Visual characteristic acquisition device, visual characteristic acquisition method, and program

Abstract

To provide a visual property acquisition device which can correct a color of a reflection object such as a printed matter reproduced on a display or the like according to the view of an observer without using a photometric device.SOLUTION: A visual property acquisition device comprises: a camera side tristimulus value calculation unit which calculates a tristimulus value on a camera side using a camera pixel value in an image of a color chart; a display pixel value acquisition unit which acquires a display pixel value being a pixel value in a light emission color chart after adjustment in which colors are adjusted such that the view in the light emission color chart displayed on a display matches the view in the color chart; a display side tristimulus value calculation unit which calculates a tristimulus value on a display side on the basis of a relation between the spectral radiance corresponding to the display pixel value and the tristimulus value in a user color-matching function candidate; and a color-matching function decision unit which decides a color-matching function applied to the user on the basis of a difference between the tristimulus value on the camera side and the tristimulus value on the display side.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a visual characteristic acquisition device, a visual characteristic acquisition method, and a program. [Background technology]

[0002] It has been pointed out that there are individual differences in human visual characteristics, which significantly affect the appearance of colors in luminous objects such as displays. Therefore, when reproducing the color appearance of a reflective object such as a printed matter on a display, for example, if the reproduction is done using a uniform method that is not dependent on the individual observer who is observing the display, the colors of the printed matter and the display reproduction will appear different depending on the observer.

[0003] To solve this problem, a technology has been disclosed that acquires the visual characteristics of each observer and uses the information to reproduce colors on a display for each observer. For example, Non-Patent Document 1 discloses a technology that defines a visual model with age and viewing angle as parameters and reproduces the colors of reproduced objects on a display for each visual model. Patent Document 1 also discloses a method of calculating the spectral sensitivity of cones for each observer and using the calculated sensitivity to correct the image displayed on the display so that the color appearance of the image on the source side matches that of the observer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-120796 A [Non-patent literature]

[0005] [Non-Patent Document 1] CIE 170-1: “FUNDAMENTAL CHROMATICITY DIAGRAM WITH PHYSIOLOGICAL AXES - PART1”, 2006 Summary of the Invention [Problem to be solved by the invention]

[0006] In the method of Patent Document 1, it is necessary to obtain the spectral luminance characteristics of both the source side and the display side. When the source side is a reflective material such as a printed matter, the reflectance of the printed matter can be known by distributing a chart or the like to the observer or using an easily available package or the like. However, the observation light source depends on the observer's environment and cannot be known in advance. For this reason, the spectral luminance characteristics of the source side cannot be obtained. In order to obtain the spectral information of the observation light source according to the observation environment, a dedicated device (photometric device) capable of obtaining the spectral information is required. However, it is rare for general users to own a photometric device. Therefore, there is a problem that it is a heavy burden for general users to own a photometric device to correct the display image.

[0007] The present invention has been made in light of the above-mentioned problems, and aims to provide a visual characteristic acquisition device, a visual characteristic acquisition method, and a program that can correct the color of a reflective object such as a printed matter reproduced on a display or the like in accordance with how the observer sees it, without using a photometric device. [Means for solving the problem]

[0008] The visual characteristic acquisition device of the present invention includes a camera pixel value acquisition unit that acquires camera pixel values, which are pixel values ​​in an image of a color patch captured by a camera; a reference tristimulus value calculation unit that uses the camera pixel values ​​and a camera profile to calculate reference tristimulus values, which are tristimulus values ​​corresponding to the camera pixel values ​​in a reference color matching function; a camera side tristimulus value calculation unit that uses the reference tristimulus values ​​to calculate camera side tristimulus values ​​in a user color matching function candidate, which is a candidate for a color matching function to be applied to a user; a display pixel value acquisition unit that acquires display pixel values, which are pixel values ​​in the luminescent color patch after adjustment by the user so that the appearance of the luminescent color patch displayed on a display matches the appearance of the color patch; and a conversion table to calculate a spectral radiance corresponding to the display pixel value by converting the display pixel value into a spectral radiance; a display-side tristimulus value calculation unit to calculate display-side tristimulus values ​​in the user's color matching function candidate based on a relationship between the spectral radiance corresponding to the display pixel value and the tristimulus values ​​in the user's color matching function candidate; and a color matching function determination unit to determine a color matching function to be applied to the user based on a difference between the camera-side tristimulus values ​​in the user's color matching function candidate calculated by the camera-side tristimulus value calculation unit and the display-side tristimulus values ​​in the user's color matching function candidate calculated by the display-side tristimulus value calculation unit.

[0009] In the visual characteristic acquisition method of the present invention, a camera pixel value acquisition unit acquires camera pixel values ​​which are pixel values ​​in an image of a color patch captured by a camera, a reference tristimulus value calculation unit calculates reference tristimulus values ​​which are tristimulus values ​​corresponding to the camera pixel values ​​in a reference color matching function using the camera pixel values ​​and a camera profile, a camera-side tristimulus value calculation unit calculates camera-side tristimulus values ​​in a user color matching function candidate which is a candidate for a color matching function to be applied to a user using the reference tristimulus values, a display pixel value acquisition unit acquires display pixel values ​​which are pixel values ​​in the emission color patch after adjustment by the user so that the appearance of the emission color patch displayed on a display matches the appearance of the color patch, and a spectral radiance calculation unit uses the display pixel value and a conversion table to convert the display pixel value into a spectral radiance, thereby calculating a spectral radiance corresponding to the display pixel value, a display-side tristimulus value calculation unit calculates display-side tristimulus values ​​in the user color matching function candidate based on the relationship between the spectral radiance corresponding to the display pixel value and the tristimulus values ​​in the user color matching function candidate, and a color matching function determination unit determines a color matching function to be applied to the user based on the difference between the camera-side tristimulus values ​​in the user color matching function candidate calculated by the camera-side tristimulus value calculation unit and the display-side tristimulus values ​​in the user color matching function candidate calculated by the display-side tristimulus value calculation unit.

[0010] The program of the present invention includes a camera pixel value acquisition step of acquiring camera pixel values, which are pixel values ​​in an image of a color patch captured by a camera, a reference tristimulus value calculation step of calculating reference tristimulus values, which are tristimulus values ​​corresponding to the camera pixel values ​​in a reference color matching function, using the camera pixel values ​​and a camera profile, a camera side tristimulus value calculation step of calculating camera side tristimulus values ​​in a user color matching function candidate, which is a candidate for a color matching function to be applied to a user, using the reference tristimulus values, a display pixel value acquisition step of acquiring display pixel values, which are pixel values ​​in the emission color patch after color adjustment by the user so that the appearance of the emission color patch displayed on a display matches the appearance of the color patch, and a display-side tristimulus value calculation step of calculating display-side tristimulus values ​​in the user's color matching function candidates based on a relationship between the spectral radiance corresponding to the display pixel values ​​and the tristimulus values ​​in the user's color matching function candidates; and a user color matching function determination step of determining a color matching function to be applied to the user based on a difference between the camera-side tristimulus values ​​in the user's color matching function candidates calculated in the camera-side tristimulus value calculation step and the display-side tristimulus values ​​in the user's color matching function candidates calculated in the display-side tristimulus value calculation step. Effect of the Invention

[0011] According to the present invention, the color of a reflective object such as a printed matter reproduced on a display or the like can be corrected according to how the observer sees it, without using a photometric device. [Brief description of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating an outline of a visual characteristic acquisition system 1 according to a first embodiment. [Diagram 2] 1 is a block diagram showing an example of the configuration of a visual characteristic acquisition device 10 according to a first embodiment. [Diagram 3] 4A to 4C are diagrams illustrating processing performed by a camera-side processing unit 11 in the first embodiment. [Figure 4] 4 is a diagram for explaining processing performed by a display-side processing unit 12 in the first embodiment. FIG. [Diagram 5] 4A to 4C are diagrams illustrating the processing performed by a color matching function determination unit 13 according to the first embodiment. [Figure 6] 4 is a flowchart showing the flow of processing performed by the visual characteristic acquisition device 10 of the first embodiment. [Figure 7] FIG. 1 is a diagram illustrating an outline of a visual characteristic acquisition system 1A according to a second embodiment. [Figure 8] 13 is a diagram for explaining a process performed by a display-side processor 12A according to the second embodiment. FIG. [Figure 9] 13A to 13C are diagrams illustrating the processing performed by a color matching function determination unit 13A according to the second embodiment. [Figure 10] 10 is a flowchart showing the flow of processing performed by a visual characteristic acquisition device 10A according to a second embodiment. [Figure 11] FIG. 11 is a diagram illustrating a process performed by a camera-side processor 11B in a modified example of the second embodiment. [Figure 12] 13 is a flowchart showing the flow of processing performed by a visual characteristic acquisition device 10B of a modified example of the second embodiment. [Figure 13] FIG. 13 is a diagram showing an outline of a visual characteristic acquisition system 1C according to a third embodiment. [Figure 14] 13A to 13C are diagrams illustrating processing performed by a camera side processing unit 11C in the third embodiment. [Figure 15] 13 is a diagram for explaining a process performed by a display-side processor 12C according to the third embodiment. FIG. [Figure 16] 13A to 13C are diagrams illustrating a process performed by a color matching function determination unit 13C according to the third embodiment. [Figure 17] 13 is a flowchart showing the flow of processing performed by a visual characteristic acquisition device 10C according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, a visual characteristic acquisition device according to an embodiment will be described with reference to the drawings.

