Illumination device and illumination control method

Abstract

This illumination device comprises: a first color difference decomposition processing unit that calculates a first change amount related to an intensity of a color difference between a colorimetric value of an aimed color under reference illumination light and a colorimetric value of the aimed color under target illumination light; a color difference evaluation unit that performs evaluation regarding each of the specific color and the aimed color on the basis of the first change amount, the second change amount, and one of a third change amount and a fourth change amount, the third change amount being related to a color difference between a colorimetric value of the specific color under the reference illumination light and a colorimetric value of the specific color under the target illumination light, or an intensity of a color difference between the colorimetric value of the specific color under the reference illumination light and the colorimetric value of the specific color under the target illumination light, and the fourth change amount being related to a color phase of the color difference; a target illumination light calculation unit that calculates, on the basis of the evaluation result of the color difference evaluation unit, an illumination light spectrum in which the change in the appearance of the aimed color is maximized; and a target illumination light output unit that outputs illumination light based on the illumination light spectrum calculated by the target illumination light calculation unit.　

Description

Lighting device and lighting control method

[0001] The present invention relates to a lighting device and a lighting control method.

[0002] A method has been proposed for calculating an illumination spectrum that maximizes the change in appearance of a target color while maintaining the appearance of a specific color (e.g., white) (see, for example, Patent Document 1). In the method described in Patent Document 1, the color difference (CIE L) between the pre- and post-processing colors is used as the amount of change in color appearance. ＊ a ＊ b ＊ The illumination spectrum that maximizes the color difference is calculated by using the color difference, u′v′ color difference, etc. Furthermore, Patent Document 1 also describes a method of limiting color change to saturation (vividness).

[0003] Japanese Patent Application Laid-Open No. 2019-204707

[0004] In Patent Document 1, the amount of change in the target color is simply measured as color difference or saturation, and changes in hue (color tone) are not taken into consideration. Generally, color difference is defined as the distance (Euclidean distance) between two colors in a uniform color space. Changing the hue may leave a stronger impression on the observer than changing the saturation. For example, when only the saturation is changed, some observers may evaluate the result as "only the color intensity has changed" or "only the color brightness has changed." However, the technology described in Patent Document 1 has the problem of not being able to take changes in hue into account.

[0005] In view of the above circumstances, an object of the present invention is to provide a technique capable of calculating an illumination light spectrum that takes into account changes in hue and maximizes the change in appearance of a target color.

[0006] One aspect of the present invention is an illumination device comprising: a first color difference decomposition processing unit that calculates a first amount of change in saturation in the color difference between the colorimetric values ​​of a target color under reference illumination and the colorimetric values ​​of the target color under target illumination, and a second amount of change in hue in the color difference; a color difference evaluation unit that evaluates each of the specific color and the target color based on the first amount of change and the second amount of change, either the color difference between the colorimetric values ​​of a specific color under reference illumination and the colorimetric values ​​of the specific color under target illumination, or a third amount of change in saturation in the color difference between the colorimetric values ​​of the specific color under reference illumination and the colorimetric values ​​of the specific color under target illumination, and a fourth amount of change in hue in the color difference; a target illumination light calculation unit that calculates an illumination light spectrum that maximizes the change in appearance of the target color based on the evaluation result of the color difference evaluation unit; and a target illumination light output unit that outputs illumination light based on the illumination light spectrum calculated by the target illumination light calculation unit.

[0007] One aspect of the present invention is a lighting control method that calculates a first change amount related to saturation in the color difference between the colorimetric value of a target color under reference illumination and the colorimetric value of the target color under target illumination, and a second change amount related to hue in the color difference; evaluates the specific color and the target color based on either the color difference between the colorimetric value of a specific color under reference illumination and the colorimetric value of the specific color under target illumination, or a third change amount related to saturation in the color difference between the colorimetric value of the specific color under reference illumination and the colorimetric value of the specific color under target illumination, and a fourth change amount related to hue in the color difference, as well as the first change amount and the second change amount; calculates an illumination light spectrum that maximizes the change in appearance of the target color based on the evaluation results; and outputs illumination light based on the calculated illumination light spectrum.

[0008] According to the present invention, it is possible to calculate an illumination light spectrum that takes into account changes in hue and maximizes the change in appearance of a target color.

[0009] FIG. 1 is a diagram showing an example of the configuration of a conventional lighting device; FIG. 2 is a diagram showing an example of the configuration of a lighting device in a first embodiment; FIG. 3 is a diagram showing an example of the configuration of a color difference decomposition processing unit in the first embodiment; FIG. 4 is a flowchart showing the flow of processing by the lighting device in the first embodiment; FIG. 5 is a diagram showing an example of the configuration of a lighting device in a second embodiment; and FIG. 6 is a diagram showing an example of the configuration of a color difference decomposition processing unit in the second embodiment.

[0010] An embodiment of the present invention will be described below with reference to the drawings. In the following description, a color whose appearance does not change even when the illumination light spectrum is changed will be referred to as a "specific color," and a color whose appearance changes when the illumination light spectrum is changed will be referred to as a "target color."

[0011] (Conventional Configuration) Before describing the configuration of the lighting device of the present invention, the configuration of a conventional lighting device 100 will be described. FIG. 1 is a diagram showing an example of the configuration of the conventional lighting device 100. The lighting device 100 outputs lighting light (hereinafter referred to as "target lighting light") that changes only the appearance of a target color, while leaving the appearance of a specific color unchanged from that under lighting light that serves as a reference (hereinafter referred to as "reference lighting light"). The lighting device 100 includes a reference lighting light setting unit 101, a specific color setting unit 102, a target color setting unit 103, a first specific color calculation unit 104, a second specific color calculation unit 105, a first color difference calculation unit 106, a first target color calculation unit 107, a second target color calculation unit 108, a second color difference calculation unit 109, a color difference condition setting unit 110, a color difference evaluation unit 111, a target lighting light calculation unit 112, and a target lighting light output unit 113.

[0012] The reference illuminant setting unit 101 inputs the spectrum of the reference illuminant or defines the spectrum of the reference illuminant. The reference illuminant setting unit 101 outputs information indicating the input or defined spectrum of the reference illuminant to the first specific color calculation unit 104 and the first target color calculation unit 107. Note that in the following processing, it is assumed that the spectral spectrum of this "reference illuminant" does not change.

