and the B primary colors supplied from the primary color spectral distribution setting unit 106 by the ratios r i _,j,k , g _i,j,k , and bi _,j,k, respectively, according to equation (4).
Then, the display color calculation unit 107 calculates each of the tristimulus values _{Xd i,j,k , Yd i,j ,k} and Zd _i,j,k of the display color perceived by a specified observer with the spectral distribution d i,j _, k (λ) of the display color perceived by the specified observer using the display device with the above-mentioned composite spectral distribution, using the following equation (5):

When calculating color difference, which will be described later, the display color calculation unit 107 fixes each of the tristimulus values Xd _{i ,j,k ,} Yd i,j _{,k , and Zd i,j,} k of the display color perceived by a specific observer using a color matching function for a specific observer and calculates it using equation (5), so as to make each of the spectral distributions d i, _j,k (λ) perceived by each observer i into comparable numerical values.
For this predetermined observer, for example, color matching functions for a 2-degree visual field and a 10-degree visual field provided by CIE, or a color matching function for any observer i selected by the operator, is used.

The display device primary color optimization unit 108 determines, using the following equation (6), one of the observers i as the reference observer, the differences between the tristimulus values Xd _{i,j,k ,} Yd _i,j,k , Zd _i,j,k of the other observers, and calculates an average value E of color differences of the primary colors between the tristimulus values Xd _1,j,k , Yd _1,j,k , Zd _1,j,k (tristimulus values of the reference display color) of the reference observer and each of the tristimulus values Xd _i,j,k , Yd _i,j,k , Zd _i,j,k of the other observers i.

In the above formula (6), in this embodiment, the display device primary color optimization unit 108 calculates the color difference between observer #1 (i=1) and each of observers up to observer #N (2≦i≦N). That is, in formula (6), the tristimulus values of observer #1 (i=1) are Xp1 _,j,k , _Yp1,j,k , and Zp1 _,j,k .
However, the reference observer may be any observer selected by the operator and used to calculate each of the tristimulus values Xdi _,j,k , Ydi,j, _k , and Zdi _,j,k of the display colors.

Then, the display device primary color optimization unit 108 calculates the average value of the square root of the difference between the tristimulus values of each of the observers #1 and the other observers #i (2≦i≦N) (color difference ΔE*ab) using the above formula (6) as the individual difference E of the primary colors on the display device selected by the operator.

Furthermore, the method of calculating the average color difference E of the primary colors in the display device selected by the operator is not limited to the above formula (6), and the display device primary color optimization unit 108 may be configured to calculate from the difference between each tristimulus value for observer #i (1≦i≦N) and the average tristimulus value, as shown in formula (7).
In formula (7), mean() is a function that calculates the average value in () (brackets). f() is a function calculated by selecting one of the sum, maximum value, variance, etc. in () (brackets). Also, in formula (7), the maximum value, variance, etc. may be selected and used instead of the sum of object #j (1≦j≦M) or light source #k (1≦k≦K).
The display device primary color optimization unit 108 calculates individual differences E in the primary colors of all the display devices supplied from the primary color spectral distribution setting unit 106 and selected by the operator.

FIG. 9 is a conceptual diagram showing an example of a diagram in which the display device primary color optimization unit 108 compares the average color difference values of the primary colors observed.
9A shows a collection of color difference maps in which a color difference map for each half-width of the R and G primary colors for any combination of the central wavelength and half-width of the B primary color is one block. Therefore, in this collection, the upper left block 2011 is the block at the origin, and shows the color difference maps for each combination of the R primary color half-width minimum value of 10 nm and the G primary color half-width minimum value of 10 nm.

In the column direction in FIG. 9( a ), the half-width of each of the R primary colors is shown increasing in increments of half-width set by the operator on the setting screen in FIG. 7( a ), i.e., in increments of 5 nm, from a minimum half-width of 10 nm to a maximum half-width of 60 nm.
Similarly, in the row direction in FIG. 9( a ), the half-width of the G primary color increases from a minimum half-width of 10 nm in increments of half-width increments of 5 nm set by the operator on the setting screen in FIG. 7( a ), and the half-width of each G primary color is shown up to a maximum half-width of 60 nm.
Therefore, the bottom right block 2066 is the end block, and shows the color difference map for each combination of a maximum half-width value of 60 nm for the R primary color and a maximum half-width value of 60 nm for the G primary color.

