Coloring evaluation image generation method, generation program, and coloring evaluation image generation device

Abstract

The present invention provides a method for generating a color evaluation image, which generates a color evaluation image based on a painted surface image showing the painted surface, wherein the method for generating a color evaluation image includes: a spectral reflectance calculation process, calculating the spectral reflectance of the metal color at each specified angle within an observation angle range; a colorimetric value calculation process, calculating the colorimetric value at each specified angle within the observation angle range; a histogram generation process, finding the ratio of the number of pixels for each of the shading levels; a mapping process, associating the observation angle of each specified angle within the observation angle range with each of the shading levels of the painted surface image, and; a color evaluation image generation process, generating the color evaluation image, wherein the color evaluation image is color matched according to the order of the size of the observation angle and according to the component corresponding to the ratio of the number of pixels for each of the shading levels associated with the observation angle.

Description

Technical Field

[0001] The present invention relates to a method and a program for generating a coloring evaluation image. This application claims priority based on Japanese Patent Application No. 2018-165312 filed in Japan on September 4, 2018, and the contents thereof are incorporated herein by reference. Background Art

[0002] It is difficult to evaluate the color of paint applied to industrial products such as automobiles, especially metallic paint whose color visibility varies depending on the viewing angle, before the actual industrial product is painted.

[0003] The main surface and the sub-surface of the coloring evaluation plate described in Patent Document 1 have different curvatures. Therefore, by applying the metallic coloring to the coloring evaluation plate, the coloring evaluation including the high brightness and darkness of the metallic coloring can be performed more accurately.

[0004] If there is 3D CAD shape data of industrial products, it is possible to visualize the industrial products painted with metallic paints through computer simulation, thereby evaluating the paint. However, when evaluating the appearance of industrial products at the planning stage of industrial products, 3D CAD shape data is often not available.

[0005] On the other hand, for metallic coatings whose visibility varies with observation angle, it is known to irradiate light from a specific angle onto a flat plate using the metallic coating, thereby calculating the spectral reflectance at various light receiving angles based on the spectral reflectance obtained by receiving reflected light at multiple angles.

[0006] In the method of determining the optical properties of a metal coating thin film described in Patent Document 2, it is possible to predict any spectral reflectance within a wide range of angles from high brightness to darkness of metal coating.

[0007] The device for determining the metallic coloring described in Patent Document 3 can produce a Color Simulation image (hereinafter referred to as a "CS image") as a computer-simulated image based on the spectral reflectance obtained by the above-mentioned method described in Patent Document 2, and the computer-simulated image can be used as a digital color palette. The CS image includes a computer-simulated image of the metallic coloring observed at a wide range of angles from high brightness to darkness. If the CS image is used, for example, a designer can evaluate the coloring of the metallic coloring according to the observation angle at the planning stage of an industrial product.

[0008] [Prior art literature]

[0009] [Patent Literature]

[0010] Patent Document 1: Japanese Patent No. 6068238,

[0011] Patent Document 2: Japanese Patent No. 3671088,

[0012] Patent document 3: Japanese Patent No. 4790164. Summary of the invention

[0013] [Problems to be solved by the present invention]

[0014] However, the three-dimensional shape of the painted surface of an actual industrial product varies from product to product, and the change in the shadow on the painted surface varies from product to product. Since the CS image does not take the change in the shadow on the painted surface into consideration, it is difficult to predict the overall impression when the metallic paint is applied to the painted surface of an actual industrial product from the CS image.

[0015] In view of the above circumstances, an object of the present invention is to provide a method and program for generating a coloring evaluation image that makes it easy to predict the overall impression when a metallic paint is applied to a painted surface of an industrial product.

[0016]

Methods to solve the problem

[0017] In order to solve the above-mentioned problems, the present invention proposes the following means.

[0018] The first embodiment of the present invention is a method for generating a color evaluation image based on a painted surface image that is applied to an industrial product or a model thereof, wherein the color evaluation image generation method includes: a spectral reflectance calculation step, which calculates the spectral reflectance of the metal color at each specified angle within the observation angle range based on the spectral reflectance of the metal color measured at a plurality of light receiving angles; a colorimetric value calculation step, which calculates the colorimetric value of each specified angle within the observation angle range based on the spectral reflectance; and a histogram generation step, which measures the color of the painted surface. The number of pixels at each shade level of the image, and calculating the ratio of the number of pixels at each shade level; a mapping process, associating the observation angle of each specified angle within the observation angle range with each of the shade levels of the painted surface image; and a coloring evaluation image generation process, generating the coloring evaluation image, wherein the colorimetric value calculated at each specified angle within the observation angle range is color matched according to the component corresponding to the ratio of the number of pixels at each shade level associated with the observation angle in the order of the size of the observation angle.

