JP7128471B2 - Color matching range setting method and color matching range setting device for paint color evaluation - Google Patents

Description

The present invention relates to a target color matching range setting method and a color matching range setting device for evaluating whether or not a paint color is the same as a target color.

2. Description of the Related Art In the painting of equipment such as vehicles, the color difference between the actual paint color and its target color is measured by a color difference meter to evaluate the paint color. Further, Patent Document 1 describes a method for systematically and quantitatively evaluating anisotropic paint colors such as metallic paint and pearl paint, regardless of the hue. It classifies paint colors into either absorption, reflection, or interference depending on the form of color development, creates quality judgment criteria based on lightness and lightness difference for each classification, and evaluates the quality of paint colors based on these standards. It is to do.

JP 2012-173272 A

The evaluation method described in Patent Literature 1 evaluates paint colors only based on lightness, so it is not suitable for determining the quality of chromatic colors or color matching.

On the other hand, if the color difference is measured with a color difference meter, it is possible to determine the quality of chromatic colors and perform color matching. Conventionally, in the CIE L*a*b* color coordinate system, the color difference is represented by the Euclidean distance ΔE ₇₆ =√(Δa ² +Δb ² +ΔL ² ), and the paint color becomes the target color depending on whether the color difference is close to zero. It is known to evaluate whether

However, depending on the color, there is a problem that the evaluation by the color difference ΔE ₇₆ and the visual evaluation are different. That is, it is known that the color discrimination range of the color difference ΔE ₇₆ is perfectly circular (spherical), but the color discrimination range by visual observation is elliptical.

The CIE DE2000 color difference formula is known to solve this problem. This is obtained by weighting the lightness difference ΔL*, the saturation difference ΔC*, and the hue difference ΔH* with weighting coefficients S _L , S _C , and S _H . The color difference ΔE ₀₀ has an elliptical shape with the long axis in the chroma direction, and approximates a color matching ellipse related to visual observation.

However, the color difference ΔE ₀₀ is only an approximation to the shape of the color discrimination area by visual observation. The color matching ellipse due to the color difference ΔE ₀₀ differs in size and inclination from, for example, the color matching ellipse set by the color scientist of DuPont shown in FIG. Therefore, an accurate evaluation cannot be expected with a color difference ΔE ₀₀ . On the other hand, DuPont color matching ellipse data is limited to 19 specific colors and cannot be used to evaluate other colors.

Even if a color matching ellipse of the target color for coating color evaluation is set by some method, if the coating color has a contrast due to the uneven shape of the surface of the object to be coated, the evaluation by the color matching ellipse is difficult for human beings. It may be an evaluation that deviates from the feeling. In other words, when the contrast is strong, the measured value of the paint color tends to deviate from the range of the color matching ellipse, but this is due to the contrast. are the same color.

Accordingly, the present invention provides a method and apparatus for newly setting a color matching range of a target color of a paint color for evaluating the paint color.

The present invention uses known color matching range data of reference colors to set the color matching range of the target color, and corrects the color matching range of the target color based on subjective evaluation test data.

A color matching range setting method for paint color evaluation disclosed herein is a method of setting a color matching range for evaluating whether or not a paint color is the same color as a target color in a color coordinate system,
a step of statistically obtaining and setting a basic color matching range of the target color based on data relating to color matching ranges of a plurality of reference colors in the color coordinate system;
correcting the basic color matching range of the target color based on a plurality of color data on the color coordinate system created based on subjective evaluation experiments that people perceive as the same color as the target color. It is characterized by

According to this, the basic color matching range of the target color is statistically set from the known color matching range data of the reference color. In this setting, no visual evaluation of the target color is required. In other words, it is possible to set the basic color matching range of the target color that is comparable to the color matching range of the reference color without relying on visual evaluation. Then, since the basic color matching range of the target color is corrected based on the subjective evaluation test data, it is possible to obtain color matching range data in which, for example, people perceive the same color even if there is a contrast. Color evaluation becomes more reliable.

Data relating to the color matching range of a plurality of reference colors may be, for example, a subjective evaluation of the color matching range of the reference color such as a color matching ellipse relating to a plurality of colors set by a color scientist of DuPont as shown in FIG. It is preferable to include experimental data.

Further, the color matching range data regarding the specific color obtained by the above statistical method and correction by the subjective evaluation experimental data is applied to the color matching range of the plurality of reference colors for obtaining the basic color matching range of the target color. can be added to the data.