FIG. 9B shows the configuration of any of the blocks for each combination of the half-width of the R primary color and the half-width of the G primary color in FIG. 9A.
That is, FIG. 9B shows a color difference map indicating the color difference for each center wavelength for each combination of half-widths of R and G primary colors for any combination of center wavelength and half-width for B primary color.
In this color difference map, the color difference for each central wavelength of the R primary color and the G primary color is used as a gradient, and in the case of 256 gradients, for example, the color difference is quantized from "0" to "255." The color differences are normalized by dividing each color difference by a maximum color difference, which is, for example, the maximum value of the average values of the color differences acquired by the display device primary color optimization unit 108, and then quantized by dividing into a range of 256. As the color difference (gradation) approaches "0," it approaches black in the color difference map, while as the color difference approaches "255," it approaches white in the color difference map.

In the color difference map of FIG. 9B, the vertical axis indicates the central wavelength (nm) of the G primary color, and the vertical axis indicates the central wavelength (nm) of the R primary color.
In this color difference map, the central wavelengths of the R primary colors are shown in the column direction in increments of the central wavelength width set by the operator on the setting screen of Figure 7 (a) by the operator, i.e., in increments of 10 nm, from a minimum central wavelength of 580 nm to a maximum central wavelength of 650 nm.
Similarly, in this color difference map, the central wavelengths of the G primary colors are shown in the row direction in increments of the central wavelength width set by the operator on the setting screen of Figure 7 (a), i.e., in increments of 10 nm, from a minimum central wavelength of 500 nm to a maximum central wavelength of 580 nm.

10 is a diagram showing a collection of color difference maps in which the display device primary color optimization unit 108 selects a printed matter as an object classification and compares the average color difference values of each observed primary color. The printed matter in FIG. 10 is printed using offset printing.
Fig. 10(a) shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 450 nm and a half-width of 15 nm for B primary color, the classification of which corresponds to a printed matter. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in Fig. 9(a) already described. The configuration of the color difference maps in each block is also the same as that in Fig. 9(b) already described.

Therefore, in FIG. 10A, the upper left block 3011 of the collection is the block of origin, and shows the color difference map for each combination of an R primary color with a half-width minimum of 10 nm and a G primary color with a half-width minimum of 10 nm.
The bottom right block 3066 is the end block, and shows the color difference map for each combination of a maximum half-width value of 60 nm for the R primary color and a maximum half-width value of 60 nm for the G primary color.

10B shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 450 nm and a half-width of 20 nm for B primary color, the classification of which corresponds to a printed matter. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.
10C shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 450 nm and a half-width of 30 nm for B primary color, the classification of which corresponds to a printed matter. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.

Figure 11 is a diagram showing the spectral radiance of the light source used by the display device primary color optimization unit 108 when calculating the color difference of the primary colors of the display device. This Figure 11 shows the spectral radiance of the light source used by the object color calculation unit 105 to calculate the color differences of Figure 10 already explained and Figures 13, 14, 15, 16, and 17 described later. In Figure 11, the horizontal axis shows the wavelength, and the vertical axis shows the radiance (values for each primary color normalized to 100 for radiance at 560 nm). It can be seen that the light source used (solid line) has a different spectral distribution from the standard light A (dotted line) described for reference and, for example, the CIE standard light source D65 (dotted line), and the obtained object colors are different.

Figure 12 is a diagram showing the spectral reflectance of the substrate of the printed matter used by the display device primary color optimization unit 108 when calculating the color difference of the primary colors of the display device. This Figure 12 shows the spectral reflectance of the printed matter used by the object color calculation unit 105 to calculate the color difference of Figure 10 already explained. In Figure 12, the horizontal axis shows the wavelength, and the vertical axis shows the spectral reflectance (reflectance: spectral reflectance of the printed matter). The spectral reflectance (reflectance) of the printed matter used shows an almost flat curve shape in the human visible band from 380 nm to 730 nm.

FIG. 13 illustrates a collection of color difference maps in which the display primary color optimizer 108 selects skin as the object classification and compares the average color difference of each of the observed primary colors.
The skin used to calculate the color difference in Figure 13 was each part of the face, and the skin data in "Reference ISO/TR 16066:2003 Graphic technology-Standard object colour spectra database for colour reproduction evaluation (SOCS)" was used as the spectral reflectance data.
As for the environmental light source of the skin, the spectral radiance data in FIG. 11 was used, as in the case of calculating the color difference of the print in FIG.
13A shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 450 nm and a half-width of 15 nm for B primary color, the object classification of which corresponds to skin. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.