[0014] (First embodiment) First, a first embodiment will be described. Fig. 1 is a diagram showing an outline of a visual characteristic acquisition system 1 according to the first embodiment. The visual characteristic acquisition system 1 includes, for example, a camera CM, a display D, and a visual characteristic acquisition device 10.

[0015] The camera CM is an imaging device that captures color chart i and color chart w under an observation light source KL. The observation light source KL may be any light source, such as a fluorescent lamp, an LED (light emitting diode) lamp, an incandescent lamp, sunlight, or a combination of these. Here, the symbols (i and w) added to the end of the color chart indicate the color of the color chart. Here, the color chart i is a color chart other than white (colored). The color chart w is a white color chart. The color charts i and w are color charts with known spectral reflectance. In the following description, the color chart i may be referred to as a "colored color chart" or simply as a "color chart". The color chart w may be referred to as a "white color chart" or simply as a "color chart".

[0016] In addition, in this figure, an example is shown in which a single-color color chart i and a single-color color chart w are used, but the present invention is not limited to this. Instead of the single-color color chart i and the single-color color chart w, a color chart on which a plurality of color charts are arranged may be used. Also, as in the example of this figure, a color chart with a white frame may be used, or a color chart without a white frame may be used. However, since a color chart on which the color of the color chart and a reference color such as a white frame are arranged tends to make it easier for the human eye to accurately grasp the appearance of the color chart, it is preferable to use a color chart with a white frame. Also, when a color chart with a white frame is used, the white frame of the color chart i may be used instead of the color chart w (white color chart).

[0017] Display D is a display device such as a liquid crystal display. Display D displays an image according to the control of a computer device (not shown) such as a PC. Display D displays an image of a color chart. In the following description, the image of the color chart displayed on display D is referred to as a "luminescent color chart." Note that the image of the color chart displayed on display D may be an image of a color chart captured by a camera CM, or may be an image of a color chart created independently of the camera CM.

[0018] The display D is provided with a functional unit that adjusts the colors in the image to be displayed. The user U compares the colors of the light-emitting color chart displayed on the display D with the colors of the color chart under the observation light source KL, and adjusts the colors of the light-emitting color chart so that the appearance of both colors matches. In the following, the light-emitting color chart after adjustment, in which the color of the color chart i under the observation light source KL and the color chart i seen through the display D match for the user U, is referred to as an "light-emitting color chart i'" or a "colored light-emitting color chart." In addition, the light-emitting color chart after adjustment, in which the color of the color chart w under the observation light source KL and the color of the color chart w displayed on the display D appear to be the same color for the user U, is referred to as an "light-emitting color chart w'" or a "white light-emitting color chart."

[0019] The visual characteristic acquisition device 10 is a computer device that determines a color matching function suitable for a user U. The visual characteristic acquisition device 10 is, for example, a PC or a server device. The visual characteristic acquisition device 10 acquires pixel values ​​(camera pixel values) in an image of a color chart captured by a camera CM. In the following description, the camera pixel values ​​in an image of a color chart i are defined as (R i , G i , B i The camera pixel value in the image of the color chip w is expressed as (R w , G w , B w In addition, when there is no need to distinguish between colors, the parameters indicating the color (i and w) are omitted and the value is simply written as the camera pixel value (R, G, B).

[0020] Specifically, the visual characteristic acquisition device 10 calculates the camera pixel value (R i , B i , G i In addition, the visual characteristic acquisition device 10 acquires the camera pixel value (R w , B w , G w ) to get the

[0021] Furthermore, the visual characteristic acquisition device 10 acquires pixel values ​​(display pixel values) of the luminescent color chip after adjustment of the color in the state displayed on the display D. In the following description, the display pixel value of the luminescent color chip i' is defined as (R' i , G' i , B' i The display pixel value for the luminous color chip w' is expressed as (R' w , G' w , B' w In addition, when there is no need to distinguish between colors, the parameters indicating the color (i and w) are omitted and the display pixel values ​​are simply written as (R', G', B').

[0022] Specifically, the visual characteristic acquisition device 10 calculates the pixel value (R' i , G' i , B' i In addition, the visual characteristic acquisition device 10 acquires the display pixel value (R' w , G' w , B' w ) to get the

[0023] The visual characteristic acquisition device 10 determines a color matching function suitable for the user U based on the camera pixel values ​​(R, G, B) acquired from the camera CM and the display pixel values ​​(R', G', B') acquired from the display D, and outputs the result.

[0024] 2 is a block diagram showing an example of the configuration of the visual characteristic acquisition device 10 according to the first embodiment. The visual characteristic acquisition device 10 includes, for example, a camera-side processing unit 11, a display-side processing unit 12, and a color matching function determination unit 13.

[0025] The camera-side processing unit 11 is a functional unit that performs signal processing using information acquired from the camera CM, i.e., camera pixel values ​​(R, G, B). The camera-side processing unit 11 includes a camera pixel value acquisition unit 111, a reference tristimulus value calculation unit 112, and a camera-side tristimulus value calculation unit 113.

[0026] The camera pixel value acquisition unit 111 acquires camera pixel values ​​and outputs the acquired camera pixel values ​​to the reference tristimulus value calculation unit 112. The reference tristimulus value calculation unit 112 converts the camera pixel values ​​acquired from the camera pixel value acquisition unit 111 into tristimulus values ​​in a reference color matching function (reference tristimulus values) using a camera profile 114.

[0027] The camera profile 114 is information stored in a storage unit (not shown) of the visual characteristic acquisition device 10. The camera profile 114 is information indicating the relationship between tristimulus values ​​(X, Y, Z) calculated by a reference color matching function for a color patch having a known spectral reflectance under a specific light source, and the camera pixel values ​​(R, G, B) of the color patch captured by the camera CM. The above-mentioned specific light source is, for example, a light source selected by a function (auto white balance function) that automatically adjusts the white balance of the camera for the imaging environment. The reference color matching function is a reference color matching function, and for example, CIE1931, which is the CIE (International Commission on Illumination) colorimetric standard observer color matching function, is used.

[0028] Note that the light source information (information on the specific light source described above) in the camera profile 114 is not limited to that selected by auto white balance. For example, a D50 standard light source or a D65 standard light source may be applied as the light source information in the camera profile 114, or a light source that is a combination of these or a light source set by the user may be used.

[0029] Furthermore, it goes without saying that the reference tristimulus value calculation unit 112 may convert the camera pixel values ​​into tristimulus values ​​in the reference color matching function by using other information, without using the camera profile 114. The other information here is, for example, information indicating the relationship between the tristimulus values ​​(X, Y, Z) calculated by the reference color matching function for a color patch whose spectral reflectance under a specific light source is known, and the camera pixel values ​​(R, G, B) of the captured color patch.

[0030] The camera-side tristimulus value calculation unit 113 uses the reference tristimulus values ​​to calculate camera-side tristimulus values ​​of candidate color matching functions to be applied to the user U. In the following description, the candidate color matching functions to be applied to the user may be referred to as "other color matching functions" or "color matching functions" to distinguish them from the reference color matching functions. Moreover, the candidate color matching functions to be applied to the user are an example of "user color matching function candidates."

[0031] In the visual characteristic acquisition system 1, a plurality of (N) color matching functions that are candidates to be applied to the user are prepared in advance. N is an integer equal to or greater than 2. For example, a color matching function that is a candidate to be applied to the user U is a color matching function that is created by linearly converting the spectral sensitivity characteristics of the human cones described in CIE170-1.

[0032] The camera-side tristimulus value calculation unit 113 calculates camera-side tristimulus values ​​for each of all or some of the N color matching functions that are candidates for application to the user. The camera-side tristimulus values ​​for other color matching functions are obtained by expressing the colors of the color chart captured by the camera CM as tristimulus values ​​for the color matching functions. The method by which the camera-side tristimulus value calculation unit 113 calculates the camera-side tristimulus values ​​will be described in detail later.

[0033] The display-side processing unit 12 is a functional unit that performs signal processing using information acquired from the display D, i.e., display pixel values ​​(R', B', G'). The display-side processing unit 12 includes a display pixel value acquisition unit 121, a spectral radiance calculation unit 122, a display-side tristimulus value calculation unit 123, and a LUT (lookup table) 124. The LUT (lookup table) 124 is an example of a "conversion table".

[0034] The display pixel value acquisition unit 121 acquires a display pixel value, and outputs the acquired display pixel value to the spectral radiance calculation unit 122. The spectral radiance calculation unit 122 converts the display pixel value acquired from the display pixel value acquisition unit 121 into a spectral radiance using the LUT .

[0035] The LUT 124 is information stored in a storage unit (not shown) of the visual characteristic acquisition device 10. The LUT 124 is, for example, a LUT (look-up table) that describes the relationship between display pixel values ​​(R', G', B') and spectral radiance. The LUT 124 is created, for example, according to the characteristics of the spectral radiance of the display D that are measured in advance.

[0036] The display-side tristimulus value calculation unit 123 calculates display-side tristimulus values ​​in the candidate color matching functions to be applied to the user U, using the relationship between the spectral radiance and the tristimulus values ​​in the candidate color matching functions to be applied to the user U. The display-side tristimulus value calculation unit 123 calculates display-side tristimulus values ​​for each color matching function for which the camera-side tristimulus values ​​have been calculated, among the N candidate color matching functions to be applied to the user. The display-side tristimulus values ​​in the color matching functions are the colors of the luminous color chip displayed on the display D expressed as tristimulus values ​​in the color matching functions. A method in which the display-side tristimulus value calculation unit 123 calculates the display-side tristimulus values ​​will be described in detail later.