[0019] According to the second embodiment of the present invention, in the method for generating a coloring evaluation image of the first embodiment, in the mapping process, the highest density level can be associated with the smallest angle in the observation angle range, and the lowest density level can be associated with the largest angle in the observation angle range.

[0020] According to the third embodiment of the present invention, in the method for generating a coloring evaluation image of the first embodiment or the second embodiment, in the coloring evaluation image generating step, a two-dimensional coloring evaluation image can be generated, and for the coloring evaluation image, the colorimetric values ​​can be configured in the order of the angles in the observation angle range and the order of the raster scanning.

[0021] The fourth mode of the present invention is a program for generating a color evaluation image. It is a program for causing a computer to generate a color evaluation image based on a painted surface image showing a painted surface, wherein the program for generating the color evaluation image executes: a spectral reflectance calculation step, which calculates the spectral reflectance of the metal color at each specified angle within the observation angle range based on the spectral reflectance of the metal color measured at multiple light receiving angles; a colorimetric value calculation step, which calculates the colorimetric value at each specified angle within the observation angle range based on the spectral reflectance; a histogram generation step, which measures the number of pixels at each shading level of the painted surface image and finds the ratio of the number of pixels at each shading level; a mapping step, which associates the observation angle of each specified angle within the observation angle range with each shading level of the painted surface image; and a color evaluation image generation step, which generates the color evaluation image, which is arranged in the order of the size of the observation angle and according to the component corresponding to the ratio of the number of pixels at each shading level associated with the observation angle, and the colorimetric value calculated for each specified angle within the observation angle range.

[0022] According to the fifth embodiment of the present invention, in the generation procedure of the coloring evaluation image of the fourth embodiment, in the mapping process, the highest density level can be associated with the smallest angle in the observation angle range, and the lowest density level can be associated with the largest angle in the observation angle range.

[0023] According to the sixth embodiment of the present invention, in the generation procedure of the coloring evaluation image of the fourth embodiment or the fifth embodiment, in the coloring evaluation image generation step, a two-dimensional coloring evaluation image can be generated, and for the coloring evaluation image, the colorimetric values ​​can be configured in the order of the angles in the observation angle range and the order of the raster scanning.

[0024] The seventh mode of the present invention is a device for generating a color evaluation image, which is a device for generating a color evaluation image based on a painted surface image showing a painted surface, wherein the color evaluation image generating device includes: a spectral reflectance calculation unit, which calculates the spectral reflectance of the metal color at each specified angle within the observation angle range based on the spectral reflectance of the metal color measured at multiple light receiving angles; a colorimetric value calculation unit, which calculates the colorimetric value of each specified angle within the observation angle range based on the spectral reflectance; a histogram generating unit, which measures the number of pixels of each shading level of the painted surface image and calculates the ratio of the number of pixels for each shading level; a mapping unit, which associates the observation angle of each specified angle within the observation angle range with each shading level of the painted surface image; and a color evaluation image generating unit, which generates the color evaluation image, which is arranged in the order of the size of the observation angle and according to the component corresponding to the ratio of the number of pixels for each shading level associated with the observation angle, and the colorimetric value calculated for each specified angle within the observation angle range.

[0025] According to the eighth aspect of the present invention, in the coloring evaluation image generating device of the seventh aspect, the mapping unit can associate the highest density level with the smallest angle in the observation angle range, and associate the lowest density level with the largest angle in the observation angle range.

[0026] According to the ninth aspect of the present invention, in the coloring evaluation image generating device of the seventh aspect or the eighth aspect, the coloring evaluation image generating unit generates a two-dimensional coloring evaluation image, and for the coloring evaluation image, the colorimetric values ​​can be configured in the order of the angles in the observation angle range and the order of raster scanning.