Therefore, in FIG. 13A, the upper left block 3111 of the collection is the block of origin, and shows the color difference map for each combination of a R primary color with a half-width minimum of 10 nm and a G primary color with a half-width minimum of 10 nm.
The bottom right block 3166 is the end block, and shows the color difference map for each combination of a maximum half-width value of 60 nm for the R primary color and a maximum half-width value of 60 nm for the G primary color.

13B shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 450 nm and a half-width of 20 nm for B primary color, the object classification of which corresponds to skin. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.
13C shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 450 nm and a half-width of 30 nm for B primary color, the object classification of which corresponds to skin. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.

FIG. 14 illustrates a collection of color difference maps in which the display primary color optimizer 108 selects paintings (eg, oil paintings) as an object classification and compares the average color difference values for each of the viewed primaries.
The painting used in calculating the color difference in FIG. 14 was an oil painting, and the data on spectral reflectance was taken from the oil painting data in the document ISO/TR 16066:2003 Graphic technology - Standard object colour spectra database for colour reproduction evaluation (SOCS).
As for the environmental light source of the oil painting, the spectral radiance data in FIG. 11 was used, in the same manner as in calculating the color difference of the print in FIG.
14A shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 450 nm and a half-width of 15 nm for B primary color, the classification of which corresponds to oil painting. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.

Therefore, in FIG. 14A, the upper left block 3211 of the collection is the block of origin, and shows the color difference map for each combination of an R primary color with a half-width minimum of 10 nm and a G primary color with a half-width minimum of 10 nm.
The bottom right block 3266 is the end block, and shows the color difference map for each combination of a maximum half-width value of 60 nm for the R primary color and a maximum half-width value of 60 nm for the G primary color.

14B shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 450 nm and a half-width of 20 nm for B primary color, the classification of which corresponds to oil painting. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.
14C shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 450 nm and a half-width of 30 nm for B primary color, the classification of which corresponds to oil painting. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.

FIG. 15 illustrates a collection of color difference maps in which the display primary color optimizer 108 selects paintings (eg, watercolors) as an object classification and compares the average color difference values for each of the observed primaries.
The painting used in calculating the color difference in FIG. 15 was a watercolor painting, and the data on the spectral reflectance was taken from the watercolor painting data in the document ISO/TR 16066:2003 Graphic technology - Standard object colour spectra database for colour reproduction evaluation (SOCS).
As for the environmental light source of the watercolor painting, the spectral radiance data in FIG. 11 was used, as in the calculation of the color difference of the print in FIG.

15A shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 450 nm and a half-width of 15 nm for B primary color, the object classification of which corresponds to watercolor painting. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.

Therefore, in FIG. 15A, the upper left block 3311 of the collection is the block of origin, and shows the color difference map for each combination of a half-width minimum value of 10 nm for the R primary color and a half-width minimum value of 10 nm for the G primary color.
The bottom right block 3366 is the end block, and shows the color difference map for each combination of a maximum half-width value of 60 nm for the R primary color and a maximum half-width value of 60 nm for the G primary color.

15B shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 450 nm and a half-width of 20 nm for B primary color, the object classification of which corresponds to watercolor painting. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.
15C shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 450 nm and a half-width of 30 nm for B primary color, the object classification of which corresponds to watercolor painting. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.

FIG. 16 illustrates a collection of color difference maps in which the display primary color optimizer 108 selects printed matter as an object classification and compares the average color difference values for each of the observed primaries.
The printing method used for calculating the color difference in FIG. 16 was offset printing, and the spectral reflectance data used was the same as the spectral reflectance data in FIG. 12 used for calculating the color difference of the primary colors in FIG. 10.
As for the environmental light source of the print, the data of the spectral radiance in FIG. 11 was used, as in the case of calculating the color difference of the print in FIG.
16A shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 460 nm and a half-width of 15 nm for B primary color, the classification of which corresponds to a printed matter. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.

Therefore, in FIG. 16A, the upper left block 3411 of the collection is the block of origin, and shows the color difference map for each combination of a half-width minimum value of 10 nm for the R primary color and a half-width minimum value of 10 nm for the G primary color.
The bottom right block 3466 is the end block, and shows the color difference map for each combination of a maximum half-width value of 60 nm for the R primary color and a maximum half-width value of 60 nm for the G primary color.