[0037] The color matching function determination unit 13 determines a color matching function to be applied to the user U. The color matching function determination unit 13 obtains the camera-side tristimulus values ​​of the color matching function that is a candidate to be applied to the user U, calculated by the camera-side tristimulus value calculation unit 113. The color matching function determination unit 13 obtains the display-side tristimulus values ​​of the corresponding color matching function, calculated by the display-side tristimulus value calculation unit 123. On the display D side, the color of the emitted color patch displayed on the display D is adjusted so that it matches the appearance of the color patch for the user U. That is, for a certain color matching function, if the camera-side tristimulus values ​​and the display-side tristimulus values ​​match or are close to each other, the color matching function can be regarded as equivalent to the color matching function for the user U. When a printed matter is reproduced on a display, the color matching function can be used to display the printed matter and the display reproduction in such a way that the user U feels that the colors of the printed matter and the display reproduction look equivalent.

[0038] The color matching function determination unit 13, for example, acquires camera-side tristimulus values ​​and display-side tristimulus values ​​for each of N candidate color matching functions to be applied to the user U. The color matching function determination unit 13 calculates the difference between the camera-side tristimulus values ​​and the display-side tristimulus values ​​for each color matching function. The difference here is, for example, the distance between two tristimulus values ​​in a color space. The color matching function determination unit 13 determines the color matching function with the smallest difference among the differences for each color matching function as the color matching function to be applied to the user U.

[0039] Alternatively, the color matching function determination unit 13 may determine that another color matching function is the color matching function to be applied to user U if the difference between the camera-side tristimulus values ​​and the display-side tristimulus values ​​in that function is less than a predetermined threshold value.

[0040] 3 is a diagram for explaining the processing performed by the camera side processing unit 11 of the first embodiment. As shown in FIG. 3, the camera pixel value acquisition unit 111 acquires the camera pixel value (R i , G i , B i ), and the camera pixel value in the image of the color chip w (R w , Gw , B w The camera pixel value acquisition unit 111 outputs the acquired camera pixel values ​​to the reference tristimulus value calculation unit 112.

[0041] The reference tristimulus value calculation unit 112 converts the camera pixel values ​​acquired from the camera pixel value acquisition unit 111 into tristimulus values ​​in a reference color matching function (reference tristimulus values) using a camera profile 114. The method by which the reference tristimulus value calculation unit 112 converts pixel values ​​into tristimulus values ​​using the camera profile 114 has already been explained, so an explanation of this will be omitted here. The reference tristimulus value calculation unit 112 converts the camera pixel values ​​(R i , G i , B i ) to the reference tristimulus value (X i , Y i , Z i ) using the camera profile 114. w , G w , B w ) to the reference tristimulus value (X w , Y w , Z w )

[0042] The reference tristimulus value calculation unit 112 calculates the camera pixel value (R i , G i , B i ) corresponding to the reference tristimulus value (X i , Y i , Z i ) is normalized. Normalization here means canceling the light source information in the camera profile 114. The light source information here is the information on the light source (observation light source information) used when the reference tristimulus value calculation unit 112 converts the camera pixel values ​​into tristimulus values ​​in the reference color matching function. i , Y i , Z i ) can be normalized to reduce the influence on the determination of the color matching function to be applied to the user U when the illumination in the camera profile 114 and the viewing light source KL are different.

[0043] For example, when the observation illuminant KL is a fluorescent lamp with a color temperature of 6500K and the D65 standard illuminant is selected as the illuminant information in the camera profile 114, it is considered that there is almost no change in the ratio of each component in the tristimulus values ​​(X, Y, Z) between the reference tristimulus values ​​converted using the camera profile 114 and the reference tristimulus values ​​calculated under the observation illuminant KL. On the other hand, when the observation illuminant KL is a fluorescent lamp with a color temperature of 5000K and the D65 standard illuminant is selected as the illuminant information in the camera profile 114, it is considered that there is a high possibility that the ratio of each component in the reference tristimulus values ​​obtained by each is significantly different. In this case, when the color matching function to be applied to the user U is determined, an inconsistency with the tristimulus values ​​on the display side may occur. As a measure to suppress the occurrence of such an inconsistency, the reference tristimulus value calculation unit 112 performs normalization, which will be described later.

[0044] The reference tristimulus value calculation unit 112 calculates the reference tristimulus values ​​(X i , Y i , Z i ) to the camera pixel value (R w , G w , B w ) corresponding to the reference tristimulus value (X w , Y w , Z w Specifically, the reference tristimulus value calculation unit 112 normalizes the reference tristimulus values ​​(X i , Y i , Z i ) to the reference tristimulus value (X w , Y w , Z w ) to obtain the normalized tristimulus values ​​of the reference color matching functions, that is, the normalized tristimulus values ​​of the reference color matching functions (X i / X w , Y i / Y w , Z i / Z w The reference tristimulus value calculation unit 112 outputs the calculated normalized tristimulus values ​​of the reference color matching functions to the camera-side tristimulus value calculation unit 113.

[0045] The camera-side tristimulus value calculation unit 113 converts the normalized tristimulus values ​​of the reference color matching function into normalized tristimulus values ​​in another color matching function using a normalization transformation matrix. The normalization transformation matrix is ​​a matrix that converts the normalized tristimulus values ​​of the reference color matching function into normalized tristimulus values ​​in another color matching function.

[0046] In the following, the camera pixel value (R i , G i , B i ) is the tristimulus value corresponding to (X ki , Y ki , Z ki ) (1≦k≦N). Also, the camera pixel value (R w , G w , B w ) is the tristimulus value corresponding to (X kw , Y kw , Z kw ) (1≦k≦N). The normalized tristimulus values ​​in the kth color matching function are expressed as (X ki / X kw , Y ki / Y kw , Z ki / Z kw ) is written as

[0047] The camera-side tristimulus value calculation unit 113 calculates normalized tristimulus values ​​in other color matching functions by the following equation (1).

[0048]

number

[0049] The normalization transformation matrix M in Eq. (1) norm_std→k is a matrix that transforms the normalized tristimulus values ​​in the reference color matching function into the normalized tristimulus values ​​in the k-th color matching function. The normalization transformation matrix M norm_std→k are created corresponding to each of the candidate color matching functions to be applied to the user U. In other words, when there are N candidate color matching functions to be applied to the user U, the corresponding N normalization transformation matrices M norm_std→k(1≦k≦N) is created. The normalization transformation matrix M norm_std→k A method for creating the normalization transformation matrices will be described in detail later. In this embodiment, it is assumed that normalization transformation matrices corresponding to the respective color matching functions are created and stored in advance.

[0050] The camera-side tristimulus value calculation unit 113 calculates normalized tristimulus values ​​in the other color matching functions as camera-side tristimulus values. The camera-side tristimulus value calculation unit 113 outputs the calculated camera-side tristimulus values ​​to the color matching function determination unit 13.

[0051] 4 is a diagram for explaining the processing performed by the display side processing unit 12 according to the first embodiment. As shown in FIG. 4, the display pixel value acquisition unit 121 acquires the display pixel value (R' i , G' i , B' i ), and the display pixel value (R' w , G' w , B' w The display pixel value acquisition unit 121 outputs the acquired display pixel value to the spectral radiance calculation unit 122.

[0052] The spectral radiance calculation unit 122 converts the display pixel value acquired from the display pixel value acquisition unit 121 into a spectral radiance in a reference color matching function using the LUT 124. In the following description, the display pixel value (R' i , G' i , B' i ) is the spectral radiance (a function with wavelength λ as a variable) at i (λ). Also, the display pixel value (R' w , G' w , B' w ) is the spectral radiance (a function with wavelength λ as a variable) at w This is denoted as (λ).

[0053] The spectral radiance calculation unit 122 converts the display pixel value into a spectral radiance using the LUT 124 (for example, an LUT). The spectral radiance calculation unit 122 converts the display pixel value (R' i , G' i , B' i ) and the spectral radiance E' i (λ). In addition, the spectral radiance calculation unit 122 converts the display pixel value (R' w , G' w , B' w ) and the spectral radiance E' w The spectral radiance calculation unit 122 converts the display pixel values ​​into spectral radiance using the LUT 124, thereby calculating the spectral radiance, and outputs the calculated spectral radiance to the display-side tristimulus value calculation unit 123.

[0054] The display-side tristimulus value calculation section 123 calculates tristimulus values ​​corresponding to the spectral radiance in the color matching function by integrating the product of the spectral radiance and the color matching function.

[0055] In the following description, the kth color matching function to be applied to the user U is defined as a function of wavelength λ as (x k (λ), y k (λ), z k (λ)) (1≦k≦N). Also, the display pixel value (R' i , G' i , B' i The tristimulus value corresponding to (X' ki , Y' ki , Z' ki ) and the display pixel value (R' w , G' w , B' w The tristimulus value corresponding to (X' kw , Y' kw , Z' kw ) is written as

[0056] The display tristimulus value calculation unit 123 calculates the integral value obtained by integrating the spectral radiance and the other color matching function in a predetermined wavelength range as the tristimulus value in the other color matching function. The display tristimulus value calculation unit 123 calculates the display pixel value (R' i , G' i , B' i ) corresponding tristimulus value (X' ki , Y' ki , Z' ki ) is calculated.