In one embodiment, the color coordinate system is a three-dimensional color space coordinate system,
The color matching range of each of the plurality of reference colors is defined by an ellipsoidal formula,
Coefficients associated with a plurality of other reference colors for predicting coefficients of an ellipsoidal equation associated with a specific reference color of the plurality of reference colors based on corresponding coefficients of the other plurality of reference colors. A prediction formula defined by a weighted average of the coefficients weighted by the distance from the reference color and the tuning parameter,
The step of setting the basic color matching range of the target color includes:
calculating distances between the plurality of reference colors;
predicting each of said coefficients of said plurality of reference colors according to said prediction formula;
determining a tuning parameter based on the predicted value of the coefficient by the prediction formula and the actual value;
obtaining a calculation formula for obtaining each coefficient of the target color ellipsoidal formula by applying the determined tuning parameter to the prediction formula;
and calculating an ellipsoidal formula that defines the basic color matching range of the target color by weighted average of coefficients related to the plurality of preset reference colors, using the formula.

According to this, it is possible to set a highly reliable and useful basic color matching range of the target color that is comparable to the color matching range of the reference color.

In one embodiment, the step of correcting the base color matching range of the target color comprises:
generating a convex hull containing a plurality of color data based on the subjective evaluation experiment;
correcting each coefficient of the ellipsoidal formula by least-squares estimation so that the ellipsoid defining the basic color matching range of the target color fits the convex hull.

According to this, highly reliable color matching range data relating to the target color can be obtained.

A color matching range setting device for paint color evaluation disclosed herein is a device for setting a color matching range for evaluating whether or not a paint color is the same color as a target color in a color coordinate system,
storage means for storing set and stored color matching ranges in the color coordinate system for each of a plurality of reference colors; color matching range setting means for the target colors; subjective evaluation data setting means; and color matching range correcting means. with
The target color matching range setting means statistically obtains the basic color matching range of the target color based on data relating to color matching ranges of a plurality of reference colors set in advance in the color coordinate system. Set,
The subjective evaluation data setting means sets, on the color coordinate system, a plurality of color data created based on subjective evaluation experiments that people perceive as the same color as the target color,
The color matching range correction means is characterized by correcting the basic color matching range of the target color based on the plurality of color data.

According to this, from the known color matching range data of the reference color, it is possible to set the basic color matching range of the target color that is comparable to the color matching range of the reference color without relying on visual evaluation. Then, since the basic color matching range of the target color is corrected based on subjective evaluation test data, for example, it is possible to obtain color matching range data in which people perceive the same color even if there is contrast. Color evaluation becomes more reliable.

In one embodiment, the color coordinate system is a three-dimensional color space coordinate system,
The color matching range of each of the plurality of reference colors is defined by an ellipsoidal formula,
A reference specific to the coefficients of the other plurality of reference colors for predicting each coefficient of the ellipsoidal formula for a specific reference color among the plurality of reference colors based on the corresponding coefficients of the other plurality of reference colors. a prediction formula defined by a weighted average of the coefficients weighted by the distance from the color and the tuning parameter;
The target color matching range setting means calculates the distances between the plurality of reference colors, predicts the coefficients of the plurality of reference colors by the prediction formula, and predicts the coefficients by the prediction formula. A tuning parameter is determined based on the actual values, and a calculation formula in which the tuning parameter is given to the prediction formula is used to determine the target color by a weighted average of coefficients related to the plurality of preset reference colors. Find the ellipsoid formula that defines the basic color matching range.

According to this, it is possible to set a highly reliable and useful basic color matching range of the target color that is comparable to the color matching range of the reference color.

In one embodiment, the color matching range correcting means generates a convex hull containing a plurality of color data based on the subjective evaluation experiment, and the ellipsoid defining the basic color matching range of the target color forms the convex hull. Correct each coefficient of the ellipsoidal equation by least-squares estimation to fit.

According to this, highly reliable color matching range data relating to the target color can be obtained.

In one embodiment, the paint color is a metallic paint color. A coating film obtained by metallic coating has strong optical anisotropy in which the color tone varies depending on the viewing angle. The color matching range data obtained by the above color matching range setting method or the above color matching range setting device is useful for the coating color evaluation of the coating film having such optical anisotropy.

In one embodiment, the metallic coating is applied to the vehicle body or exterior parts of the vehicle.