[0027] [Effects of the invention]

[0028] According to the coloring evaluation image generation method, generation program, and coloring evaluation image generation device of the present invention, a coloring evaluation image can be generated that makes it easy to predict the overall impression when metallic painting is applied to the painted surface of an industrial product. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a block diagram of a coloring evaluation image generating device that executes a coloring evaluation image generating program according to one embodiment of the present invention.

[0030] Figure 2 This is a diagram showing the configuration of a computer of a coloring evaluation image generating device according to one embodiment of the present invention.

[0031] Figure 3This is a functional block diagram of a computer of a coloring evaluation image generating device according to an embodiment of the present invention.

[0032] Figure 4 This is a two-dimensional image of a car (sedan) which is an evaluation target of the coloring evaluation image generation method according to one embodiment of the present invention.

[0033] Figure 5 is based on Figure 4 Generated painted surface image.

[0034] Figure 6 yes Figure 5 Histogram of .

[0035] Figure 7 This is a two-dimensional image of a car (SUV) which is an evaluation target of the method for generating a coloring evaluation image according to one embodiment of the present invention.

[0036] Figure 8 is based on Figure 7 Generated painted surface image.

[0037] Fig. 9 yes Figure 8 Histogram of .

[0038] Fig.10 This is an example of measuring the spectral reflectance of metallic painting in the method of generating a painting evaluation image according to one embodiment of the present invention.

[0039] Fig.11 It is an explanatory diagram of generation of a coloring evaluation image in a coloring evaluation image generation step of a coloring evaluation image generation method according to an embodiment of the present invention.

[0040] Fig.12 This is a color evaluation image of a sedan when a Toyota 1D2 Gray M (silver metallic color) is subjected to metallic coloring.

[0041] Fig.13 This is a color evaluation image of a sedan when a Toyota 4S3 Light Orange Mica M (Beige Metallic) is subjected to metallic painting.

[0042] Fig.14 This is a color evaluation image of an SUV vehicle when a metallic color is applied to the Toyota 1D2 Gray M (silver metallic color) color.

[0043] Fig.15 This is a color evaluation image of an SUV vehicle when a Toyota 4S3 light orange mica color M (beige metallic color) is subjected to metallic coloring. DETAILED DESCRIPTION

[0044] Reference Figures 1 to 15One embodiment of the present invention will be described.

[0045] The method for generating a coloring evaluation image according to the present embodiment is a method for generating a coloring evaluation image based on a painted surface image showing a painted surface applied to an industrial product or a model thereof, and is implemented, for example, by a coloring evaluation image generating program executed by a program executable computer.

[0046] Figure 1 1 is a block diagram of a coloring evaluation image generating device 100 that executes a program for generating a coloring evaluation image. The coloring evaluation image generating device 100 includes an image input unit 1, a computer 2 that can execute the program, and an image output unit 3 such as an LCD display.

[0047] Figure 2 It is a structural diagram of computer 2.

[0048] The computer 2 is an executable program processing device having a processor 20, a memory 21 into which a program can be loaded, a storage unit 22 which can store programs and data, and an input / output control unit 23. The functions of the computer 2 are realized by the processor 20 executing the program provided to the computer 2.

[0049] Figure 3 This is a functional block diagram of the computer 2 when the computer 2 executes the coloring evaluation image generation program. The functional block includes a spectral reflectance calculation unit 51 , a colorimetric value calculation unit 52 , a histogram generation unit 53 , a mapping unit 54 , and a coloring evaluation image generation unit 55 .

[0050] Figure 4 and Figure 7 The object of the method for generating a coloring evaluation image according to the present embodiment is a two-dimensional image (photograph, illustration, etc.) of a car. Figure 4 The image of the car shown is called the "car image". Figure 7 The image of the SUV vehicle shown is referred to as an “SUV vehicle image.” The sedan image and the SUV image are input to a computer 2 using an image input unit 1 such as a scanner.

[0051] Figure 4 The sedan shown is Figure 7 The three-dimensional shape of the painted surface of the SUV shown is different. Even when the same metallic paint is applied to the painted surface, the change in the shadow of the painted surface is different for sedans and SUVs. The method for generating a color evaluation image according to the present embodiment can predict, for example, the change in the shadow of a painted surface image (two-dimensional image) showing the painted surface applied to an industrial product or its model, based on the change in the shadow of the painted surface. Figure 4 The sedan shown and Figure 7 The overall impression when metallic paint is applied to the painted surface of the SUV shown.