[0057]

number

[0058] In formula (2), (X' ki ), (Y' ki ), (Z' ki ) is the display pixel value (R' i , G' i , B' i ) are the X, Y, and Z tristimulus values ​​corresponding to the color j. j is a constant. i (λ) is the spectral radiance of the emission color chip i'. (x k (λ), (y k (λ), (z k (λ)) is the k-th candidate color matching function to be applied to user U. λ is the wavelength.

[0059] In Figure 4, the function corresponding to equation (2) is SS k In the following explanation, the calculation of the tristimulus values ​​by executing the integration process corresponding to the formula (2) is referred to as the function SS k This is sometimes referred to as "applying (λ)".

[0060] The display-side tristimulus value calculation unit 123 calculates the display pixel value (R' w , G' w , B' wSimilarly, by applying equation (2) to the display pixel value (R' w , G' w , B' w ) to calculate the tristimulus values.

[0061] In the above, the display tristimulus value calculation unit 123 calculates the function SS k In the above description, the tristimulus values ​​are calculated by applying (λ) to the display-side tristimulus value calculation unit 123. However, the present invention is not limited to this. For example, the display-side tristimulus value calculation unit 123 may calculate tristimulus values ​​(X k ', Y k ', Z k It is also possible to store display profile information indicating the relationship between the color matching functions (R', G', B') and the display pixel values ​​(R', G', B'), and use the display profile information to calculate the tristimulus values ​​corresponding to the display pixel values ​​in other color matching functions.

[0062] The display-side tristimulus value calculation unit 123 calculates the display pixel value (R' i , G' i , B' i ) corresponding tristimulus value (X' ki , Y' ki , Z' ki ) is normalized.

[0063] The display-side tristimulus value calculation unit 123 calculates the tristimulus values ​​(X' ki , Y' ki , Z' ki ) to the display pixel value (R' w , G' w , B' w ) corresponding tristimulus value (X' kw , Y' kw , Z' kw ) to obtain the tristimulus values ​​in the normalized color matching function, that is, the normalized tristimulus values ​​(X' ki / X' kw , Y' ki / Y' kw , Z' ki / Z'kw The display-side tristimulus value calculation unit 123 outputs the calculated normalized tristimulus values ​​of the reference color matching functions to the color matching function determination unit 13.

[0064] 5 is a diagram for explaining the process performed by the color matching function determination unit 13 of the first embodiment. As shown in FIG. 5, the color matching function determination unit 13 calculates the distance e k Calculate the distance e k is the other color matching function (x k (λ), y k (λ), z k The camera-side normalized tristimulus values ​​P(X(λ)) in the color space defined by ki / X kw , Y ki / Y kw , Z ki / Z kw ) and the display side normalized tristimulus value P'(X' ki / X' kw , Y' ki / Y' kw , Z' ki / Z' kw ) is the distance between the coordinates.

[0065]

number

[0066] The color matching function determination unit 13 determines the distance e k The kth color matching function for which is minimum is found, and the kth color matching function is determined as the color matching function to be applied to user U.

[0067] In addition, the distance e k The formula for calculating is not limited to formula (3). For example, the color matching function determination unit 13 may assign different weights to each term in formula (3) and calculate the square root of the sum of the weighted terms as the distance e k It is also possible to use the following.

[0068] In addition, the color matching function determination unit 13 calculates the distance e k Calculate the distance e kThe kth color matching function for which the average value of is minimized may be determined as the color matching function to be applied to user U.

[0069] Here, the normalization transformation matrix M norm_std→k First, the visual characteristic acquisition system 1 calculates the tristimulus values ​​(X i , Y i , Z i ) is required.

[0070]

number

[0071] In equation (4), (X i , Y i , Z i ) is the camera pixel value (R i , G i , B i ) are the X, Y, and Z values ​​of the tristimulus values ​​corresponding to the light source information in the camera profile 114. l (lower case el) is a constant. E(λ) is the spectral radiance corresponding to the light source information in the camera profile 114. i (λ) is the spectral reflectance of color chip i. x(λ), y(λ), and z(λ) are reference color matching functions. λ is the wavelength.

[0072] In the visual characteristic acquisition system 1, the tristimulus values ​​(X w , Y w , Z w ) is required.

[0073] In the visual characteristic acquisition system 1, the tristimulus values ​​(X i , Y i , Z i ) into tristimulus values ​​(X w , Y w , Z w ) to obtain the normalized tristimulus values ​​(X i / X w , Yi / Y w , Z i / Z w ) is calculated.

[0074] In the visual characteristic acquisition system 1, normalized tristimulus values ​​corresponding to each of the multiple color chips i (1≦i≦M) in the reference color matching function are calculated by applying the formula (4). Specifically, the spectral radiance of the light source information in the camera profile 114 is substituted for E(λ) in the formula (4). In addition, R i The spectral reflectance of each of the M color chips i is substituted into (λ). This gives the tristimulus value (X i , Y i , Z i ), the tristimulus value (X w , Y w , Z w ), and the normalized tristimulus values ​​(X i / X w , Y i / Y w , Z i / Z w ) can be calculated for each of the M color samples i.

[0075] Furthermore, the visual characteristic acquisition system 1 applies formula (4) to calculate normalized tristimulus values ​​corresponding to each of a plurality of color chips i (1≦i≦M) in the k-th color matching function that is a candidate for application to the user U. Specifically, the spectral radiance of the light source information in the camera profile 114 is substituted for E(λ) in formula (4). Also, R i The spectral reflectance of each of the M color chips i is substituted into (λ). Furthermore, the X, Y, and Z values ​​of the tristimulus values ​​in the kth color matching function are substituted into x(λ), y(λ), and z(λ) in equation (4). This gives the tristimulus values ​​(X ki , Y ki , Z ki ), the tristimulus value (X kw , Y kw , Z kw ), and the normalized tristimulus values ​​(X ki / X kw , Y ki / Y kw , Z ki / Z kw ) can be calculated for each of the M color chips i. Then, the following equation (5) is established.

[0076]

number

[0077] The left side of the formula (5) is the normalized tristimulus value corresponding to each of the multiple color chips i (1≦i≦M) in the k-th color matching function. The right side is the normalized tristimulus value corresponding to each of the multiple color chips i (1≦i≦M) in the reference color matching function. Normalization transformation matrix M norm_std→k is a matrix that transforms the normalized tristimulus values ​​in the reference color matching function into the normalized tristimulus values ​​in the kth color matching function. The normalization transformation matrix M norm_std→k This calculates the normalization transformation matrix M norm_std→k can be created.

[0078] FIG. 6 is a flowchart showing the flow of processing performed by the visual characteristic acquisition device 10 of the first embodiment.

[0079] (Step S10) The visual characteristic acquisition device 10 acquires the camera pixel values ​​of a color chart i (a colored color chart) and a color chart w (a white color chart). The visual characteristic acquisition device 10 acquires the camera pixel values ​​(R i , G i , B i ) is acquired. In addition, the visual characteristic acquisition device 10 acquires the camera pixel value (R w , G w , B w ) to get the (Step S11) The visual characteristic acquisition device 10 converts each camera pixel value into a tristimulus value corresponding to the camera pixel value in the reference color matching function. i, G i , B i ) is the camera pixel value (R i , G i , B i ) the corresponding tristimulus value (X i , Y i , Z i ) The visual characteristic acquisition device 10 converts the camera pixel value (R w , G w , B w ) is the camera pixel value (R w , G w , B w ) the corresponding tristimulus value (X w , Y w , Z w ) (Step S12) The visual characteristic acquisition device 10 normalizes the tristimulus values. The visual characteristic acquisition device 10 normalizes the tristimulus values ​​(X i , Y i , Z i ) into tristimulus values ​​(X w , Y w , Z w ) to obtain the camera pixel value (R i , G i , B i ) the corresponding normalized tristimulus values ​​(X i / X w , Y i / Y w , Z i / Z w ) is calculated. (Step S13) The visual characteristic acquisition device 10 converts the normalized tristimulus values ​​from those corresponding to the reference color matching functions to those corresponding to color matching functions that are candidates to be applied to the user U. The visual characteristic acquisition device 10 converts the normalized tristimulus values ​​from those corresponding to the reference color matching functions to those corresponding to color matching functions that are candidates to be applied to the user U. norm_std→k Using the normalized tristimulus values ​​(X i / X w , Y i / Y w , Z i / Z w ) to the normalized tristimulus value (X ki / Xkw , Y ki / Y kw , Z ki / Z kw )

[0080] (Step S14) Meanwhile, the visual characteristic acquisition device 10 acquires the display pixel values ​​of the emission color chart i' (color emission color chart) and the emission color chart w' (white emission color chart). The visual characteristic acquisition device 10 acquires the display pixel values ​​(R' i , G' i , B' i In addition, the visual characteristic acquisition device 10 acquires the display pixel value (R' w , G' w , B' w ) to get the (Step S15) The visual characteristic acquisition device 10 converts the display pixel values ​​into spectral radiance. The visual characteristic acquisition device 10 converts the display pixel values ​​(R' i , G' i , B' i ) using the LUT to calculate the spectral radiance E' i (λ). The visual characteristic acquisition device 10 converts the display pixel value (R' w , G' w , B' w ) using the LUT to calculate the spectral radiance E' w (λ). (Step S16) The visual characteristic acquisition device 10 converts the spectral radiance into tristimulus values ​​of other color matching functions. k By applying (λ), the spectral radiance E' in the kth color matching function is calculated. i (λ) corresponds to the tristimulus value (X' ki , Y' ki , Z' ki The visual characteristic acquisition device 10 calculates the function SS k By applying (λ), the spectral radiance E' in the kth color matching function is calculated. w (λ) corresponds to the tristimulus value (X' kw , Y'kw , Z' kw ) is calculated. (Step S17) The visual characteristic acquisition device 10 normalizes the tristimulus values ​​in the other color matching functions. ki , Y' ki , Z' ki ) into tristimulus values ​​(X' kw , Y' kw , Z' kw ) to obtain the display pixel value (R' ki , G' ki , B' ki ) corresponding to the normalized tristimulus value (X' ki / X' kw , Y' ki / Y' kw , Z ki / Z kw ) is calculated.