According to the present invention, a basic color matching range of a target color comparable to the color matching range of the reference color can be set from the known color matching range data of the reference color without visual evaluation. Since the range is corrected based on subjective evaluation experimental data, for example, it is possible to obtain color matching range data in which people perceive the same color even if there is contrast, and the reliability of paint color evaluation is increased.

FIG. 10 is a diagram showing the distribution of a plurality of reference color matching ranges in a color coordinate system; FIG. 2 is a block diagram showing a configuration example of a color matching range setting device; FIG. 10 is a processing flow diagram of target color matching range setting control; FIG. 10 is a diagram showing the distribution in the color coordinate system of basic color matching ranges of a plurality of target colors with different light receiving angles set by color matching range setting control; The figure which shows the colorimetric method. FIG. 4 is an explanatory diagram of correction based on subjective evaluation data of the basic color matching range of the target color;

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated based on drawing. The following description of preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its applications or uses.

The ellipsoidal plot shown in FIG. 1 shows the color matching range of 19 colors set by DuPont color scientists as multiple reference colors in the CIE L ^* a ^* b ^* three-dimensional color space coordinate system. . That is, the color matching range of each of the 19 colors is defined by an ellipsoid centered on each color represented by L ^* , a ^* and b ^* . As is clear from the figure, the size, inclination, and ratio of the long axis to the short axis of the ellipsoid indicating the color matching range differ depending on hue and lightness.

Therefore, in the evaluation of whether or not the paint color is the same color as the target color, as shown in FIG. There is a need.

A method and device for setting the color matching range of the target color will be described below. This color matching range setting method and setting device is for color matching between the paint color (target color) of the vehicle body and the paint color of the bumper when the steel plate body of the vehicle is metallically painted and the plastic bumper is similarly metallically painted. It is useful for setting the color matching range for

<Color matching range setting device for paint color evaluation>
FIG. 2 shows a configuration example of a color matching range setting device. 21 is a CPU; 22 is a display such as a CRT as a display means; 23 is a keyboard as a means for inputting data such as target colors and subjective evaluation data; RAM as data storage means for temporarily storing various data and processing results, HDD for storing programs for setting color matching ranges of target colors, color matching range data for reference colors, subjective evaluation data, etc. 27 is a communication interface for communicating with an external information system via a communication network, and 28 is a printer for printing processing results and the like. These components are connected via a bus 29, and the CPU 21 sets the color matching range of the target color according to a program stored in the storage device 26. FIG. The CPU 21 constitutes data acquisition means, color matching range setting means, subjective evaluation data setting means, determination means, color matching range correction means, output means, and the like.

The data acquisition means includes color coordinate system (CIE L ^* a ^* b ^* three-dimensional color space coordinate system) data, target color data, color matching range data relating to a plurality of reference colors, subjective evaluation data, target color, etc. A coefficient prediction formula and the like are obtained from the storage device 26 in order to obtain a coefficient calculation formula for setting the color range. The color matching range setting means statistically obtains and sets the basic color matching range of the target color based on the color matching range data of the reference color in the color coordinate system. The subjective evaluation data setting means sets the subjective evaluation data on the color coordinate system. The determination means determines whether the subjective evaluation data is within the basic color matching range. The color matching range correcting means corrects the basic color matching range of the target color based on the subjective evaluation data when the subjective evaluation data deviates from the basic color matching range, and sets the color matching range for evaluation on the color coordinate system. do. The output means outputs the basic color matching range of the target color and the color matching range for evaluation to the storage device 26 as a data file.

A coefficient prediction formula for obtaining a calculation formula for setting the color matching range of the target color will be described. The color matching range of 19 DuPont colors as a plurality of reference colors is defined by the ellipsoid as described above. The ellipsoid can be expressed by the following polynomial (ellipsoidal formula) (1).

a, b and L respectively represent a ^* , b ^* and L ^* in the color coordinate system. The subscripted g's are coefficients, each having the following properties.

g ₁₁ ; Change the diameter of the ellipsoid in the a direction.

g ₂₂ ; Change the diameter of the ellipsoid in the b direction.

g ₃₃ ; Change the diameter of the ellipsoid in the L direction.

g ₁₂ ; Change the slope between a and b of the ellipsoid.

g ₁₃ ; Change the slope of the ellipsoid between a and L. g 13 ;

g ₂₃ ; Change the slope of the ellipsoid between b and L. g 23 ;

The coefficient prediction formula is a formula for predicting each coefficient of the ellipsoidal formula for any one of the 19 colors based on the corresponding coefficients of the remaining 18 colors. defined in The weights given to the coefficients of the ellipsoidal formula for the 18 colors are each of the 18 colors, the corresponding color, the distance (the distance between the centers of the ellipsoid) D, and the tuning parameter γ. The weight is given by an exponential function.