[0052] Input to computer 2 Figure 4 The sedan image shown and Figure 7 The SUV vehicle image shown is subjected to a pre-processed image. From each image, a "painted surface image" is generated by extracting only the image portion of the actual painted surface. Figure 5 This is a painted surface image 60A generated based on the car image. Figure 8 This is a painted surface image 60B generated based on the SUV vehicle image.

[0053] The painted surface image 60A and the painted surface image 60B of the present embodiment are images obtained by converting the sedan image and the SUV image as color images into 8-bit grayscale images. It should be noted that the painted surface image is not limited to a grayscale image. The painted surface image can be an image composed of brightness values ​​(hereinafter referred to as "shade levels") equivalent to an image displayed with an arbitrary number of bits, such as the Y component of a YUV signal or the G component of an RGB signal.

[0054] In generating a painted surface image, it is desirable that the painted surface image does not include a portion where the shadow of the painted surface does not change based on the three-dimensional shape of the painted surface itself, such as a portion where the shadow of a side mirror is reflected. This is to accurately predict the shadow change of the painted surface caused by the three-dimensional shape of the painted surface when the painted surface is painted with a metallic paint.

[0055] Next, the method for generating a coloring evaluation image according to the present embodiment will be described in detail.

[0056] The method for generating a coloring evaluation image according to the present embodiment includes a spectral reflectance calculation step S1 , a colorimetric value calculation step S2 , a histogram generation step S3 , a mapping step S4 , and a coloring evaluation image generation step S5 .

[0057] The spectral reflectance calculation unit 51 uses a method for determining the optical properties of a metal coating, such as that described in Patent Document 2 listed in the prior art literature, to calculate the spectral reflectance of the metal coating at each specified angle in the observation angle range (0 degrees to 75 degrees) based on the spectral reflectance of the metal coating measured at multiple light receiving angles (spectral reflectance calculation process S1).

[0058] Fig.10 This is an example of measuring the spectral reflectance of metallic paint.

[0059] For example, Fig.10As shown in FIG. 1 , the spectral reflectance of the metallic coating is measured under the conditions of incident angle: 45 degrees, light receiving angle (5 angles): high brightness 15 degrees and 25 degrees, front 45 degrees, dark 75 degrees and 110 degrees. The metallic coating is selected from, for example, the automatic color chart (Kansai paint) in the sample book of automobile repair paint. For example, the spectral reflectance of the selected metallic coating is measured using the 5-angle spectrophotometer MA-68II of X-Rite.

[0060] Next, the spectral reflectance calculation unit 51 calculates the spectral reflectance of the metal coating at each specified angle within the observation angle range (0 degrees to 75 degrees) based on the spectral reflectance of the five angles measured. The spectral reflectance calculation unit 51 can derive a formula for calculating the spectral reflectance of the metal coating at each arbitrary angle. The specified angle in this embodiment is about 0.3 degrees (observation angle range / shade level = 75 degrees / 256 = about 0.3 degrees). The calculated spectral reflectance is recorded in the memory 21 of the computer 2 together with the corresponding specified angle.

[0061] The colorimetric value calculation unit 52 uses, for example, a method for determining the optical properties of a metal coating film described in Patent Document 2 cited in the prior art documents, and calculates the colorimetric value (metallic color) at each specified angle within the observation angle range (0 degrees to 75 degrees) based on the spectral reflectance calculated by the spectral reflectance calculation unit 51 (colorimetric value calculation step S2). The colorimetric value calculation unit 52 can derive a formula for calculating the colorimetric value at each arbitrary angle. The calculated colorimetric value is recorded in the memory 21 of the computer 2 together with the corresponding specified angle.

[0062] The histogram generating unit 53 measures the number of pixels for each gradation level of the painted surface image prepared in advance, and obtains the ratio of the number of pixels for each gradation level (histogram generating step S3 ).

[0063] Figure 6 It is a histogram of the number of pixels for each gradation level of the painted surface image 60A of the passenger car. Fig. 9 6B is a histogram of the number of pixels for each gradation level of the painted surface image 60B of the SUV. Since the painted surface image 60A and the painted surface image 60B of the present embodiment are 8-bit grayscale images, the gradation levels are 256 levels [0 to 255].