[0013] The specific color setting unit 102 sets a specific color that does not change in appearance even when the illumination light is changed from the reference illumination light. The specific color setting unit 102 receives as input the spectral reflectance or reflectance spectrum of a material having the specific color and the illumination light spectrum when the reflectance spectrum is measured. The number of specific colors may be zero or more, and may be multiple. When the reflectance spectrum of the corresponding material is input, the specific color setting unit 102 calculates the spectral reflectance using the illumination light spectrum when the reflectance spectrum is measured. The specific color setting unit 102 outputs information indicating the spectral reflectance of the material having the specific color, obtained by input or calculation, to the first specific color calculation unit 104 and the second specific color calculation unit 105.

[0014] The target color setting unit 103 sets a target color that changes color depending on the target illumination light. The target color setting unit 103 receives as input the spectral reflectance of a material having the target color, or the reflected light spectrum and the illumination light spectrum when the reflected light spectrum is measured. When a reflected light spectrum is input, the target color setting unit 103 calculates the spectral reflectance using the illumination light spectrum when the reflected light spectrum is measured. There may be multiple target colors. The target color setting unit 103 outputs information indicating the spectral reflectance of the material having the target color to the first target color calculation unit 107 and the second target color calculation unit 108.

[0015] The first specific color calculation unit 104 receives as input information indicating the spectrum of the reference illumination light output from the reference illumination light setting unit 101 and information indicating the spectral reflectance of a material having the specific color output from the specific color setting unit 102. The first specific color calculation unit 104 calculates the colorimetric value of a specific color under the reference illumination light (hereinafter referred to as "reference specific color") using the input information indicating the spectrum of the reference illumination light, the information indicating the spectral reflectance of the material having the specific color, and a color matching function of the human eye.

[0016] Here, the wavelength is λ, the reference illumination light spectrum is w(λ), the spectral reflectance of a specific color is r'(λ), and the color matching function of the human eye is c ｔ (λ), when t={X, Y, Z}, the colorimetric value q of the reference specific color ｔ (t={X, Y, Z}) can be expressed by the following equation (1).

[0017]

[0018] The first specific color calculation unit 104 calculates the colorimetric value q of the reference specific color based on the above formula (1). ｔ When the specific color is white, the spectral reflectance r'(λ) has the same value at all wavelengths. Therefore, when the specific color is white, the colorimetric value q of the reference specific color is calculated. ｗｈｉｔｅｔ (t={X, Y, Z}) can be expressed by the following equation (2).

[0019]

[0020] The first specific color calculation unit 104 calculates the colorimetric value (q ｔ or q ｗｈｉｔｅｔ ) to the first color difference calculation unit 106.

[0021] The second specific color calculation unit 105 receives as input information indicating the spectrum of the target illumination light output from the target illumination light calculation unit 112 and information indicating the spectral reflectance of the material having the specific color output from the specific color setting unit 102. The second specific color calculation unit 105 calculates the colorimetric value of the specific color under the target illumination light (hereinafter referred to as the "target specific color") using the input information indicating the spectrum of the target illumination light, the information indicating the spectral reflectance of the material having the specific color, and a color matching function of the human eye.

[0022] Here, the wavelength is λ, the target illumination light spectrum is w'(λ), the spectral reflectance of a specific color is r'(λ), and the color matching function of the human eye is c ｔ (λ), when t={X, Y, Z}, the colorimetric value q' of the target specific color ｔ (t={X, Y, Z}) can be expressed by the following equation (3).

[0023]

[0024] The second specific color calculation unit 105 calculates the colorimetric value q' of the target specific color based on the above formula (3). ｔ The second specific color calculation unit 105 calculates the colorimetric value (q') of the target specific color obtained by the formula (3). ｔ or q' ｗｈｉｔｅｔ ) to the first color difference calculation unit 106.

[0025] The first color difference calculation unit 106 calculates the colorimetric value (q ｔ or q ｗｈｉｔｅｔ ) and the colorimetric value (q') of the target specific color output from the second specific color calculation unit 105. ｔ or q' ｗｈｉｔｅｔ The first color difference calculation unit 106 receives the colorimetric value (q ｔ or q ｗｈｉｔｅｔ ) and the colorimetric value (q') of the target specific color ｔ or q' ｗｈｉｔｅｔ ) for each piece of information indicating the color difference in a predetermined uniform color space.

[0026] Here, V( ) is expressed as CIE L ＊ a ＊ b ＊ The operator for calculating the value, ||V(q')-V(q)||, is ＊ a ＊ b ＊ The operator for calculating the color difference in the color space is L. ＊ a ＊ b ＊ The color difference in the color space is expressed by the following equation (4).

[0027]

[0028] L in formula (4) ＊´ represents the brightness of the target specific color, and a ＊´ and b ＊´ represents the chromaticity indicating the hue and saturation of the target specific color, and L ＊ represents the brightness of the reference specific color, and a ＊ and b ＊ represents the chromaticity that indicates the hue and saturation of the reference specific color.

[0029] The first color difference calculation unit 106 calculates ||V(q')-V(q)|| as the color difference {(a ＊´ -a ＊ ) ２ +(b ＊´ -b ＊ ) ２} １／２ For brightness, the absolute value of the difference in Y value shown in the following equation (5) may be used.

[0030]

[0031] The first color difference calculation unit 106 outputs information indicating the color difference regarding the specific color obtained by the calculation to the color difference evaluation unit 111. Note that, as an example, the CIE L ＊ a ＊ b ＊ We have given an example of calculating color differences in color space. ＊ a ＊ b ＊ L instead of value ＊ You can also use the u'v' value. In that case, change U() to L ＊ The operator for calculating the u'v' values, ||U(q')-U(q)||, is ＊ It can be an operator that calculates color differences in the u'v' color space.

[0032] The first target color calculation unit 107 receives as input information indicating the spectrum of the reference illumination light output from the reference illumination light setting unit 101 and information indicating the spectral reflectance of the material having the target color output from the target color setting unit 103. The first target color calculation unit 107 calculates the colorimetric value of the target color under the reference illumination light (hereinafter referred to as "reference target color") using the input information indicating the spectrum of the reference illumination light, the information indicating the spectral reflectance of the material having the target color, and the color matching function of the human eye.