When the above ₁₉ colors are numbered i=1, 2, . ₁₁₍₁₉₎ , the coefficient prediction formula (2) is as follows.

Here, D _i-19 and D _k-19 represent the distance between the 19th color and each of the remaining 18 colors. For example, the distance D _1-19 between the first color (a ₁ , b ₁ , L ₁ ) and the 19th color (a ₁₉ , b ₁₉ , L ₁₉ ) is given by the following equation (3). (a ₁ , b ₁ , L ₁ ) and (a ₁₉ , b ₁₉ , L ₁₉ ) represent the values of the color coordinates (a, b, L) of the 1st color and the 19th color. , which are the color coordinates of the center of the ellipsoid representing the color matching range of each color.

Other coefficient predictions g' ₂₂₍₁₉₎ , g' ₃₃₍₁₉₎ , g' ₁₂₍₁₉₎ , g' ₁₃₍₁₉₎ and g' ₂₃₍₁₉₎ are also g' _{11( 19)} can be expressed by the same formula.

The subjective evaluation data is a plurality of color data on the color coordinate system created based on subjective evaluation experiments, which people perceive as the same color as the target color.

If the orientation of the surface of the object to be coated changes due to surface irregularities or the like, contrast (brightness and darkness) will appear because the direction of reflection of light will be different on the surface that is oriented differently from the viewpoint of the observer. That is, even if the same paint is uniformly applied to the object to be coated, the values of the color coordinates (a, b, L) will be different on surfaces facing different directions. However, since this is due to the contrast, even if the coordinate values of the color are different, people may perceive it as the same color. Therefore, even if there is a color difference due to such contrast, it is preferable that the paint color is evaluated to be the same color as the target color.

Therefore, by creating multiple test pieces with different colors in consideration of contrast, and comparing with the target color, the color of those test pieces should be equal to the target color. Get the evaluation result. Color data (a _add , b _add , L _add ) are obtained by measuring the color of the test piece evaluated as color matching with a colorimeter. A plurality of color data obtained from this subjective evaluation experiment are stored in the storage device 26 by the input means. (a _add , b _add , L _add ) are the coordinate values of the color evaluated by the subjective evaluation experiment to be equivalent to the target color.

<Target Color Matching Range Setting Processing>
Next, the target color matching range setting process executed by the color matching range setting device will be described with reference to the flowchart shown in FIG.

In step S1, color coordinate system data, target color data (a _t , b _t , L _t ), color data (a _i , bi, L _{i )} of each of a plurality of reference colors (19 colors), and color matching range Data (ellipsoid formula), subjective evaluation data (a _add , b _add , L _add ), coefficient prediction formulas for obtaining coefficient calculation formulas for setting the color matching range of the target color, etc. are acquired from the storage device 26 . (a _t ,b _t ,L _t ) are the coordinate values of the target color, and (a _i ,b _i ,L _i ) are the coordinate values of each reference color (i=1 to 19).

In step S2, the distance D _{i-i between the reference colors (ai, bi, L i ) and the} target colors (at, b _t , L _t ) and the plurality of reference colors ( _ai , bi, L _{i )} are ), the distance _Dt-i to each of them is obtained by a distance calculation formula similar to the formula (3).

In step S3, each coefficient of the ellipsoidal formula (see formula (1)) representing the color matching range for each reference color is predicted between the reference colors. That is, assuming that the coefficient of one reference color out of a plurality of reference colors is unknown, prediction is sequentially performed for all the reference colors from the coefficients of the remaining reference colors. A specific description will be given below.