[0064] exist Figure 6 and Fig. 9 In the figure, the area indicated by "h" represents the area of ​​high brightness (observation angles of 15 degrees and 25 degrees), the area indicated by "f" represents the area of ​​front view (observation angle of 45 degrees), and the area indicated by "s" represents the area of ​​darkness (observation angles of 75 degrees and 110 degrees).

[0065] The number of pixels at each shading level (the number of measured pixels) is obtained from a histogram of the number of pixels at each shading level of the painted surface image 60A and the painted surface image 60B. The histogram generation unit 53 generates a "corrected pixel number" by removing the number of pixels at shading levels near the maximum and near the minimum (for example, almost black [0 to 5], almost white [254 to 255]) from the measured pixel number. The reason for this is that the pixels at shading levels near the maximum and near the minimum are likely to be unable to represent the shadow of the painted surface caused by the three-dimensional shape of the painted surface itself, and therefore it is desired to delete them during the generation of the color evaluation image. For example, Figure 6 and Fig. 9 As shown in the figure, there are a lot of pixels near the maximum shade level shown on the horizontal axis. By deleting these pixels during the generation of the color evaluation image, a histogram that more accurately extracts the shadow changes of the painted surface can be created. Furthermore, by removing the pixels near the minimum shade level shown on the horizontal axis, a histogram that more accurately extracts the features in the area from s (dark) to h (high brightness) can be created.

[0066] Next, the histogram generation unit 53 obtains the ratio of the number of corrected pixels for each gradation level [0 to 255] to the total number of corrected pixels. Figure 5 The measured pixel count, the corrected pixel count, and the ratio calculated based on the corrected pixel count of the painted surface image of the passenger car are shown. The calculated ratio is recorded in the memory 21 of the computer 2 together with the corresponding shading level.

[0067] [Table 1]

[0068]

[0069] The mapping unit 54 associates the observation angle of each predetermined angle in the observation angle range (0 degrees to 75 degrees) with each shade level of the painted surface image 60A and the painted surface image 60B (mapping process S4). In the present embodiment, the shade level 255 (white) corresponds to the high brightness 0 degrees, and the shade level 0 (black) corresponds to the dark 75 degrees. The highest shade level corresponds to the smallest angle within the observation angle range, and as the shade level gradually decreases, it corresponds to the gradually larger observation angle, and the lowest shade level corresponds to the largest angle within the observation angle range.

[0070] Table 2 shows the observation angle corresponding to each of the shading levels [0 to 255] calculated by linear interpolation.

[0071] [Table 2]

[0072] Observation angle Shade level 75.0 0 74.7 1 74.4 2 74.1 3 73.8 4 73.5 5 73.2 6 72.9 7 72.6 8 72.4 9 72.1 10 71.8 11 71.5 12 71.2 13 70.9 14 70.6 15 22.1 180 21.8 181 21.5 182 21.2 183 20.9 184 20.6 185 20.3 186 20.0 187 19.7 188 19.4 189 2.9 245 2.6 246 2.4 247 2.1 248 1.8 249 1.5 250 1.2 251 0.9 252 0.6 253 0.3 254 0.0 255

[0073] The coloring evaluation image generating unit 55 generates a coloring evaluation image 70, which is color-matched according to the colorimetric value (metallic color) calculated for each specified angle within the observation angle range (0 degrees to 75 degrees) in the order of the size of the observation angle and according to the component corresponding to the ratio of the number of pixels of each lightness and darkness level associated with the observation angle (coloring evaluation image generating step S5).

[0074] In the present embodiment, the coloring evaluation image 70 is a two-dimensional image having a width of 128 pixels and a height of 200 pixels, and a total number of pixels of 25,600 pixels. The number of pixels for each shading level (hereinafter referred to as "CSX pixel number") is calculated by multiplying 25,600 pixels by the ratio shown in Table 1. Table 3 shows the calculated CSX pixel number. Table 3 lists the measured pixel number, the corrected pixel number, the ratio calculated based on the corrected pixel number, and the observation angle corresponding to each shading level [0 to 255] shown in Tables 1 and 2.

[0075] [Table 3]

[0076]

[0077] Fig.11 It is an explanatory diagram of the generation of the coloring evaluation image 70 in the coloring evaluation image generation step S5 .