[0081] (Step S18) The visual characteristic acquisition device 10 determines a color matching function to be applied to the user U. The visual characteristic acquisition device 10 determines a color matching function to be applied to the user U based on a distance e k Calculate the distance e k The color matching function corresponding to k for which the distance e is smallest is determined as the color matching function to be applied to the user U. k is the normalized tristimulus value P(X ki / X kw , Y ki / Y kw , Z ki / Z kw ) and the display side normalized tristimulus value P'(X' ki / X' kw , Y' ki / Y' kw , Z' ki / Z' kw ) distance.

[0082] In the above-mentioned flowchart, an example has been described in which the processing on the display side (steps S14 to S17) is executed after the processing on the camera side (steps S10 to S13). However, this is not limited to this. The processing on the camera side may be executed after the processing on the display side. Furthermore, the processing on the camera side and the processing on the display side may be executed in parallel.

[0083] As described above, the visual characteristic acquisition device 10 according to the first embodiment includes a camera pixel value acquisition unit 111, a reference tristimulus value calculation unit 112, a camera-side tristimulus value calculation unit 113, a display pixel value acquisition unit 121, a spectral radiance calculation unit 122, a display-side tristimulus value calculation unit 123, and a color matching function determination unit 13. The camera pixel value acquisition unit 111 acquires the camera pixel values ​​(colored camera pixel values, white camera pixel values) of the color patch i and the color patch w. The reference tristimulus value calculation unit 112 calculates and normalizes reference tristimulus values ​​(colored reference tristimulus values, white reference tristimulus values) based on the respective camera pixel values. The camera-side tristimulus value calculation unit 113 converts the normalized reference tristimulus values ​​(normalized reference tristimulus values) into normalized tristimulus values ​​in another color matching function, and sets them as camera-side tristimulus values. The display pixel value acquisition unit 121 acquires the display pixel values ​​(colored display pixel value, white display pixel value) of the emission color chip i' and the emission color chip w'. The spectral radiance calculation unit 122 calculates the spectral radiance (colored spectral radiance, white spectral radiance) based on the respective display pixel values. The display side tristimulus value calculation unit 123 calculates and normalizes tristimulus values ​​(display side colored tristimulus value, display side white tristimulus value) in other color matching functions from the respective spectral radiances. The color matching function determination unit 13 determines a color matching function to be applied to the user according to the difference between the normalized tristimulus values ​​on the camera side and the display side. In this way, the visual characteristic acquisition device 10 according to the first embodiment can determine a color matching function suitable for the user without using a photometric device. That is, the visual characteristic of the user can be acquired. Therefore, the color appearance of a reflective object such as a printed matter can be reproduced on the display according to the user's appearance.

[0084] Second embodiment Here, a second embodiment will be described. FIG. 7 is a diagram showing an outline of a visual characteristic acquisition system 1A according to the second embodiment. In the visual characteristic acquisition system 1A, the color of the white light-emitting color patch is not adjusted. That is, in this embodiment, the display pixel value (R' w , G' w , B' w In the following description, the differences from the above-described embodiment will be described, and the same components as those in the above-described embodiment will be denoted by the same reference numerals and description thereof will be omitted.

[0085] 8 is a diagram for explaining the process performed by the display-side processor 12A of the second embodiment. As shown in FIG. 8, in this embodiment, the display pixel value of the color chip w′ (white light-emitting color chip) is not acquired, and the tristimulus values ​​(X w , Y w , Z w ) is used for the processing. w , Y w , Z w ) is the camera pixel value (R w , G w , B w ) are the tristimulus values ​​corresponding to

[0086] The display-side tristimulus value calculation unit 123A calculates the tristimulus values ​​(X w , Y w , Z w ) to the tristimulus values ​​(X kw , Y kw , Z kw ) The conversion matrix is ​​a matrix that converts the tristimulus values ​​of the reference color matching function into tristimulus values ​​in another color matching function. The display-side tristimulus value calculation unit 123A calculates the tristimulus values ​​in the other color matching function by the following equation (6).

[0087]

number

[0088] The transformation matrix M in equation (6) std→k is a matrix that transforms the tristimulus values ​​in the reference color matching function into the tristimulus values ​​in the k-th color matching function. std→k are created corresponding to each of the candidate color matching functions to be applied to the user U. In other words, when there are N candidate color matching functions to be applied to the user U, the corresponding N transformation matrices M std→k (1≦k≦N) is created. std→k A method for creating the color matching functions will be described in detail later. In this embodiment, it is assumed that transformation matrices corresponding to the respective color matching functions are created and stored in advance.

[0089] Here, the tristimulus values ​​calculated from the camera pixel values ​​are multiplied by the tristimulus values ​​calculated from the display pixel values ​​(X' ki , Y' ki , Z' ki ) is likely to be inconsistent in scale. If normalization is performed when the scales are not inconsistent, it will be difficult to cancel the lighting information.

[0090] To deal with this, the display-side tristimulus value calculation unit 123A performs scale adjustment. The scale adjustment here is to match the scale of the colored light emission color chip i' on the display side to the scale of the white color chip w on the camera side. The display-side tristimulus value calculation unit 123A, for example, i , G' i , B' i ) corresponding to the spectral radiance E' i (λ) is calculated from the tristimulus value (X' i , Y' i , Z' i ) Y value (Y' i ) is calculated. The display-side tristimulus value calculation unit 123A also calculates the camera pixel value (R i , G i , B i ) is calculated from the tristimulus values ​​(X i , Yi , Z i ) Y value at (Y i The display tristimulus value calculation unit 123A calculates the Y value (Y' i ) and the Y value (Y i ) for the constant j in equation (2), (j=Y i / Y' i )

[0091] In the above, the case where the scale adjustment is performed using the Y value of the tristimulus values ​​(X, Y, Z) has been described as an example. However, the present invention is not limited to this. The scale adjustment may be performed using any one of the three elements of the tristimulus values ​​(X, Y, Z). For example, the scale adjustment may be performed using the X value of the tristimulus values ​​(X, Y, Z), or the scale adjustment may be performed using the Z value. In addition, the scale adjustment may be performed using any two elements of the three elements of the tristimulus values ​​(X, Y, Z), or the scale adjustment may be performed using all three elements.

[0092] The display-side tristimulus value calculation unit 123A normalizes the tristimulus values. The tristimulus values ​​to be normalized here are the scale-adjusted spectral radiance E' i (λ) was used to calculate the tristimulus value (X' ki , Y' ki , Z' ki The display-side tristimulus value calculation unit 123A calculates the tristimulus values ​​(X' ki , Y' ki , Z' ki ) is the camera pixel value (R w , G w , B w ) corresponding tristimulus value (X kw , Y kw , Z kw In this case, the normalized tristimulus values ​​of the kth color matching function are (X' ki / X kw , Y' ki / Y kw , Z'ki / Z kw )

[0093] 9 is a diagram for explaining the process performed by the color matching function determination unit 13A of the second embodiment. As shown in FIG. 9, the color matching function determination unit 13A determines the distance e k The normalized tristimulus values ​​P(X ki / X kw , Y ki / Y kw , Z ki / Z kw ) and the display side normalized tristimulus value P'(X' ki / X kw , Y' ki / Y kw , Z' ki / Z kw ) to find the distance between the coordinates.

[0094] Here, the transformation matrix M std→k The method for creating the tristimulus values ​​(X i , Y i , Z i ) into a 3-by-1 matrix v i It can be written as:

[0095]

number

[0096] The matrix S in equation (7) is a 3-row, 401-column matrix that represents the reference color matching function. i is a 401-row, 401-column matrix indicating the spectral reflectance of color chip i. Matrix E is a 401-row, 1-column matrix indicating the spectral radiance of observation illuminant KL. The 401 columns (rows) here correspond to the wavelength interval 380 to 780 nm expressed with a resolution of 1 nm.

[0097] In addition, as shown in the following equation (8), the tristimulus value (X ki , Y ki , Z ki) into a 3-by-1 matrix v ki It can be written as:

[0098]

number

[0099] Matrix S in Eq. (8) k is a 3-by-401 matrix that represents the k-th color matching function. i is a 401-row, 401-column matrix indicating the spectral reflectance of color chip i. Matrix E is a 401-row, 1-column matrix indicating the spectral radiance of observation illuminant KL. The 401 columns (rows) here correspond to the wavelength interval 380 to 780 nm expressed with a resolution of 1 nm.

[0100] Using equations (7) and (8), equation (6) can be expressed as the following equation (9).