[0033] Here, the wavelength is λ, the reference illumination light spectrum is w(λ), the spectral reflectance of the target color is r(λ), and the color matching function of the human eye is c ｔ (λ), when t={X, Y, Z}, the colorimetric value p of the reference target color ｔ (t={X, Y, Z}) can be expressed by the following equation (6).

[0034]

[0035] The first target color calculation unit 107 calculates the colorimetric value of the reference target color based on the above formula (6). The first target color calculation unit 107 calculates the colorimetric value of the reference target color (p ｔ ) to the second color difference calculation unit 109.

[0036] The second target color calculation unit 108 receives as input information indicating the spectrum of the target illumination light output from the target illumination light calculation unit 112 and information indicating the spectral reflectance of the material having the target color output from the target color setting unit 103. The second target color calculation unit 108 calculates the colorimetric value of the target color under the target illumination light (hereinafter referred to as "target target color") using the input information indicating the spectrum of the target illumination light, the information indicating the spectral reflectance of the material having the target color, and the color matching function of the human eye.

[0037] Here, the wavelength is λ, the target illumination light spectrum is w'(λ), the spectral reflectance of the target color is r(λ), and the color matching function of the human eye is c ｔ (λ), when t={X, Y, Z} is defined, the colorimetric value p' of the target color ｔ (t={X, Y, Z}) can be expressed by the following equation (7).

[0038]

[0039] The second target color calculation unit 108 calculates the colorimetric value of the target target color based on the above formula (7). The second target color calculation unit 108 calculates the colorimetric value (p' ｔ ) to the second color difference calculation unit 109.

[0040] The second color difference calculation unit 109 calculates the colorimetric value (p ｔ ) and the colorimetric value (p') of the target color output from the second target color calculation unit 108. ｔ The second color difference calculation unit 109 calculates the colorimetric value (p ｔ ) and the colorimetric value of the target color (p' ｔ ) in a predetermined uniform color space. The second color difference calculation unit 109 calculates the color difference based on equation (4) in the same way as the first color difference calculation unit 106. The second color difference calculation unit 109 outputs information indicating the color difference related to the target color obtained by the calculation to the color difference evaluation unit 111.

[0041] The color difference condition setting unit 110 sets conditions for evaluating color differences. The color difference condition setting unit 110 is composed of a first color difference threshold setting unit 114 and a second color difference threshold setting unit 115. The first color difference threshold setting unit 114 sets a threshold for evaluating a color difference related to a specific color in the color difference evaluation unit 111. The second color difference threshold setting unit 115 sets a threshold for evaluating a color difference related to a target color in the color difference evaluation unit 111. The threshold for evaluating a color difference related to the specific color and the threshold for evaluating a color difference related to the target color are set in advance.

[0042] The color difference evaluation unit 111 receives as input the information indicating the color difference regarding the specific color output from the first color difference calculation unit 106 and the information indicating the color difference regarding the target color output from the second color difference calculation unit 109. The color difference evaluation unit 111 evaluates the input information indicating the color difference regarding the specific color and the information indicating the color difference regarding the target color based on a predetermined evaluation criterion (for example, a threshold value).

[0043] Specifically, the color difference evaluation unit 111 compares a value specified by the information indicating the color difference related to the specific color with the color difference threshold related to the specific color set by the first color difference threshold setting unit 114. Furthermore, the color difference evaluation unit 111 compares a value specified by the information indicating the color difference related to the target color with the color difference threshold related to the target color set by the second color difference threshold setting unit 115.

[0044] The color difference evaluation unit 111 evaluates that the color difference for the specific color is appropriate if the value specified by the information indicating the color difference for the specific color is equal to or less than the threshold value for the color difference for the specific color. Similarly, the color difference evaluation unit 111 evaluates that the color difference for the target color is appropriate if the value specified by the information indicating the color difference for the target color is equal to or greater than the threshold value for the color difference for the target color.

[0045] On the other hand, if the value specified by the information indicating the color difference for the specific color is equal to or greater than the threshold value for the color difference for the specific color, the color difference evaluation unit 111 evaluates that the color difference for the specific color is inappropriate. Similarly, if the value specified by the information indicating the color difference for the target color is less than the threshold value for the color difference for the target color, the color difference evaluation unit 111 evaluates that the color difference for the target color is inappropriate. The color difference evaluation unit 111 outputs the evaluation result to the target illumination light calculation unit 112. Note that, if the maximum color difference is obtained after repeating the process for the threshold value for the color difference for the target color a predetermined number of times, the color difference evaluation unit 111 may replace the threshold value with the obtained maximum color difference.

[0046] The target illumination light calculation unit 112 receives the initial variables of the generation algorithm or the evaluation results from the color difference evaluation unit 111. The target illumination light calculation unit 112 synthesizes an illumination light spectrum for realizing a set color change with respect to the target color. Note that the target illumination light calculation unit 112 may perform a simulation using software on a computer instead of synthesizing an actual illumination light.

[0047] If both evaluation results by the color difference evaluation unit 111 indicate that the target illumination light calculation unit 112 is appropriate, it outputs the appropriate illumination light spectrum to the target illumination light output unit 113. On the other hand, if any one of the evaluation results by the color difference evaluation unit 111 indicates that the target illumination light calculation unit 112 is inappropriate, it stores the best illumination light spectrum obtained through processing up to that point, updates variables in a preset generation algorithm, and performs recalculation.

[0048] The target illumination light output unit 113 outputs light having the target illumination light spectrum output from the target illumination light calculation unit 112 .

[0049] In the conventional configurations described above, the amount of change in the target color is simply the color difference, as described above, and therefore the balance of changes in saturation and hue (color tint) is not taken into consideration. Therefore, the present invention describes a method for adjusting the saturation and hue of the expected color difference when calculating an illumination spectrum that maximizes the color difference for the target color. Specifically, the present invention decomposes the color difference between two colors in a uniform color space into saturation and hue, sets thresholds for each of the decomposed saturation and hue, and converts the evaluation value into a function (e.g., a function such as a weighted linear sum of the saturation and hue components, as the simplest example) so that the respective proportions of the evaluation value that replaces the conventional color difference can be adjusted. This method enables the calculation of an illumination spectrum that maximizes the change in hue (color tint) for the target color, and evaluates the illumination spectrum taking the change in hue (color tint) into consideration. Details of this method are described below.