To predict the coefficient g _{11 (19)} of the ellipsoidal formula representing the color matching range of the 19th reference color (a ₁₉ , b ₁₉ , L ₁₉ ) out of the 19 reference colors, the coefficient prediction formula of formula (2) is used. use. Substitute the distance D _i-19 (D _k-19 ) between the 19th reference color and each of the remaining reference colors (18 colors) and the coefficient g _11(i) of each of the reference colors (18 colors) into this prediction formula. , the weighted average of the distance and tuning parameters of the coefficient g _11(i) is used to obtain the coefficient prediction value g′ ₁₁₍₁₉₎ for the 19th reference color. Similarly, predicted values g' ₂₂₍₁₉₎ , g' ₃₃₍₁₉₎ , g' ₁₂₍₁₉₎ , g' ₁₃₍₁₉₎ and g' ₂₃₍₁₉ ) of other coefficients related to the 19th reference color ₎ . Further, each coefficient prediction value for each of the remaining 18 colors out of the 19 reference colors is obtained in the same manner as for the 19th reference color.

In step S4, for each of the coefficients g ₁₁ , g ₂₂ , g ₃₃ , g ₁₂ , g ₁₃ and g ₂₃ of the ellipsoidal formula of Equation 2, the tuning parameter γ of the coefficient prediction formula (see formula (2)) is obtained. That is, γ that minimizes the Kullback library pseudo-distance from the predicted value g' ₍₁₉₎ to the actual value g ₍₁₉₎ of the coefficients g ₁₁ , g ₂₂ , g ₃₃ , g ₁₂ , g ₁₃ and g ₂₃ is determined. The constraints in this case are as follows.

g' _11(i) >0
g' _11(i) g' _22(i) -g' _12(i) ² >0
g' _11(i) g' _22(i) g' _33(i) +2g' _12(i) g' _13(i) g' _{23(i) -} g' _11(i) g' _23(i) ²
−g′ _12(i) ² g′ _33(i) −g′ _13(i) ² g′ _22(i) >0

γ obtained in step S4 is substituted into each prediction formula for coefficients g ₁₁ , g ₂₂ , g ₃₃ , g ₁₂ , g ₁₃ and g ₂₃ to set a calculation formula for obtaining each coefficient of the ellipsoidal formula for the target color. (Step S5). By substituting the distance D _{t-i between} the target color (a _t , b _t , L _t ) and each of the 19 reference colors (a _i , bi, L _i ) into each of the obtained coefficient calculation formulas, Calculate the coefficients g _11(t) , g _22(t) , g _33(t) , g _12(t) , g _13(t) and g _23(t) of the target color ellipsoid formula (basic color matching range) (step S6).

FIG. 4 shows the basic color matching range of the target color obtained by the processing of steps S1 to S6. It is preferable to evaluate whether or not the paint color is the same color as the target color at a plurality of light-receiving angles in order to increase the reliability of the evaluation result. The figure shows that the basic color matching range of the target color is set for each light-receiving angle. Here, the illumination angle of the light source 41 with respect to the coated test piece 15 is 45°, and the light receiving angle by the colorimeter 42 is the tilt angle from the specular reflection direction to the light source 41 side, with the specular reflection direction being 0°. represents.

Next, in step S7, it is determined whether or not at least one of the plurality of color data (a _add , b _add , L _add ) obtained by the subjective evaluation experiment is outside the basic color matching range of the target color. When there is color data (a _add ,b _add ,L _add ) _outside the basic color matching range of _the target color, _convex hull (basic A collection of data on the edge of the color matching range) is generated (step S8). Then, the coefficients of the ellipsoidal formula are corrected by least-squares estimation so that the target color ellipsoid (basic color matching range) fits the convex hull (step S9, setting color matching range for evaluation). FIG. 6 shows an example in which the basic color matching range 1 is corrected to the evaluation color matching range 2 based on six pieces of color data (a _add1 , b _add1 , L _add1 ) to (a _add6 , b _add6 , L _add6 ). show.

As described above, according to the present embodiment, the basic color matching range 1 of the target color that is comparable to the color matching range of the reference colors is set from a plurality of known color matching range data of the reference colors without visual evaluation. can do. Then, this basic color matching range 1 is corrected based on subjective evaluation experimental data to obtain an evaluation color matching range 2 . Therefore, it is possible to obtain color matching range data in which people perceive the same color even if there is contrast, and the reliability of paint color evaluation is improved.

Note that the color coordinate system is not limited to CIE L ^* a ^* b ^* , and other coordinate systems such as RGB and XYZ may be adopted.

Also, the color coordinate system is not limited to three dimensions, and may be two dimensions such as a ^* b ^* , for example.