[0101]

number

[0102] By transforming equation (7), it can be expressed as the following equation (10). T in equation (10) represents the transposition symbol.

[0103]

number

[0104] By substituting equation (10) into equation (8), the following equation (11) is obtained.

[0105]

number

[0106] Based on equation (11), the following equation (12) is given, which gives the transformation matrix M std→k can be created.

[0107]

number

[0108] In addition, the transformation matrix M std→k is created corresponding to each of the N color matching functions that are candidates to be applied to the user U, and further needs to be created for each of the multiple light source information that can be used in the camera profile 114.

[0109] Fig. 10 is a flowchart showing the flow of processing performed by a visual characteristic acquisition device 10A of the second embodiment. The processing on the camera side of this embodiment is the same as that of the first embodiment described above. That is, the processing shown in steps S20 to S23 in Fig. 10 is equivalent to the processing shown in steps S10 to S13 in Fig. 6, and therefore a description thereof will be omitted.

[0110] (Step S24) On the other hand, the visual characteristic acquisition device 10A acquires the display pixel value of the emission color chip i' (color emission color chip). The visual characteristic acquisition device 10A acquires the display pixel value (R' i , G' i , B' i ) to get the (Step S25) The visual characteristic acquisition device 10A converts the display pixel values ​​into spectral radiance. i , G' i , B' i ) using the LUT to calculate the spectral radiance E' i (λ). (Step S26) The visual characteristic acquisition device 10A converts the spectral radiance into tristimulus values ​​of another color matching function. k By applying (λ), the spectral radiance E' in the kth color matching function is calculated. i (λ) corresponds to the tristimulus value (X' ki , Y' ki , Z' ki ) is calculated. Here, the visual characteristic acquisition device 10A performs scale adjustment as necessary. The visual characteristic acquisition device 10A adjusts the scale by adjusting the constant j in the formula (2) as follows: (j=Y i / Y' i ) to perform scale adjustment. i ) is the camera pixel value (R i , G i , B i ) corresponding tristimulus value (X i , Y i , Z i ) is the Y value of the Y value (Y' i ) is the spectral radiance E' in the reference color matching function i (λ) corresponds to the tristimulus value (X' i , Y' i , Z' i ) is the Y value of

[0111] (Step S27) The visual characteristic acquisition device 10A calculates the camera pixel value (R w , G w , B w ) the corresponding tristimulus value (X w , Y w , Z w ) to get the (Step S28) The visual characteristic acquisition device 10A calculates the camera pixel value (R w , G w , B w ) the corresponding tristimulus value (X w , Y w , Z w ) is the camera pixel value (R w , G w , B w ) the corresponding tristimulus value (X kw , Y kw , Z kw ) (Step S29) The visual characteristic acquisition device 10A normalizes the tristimulus values ​​in the k-th color matching function. i(λ) corresponds to the tristimulus value (X' ki , Y' ki , Z' ki ) is the camera pixel value (R w , G w , B w ) the corresponding tristimulus value (X kw , Y kw , Z kw ) to obtain the tristimulus values ​​(X' ki , Y' ki , Z' ki ) is normalized. (Step S30) The visual characteristic acquisition device 10A determines a color matching function to be applied to the user U. The visual characteristic acquisition device 10A determines a color matching function to be applied to the user U. k Calculate the distance e k The color matching function corresponding to k for which the distance e is smallest is determined as the color matching function to be applied to the user U. k is the normalized tristimulus value P(X ki / X kw , Y ki / Y kw , Z ki / Z kw ) and the display side normalized tristimulus value P'(X' ki / X kw , Y' ki / Y kw , Z' ki / Z kw ) distance.

[0112] In the above-mentioned flowchart, an example has been described in which the camera-side processing (steps S20 to S23) is executed first, followed by the display-side processing (steps S24 to S29). However, this is not limiting. The camera-side processing may be executed after the display-side processing. Furthermore, the camera-side processing and the display-side processing may be executed in parallel.

[0113] As described above, the visual characteristic acquisition device 10A according to the second embodiment includes the camera pixel value acquisition unit 111, the reference tristimulus value calculation unit 112, the camera-side tristimulus value calculation unit 113, the display pixel value acquisition unit 121A, the spectral radiance calculation unit 122, the display-side tristimulus value calculation unit 123A, and the color matching function determination unit 13. The display pixel value acquisition unit 121A acquires the display pixel value of the colored light-emitting color chip i'. The display-side tristimulus value calculation unit 123A normalizes with the camera pixel value of the white light-emitting color chip w. Therefore, in the visual characteristic acquisition device 10A according to the second embodiment, it is not necessary to acquire the display pixel value of the white light-emitting color chip w'. This can reduce the user's effort.

[0114] (Modification of the second embodiment) Here, a modified example of the second embodiment will be described. In this embodiment, normalized tristimulus values ​​in the reference color matching function are not calculated on the camera side. In other words, this embodiment differs from the above-mentioned embodiment in that tristimulus values ​​in other color matching functions are calculated directly from the tristimulus values ​​in the reference color matching function on the camera side. In the following description, differences from the above-mentioned embodiment will be described, and the same reference numerals will be used to designate the same components as the above-mentioned embodiment, and description thereof will be omitted.

[0115] 11 is a diagram for explaining the processing performed by the camera-side processing unit 11B in the modified example of the second embodiment. As shown in FIG. 11, the camera-side tristimulus value calculation unit 113B calculates the reference tristimulus values ​​(X i , Y i , Z i The camera-side tristimulus value calculation unit 113B obtains the obtained reference tristimulus values ​​(X i , Y i , Z i ) into the transformation matrix M std→k Using the k-th color matching function, the camera pixel value (R i , G i , B i ) corresponding tristimulus value (X ki , Y ki , Z ki ) is calculated. ki , Yki , Z ki ) is an example of a "camera-side chromatic tristimulus value".

[0116] In addition, the camera-side tristimulus value calculation unit 113B calculates the reference tristimulus values ​​(X w , Y w , Z w The camera-side tristimulus value calculation unit 113B obtains the obtained reference tristimulus values ​​(X w , Y w , Z w ) into the transformation matrix M std→k Using the k-th color matching function, the camera pixel value (R w , G w , B w ) corresponding tristimulus value (X kw , Y kw , Z kw ) is calculated. kw , Y kw , Z kw ) is an example of a "camera-side white tristimulus value."

[0117] The camera-side tristimulus value calculation unit 113B normalizes the tristimulus values. The object of normalization here is the camera pixel value (R i , G i , B i ) corresponding tristimulus value (X ki , Y ki , Z ki The camera-side tristimulus value calculation unit 113B calculates the tristimulus values ​​(X ki , Y ki , Z ki ) is the camera pixel value (R w , G w , B w ) corresponding tristimulus value (X kw , Y kw , Z kw ) to obtain the tristimulus values ​​(X ki , Y ki , Z ki ) is normalized.

[0118] Fig. 12 is a flowchart showing the flow of processing performed by a visual characteristic acquisition device 10B in a modified example of the second embodiment. The processing on the display side (steps S44 to S49), part of the processing on the camera side (steps S40 to S41), and step S50 in this embodiment are equivalent to the processing shown in S24 to S29, S20 to S21, and S30 in Fig. 10, and therefore description thereof will be omitted.

[0119] (Step S42) The visual characteristic acquisition device 10B converts the tristimulus values ​​in the reference color matching function into tristimulus values ​​in another color matching function. i , G i , B i ) the corresponding tristimulus value (X i , Y i , Z i ) into the transformation matrix M std→k Using the k-th color matching function, the tristimulus value (X ki , Y ki , Z ki ) in the reference color matching function. w , G w , B w ) the corresponding tristimulus value (X w , Y w , Z w ) into the transformation matrix M std→k Using the k-th color matching function, the tristimulus value (X kw , Y kw , Z kw )

[0120] (Step S42) The visual characteristic acquisition device 10B normalizes the tristimulus values ​​in the other color matching functions. The visual characteristic acquisition device 10B normalizes the tristimulus values ​​(X ki , Y ki , Z ki ) to the tristimulus value (X kw , Y kw , Z kw ) to obtain the tristimulus values ​​(X ki , Yki , Z ki ) is normalized.

[0121] As described above, the visual characteristic acquisition device 10B according to the modified example of the second embodiment includes the camera pixel value acquisition unit 111, the reference tristimulus value calculation unit 112, the camera-side tristimulus value calculation unit 113B, the display pixel value acquisition unit 121, the spectral radiance calculation unit 122, the display-side tristimulus value calculation unit 123, and the color matching function determination unit 13. The camera-side tristimulus value calculation unit 113B converts the reference tristimulus values ​​into tristimulus values ​​in another color matching function without normalizing the reference tristimulus values, and normalizes the converted tristimulus values. As a result, the visual characteristic acquisition device 10B according to the modified example of the second embodiment determines the normalization transformation matrix M norm_std→k Therefore, it is not necessary to store the normalization transformation matrix that needs to be prepared for each color matching function and each piece of light source information in the above embodiment. Therefore, it is possible to reduce the memory capacity.