16B shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 460 nm and a half-width of 20 nm for B primary color, the classification of which corresponds to a printed matter. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.
16C shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 460 nm and a half-width of 30 nm for B primary color, the classification of which corresponds to a printed matter. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.

FIG. 17 illustrates a collection of color difference maps in which the display primary color optimizer 108 selects skin as the object classification and compares the average color difference of each of the observed primary colors.
The skin used to calculate the color difference in Figure 17 was each part of the face, as in Figure 13, and the skin data from "Reference ISO/TR 16066:2003 Graphic technology-Standard object colour spectra database for colour reproduction evaluation (SOCS)" was used as the spectral reflectance data.
As for the environmental light source of the skin, the spectral radiance data in FIG. 11 was used, as in the case of calculating the color difference of the print in FIG.
17A shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 460 nm and a half-width of 15 nm for B primary color, the object classification of which corresponds to skin. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.

Therefore, in FIG. 17A, the upper left block 3511 of the collection is the block of origin, and shows the color difference map for each combination of a half-width minimum value of 10 nm for the R primary color and a half-width minimum value of 10 nm for the G primary color.
The bottom right block 3566 is the end block, and shows the color difference map for each combination of a maximum half-width value of 60 nm for the R primary color and a maximum half-width value of 60 nm for the G primary color.

17B shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 460 nm and a half-width of 20 nm for B primary color, the object classification of which corresponds to skin. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.
17C shows a collection of color difference maps in which a block is made up of color difference maps for each half-width of R and G primary colors in a combination of a central wavelength of 460 nm and a half-width of 30 nm for B primary color, the object classification of which corresponds to skin. The arrangement in the column direction (half-width of R primary color) and row direction (half-width of G primary color) in this collection is the same as that in FIG. 9A, which has already been described.

Comparing the color differences in the color difference maps of Figures 10, 13, 14, and 15, it can be seen that the color differences in the central wavelength band and half-width wavelength width vary greatly for each of the object classifications of prints, skin, oil paintings, and watercolors.
For example, when comparing the color difference map of block 3066 in FIG. 10( a), whose object classification is a printed material, with the color difference map of block 3266 in FIG. 14( a), whose object classification is an oil painting, although the central wavelength and half-width of the B primary color are the same and the half-widths of the R primary color and the G primary color are the same, the color differences corresponding to the combination of central wavelengths of the R primary color and the G primary color are significantly different.

Also, when comparing Figures 14 and 15, although they are the same paintings, due to the difference between oil painting and watercolor painting, when comparing the color difference map of block 3211 in Figure 14(a), where the object classification is oil painting, with the color difference map of block 3311 in Figure 15(a), where the object classification is watercolor painting, the central wavelength and half-width of the B primary color are the same, and the half-width of the R primary color and the G primary color are the same, but the color differences corresponding to the combination of central wavelengths of the R primary color and the G primary color are significantly different.

Next, when comparing Figures 10 and 16, although the object classification is the same (printed matter), and the half-widths of the R and G primary colors are the same, and the half-widths of the B primary color are also the same, only the central wavelength of the B primary color is different, and the color differences corresponding to the combinations of the central wavelengths of the R and G primary colors are significantly different.
Furthermore, when comparing Figures 13 and 17, although the object classification is the same (skin), and the half-widths of the R and G primary colors are the same, and the half-widths of the B primary color are also the same, only the central wavelength of the B primary color is different, and the color differences corresponding to the combinations of the central wavelengths of the R and G primary colors are significantly different.

Therefore, it can be seen that depending on the type of object classified by the object classification or the combination of central wavelength and half-width, the color difference perceived by each observer (individual differences in color perception) varies greatly depending on each combination of central wavelength and half-width of each of the R primary color, G primary color, and B primary color.
In this way, by classifying the objects and the light source of the observing environment, it is possible to classify and identify to a certain extent the objects (objects) observed on the display device (i.e., classify the spectral reflectance) and also classify the light source of the observing environment (i.e., classify the spectral radiance), and it is possible to obtain with high accuracy the central wavelength and half-width range of the primary colors of the display device, which can keep the color difference within the color difference range corresponding to each object (the acceptable range of color difference in which each observer can perceive the same color).