[0050] 2 is a diagram showing an example of the configuration of an illumination device 10 according to the first embodiment. The illumination device 10 includes a reference illumination light setting unit 11, a specific color setting unit 12, a target color setting unit 13, a first specific color calculation unit 14, a second specific color calculation unit 15, a color difference calculation unit 16, a first target color calculation unit 17, a second target color calculation unit 18, a first color difference decomposition processing unit 19, a color difference condition setting unit 20, a color difference evaluation unit 21, a target illumination light calculation unit 22, and a target illumination light output unit 23.

[0051] The reference illumination light setting unit 11, specific color setting unit 12, target color setting unit 13, first specific color calculation unit 14, second specific color calculation unit 15, color difference calculation unit 16, first target color calculation unit 17, second target color calculation unit 18, target illumination light calculation unit 22, and target illumination light output unit 23 in the illumination device 10 perform the same processing as the functional units with the same names shown in Fig. 1. Note that the color difference calculation unit 16 has a different name from the functional unit shown in Fig. 1, but performs the same processing as the first color difference calculation unit 106. The following description will focus on the configuration that differs from the conventional illumination device 100.

[0052] The first color difference decomposition processing unit 19 receives as input information indicating the colorimetric values ​​of the reference target color output from the first target color calculation unit 17 and information indicating the colorimetric values ​​of the target target color output from the second target color calculation unit 18. Based on the input information indicating the colorimetric values ​​of the reference target color and the information indicating the colorimetric values ​​of the target target color, the first color difference decomposition processing unit 19 decomposes the difference (color difference) between the reference target color and the target target color into a change in saturation and a change in hue. The first color difference decomposition processing unit 19 outputs the change in saturation in the color difference between the reference target color and the target target color and the change in hue in the color difference to the color difference evaluation unit 21.

[0053] As shown in FIG. 3 , the first color difference decomposition processing unit 19 is composed of a hue change amount calculation unit 27 and a saturation change amount calculation unit 28. The hue change amount calculation unit 27 receives information indicating the colorimetric values ​​of the reference target color and information indicating the colorimetric values ​​of the target target color. The hue change amount calculation unit 27 calculates the amount of change in hue based on the input information indicating the colorimetric values ​​of the reference target color and the information indicating the colorimetric values ​​of the target target color. The hue change amount calculation unit 27 outputs information indicating the calculated amount of change in hue (hereinafter referred to as "hue change amount") to the color difference evaluation unit 21. The processing by the hue change amount calculation unit 27 will be described later.

[0054] The saturation change amount calculation unit 28 receives information indicating the colorimetric values ​​of the reference target color and information indicating the colorimetric values ​​of the target target color. The saturation change amount calculation unit 28 calculates the amount of change in saturation based on the input information indicating the colorimetric values ​​of the reference target color and the information indicating the colorimetric values ​​of the target target color. The saturation change amount calculation unit 28 outputs information indicating the calculated amount of change in saturation (hereinafter referred to as "saturation change amount") to the color difference evaluation unit 21. The processing by the saturation change amount calculation unit 28 will be described later.

[0055] The color difference condition setting unit 20 sets conditions for evaluating color differences. The color difference condition setting unit 20 is composed of a color difference threshold setting unit 24, a saturation threshold setting unit 25, and a hue threshold setting unit 26. The color difference threshold setting unit 24 sets a threshold σ for evaluating a color difference related to a specific color in the color difference evaluation unit 21. For example, the color difference threshold setting unit 24 sets the threshold σ expressed by the following equation (8) in the color difference evaluation unit 21.

[0056]

[0057] Note that ||V(q')-V(q)|| is the color difference {(a ＊´ -a ＊ ) ２ +(b ＊´ -b ＊ ) ２} １／２ In this case, the color difference threshold setting unit 24 sets the threshold σ for the colorimetric value Y. Ｙ is also set in the color difference evaluation unit 21. For example, the color difference threshold setting unit 24 may set the threshold σ shown in the following equation (9) in the color difference evaluation unit 21.

[0058]

[0059] The saturation threshold setting unit 25 receives a coefficient and a threshold. The coefficient input to the saturation threshold setting unit 25 is a coefficient set to the amount of change in the saturation component related to the target color. For example, the coefficient input to the saturation threshold setting unit 25 is the weight related to saturation in the weighted linear sum given in the example above. The threshold input to the saturation threshold setting unit 25 is a threshold for evaluating the saturation component related to the target color. The saturation threshold setting unit 25 outputs the coefficient to the color difference evaluation unit 21 and sets the threshold in the color difference evaluation unit 21.

[0060] The hue threshold setting unit 26 receives a coefficient and a threshold. The coefficient input to the hue threshold setting unit 26 is a coefficient set for the amount of change in the hue component related to the target color. For example, the coefficient input to the hue threshold setting unit 26 is the weight related to the hue of the weighted linear sum given in the example above. The threshold input to the hue threshold setting unit 26 is a threshold for evaluating the hue component related to the target color. The hue threshold setting unit 26 outputs the coefficient to the color difference evaluation unit 21 and sets the threshold in the color difference evaluation unit 21.

[0061] The color difference evaluation unit 21 receives as input the information indicating the color difference for the specific color output from the color difference calculation unit 16, the information indicating the amount of hue change output from the hue change calculation unit 27, the information indicating the amount of saturation change output from the saturation change calculation unit 28, the coefficient set for the amount of change in the saturation component for the target color output from the saturation threshold setting unit 25, and the coefficient set for the amount of change in the hue component for the target color output from the hue threshold setting unit 26. Furthermore, the color difference evaluation unit 21 is set with a threshold for evaluating the color difference for the specific color, a threshold for evaluating the saturation component for the target color, and a threshold for evaluating the hue component for the target color.