[0122] (Third embodiment) Next, a third embodiment will be described. Fig. 13 is a diagram showing an outline of a visual characteristic acquisition system 1C of the third embodiment. The visual characteristic acquisition system 1C differs from the above-mentioned embodiment in that it does not acquire camera pixel values ​​in a color patch w (white color patch). In the following description, differences from the above-mentioned embodiment will be described, and configurations equivalent to those of the above-mentioned embodiment will be denoted by the same reference numerals and description thereof will be omitted. In this embodiment, it is preferable to apply the present invention when the accuracy of the auto white balance of the camera is high. In this case, the illumination information of the camera profile and the illumination information of the actual observation light source KL can be regarded as equivalent, and it is possible to omit the normalization process for canceling the illumination information. In other words, in this case, there is no need to obtain information on the color chart w (white color chart) used for canceling the illumination information.

[0123] FIG. 14 is a diagram for explaining the processing performed by the camera-side processing unit 11C of the third embodiment. As shown in FIG. 14, the camera-side tristimulus value calculation unit 113C calculates the tristimulus values ​​(Xi , Y i , Z i ) to obtain the tristimulus values ​​(X i , Y i , Z i ) is the camera pixel value (R i , G i , B i The camera-side tristimulus value calculation unit 113C calculates the tristimulus values ​​(X i , Y i , Z i ) into the transformation matrix M std→k Using the tristimulus values ​​(X ki , Y ki , Z ki ) to convert the tristimulus values ​​(X ki , Y ki , Z ki ) is the camera pixel value (R i , G i , B i ) are the tristimulus values ​​corresponding to

[0124] 15 is a diagram for explaining the processing performed by the display-side processing unit 12C of the third embodiment. As shown in FIG. 15, the display-side tristimulus value calculation unit 123C calculates the spectral radiance E' i (λ) is obtained. i (λ) is the display pixel value (R' i , G' i , B' i The display-side tristimulus value calculation unit 123C calculates the spectral radiance E' i The tristimulus values ​​(X' ki , Y' ki , Z' ki ) to convert the tristimulus values ​​(X' ki , Y' ki , Z' ki ) is the spectral radiance E' for the kth color matching function i are the tristimulus values ​​corresponding to (λ).

[0125] 16 is a diagram for explaining the process performed by the color matching function determination unit 13C of the third embodiment. As shown in FIG. 16, the color matching function determination unit 13C determines the distance e k The camera-side tristimulus values ​​in the color space are P(X ki , Y ki , Z ki ) and the display tristimulus value P'(X' ki , Y' ki , Z' ki ) to find the distance between the coordinates.

[0126] FIG. 17 is a flowchart showing the flow of processing performed by the visual characteristic acquisition device 10C of the third embodiment.

[0127] (Step S60) The visual characteristic acquisition device 10C acquires the camera pixel value of the color chart i (colored color chart). The visual characteristic acquisition device 10C acquires the camera pixel value (R i , G i , B i ) to get the (Step S61) The visual characteristic acquisition device 10C converts the camera pixel values ​​into tristimulus values ​​corresponding to the camera pixel values ​​in the reference color matching function. i , G i , B i ) is the camera pixel value (R i , G i , B i ) the corresponding tristimulus value (X i , Y i , Z i ) (Step S62) The visual characteristic acquisition device 10C converts the tristimulus values ​​corresponding to the reference color matching functions into tristimulus values ​​corresponding to other color matching functions. The visual characteristic acquisition device 10C converts the tristimulus values ​​(X i , Y i , Z i ) into the transformation matrix M std→k Using the k-th color matching function, the tristimulus value (X ki , Y ki , Zki )

[0128] (Step S63) On the other hand, the visual characteristic acquisition device 10C acquires a display pixel value in the emission color chart i' (color emission color chart). The visual characteristic acquisition device 10C acquires a display pixel value (R' i , G' i , B' i ) to get the (Step S64) The visual characteristic acquisition device 10C converts the display pixel values ​​into spectral radiance. i , G' i , B' i ) using the LUT to calculate the spectral radiance E' i (λ). (Step S65) The visual characteristic acquisition device 10C converts the spectral radiance into tristimulus values ​​of other color matching functions. i (λ) and the kth color matching function (x k (λ), y k (λ), z k The spectral radiance E' for the kth color matching function is calculated by integrating the value obtained by multiplying the wavelength by the wavelength (λ) and integrating it over a specified wavelength range. i (λ) corresponds to the tristimulus value (X' ki , Y' ki , Z' ki ) is calculated. (Step S65) The visual characteristic acquisition device 10C determines a color matching function to be applied to the user U. The visual characteristic acquisition device 10C determines a color matching function to be applied to the user U. k Calculate the distance e k The color matching function corresponding to k for which the distance e is smallest is determined as the color matching function to be applied to the user U. k is the camera tristimulus value P(X ki , Y ki , Z ki ) and the display tristimulus value P'(X' ki , Y' ki , Z' ki ) distance.

[0129] As described above, the visual characteristic acquisition device 10C according to the third embodiment includes a camera pixel value acquisition unit 111, a reference tristimulus value calculation unit 112, a camera-side tristimulus value calculation unit 113C, a display pixel value acquisition unit 121, a spectral radiance calculation unit 122, a display-side tristimulus value calculation unit 123C, and a color matching function determination unit 13C. The camera pixel value acquisition unit 111 acquires a camera pixel value, which is a pixel value in an image of a color chip i. The reference tristimulus value calculation unit 112 calculates a reference tristimulus value corresponding to the camera pixel value. The camera-side tristimulus value calculation unit 113C calculates a camera-side tristimulus value in another color matching function using the reference tristimulus value. The display pixel value acquisition unit 121 acquires a display pixel value in a light-emitting color chip i'. The spectral radiance calculation unit 122 converts the display pixel value into a spectral radiance. The display-side tristimulus value calculation unit 123C calculates a spectral radiance E' i Based on the relationship between (λ) and other color matching functions, the display-side tristimulus values ​​of the user color matching function candidates are calculated. The color matching function determination unit 13 determines the color matching functions to be applied to the user U. The color matching function determination unit 13 determines the color matching functions to be applied to the user U based on the difference between the camera-side tristimulus values ​​and the display-side tristimulus values. As a result, the visual characteristic acquisition device 10C according to the third embodiment does not need to acquire camera pixel values ​​on the color patch w. This reduces the user's effort.

[0130] In the visual characteristic acquisition device 10C according to the third embodiment described above, the camera-side tristimulus value calculation unit 113C calculates the transformation matrix M std→k The display-side tristimulus value calculation unit 123C converts the reference tristimulus values ​​using the function SS k (λ) is applied to calculate the tristimulus values. As a result, the visual characteristic acquisition device 10C according to the third embodiment has the same effects as those described above.

[0131] The visual characteristic acquisition device 10 in the above-described embodiment may be realized in whole or in part by a computer. In that case, a program for realizing this function may be recorded in a computer-readable recording medium, and the program recorded in the recording medium may be read into a computer system and executed to realize the function. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. The term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into a computer system. The term "computer-readable recording medium" may also include a medium that dynamically holds a program for a short period of time, such as a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, and a medium that holds a program for a certain period of time, such as a volatile memory inside a computer system that is a server or client in that case. The above-described program may be a program for realizing a part of the above-described function, or may be a program that can realize the above-described function in combination with a program already recorded in the computer system, or may be a program that is realized using a programmable logic device such as an FPGA.

[0132] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included. [Explanation of symbols]

[0133] 1...Visual characteristic acquisition system 10...Visual characteristic acquisition device 111...Camera pixel value acquisition unit 112...Reference tristimulus value calculation unit 113...Camera side tristimulus value calculation unit 114…Camera profile 121...Display pixel value acquisition unit 122...Spectral radiance calculation unit 123...Display side tristimulus value calculation unit 124...LUT 13...Color matching function determination section

Claims

1. a camera pixel value acquisition unit that acquires a camera pixel value, which is a pixel value in an image of a color chart captured by a camera; a reference tristimulus value calculation unit that calculates reference tristimulus values, which are tristimulus values ​​corresponding to the camera pixel values ​​in a reference color matching function, by using the camera pixel values ​​and a camera profile; a camera-side tristimulus value calculation unit that calculates camera-side tristimulus values ​​for a user color matching function candidate, which is a candidate of a color matching function to be applied to a user, using the reference tristimulus values; a display pixel value acquisition unit that acquires display pixel values, which are pixel values ​​of the luminescent color chart after the color is adjusted so that the appearance of the luminescent color chart displayed on the display coincides with the appearance of the luminescent color chart; a spectral radiance calculation unit that calculates a spectral radiance corresponding to the display pixel value by converting the display pixel value into a spectral radiance using the display pixel value and a conversion table; a display-side tristimulus value calculation unit that calculates display-side tristimulus values ​​in the user's color matching function candidates based on a relationship between the spectral radiance corresponding to the display pixel value and the tristimulus values ​​in the user's color matching function candidates; a color matching function determination unit that determines a color matching function to be applied to the user based on a difference between the camera-side tristimulus values ​​in the user's color matching function candidate calculated by the camera-side tristimulus value calculation unit and the display-side tristimulus values ​​in the user's color matching function candidate calculated by the display-side tristimulus value calculation unit; A visual characteristic acquisition device comprising:

2. the camera-side tristimulus value calculation unit calculates tristimulus values ​​in the user's color matching function candidate by converting the reference tristimulus values ​​using a conversion matrix, and sets the calculated tristimulus values ​​as camera-side tristimulus values ​​in the user's color matching function candidate; the display-side tristimulus value calculation unit multiplies the spectral radiance corresponding to the display pixel value by the user's color matching function candidate for each wavelength, integrates the multiplied value over a predetermined wavelength interval, and determines the integrated value as the display-side tristimulus value for the user's color matching function candidate. The visual characteristic acquisition device according to claim 1 .