FIG. 18 is a flowchart showing an example of the operation of a process for calculating the central wavelength and half width of the primary colors of a display device by the display device primary color design system of this embodiment.
Step S11:
The color matching function selection unit 102 displays on the display unit 109 a selection screen for selecting a group of color matching functions (observers) used when the object color calculation unit 105 described later calculates object colors.
Then, the color matching function selection unit 102 reads out from the color matching function storage unit 110 the color matching functions x _i (λ), y _i (λ), and z _i (λ) of the observer selected by the operator from each of the observers displayed on the display unit 109, and outputs them to the object color calculation unit 105.

Step S12:
The ambient light selection unit 104 displays on the display unit 109 an ambient light source selection screen for selecting a light source (spectral distribution l _k (λ)) for observing an object, which is used when the object color calculation unit 105 described later calculates the object color.
Then, the ambient light selection unit 104 reads out the spectral distribution l _k (λ) corresponding to the light source selected by the operator from each of the ambient light sources displayed on the display unit 109 from the ambient light spectral radiance storage unit 112, and outputs it to the object color calculation unit 105.

Step S13:
The object category selection unit 103 displays on the display unit 109 a selection screen for selecting an object category for selecting a spectral reflectance r _j (λ) used when the object color calculation unit 105 (described later) calculates the object color.
Then, the object classification selection unit 103 reads out the spectral reflectance r _j (λ) of the object in the classification selected by the operator from each of the object classifications displayed on the display unit 109 from the object spectral reflectance memory unit 111, and outputs it to the object color calculation unit 105 as the object spectral reflectance.

Step S14:
The object color calculation unit 105 calculates tristimulus values Xp i,j,k , Yp _i ,j,k , Zp _i ,j, _k perceived by the observer observing the object, using each of the color matching functions x _i (λ), y i (λ), and z i (λ) of the observer observing the object, the spectral distribution l _k (λ) of the light source in the environment in which the object is observed, and the spectral reflectance _{r j (} λ _{) (} object spectral _reflectance) of the observed object, using equation (1).

Step S15:
The primary color spectral distribution setting unit 106 causes the display unit 109 to display a setting screen for setting the primary colors of the display device, and allows the operator to select data for combining center wavelengths and half-widths that will generate a distribution shape of the primary colors (corresponding to FIG. 7( a)), or data for an already existing distribution shape of the primary colors (corresponding to FIG. 7( b)).
The primary color spectral distribution setting unit 106 then associates the distribution shape data generated from the combination of the central wavelength and half-width set by the operator, or the data of the distribution shape of the primary colors of the selected display device read out from the primary color spectral radiance storage unit 113, with each of the color components R, G, and B, and outputs them as primary color spectral radiance data r(λ), g(λ), and b(λ), respectively.

Step S16:
The display color calculation unit 107 calculates a spectral distribution d _i,j,k (λ _{) of an image of an object (each of the pixels which are image constituent units constituting the image of the object) on the display screen of the display device, which approximates the tristimulus values Xp i,j,k , Yp i,j ,k} , Zp _i,j,k perceived by each observer i when observing the object, using the primary color spectral radiance data r(λ), g(λ), b(λ) and each of the color matching functions x _i (λ), y _i (λ), and z _i (λ) of observer i, using the already explained equations (2) to (4).

Then, the display color calculation unit 107 calculates the tristimulus values Xd _{i,j,k , Yd i,j,k ,} and Zd _i,j,k of the display color when a specified observer perceives the spectral distribution d _i,j,k (λ) using the equation (5) already explained.

Step S17:
The display color calculation unit 107 judges whether or not the tristimulus values Xd _{i,j,k ,} Yd i,j,k , Zd i _,j,k of the display colors perceived by a predetermined observer corresponding to the spectral distributions d _{i,j,k (λ) of all observers i and the spectral distributions of the primary colors have been calculated, that is, whether or not the calculation of the tristimulus values Xd i, j,k} , Yd i, _{j ,k ,} Zd _i,j,k has been completed for all observers i selected by the operator, corresponding to all combinations of object and light source distribution shapes set or selected by the operator.

At this time, when the display color calculation unit 107 has finished calculating the tristimulus values Xd i,j _,k , Yd _i,j,k , and Zd _i,j,k for all the combinations of the object and light source distribution shapes set or selected by the operator for all the observers i selected by the operator, the process proceeds to step S18.
On the other hand, if the calculation of the tristimulus values Xd i,j,k , Yd i _,j,k , Zd _i,j,k corresponding to all combinations of objects and light source distribution shapes set or selected by the operator for all observers i selected by the operator has not been completed, the display color calculation unit 107 proceeds to step S15 and continues calculating the tristimulus values Xd _{i,j,k ,} Yd i,j _,k , Zd _i,j,k corresponding to the remaining observers i and primary colors.