[0078] The coloring evaluation image generating unit 55 arranges the colorimetric values ​​calculated at each specified angle in the coloring evaluation image 70 in the order of the size of the observation angle. In the present embodiment, the colorimetric values ​​at the observation angle of 0 degrees are arranged for the pixels in the upper left of the two-dimensional image. The colorimetric values ​​at the observation angle of 75 degrees are arranged for the pixels in the lower right of the two-dimensional image. The observation angle corresponding to the upper left of the two-dimensional image increases toward the lower right. The coloring evaluation image generating unit 55 can arrange the colorimetric values ​​in such a way that the observation angle corresponding to the upper left of the two-dimensional image increases. That is, for the two-dimensional coloring evaluation image 70 generated by the coloring evaluation image generating unit 55, the colorimetric values ​​can be arranged in the order of the raster scanning in the two-dimensional image (scanning order) and in the order of the size of the angles in the observation angle range.

[0079] When coloring the colorimetric values ​​calculated at each specified angle in the coloring evaluation image 70 in the order of the size of the observation angle, the colorimetric values ​​are arranged according to the components (number of pixels) corresponding to the ratio of the number of pixels of each gradation level associated with the observation angle. The colorimetric values ​​at each specified angle within the observation angle range (0 degrees to 75 degrees) are not evenly colored in the coloring evaluation image 70 in the order of the size of the observation angle within the observation angle range.

[0080] like Fig.11As shown, the colorimetric value at an angle of 0.6 degrees is colored for 166 pixels from the upper left of the two-dimensional image. Here, the colorimetric values ​​at angles of 0.0 degrees and 0.3 degrees are not colored in the color evaluation image 70 because the ratio of the number of pixels of the associated gradation 255 and gradation 254 is zero.

[0081] Next, the colorimetric value of the angle of 0.9 degrees is color matched for 63 pixels. This process is repeated until the angle reaches 75 degrees, and all 25,600 pixels are color matched, thereby completing the two-dimensional color evaluation image 70. The completed two-dimensional color evaluation image 70 is displayed on the image output unit 3 of the computer 2.

[0082] Fig.12 This is a color evaluation image 70A of a sedan when a Toyota 1D2 gray M (silver metallic color) is subjected to metallic coloring.

[0083] Fig.13 This is a color evaluation image 70B of a sedan when a Toyota 4S3 light orange mica color M (beige metallic color) is subjected to metallic coloring.

[0084] It is believed that: Figure 6 The h (high brightness) region of the histogram shown corresponds to the surface luminescence region of the punch line of the vehicle body. In this region, the number of pixels is large, and the distribution of the number of pixels in the f (front) region is discontinuous. Fig.12 In the color evaluation image 70A of the car shown in FIG. 1 , the h (high brightness) region becomes a band-like image. Fig.13 The same tendency is also found in the painted color evaluation image 70B of the sedan shown. The shading of the histogram appears again in the painted color evaluation image 70A and the painted color evaluation image 70B.

[0085] The greater the color flop (FF value) of a paint with a strong metallic feel, the more obvious the banded image is. Here, the FF value is a value calculated by the following calculation formula (1) based on the brightness Y value in the XYZ color system calculated based on the spectral reflectivity at a light receiving angle of 15 degrees (referred to as "Y15") and the brightness Y value in the XYZ color system calculated based on the spectral reflectivity at a light receiving angle of 45 degrees (referred to as "Y45"). For example, the FF value of the paint Toyota 1D2 Gray M is 1.621.

[0086] FF value = [2 × (Y15-Y45)] / (Y15 + Y45)... (1)

[0087] When observing an actual car, it is believed that the impression color of the entire car when observed visually for a short period of 1 to 2 seconds (this is defined as "first glance") is determined by the intensity of the high-brightness color, the intermediate color, and the dark color and their areas. Therefore, it can be said that the color evaluation image reproduces the impression color at first glance well.

[0088] Fig.14 This is a color evaluation image 70C of an SUV vehicle when a color Toyota 1D2 Gray M (silver metallic color) is subjected to metallic coloring.

[0089] Fig.15 This is a color evaluation image 70D of an SUV vehicle when a Toyota 4S3 light orange mica color M (beige metallic color) is subjected to metallic coloring.