[0062] The color difference evaluation unit 21 evaluates the input information indicating the color difference, the information indicating the amount of change in hue, and the information indicating the amount of change in saturation for the specific color based on a predetermined evaluation criterion (e.g., a threshold value or a coefficient). That is, the color difference evaluation unit 21 makes a judgment on each of the color difference, the amount of change in saturation, and the amount of change in hue. The color difference evaluation unit 21 outputs the evaluation result to the target illumination light calculation unit 22. If the color difference evaluation unit 21 determines that the evaluation result is inappropriate, it stores information indicating the best color difference, amount of change in saturation, and amount of change in hue obtained through the processing up to that point. The processing by the color difference evaluation unit 21 will be described later.

[0063] Next, the processing of the hue change amount calculation unit 27, the saturation change amount calculation unit 28, and the color difference evaluation unit 21 will be specifically described.

[0064] (Method of calculating the amount of change in saturation) First, a method of calculating the amount of change in saturation will be described. The amount of change in saturation calculation unit 28 calculates the colorimetric value [v Ｘ , v Ｙ , v Ｚ ] and the colorimetric value [v' of the target color output from the second target color calculation unit 18 Ｘ , v' Ｙ , v' Ｚ ] and each a ＊ , b ＊ Here, the vector pointing from the origin toward the coordinates indicating the color under the reference illumination is defined as A, and the vector pointing from the origin toward the coordinates indicating the color under the target illumination is defined as B. The saturation change amount calculation unit 28 calculates the saturation change amount δ based on the following equation (10): ｓAs shown in equation (10), the saturation change amount δ ｓ is expressed as the difference in length between vector A and vector B.

[0065]

[0066] (Method of Calculating the Amount of Hue Change) Next, a method of calculating the amount of hue change will be described. The amount of hue change corresponds to the angle θ between vector A and vector B. The angle θ can be expressed as the following equation (11) using the dot product A·B of vector A and vector B.

[0067]

[0068] In equation (11), θ is in the range of −π to π. The difference in hue is greatest when θ=π and −π, and under these conditions, the hue change amount δ ｃ An example of a function that maximizes k is the sin function shown in equation (12). ｃ is a coefficient set by the hue threshold setting unit 26.

[0069]

[0070] Alternatively, any of the functions shown in equation (13) may be used, but the present invention is not limited to these functions as long as they have a maximum value when θ=π and −π. In this way, the hue change amount calculation unit 27 calculates the hue change amount δ based on the above equation (12) or (13), etc. ｃ Calculate.

[0071]

[0072] (Processing by Color Difference Evaluation Unit 21) The color difference evaluation unit 21 evaluates the hue variation δ obtained by the hue variation calculation unit 27. ｃ and the saturation change amount δ is calculated by the saturation change amount calculation unit 28. ｓ For k, an evaluation function is defined using a conditional expression and each amount of change. The thresholds used in the conditional expression and the evaluation function are set by the saturation threshold setting unit 25 and the hue threshold setting unit 26. For example, the color difference evaluation unit 21 defines an evaluation function using the conditional expression and each amount of change as shown in the following equation (14). ｓ is a coefficient set by the saturation threshold setting unit 25, and σ ｓ and σ ｓ' is a threshold value set by the saturation threshold setting unit 25. ｃ and σ ｃ ' is a threshold value set by the hue threshold value setting unit 26. k is a constant.

[0073]

[0074] Here, when only saturation is emphasized (color is changed in the saturation direction), the color difference evaluation unit 21 may define an evaluation function using a conditional expression and each amount of change, as shown in the following expression (15).

[0075]

[0076] Furthermore, when only the hue is changed without changing the saturation, the color difference evaluation unit 21 may define an evaluation function using a conditional expression and each amount of change, as shown in the following equation (16).

[0077]

[0078] Furthermore, when weighting each of the saturation and hue, the color difference evaluation unit 21 may define an evaluation function using a conditional expression and each amount of change, as shown in the following equation (17).

[0079]

[0080] The color difference evaluation unit 21 uses one of the evaluation functions described above to determine whether the target illumination light spectrum satisfies the conditions. The color difference evaluation unit 21 also stores a set of necessary items from among the color difference, saturation change amount, hue change amount, and evaluation function value of the specific color in the best case obtained through repeated processing. The best case is, on the premise that the color difference of the specific color is equal to or less than the color difference threshold, when the saturation change amount is the largest if emphasis is placed on saturation, when the hue change amount is the largest if emphasis is placed on hue, or when the value is the largest if it is based on the evaluation function.

[0081] When the evaluation function is improved, the color difference evaluation unit 21 replaces the stored value. When the color difference evaluation unit 21 replaces the value, it outputs a data update instruction to the target illumination light calculation unit 22, thereby updating the illumination spectrum value stored in the target illumination light calculation unit 22.

[0082] 4 is a flowchart showing the processing flow of the lighting device 10 in the first embodiment. The reference illumination setting unit 11 sets the reference illumination (step S101). Specifically, the reference illumination setting unit 11 receives the spectrum of the reference illumination and outputs information indicating the spectrum of the received reference illumination to the first specific color calculation unit 14 and the first target color calculation unit 17. The reference illumination setting unit 11 may define the spectrum of the reference illumination.

[0083] The specific color setting unit 12 performs setting related to the specific color (step S102). Specifically, the specific color setting unit 12 receives the spectral reflectance of a material having the specific color, and outputs information indicating the received spectral reflectance of the material having the specific color to the first specific color calculation unit 14 and the second specific color calculation unit 15. Note that the specific color setting unit 12 may also receive the reflectance spectrum under a reference illumination light as an input.

[0084] The target color setting unit 13 sets the target color (step S103). Specifically, the target color setting unit 13 receives the spectral reflectance of a material having the target color as input, and outputs information indicating the spectral reflectance of the material having the input target color to the first target color calculation unit 17 and the second target color calculation unit 18. Note that the target color setting unit 13 may also receive the reference illumination light spectrum and reflected light spectrum obtained during measurement as input.

[0085] The first specific color calculation unit 14 calculates the colorimetric value of the reference specific color based on the above formula (1) or (2) using the information indicating the spectrum of the reference illumination light output from the reference illumination setting unit 11, the information indicating the spectral reflectance of the material having the specific color output from the specific color setting unit 12, and the color matching function of the human eye (step S104). The first specific color calculation unit 14 outputs information indicating the colorimetric value of the reference specific color obtained by the calculation to the color difference calculation unit 16.