Step S18:
As already described, the display device primary color optimization unit 108 calculates the average color difference E between observers i for each combination of the central wavelength and half width of the primary colors by equation (6) from the tristimulus values Xd _i,j,k , Yd _i,j,k , and Zd _i,j,k for each observer i calculated by the display color calculation unit 107. From the average color difference E calculated by equation (6), the color difference as the gradation of each pixel in each of the color difference maps of Figures 10 to 18 already described is calculated.

Step S19:
The display device primary color optimization unit 108 determines whether the calculated average color difference E falls within a color difference range preset for printed matter, painted matter, painting, skin, fabric, etc., classified by the object classification. At this time, the display device primary color optimization unit 108 extracts a combination of a center wavelength and a half width for calculating the average color difference E falling within the color difference range set for the object classification.
Then, the display device primary color optimization unit 108 obtains, for each primary color, the range of the center wavelength and half width for which the average value E falls within the color difference range.

For example, when the object classification is a printed matter, the display device primary color optimization unit 108 extracts the central wavelength of the R primary color as RCmin (nm) to RCmax (nm) and the half width as RWmin (nm) to RWmax (nm), the central wavelength of the G primary color as GCmin (nm) to GCmax (nm) and the half width as GWmin (nm) to GWmax (nm), and the central wavelength of the B primary color as BCmin (nm) to BCmax (nm) and the half width as BWmin (nm) to BWmax (nm).
Then, the display device primary color optimization unit 108 writes and stores the center wavelength and half width range for which the average value E falling within the extracted color difference range has been calculated, for each primary color, in the optimized primary color spectral radiance storage unit 114.

Similarly, for object classifications such as painted objects, paintings, skin, and fabrics, the display device primary color optimization unit 108 extracts the central wavelength of the R primary color as RCmin (nm) to RCmax (nm) and the half-width as RWmin (nm) to RWmax (nm), the central wavelength of the G primary color as GCmin (nm) to GCmax (nm) and the half-width as GWmin (nm) to GWmax (nm), and the central wavelength of the B primary color as BCmin (nm) to BCmax (nm) and the half-width as BWmin (nm) to BWmax (nm).

The spectral distribution of the backlight light source and the transmission characteristics of the color filters are designed to satisfy the wavelength range of the central wavelength and the wavelength range of the half-width of the R primary color, the wavelength range of the central wavelength and the wavelength range of the half-width of the G primary color, and the wavelength range of the central wavelength and the wavelength range of the half-width of the B primary color, in accordance with the object classification determined above.

In addition, corresponding to the object classification, each combination of the central wavelength and half-width of the R primary color that produces the smallest average color difference E, each combination of the central wavelength and half-width of the G primary color, and each combination of the central wavelength and half-width of the B primary color may be set as target values for the primary colors to be finally created, using the spectral distribution of the backlight light source and the transmission characteristics of the color filter as design values.
Furthermore, if the primary color data set selected in FIG. 7B contains a combination of primary colors that results in a color difference corresponding to the color difference range set for the object classification, that combination of primary colors is applied to the display device.

As described above, according to this embodiment, by classifying the objects to be observed by object classification (classifying the spectral reflectance) and identifying the light source of the environment in which the objects are observed (spectral distribution of the spectral radiance of the ambient light), it is possible to design the color difference between observers i to be within the color difference range set when each object is observed. This eliminates the need to correct the display color for each spectral reflectance and observer, and makes it possible to easily design the spectral radiance of the primary colors of a display device such that the display color is observed in the same way by multiple observers i.

Second Embodiment
A second embodiment of the present invention will now be described with reference to the drawings.
The configuration of a display device primary color design system according to the second embodiment of the present invention is similar to that of the first embodiment in Fig. 1. Only the operation of the display device primary color design system according to the second embodiment, which differs from the first embodiment, will be described below.

In the first embodiment, as shown in FIG. 6, a light source for observing an object is selected from a plurality of types.
On the other hand, in the second embodiment, depending on the object classification, the characteristics of the light source in the observation environment (spectral distribution of spectral radiance) are predetermined according to industry standards or the like depending on the object to be observed, or a light source with characteristics for a specific observation purpose is used.