[0090] exist Fig.14 and Fig.15 In the coloring evaluation images 70C and 70D shown, no bright spot can be observed in the h (high brightness) region. Fig.12 and Fig.13 The banded image you see is believed to be due to Fig. 9 This is because the number of pixels in the h (high brightness) area of ​​the histogram shown is small.

[0091] According to the method and program for generating a color evaluation image of the present embodiment, the colorimetric values ​​(metallic colors) at each predetermined angle within the observation angle range (0 to 75 degrees) are not evenly arranged in the order of the observation angles within the observation angle range. The color evaluation image takes into account the pixel ratio of the shade level associated with the observation angle.

[0092] That is, when the pixels of the corresponding shade level are mostly included in the painted surface image, the colorimetric value (metallic color) at a certain observation angle A is largely arranged in the painted evaluation image. On the other hand, when the pixels of the corresponding shade level are not mostly included in the painted surface image, the colorimetric value (metallic color) at a certain observation angle A is not largely arranged in the painted evaluation image.

[0093] Therefore, even without using the shape data of the three-dimensional CAD, the overall impression when the painted surface is painted with metallic paint can be predicted by the painting evaluation image generated from the change of the shadow of the painted surface in the painted surface image.

[0094] It should be noted that the generation program of the coloring evaluation image is recorded on a computer-readable storage medium. The computer system is made to read and execute the program recorded in the storage medium. In addition, the "computer system" mentioned here is a system as a hardware including OS and peripheral devices. In addition, "computer-readable storage medium" refers to removable media such as floppy disks, optical magnetic disks, ROMs, CD-ROMs, and storage devices such as hard disks built into the computer system. In addition, "computer-readable storage medium" may also include a medium that dynamically maintains the program in a short time, such as a communication line when sending a program via a network such as the Internet or a communication line such as a telephone line, and a medium that maintains the program for a certain period of time, such as a volatile memory inside a computer system that becomes a server or client at this time. In addition, the above-mentioned program can be a program for realizing a part of the aforementioned functions, or a program that can realize the aforementioned functions by combining with a program already recorded in a computer system, or a program implemented using a programmable logic device such as an FPGA (Field Programmable Gate Array).

[0095] Above, an embodiment of the present invention has been described in detail with reference to the accompanying drawings, but the specific structure is not limited to this embodiment, and also includes design changes within the scope of the main purpose of the present invention. In addition, the constituent elements shown in the above-mentioned embodiment and the modified examples shown below can be appropriately combined and constituted.

[0096] (Variant 1)

[0097] For example, in the above embodiment, the observation angle range is 0 to 75 degrees, but the observation angle range is not limited thereto. The observation angle range may be, for example, 0 to 90 degrees.

[0098] [Industrial Applicability]

[0099] The present invention can be applied to the evaluation of industrial products having a painted surface.

[0100] Description of Reference Numerals

[0101] 100: Coloring evaluation image generation device

[0102] 1: Image input unit

[0103] 2: Computer

[0104] 20: Processor

[0105] 21: Memory

[0106] 22: Storage

[0107] 23: Input and output control unit

[0108] 3: Image output unit

[0109] 60A, 60B: Painted surface image

[0110] 70, 70A, 70B, 70C, 70D: Colored evaluation images

[0111] S1: Spectral reflectance calculation process

[0112] S2: Colorimetric value calculation process

[0113] S3: Histogram generation process

[0114] S4: Mapping process

[0115] S5: Coloring evaluation image generation process

Claims

1. A method for generating a coloring evaluation image, the method being a method for generating a coloring evaluation image based on a painted surface image showing a painted surface, in, The method for generating the coloring evaluation image comprises: A spectral reflectance calculation step of calculating the spectral reflectance of the metallic coating at each predetermined angle within an observation angle range based on the spectral reflectance of the metallic coating measured at a plurality of light receiving angles; A colorimetric value calculation step of calculating a colorimetric value at each of the specified angles within the observation angle range based on the spectral reflectance; a histogram generating step of measuring the number of pixels at each shade level of the painted surface image, finding the ratio of the number of pixels at each shade level, and generating a histogram that extracts the shadow changes of the painted surface; a mapping step of associating each of the predetermined observation angles within the observation angle range with each of the shade levels of the painted surface image; and a coloring evaluation image generating step of generating the coloring evaluation image, wherein the coloring evaluation image is color-matched according to the order of the size of the observation angle and according to the component corresponding to the ratio of the number of pixels of each of the shade levels associated with the observation angle, the colorimetric value calculated at each of the prescribed angles within the observation angle range; The coloring evaluation image is an image in which pixels whose colorimetric values ​​are colored according to the order and the components are arranged in a predetermined order.