1 basic color matching range of target color 2 color matching range for evaluation of target color 21 CPU (color matching range setting means, subjective evaluation data setting means, color matching range correction means)
26 storage device (storage means)

Claims (10)

A method for setting a color matching range for evaluating whether or not a paint color is the same color as a target color in a color coordinate system,
a step of statistically obtaining and setting a basic color matching range of the target color based on data relating to color matching ranges of a plurality of reference colors in the color coordinate system;
correcting the basic color matching range of the target color based on a plurality of color data on the color coordinate system created based on subjective evaluation experiments that people perceive as the same color as the target color. A color matching range setting method for paint color evaluation characterized by: In claim 1,
The color coordinate system is a three-dimensional color space coordinate system,
The color matching range of each of the plurality of reference colors is defined by an ellipsoidal formula,
A reference specific to the coefficients of the other plurality of reference colors for predicting each coefficient of the ellipsoidal formula for a specific reference color among the plurality of reference colors based on the corresponding coefficients of the other plurality of reference colors. a prediction formula defined by a weighted average of the coefficients weighted by the distance from the color and the tuning parameter;
The step of setting the basic color matching range of the target color includes:
calculating distances between the plurality of reference colors;
predicting each of said coefficients of said plurality of reference colors according to said prediction formula;
determining a tuning parameter based on the predicted value of the coefficient by the prediction formula and the actual value;
obtaining a calculation formula for obtaining each coefficient of the target color ellipsoidal formula by applying the determined tuning parameter to the prediction formula;
and calculating an ellipsoidal formula that defines the basic color matching range of the target color by a weighted average of coefficients related to the plurality of preset reference colors, using the formula. Color matching range setting method for color evaluation. In claim 2,
The step of correcting the basic color matching range of the target color includes:
generating a convex hull containing a plurality of color data based on the subjective evaluation experiment;
and a step of correcting each coefficient of the ellipsoidal formula by least-squares estimation so that the ellipsoid defining the basic color matching range of the target color fits the convex hull. Color matching range setting method for In any one of claims 1 to 3,
A color matching range setting method for evaluating paint color, wherein the paint color is a metallic paint color. In claim 4,
A method for setting a matching color range for paint color evaluation characterized in that the metallic paint is applied to a vehicle body or an exterior part of a vehicle. A device for setting a color matching range for evaluating whether or not a paint color is the same color as a target color in a color coordinate system,
storage means for storing set and stored color matching ranges in the color coordinate system for each of a plurality of reference colors; color matching range setting means for the target colors; subjective evaluation data setting means; and color matching range correcting means. with
The target color matching range setting means statistically obtains the basic color matching range of the target color based on data relating to color matching ranges of a plurality of reference colors set in advance in the color coordinate system. Set,
The subjective evaluation data setting means sets, on the color coordinate system, a plurality of color data created based on subjective evaluation experiments that people perceive as the same color as the target color,
The color matching range setting device for paint color evaluation, wherein the color matching range correcting means corrects the basic color matching range of the target color based on the plurality of color data. In claim 6,
The color coordinate system is a three-dimensional color space coordinate system,
The color matching range of each of the plurality of reference colors is defined by an ellipsoidal formula,
A reference specific to the coefficients of the other plurality of reference colors for predicting each coefficient of the ellipsoidal formula for a specific reference color among the plurality of reference colors based on the corresponding coefficients of the other plurality of reference colors. a prediction formula defined by a weighted average of the coefficients weighted by the distance from the color and the tuning parameter;
The target color matching range setting means calculates the distances between the plurality of reference colors, predicts the coefficients of the plurality of reference colors by the prediction formula, and predicts the coefficients by the prediction formula. A tuning parameter is determined based on the actual values, and a calculation formula in which the tuning parameter is given to the prediction formula is used to determine the target color by a weighted average of coefficients related to the plurality of preset reference colors. A color matching range setting device for paint color evaluation, characterized by obtaining an ellipsoidal formula that defines a basic color matching range. In claim 7,
The color matching range correcting means includes:
A convex hull containing a plurality of color data based on the subjective evaluation experiment is generated, and each of the ellipsoidal formulas is calculated by least-squares estimation so that the ellipsoid defining the basic color matching range of the target color fits the convex hull. A color matching range setting device for paint color evaluation characterized by correcting coefficients. In any one of claims 6 to 8,
The color matching range setting device for evaluating paint color, wherein the paint color is a paint color of metallic paint. In claim 9,
The above-mentioned metallic paint is a color matching range setting device for paint color evaluation, characterized in that the metallic paint is applied to a vehicle body or an exterior part.

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