FIG. 19 is a diagram showing an example of a selection screen for selecting a light source category when observing an object displayed on the display screen of the display unit 109 by the ambient light selection unit 104 according to the second embodiment.
That is, in the second embodiment, the ambient light selection unit 104 is configured to display a screen for selecting the spectral distribution of the spectral radiance of a specific light source corresponding to an object classification or the like, as shown in FIG. 19, instead of the selection screen for the light source to be observed shown in FIG. 6.
In FIG. 19, the classification of the light source used for observation is set in accordance with the object classification, and in this embodiment, is set as a print material light source, a building material light source, sunlight, an examination room, an operating room, and the like.

A print illuminant is a light source in an environment in which an object classified as a print is observed in an object classification, and is, for example, an A illuminant or a D65 illuminant, which are specific light sources that irradiate standard illuminants (standard light) A and D65, which have relative spectral distributions established by the CIE for measuring the color of objects.
The building decoration material light source is the characteristics (spectral distribution of spectral radiance) of a light source that is a candidate for installation in a place such as a room where the building decoration material is used.

Sunlight is a light source characteristic that corresponds to building materials, such as building walls, doors, and fences, observed outdoors.
The characteristics of the light sources in each examination room and operating room are identified, for example, from the light sources based on the lighting standards for examination rooms and operating rooms specified in the Japanese Industrial Standard "JIS Z 9110" or the types of light sources used in examination rooms and operating rooms in general hospitals.
Then, the ambient light selection unit 104 reads out the spectral distribution of the environmental light source selected by the operator on the selection screen shown in FIG. 19 in accordance with the object classification from the ambient light spectral radiance storage unit 112, and outputs it to the object color calculation unit 105.

As already explained, the object color calculation unit 105 calculates tristimulus values Xp i,j,k , Yp i, _{j,k , and Zp i} ,j, _k of the object color using the spectral distribution of the light source supplied from the ambient light selection unit 104, the spectral reflectance supplied from the object classification selection unit 103, and the color matching functions supplied from _{the color matching function selection unit 102} .
As already explained, when calculating color difference, the display color calculation unit 107 fixes and calculates each of the tristimulus values Xd i,j, _{k ,} Yd i _,j,k , Zd i,j _{,k of the display color perceived by a specific observer using a color matching function of a specific observer, in order to make each of the spectral distributions d i,j,k (λ)} perceived by each observer i into comparable numerical values.
Then, the display device primary color optimization unit 108 acquires a spectral distribution of the primary colors in which the difference in color difference between observers falls within a color difference range that is set in advance for the object classified in the object classification.

As described above, according to this embodiment, similar to the first embodiment, by classifying the objects to be observed by object classification (classifying the spectral reflectance) and identifying the light source of the environment in which the objects are observed (spectral distribution of the spectral radiance of the ambient light), it is possible to design the color difference between observers i to be within the color difference range set when each object is observed. This eliminates the need to correct the display color for each spectral reflectance and observer, and makes it possible to easily design the spectral radiance of the primary colors of a display device such that the display color is observed in the same way by multiple observers i.

In addition, according to this embodiment, the color difference of the display color of the display device is calculated from the characteristics of the light source (spectral distribution of spectral radiance) of the observation environment that are predetermined by industry standards or the object color that is determined according to the characteristics of the light source used for a specific observation purpose, depending on the object classified by the object classification, and the spectral distribution of the primary colors of the display device is obtained. Therefore, it is possible to design a spectral distribution of the primary colors of the display device that reduces the individual differences between each observer i compared to the first embodiment.

A program for implementing the functions of the display device primary color design system of FIG. 1 in the present invention may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed to design the spectral distribution of the primary colors of the display device such that the color difference between observers falls within the color difference range set for the object. Note that the term "computer system" here includes hardware such as the OS (Operating System) and peripheral devices. The term "computer system" also includes a WWW (World Wide Web) system equipped with a homepage provision environment (or display environment).

In addition, "computer-readable recording media" refers to portable media such as flexible disks, optical magnetic disks, ROMs (Read Only Memory), and CD-ROMs (Compact Disc - Read Only Memory), as well as storage devices such as hard disks built into computer systems. Furthermore, "computer-readable recording media" also includes devices that hold a program for a certain period of time, such as volatile memory (RAM (Random Access Memory)) inside a computer system that acts as a server or client when a program is transmitted over a network such as the Internet or a communication line such as a telephone line.