2. The method for generating a coloring evaluation image according to claim 1, in, In the mapping step, the highest shading level is associated with the smallest angle in the observation angle range, The lowest of the shading levels is associated with the largest angle in the range of viewing angles.

3. The method for generating a coloring evaluation image according to claim 1, in, The coloring evaluation image generating step generates the two-dimensional coloring evaluation image. For the coloring evaluation image, the colorimetric values ​​are arranged in the order of the angles in the observation angle range and in the order of raster scanning.

4. A storage medium storing a color evaluation image generation program, wherein the color evaluation image generation program is a program for causing a computer to generate a color evaluation image based on a painted surface image showing a painted surface, in, The generation procedure of the coloring evaluation image executes: A spectral reflectance calculation step of calculating the spectral reflectance of the metallic coating at each predetermined angle within an observation angle range based on the spectral reflectance of the metallic coating measured at a plurality of light receiving angles; A colorimetric value calculation step of calculating a colorimetric value at each of the specified angles within the observation angle range based on the spectral reflectance; a histogram generating step of measuring the number of pixels at each shade level of the painted surface image, finding the ratio of the number of pixels at each shade level, and generating a histogram that extracts the shadow changes of the painted surface; a mapping step of associating each of the predetermined observation angles within the observation angle range with each of the shade levels of the painted surface image; as well as a coloring evaluation image generating step of generating the coloring evaluation image, wherein the coloring evaluation image is color-matched according to the order of the size of the observation angle and according to the component corresponding to the ratio of the number of pixels of each of the shade levels associated with the observation angle, the colorimetric value calculated at each of the prescribed angles within the observation angle range; The coloring evaluation image is an image in which pixels whose colorimetric values ​​are colored according to the order and the components are arranged in a predetermined order.

5. The storage medium according to claim 4, in, In the mapping step, the highest shading level is associated with the smallest angle in the observation angle range, The lowest of the shading levels is associated with the largest angle in the range of viewing angles.

6. The storage medium according to claim 4, in, In the coloring evaluation image generating step, a two-dimensional coloring evaluation image is generated. For the coloring evaluation image, the colorimetric values ​​are arranged in the order of the angles in the observation angle range and in the order of raster scanning.

7. A coloring evaluation image generating device, which is a device for generating a coloring evaluation image based on a painted surface image showing a painted surface, in, The coloring evaluation image generating device comprises: a spectral reflectance calculation unit for calculating the spectral reflectance of the metallic coating at each predetermined angle within the observation angle range based on the spectral reflectance of the metallic coating measured at a plurality of light receiving angles; a colorimetric value calculation unit, which calculates the colorimetric value of each of the specified angles within the observation angle range based on the spectral reflectance; a histogram generating unit that measures the number of pixels at each shading level of the painted surface image, obtains a ratio of the number of pixels at each shading level, and generates a histogram that extracts changes in shadows of the painted surface; a mapping unit that associates each of the predetermined observation angles within the observation angle range with each of the shade levels of the painted surface image; and a coloring evaluation image generating unit, generating the coloring evaluation image, wherein the coloring evaluation image is color-matched according to the order of the size of the observation angle and according to the component corresponding to the ratio of the number of pixels of each of the shade levels associated with the observation angle, the colorimetric value calculated at each of the prescribed angles within the observation angle range; The coloring evaluation image is an image in which pixels whose colorimetric values ​​are colored according to the order and the components are arranged in a predetermined order.

8. The coloring evaluation image generating device according to claim 7, in, The mapping unit associates the highest gradation level with a smallest angle in the observation angle range, and associates the lowest gradation level with a largest angle in the observation angle range.

9. The coloring evaluation image generating device according to claim 7, in, The coloring evaluation image generating unit generates the two-dimensional coloring evaluation image. For the coloring evaluation image, the colorimetric values ​​are arranged in the order of the angles in the observation angle range and in the order of raster scanning.

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