3. the camera pixel value acquisition unit acquires color camera pixel values, which are pixel values ​​in an image of a colored color chart that is a color chart of a color different from white, and white camera pixel values, which are pixel values ​​in an image of a white color chart that is a white color chart; The reference tristimulus value calculation unit calculating color reference tristimulus values, which are tristimulus values ​​corresponding to the color camera pixel values ​​in a reference color matching function, using the color camera pixel values ​​and the camera profile; calculating white reference tristimulus values, which are tristimulus values ​​corresponding to the white camera pixel values ​​in a reference color matching function, using the white camera pixel values ​​and the camera profile; The camera-side tristimulus value calculation unit Calculating camera-side chromatic tristimulus values ​​in the user color matching function candidate by converting the chromatic reference tristimulus values ​​using a conversion matrix; calculating camera-side white tristimulus values ​​in the user color matching function candidate by transforming the white reference tristimulus values ​​using the transformation matrix; the normalized tristimulus values ​​obtained by normalizing the camera-side chromatic tristimulus values ​​with the camera-side white tristimulus values ​​are set as camera-side tristimulus values ​​in the user color matching function candidates; The display-side tristimulus value calculation unit multiplying the spectral radiance corresponding to the display pixel value by the user's color matching function candidate for each wavelength, integrating the multiplied value over a predetermined wavelength interval, and setting the integrated value as a display-side color tristimulus value in the user's color matching function candidate; The tristimulus values ​​obtained by normalizing the display-side color tristimulus values ​​with the camera-side white tristimulus values ​​are set as the display-side tristimulus values ​​in the user color matching function candidates. The visual characteristic acquisition device according to claim 1 .

4. the display-side tristimulus value calculation unit adjusts a scale of the spectral radiance corresponding to the display pixel value so that the tristimulus value calculated based on the camera pixel value and the tristimulus value calculated based on the display pixel value have the same magnitude. The visual characteristic acquisition device according to claim 3 .

5. the display-side tristimulus value calculation unit adjusts a scale of the spectral radiance based on a Y value of the tristimulus value according to the spectral radiance corresponding to the display pixel value in the reference color matching function and a Y value of the colored reference tristimulus value. The visual characteristic acquisition device according to claim 4 .

6. the camera pixel value acquisition unit acquires color camera pixel values, which are pixel values ​​in an image of a colored color chart that is a color chart of a color different from white, and white camera pixel values, which are pixel values ​​in an image of a white color chart that is a white color chart; The reference tristimulus value calculation unit calculating color reference tristimulus values, which are tristimulus values ​​corresponding to the color camera pixel values ​​in a reference color matching function, using the color camera pixel values ​​and the camera profile; calculating white reference tristimulus values, which are tristimulus values ​​corresponding to the white camera pixel values ​​in a reference color matching function, using the white camera pixel values ​​and the camera profile; Calculating normalized reference tristimulus values ​​by normalizing the colored reference tristimulus values ​​with the white reference tristimulus values; The camera-side tristimulus value calculation unit Calculating normalized tristimulus values ​​in the user color matching function candidates by converting the normalized reference tristimulus values ​​using a normalization transformation matrix; The normalized tristimulus values ​​in the user's color matching function candidate are set to camera-side tristimulus values ​​in the user's color matching function candidate, The display-side tristimulus value calculation unit multiplying the spectral radiance corresponding to the display pixel value by the user's color matching function candidate for each wavelength, integrating the multiplied value over a predetermined wavelength interval, and setting the integrated value as a display-side color tristimulus value in the user's color matching function candidate; The white reference tristimulus values ​​are converted using a conversion matrix to obtain white tristimulus values ​​in the user color matching function candidate. the display-side color tristimulus values ​​are normalized by the white tristimulus values ​​in the user's color matching function candidates to obtain normalized tristimulus values, which are then used as the display-side tristimulus values ​​in the user's color matching function candidates; The visual characteristic acquisition device according to claim 1 .

7. the camera pixel value acquisition unit acquires color camera pixel values, which are pixel values ​​in an image of a colored color chart that is a color chart of a color different from white, and white camera pixel values, which are pixel values ​​in an image of a white color chart that is a white color chart; The reference tristimulus value calculation unit calculating color reference tristimulus values, which are tristimulus values ​​corresponding to the color camera pixel values ​​in a reference color matching function, using the color camera pixel values ​​and the camera profile; calculating white reference tristimulus values, which are tristimulus values ​​corresponding to the white camera pixel values ​​in a reference color matching function, using the white camera pixel values ​​and the camera profile; Calculating normalized reference tristimulus values ​​by normalizing the colored reference tristimulus values ​​with the white reference tristimulus values; The camera-side tristimulus value calculation unit Calculating normalized tristimulus values ​​in the user color matching function candidates by converting the normalized reference tristimulus values ​​using a normalization transformation matrix; The normalized tristimulus values ​​in the user's color matching function candidate are set to camera-side tristimulus values ​​in the user's color matching function candidate, The display pixel value acquisition unit is obtaining a color display pixel value, which is a pixel value on a color emission color chip after color adjustment so that an appearance on the color emission color chip of a color different from white matches an appearance on the color emission color chip; Obtaining a white display pixel value, which is a pixel value on the white light-emitting color chart after color adjustment so that the appearance of the white light on the white light-emitting color chart matches the appearance on the white color chart; The spectral radiance calculation unit calculating a colored spectral radiance corresponding to the colored display pixel value by converting the colored display pixel value into a spectral radiance using the colored display pixel value and the conversion table; calculating a white color spectral radiance corresponding to the white color display pixel value by converting the white color display pixel value into a spectral radiance using the white color display pixel value and the conversion table; The display-side tristimulus value calculation unit multiplying the colored spectral radiance by the user's color matching function candidate for each wavelength, integrating the multiplied value over a predetermined wavelength interval, and calculating the integrated value as a display-side colored tristimulus value corresponding to the colored spectral radiance; multiplying the white spectral radiance by the user's color matching function candidate for each wavelength, integrating the multiplied value over a predetermined wavelength interval, and calculating the integrated value as a white tristimulus value corresponding to the white spectral radiance; The display-side color tristimulus values ​​are normalized by the white tristimulus values ​​to be the display-side tristimulus values ​​in the user color matching function candidates. The visual characteristic acquisition device according to claim 1 .

8. A visual characteristic acquisition method executed by a computer of a visual characteristic acquisition device, comprising: a camera pixel value acquisition unit acquires a camera pixel value, which is a pixel value in an image of the color chart captured by the camera; a reference tristimulus value calculation unit calculates reference tristimulus values, which are tristimulus values ​​corresponding to the camera pixel values ​​in a reference color matching function, using the camera pixel values ​​and a camera profile; a camera-side tristimulus value calculation unit calculates camera-side tristimulus values ​​of a user color matching function candidate, which is a candidate of a color matching function to be applied to a user, using the reference tristimulus values; a display pixel value acquisition unit acquires display pixel values, which are pixel values ​​of the emission color chart after color adjustment in which the appearance of the emission color chart displayed on the display coincides with the appearance of the emission color chart; a spectral radiance calculation unit converts the display pixel value into a spectral radiance using the display pixel value and a conversion table, thereby calculating a spectral radiance corresponding to the display pixel value; a display-side tristimulus value calculation unit calculates display-side tristimulus values ​​in the user's color matching function candidates based on a relationship between the spectral radiance corresponding to the display pixel value and the tristimulus values ​​in the user's color matching function candidates; a color matching function determination unit determines a color matching function to be applied to the user based on a difference between the camera-side tristimulus values ​​in the user color matching function candidate calculated by the camera-side tristimulus value calculation unit and the display-side tristimulus values ​​in the user color matching function candidate calculated by the display-side tristimulus value calculation unit; Visual characteristic acquisition method.

9. A computer of the visual characteristic acquisition device a camera pixel value acquisition step of acquiring a camera pixel value which is a pixel value in an image of a color chart captured by a camera; a reference tristimulus value calculation step of calculating reference tristimulus values, which are tristimulus values ​​corresponding to the camera pixel values ​​in a reference color matching function, using the camera pixel values ​​and a camera profile; a camera-side tristimulus value calculation step of calculating camera-side tristimulus values ​​of a user color matching function candidate, which is a candidate of a color matching function to be applied to a user, using the reference tristimulus values; a display pixel value acquisition step of acquiring display pixel values, which are pixel values ​​of the luminescent color chart after the color is adjusted so that the appearance of the luminescent color chart displayed on the display coincides with the appearance of the luminescent color chart; a spectral radiance calculation step of converting the display pixel value into a spectral radiance using the display pixel value and a conversion table, thereby calculating a spectral radiance corresponding to the display pixel value; a display-side tristimulus value calculation step of calculating display-side tristimulus values ​​in the user's color matching function candidates based on a relationship between the spectral radiance corresponding to the display pixel value and the tristimulus values ​​in the user's color matching function candidates; a user color matching function determination step of determining a color matching function to be applied to the user based on a difference between the camera-side tristimulus values ​​of the user color matching function candidate calculated in the camera-side tristimulus value calculation step and the display-side tristimulus values ​​of the user color matching function candidate calculated in the display-side tristimulus value calculation step; A program that executes the following.

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