The above program may also be transmitted from a computer system in which the program is stored in a storage device or the like to another computer system via a transmission medium, or by transmission waves in the transmission medium. Here, the "transmission medium" that transmits the program refers to a medium that has the function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The above program may also be one that realizes part of the above-mentioned functions. Furthermore, it may be a so-called difference file (difference program) that can realize the above-mentioned functions in combination with a program already recorded in the computer system.

The above describes an embodiment of the present invention in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like that do not deviate from the gist of the present invention are also included.

1... Display device primary color design system 101... Data input section 102... Color matching function selection section 103... Object classification selection section 104... Ambient light selection section 105... Object color calculation section 106... Primary color spectral distribution setting section 107... Display color calculation section 108... Display device primary color optimization section 109... Display section 110... Color matching function storage section 111... Object spectral reflectance storage section 112... Ambient light spectral radiance storage section 113... Primary color spectral radiance storage section 114... Optimized primary color spectral radiance storage section

Claims (8)

an object color calculation unit that calculates, as object colors, colors that are perceived by different observers under a light source in an environment in which an object belonging to a predetermined material classification is observed according to each of the color matching functions;
a display color calculation unit that calculates an approximate composite spectral distribution of the display device that approximates each of the object colors and corresponds to each of the object colors, from the spectral distributions of candidate primary colors that are candidates for the primary colors of the display device and each of the color matching functions , and calculates, from the approximate composite spectral distribution , a display color observed using the color matching function of one observer selected from observer candidates including each of the different observers;
a display device primary color optimization unit that calculates a color difference between the display color of the one observer and a reference that is determined based on the display colors of each of the observer candidate, and determines, based on the color difference , from the spectral distributions of the candidate primary colors, a spectral distribution of the primary colors of the display device that brings the color difference within a color difference range corresponding to the object . 2. The display device primary color design system according to claim 1, wherein the classification includes at least one of a print, a paint, a painting, skin, and a texture. 3. The display device primary color design system according to claim 2, wherein, when the classification is the printed matter, the object is set in a sub-classification according to at least each combination of a base material and an ink to be printed. 3. The display device primary color design system according to claim 2, wherein, when the classification is skin, the object is set at least in subclassification according to body parts. 5. The display device primary color design system according to claim 1, wherein the object color calculation unit calculates the object color by integrating a product of color matching functions of the different observers, a spectral reflectance of the object, and a spectral distribution of the environment over a wavelength. The reference is the display color of a reference observer selected from the observer candidates, or an average of the display colors of each of the observer candidates.
6. The display device primary color design system according to claim 1, an object color calculation step in which an object color calculation unit calculates, as object colors, colors perceived by different observers under a light source in an environment in which the object is observed, for an object belonging to a predetermined material classification, according to color matching functions of the different observers;
a display color calculation step in which a display color calculation unit calculates an approximate composite spectral distribution in the display device that approximates each of the object colors and corresponds to each of the object colors, from the spectral distributions of candidate primary colors that are candidates for light sources of the primary colors of the display device and each of the color matching functions, and calculates, from the approximate composite spectral distribution, a display color observed using the color matching function of one observer selected from observer candidates including each of the different observers;
a display device primary color optimization process in which a display device primary color optimization unit calculates a color difference between the display color of the one observer and a reference which is determined on the basis of the display color of each of the observer candidates , and determines, based on the color difference, from the spectral distributions of the candidate primary colors, a spectral distribution of the primary colors of the display device which brings the color difference within a color difference range corresponding to the object . Computer,
an object color calculation means for calculating, as object colors, colors perceived by different observers under a light source in an environment in which an object belonging to a predetermined material classification is observed according to each of the color matching functions of different observers;
a display color calculation means for calculating an approximate composite spectral distribution in the display device that approximates each of the object colors and corresponds to each of the object colors, from the spectral distributions of candidate primary colors that are candidates for a light source of the primary colors of the display device and each of the color matching functions, and calculating, from the approximate composite spectral distribution, a display color observed using the color matching function of one observer selected from observer candidates including each of the different observers;
a program for causing the display device primary color optimization means to function as a display device primary color optimization means for calculating a color difference between the display color of the one observer and a reference that is determined based on the display colors of each of the observer candidate , and determining, based on the color difference, from the spectral distributions of the candidate primary colors, a spectral distribution of the primary colors of the display device that brings the color difference within a color difference range corresponding to the object .

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