[0086] The second specific color calculation unit 15 calculates the colorimetric value of the target specific color based on the above formula (3) using the information indicating the spectrum of the target illumination light output from the target illumination light calculation unit 22, the information indicating the spectral reflectance of the material having the specific color output from the specific color setting unit 12, and the color matching function of the human eye (step S105). The second specific color calculation unit 15 outputs information indicating the colorimetric value of the target specific color obtained by the calculation to the color difference calculation unit 16.

[0087] The color difference calculation unit 16 calculates the color difference between the information indicating the colorimetric value of the reference specific color output from the first specific color calculation unit 14 and the colorimetric value (q' ｔ The color difference calculation unit 16 calculates the color difference for the specific color based on the information indicating the color difference for the specific color (step S106). The color difference calculation unit 16 outputs the information indicating the color difference for the specific color obtained by the calculation to the color difference evaluation unit 21.

[0088] The first target color calculation unit 17 calculates the colorimetric values ​​of the reference target color based on the above formula (6) using the information indicating the spectrum of the reference illumination light output from the reference illumination setting unit 11, the information indicating the spectral reflectance of the material having the target color output from the target color setting unit 13, and the color matching function of the human eye (step S107). The first target color calculation unit 17 outputs information indicating the colorimetric values ​​of the reference target color obtained by the calculation to the first color difference separation processing unit 19.

[0089] The second target color calculation unit 18 calculates the colorimetric values ​​of the target target color based on the above formula (7) using the information indicating the spectrum of the target illumination light output from the target illumination light calculation unit 22, the information indicating the spectral reflectance of the material having the specific color output from the target color setting unit 13, and the color matching function of the human eye (step S108). The second target color calculation unit 18 outputs information indicating the colorimetric values ​​of the target target color obtained by the calculation to the first color difference decomposition processing unit 19.

[0090] The first color difference decomposition processing unit 19 calculates the amount of change in the target color based on the information indicating the colorimetric values ​​of the reference target color output from the first target color calculation unit 17 and the information indicating the colorimetric values ​​of the target target color output from the second target color calculation unit 18 (step S109). Specifically, the hue change amount calculation unit 27 in the first color difference decomposition processing unit 19 calculates the amount of change in hue δ in the target color based on the above formula (12) or (13), etc. ｃ Furthermore, the saturation change amount calculation unit 28 in the first color difference decomposition processing unit 19 calculates the saturation change amount δ for the target color based on the above formula (10). ｓ The first color difference decomposition processing unit 19 calculates the calculated hue change amount δ for the target color. ｃ and the saturation change amount δ ｓ The color difference evaluation unit 21 outputs information indicating the above.

[0091] The color difference condition setting unit 20 sets thresholds for the color difference evaluation unit 21 (step S110). Specifically, the color difference condition setting unit 20 sets the threshold value σ shown in the above equation (9), a threshold value for evaluating the saturation component of the target color, and a threshold value for evaluating the hue component of the target color to the color difference evaluation unit 21. Furthermore, the color difference condition setting unit 20 outputs a coefficient to be set for the amount of change in the saturation component of the target color and a coefficient to be set for the amount of change in the hue component of the target color to the color difference evaluation unit 21.

[0092] The color difference evaluation unit 21 evaluates the information indicating the color difference, the information indicating the amount of hue change, and the information indicating the amount of saturation change for the specific color based on the information indicating the color difference, the information indicating the amount of hue change, the information indicating the amount of saturation change, the coefficients, and the set thresholds (step S111). The color difference evaluation unit 21 outputs the evaluation result to the target illumination light calculation unit 22. The target illumination light calculation unit 22 determines whether the evaluation result output from the color difference evaluation unit 21 is appropriate (step S112).

[0093] If the target illumination light calculation unit 22 determines that the evaluation result output from the color difference evaluation unit 21 is inappropriate (step S112-NG), the target illumination light calculation unit 22 updates the variables in the preset generation algorithm and performs recalculation (step S113). Thereafter, the target illumination light calculation unit 22 determines whether or not the recalculation has been performed a predetermined number of times (step S114).

[0094] If the target illumination light calculation unit 22 determines that the recalculation has been performed the predetermined number of times (step S114—YES), the target illumination light calculation unit 22 outputs the best result among the predetermined number of recalculations to the target illumination light output unit 23 (step S115). The best result is the illumination light spectrum based on the color difference, saturation change amount, and hue change amount of the specific color that has the best evaluation result.

[0095] If the target illumination light calculation unit 22 determines that recalculation has not been performed the predetermined number of times (step S114-NO), the target illumination light calculation unit 22 outputs information indicating the illumination light spectrum of the target illumination light obtained by the recalculation to the second specific color calculation unit 15 and the second target color calculation unit 18. Thereafter, the lighting device 10 executes the processes from step S104 to step S109, and the color difference evaluation unit 21 performs evaluation again.

[0096] If the target illumination light calculation unit 22 determines in the process of step S112 that the evaluation result output from the color difference evaluation unit 21 indicates that it is appropriate (step S112-OK), or after the process of step S115 is completed, the target illumination light calculation unit 22 outputs information indicating the illumination light spectrum to the target illumination light output unit 23. The target illumination light output unit 23 outputs illumination light based on the information indicating the illumination light spectrum output from the target illumination light calculation unit 22 (step S116).

[0097] 4 is an example, and the order of the processes may be reversed. For example, the processes from step S101 to step S103 may be performed in parallel because they are executed by independent functional units, or the processes of step S102 and step S103 may be executed before the process of step S101. Furthermore, the processes from step S104 to step S106 and the processes from step S107 to step S109 may be executed in parallel. The processes from step S107 to step S109 may be executed before the processes of step S104 to step S106.

[0098] The lighting device 10 configured as described above includes a first color difference decomposition processing unit 19 that calculates the amount of change in saturation and the amount of change in hue in the color difference between a reference target color and a target target color; a color difference evaluation unit 21 that evaluates each of the specific color and the target color based on the color difference between the colorimetric value of the reference specific color and the colorimetric value of the target specific color, the amount of change in saturation, and the amount of change in hue; a target illumination light calculation unit 22 that calculates the illumination light spectrum that maximizes the change in appearance of the target color based on the evaluation result of the color difference evaluation unit 21; and a target illumination light output unit 23 that outputs illumination light based on the illumination light spectrum calculated by the target illumination light calculation unit 22.

[0099] In this way, the lighting device 10 is configured to be able to adjust the saturation and hue of the expected color difference in calculating the illumination spectrum that maximizes the change in appearance of the target color. This makes it possible to calculate the illumination spectrum that maximizes the change in appearance of the target color, taking into account the degree of change in saturation and hue.

[0100] Second Embodiment In the first embodiment, a configuration was described in which the difference (color difference) between a reference target color and a target target color is decomposed into a change in saturation and a change in hue. In the second embodiment, a configuration will be described in which the difference (color difference) between the colorimetric value of a reference specific color output from the first specific color calculation unit 14 and the colorimetric value of a target specific color output from the second specific color calculation unit 15 is decomposed into a change in saturation and a change in hue.

[0101] 5 is a diagram showing an example of the configuration of an illumination device 10a according to the second embodiment. The illumination device 10a includes a reference illumination light setting unit 11, a specific color setting unit 12, a target color setting unit 13, a first specific color calculation unit 14, a second specific color calculation unit 15, a first target color calculation unit 17, a second target color calculation unit 18, a first color difference decomposition processing unit 19, a color difference condition setting unit 20a, a color difference evaluation unit 21a, a target illumination light calculation unit 22, a target illumination light output unit 23, and a second color difference decomposition processing unit 29.

[0102] The illumination device 10a differs in configuration from the illumination device 10 in that it includes a color difference condition setting unit 20a and a color difference evaluation unit 21a instead of the color difference condition setting unit 20 and the color difference evaluation unit 21, does not include the color difference calculation unit 16, and newly includes a second color difference decomposition processing unit 29. The other configurations of the illumination device 10a are the same as those of the illumination device 10. The following description will focus on the differences from the illumination device 10.

[0103] The second color difference decomposition processing unit 29 receives as input information indicating the measured values ​​of the reference specific color output from the first specific color calculation unit 14 and information indicating the colorimetric values ​​of the target specific color output from the second target color calculation unit 18. Based on the input information indicating the colorimetric values ​​of the reference specific color and the information indicating the colorimetric values ​​of the target specific color, the second color difference decomposition processing unit 29 decomposes the difference (color difference) between the reference specific color and the target specific color into a change in saturation and a change in hue. The second color difference decomposition processing unit 29 outputs the change in saturation in the color difference between the colorimetric values ​​of the reference specific color and the colorimetric values ​​of the target specific color to the color difference evaluation unit 21 a and the change in hue in the color difference.

[0104] As shown in FIG. 6 , the second color difference decomposition processing unit 29 is composed of a hue change amount calculation unit 32 and a saturation change amount calculation unit 33. The hue change amount calculation unit 32 receives information indicating the colorimetric values ​​of the reference specific color and information indicating the colorimetric values ​​of the target specific color. The hue change amount calculation unit 32 calculates the amount of change in hue based on the input information indicating the colorimetric values ​​of the reference specific color and the information indicating the colorimetric values ​​of the target specific color. The hue change amount calculation unit 32 outputs information indicating the calculated amount of hue change to the color difference evaluation unit 21 a. The processing by the hue change amount calculation unit 32 is similar to that of the hue change amount calculation unit 27, except for the target.

[0105] The saturation change amount calculation unit 33 receives information indicating the colorimetric values ​​of the reference specific color and information indicating the colorimetric values ​​of the target specific color. The saturation change amount calculation unit 33 calculates the amount of change in saturation based on the input information indicating the colorimetric values ​​of the reference specific color and the information indicating the colorimetric values ​​of the target specific color. The saturation change amount calculation unit 33 outputs information indicating the calculated amount of change in saturation to the color difference evaluation unit 21a. The processing by the saturation change amount calculation unit 33 is similar to that of the saturation change amount calculation unit 28, except for the target.

[0106] The color difference condition setting unit 20a sets conditions for evaluating color differences. The color difference condition setting unit 20a is composed of a saturation threshold setting unit 25, a hue threshold setting unit 26, a saturation threshold setting unit 30, and a hue threshold setting unit 31. The saturation threshold setting unit 30 receives a coefficient and a threshold. The coefficient input to the saturation threshold setting unit 30 is a coefficient set for the amount of change in a saturation component related to a specific color. The threshold input to the saturation threshold setting unit 30 is a threshold for evaluating a saturation component related to the specific color. The saturation threshold setting unit 30 outputs the coefficient to the color difference evaluation unit 21a and sets the threshold in the color difference evaluation unit 21a.

[0107] The hue threshold setting unit 31 receives a coefficient and a threshold. The coefficient input to the hue threshold setting unit 31 is a coefficient set for the amount of change in the hue component related to a specific color. The threshold input to the hue threshold setting unit 31 is a threshold for evaluating the hue component related to the specific color. The hue threshold setting unit 31 outputs the coefficient to the color difference evaluation unit 21 a and sets the threshold in the color difference evaluation unit 21 a.

[0108] Color difference evaluation unit 21a receives as input information indicating the amount of hue change related to the target color output from hue change calculation unit 27, information indicating the amount of saturation change related to the target color output from saturation change calculation unit 28, a coefficient to be set for the amount of change in the saturation component related to the target color output from saturation threshold setting unit 25, a coefficient to be set for the amount of change in the hue component related to the target color output from hue threshold setting unit 26, information indicating the amount of hue change related to the specific color output from hue change calculation unit 32, information indicating the amount of saturation change related to the specific color output from saturation change calculation unit 33, a coefficient to be set for the amount of change in the saturation component related to the specific color output from saturation threshold setting unit 30, and a coefficient to be set for the amount of change in the hue component related to the specific color output from hue threshold setting unit 31. Color difference evaluation unit 21a also receives as input a threshold for evaluating the saturation component related to the target color, a threshold for evaluating the hue component related to the target color, a threshold for evaluating the saturation component related to the specific color, and a threshold for evaluating the hue component related to the specific color.

[0109] The color difference evaluation unit 21a evaluates the input information indicating the amount of hue change related to the target color, the information indicating the amount of saturation change related to the target color, the information indicating the amount of hue change related to the specific color, and the information indicating the amount of saturation change related to the specific color based on a predetermined evaluation criterion (e.g., a threshold value or a coefficient). That is, the color difference evaluation unit 21a makes a judgment on the amount of saturation change and the amount of hue change related to each of the specific color and the target color.

[0110] The color difference evaluation unit 21a evaluates the hue change amount δ of the target color obtained by the first color difference decomposition processing unit 19. ｃ and the saturation change amount δ for the target color ｓ and defines an evaluation function using a conditional expression and each amount of change for the amount of hue change related to the specific color and the amount of saturation change related to the target color obtained by the second color difference decomposition processing unit 29. The thresholds used in the conditional expression and the evaluation function are set by the color difference condition setting unit 20a. For example, the color difference evaluation unit 21a defines an evaluation function using the conditional expression and each amount of change in the same way as the color difference evaluation unit 21.

[0111] The color difference evaluation unit 21a outputs the evaluation result to the target illumination light calculation unit 22. If the color difference evaluation unit 21a determines that the evaluation result is inappropriate, it stores information indicating the best color difference, saturation change amount, and hue change amount obtained through the processing up to that point.

[0112] The lighting device 10a configured as described above is configured to be able to adjust the saturation and hue of the color difference not only for the target color but also for the specific color in calculating the illumination light spectrum that maximizes the color difference for the target color. This makes it possible to calculate the illumination light spectrum that maximizes the change in the appearance of the target color by taking into account changes in the hue not only for the target color but also for the specific color.

[0113] (Modifications Common to the First and Second Embodiments) The lighting device 10, 10a in each embodiment does not need to be configured with all functional units included in a single housing, and the lighting device 10, 10a may be configured with multiple housings. For example, the lighting device 10, 10a may be configured with the target illumination light output unit 23 included in a first housing and functional units other than the target illumination light output unit 23 included in a second housing. In such a configuration, the first and second housings are connected to each other so as to be able to communicate with each other via wire or wirelessly. The target illumination light output unit 23 included in the first housing outputs illumination light based on information indicating the illumination light spectrum transmitted from the target illumination light calculation unit 22 included in the second housing.

[0114] Some or all of the functional units of the lighting device 10, 10a are realized as software by a processor such as a central processing unit (CPU) executing a program stored in a storage device having a non-volatile storage medium (non-transitory storage medium) and a storage unit. The program may be recorded on a computer-readable non-transitory storage medium. Examples of computer-readable non-transitory storage media include portable media such as flexible disks, magneto-optical disks, read-only memories (ROMs), and compact disc read-only memories (CD-ROMs), and storage devices such as hard disks built into computer systems.

[0115] Some or all of the functional units of the lighting device 10, 10a may be realized using hardware including an electronic circuit (electronic circuit or circuitry) using, for example, an LSI (Large Scale Integrated circuit), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array).

[0116] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0117] The present invention can be applied to an illumination device that outputs target illumination light.

[0118] DESCRIPTION OF SYMBOLS 10, 10a... Lighting device, 11... Reference illumination light setting unit, 12... Specific color setting unit, 13... Target color setting unit, 14... First specific color calculation unit, 15... Second specific color calculation unit, 16... Color difference calculation unit, 17... First target color calculation unit, 18... Second target color calculation unit, 19... First color difference decomposition processing unit, 20... Color difference condition setting unit, 21, 21a... Color difference evaluation unit, 22... Target illumination light calculation unit, 23... Target illumination light output unit, 24... Color difference threshold setting unit, 25... Saturation threshold setting unit, 26... Hue threshold setting unit, 27... Hue change amount calculation unit, 28... Saturation change amount calculation unit, 29... Second color difference decomposition processing unit, 30... Saturation threshold setting unit, 31... Hue threshold setting unit, 32... Hue change amount calculation unit 33... Saturation change amount calculation unit

Claims

1. A lighting device comprising: a first color difference resolution processing unit that calculates a first amount of change in saturation in the color difference between the colorimetric value of a target color under reference illumination and the colorimetric value of the target color under target illumination, and a second amount of change in hue in the color difference; a color difference evaluation unit that evaluates each of the specific color and the target color based on either the color difference between the colorimetric value of a specific color under reference illumination and the colorimetric value of the specific color under target illumination, or a third amount of change in saturation in the color difference between the colorimetric value of the specific color under reference illumination and the colorimetric value of the specific color under target illumination, and a fourth amount of change in hue in the color difference, and the first amount of change and the second amount of change; a target illumination light calculation unit that calculates an illumination light spectrum that maximizes the change in appearance of the target color based on the evaluation result of the color difference evaluation unit; and a target illumination light output unit that outputs illumination light based on the illumination light spectrum calculated by the target illumination light calculation unit.

2. The lighting device according to claim 1, wherein the color difference evaluation unit performs evaluation of each of the specific color and the target color based on an evaluation function defined using the first change amount and the second change amount calculated by the first color difference decomposition processing unit.

3. The lighting device according to claim 1, further comprising a second color difference decomposition processing unit that calculates the third change amount and the fourth change amount, wherein the color difference evaluation unit performs evaluation of each of the specific color and the target color based on an evaluation function defined using the first change amount and the second change amount calculated by the first color difference decomposition processing unit and the third change amount and the fourth change amount calculated by the second color difference decomposition processing unit.

4. A lighting control method comprising: calculating a first amount of change in saturation in the color difference between the colorimetric value of a target color under reference illumination and the colorimetric value of said target color under target illumination; evaluating said specific color and said target color based on either the color difference between the colorimetric value of a specific color under reference illumination and the colorimetric value of said specific color under target illumination, or a third amount of change in saturation in the color difference between the colorimetric value of said specific color under reference illumination and the colorimetric value of said specific color under target illumination, and a fourth amount of change in hue in said color difference, as well as said first amount of change and said second amount of change; calculating an illumination light spectrum that maximizes the change in appearance of the target color based on the evaluation results; and outputting illumination light based on the calculated illumination light spectrum.

Images