Information Processing Apparatus, Information Processing Method, and Program

Abstract

To provide a technique for creating color conversion parameters for high-precision conversion.SOLUTION: An information processing device includes means for acquiring information about geometric conditions for capturing a color chart illuminated by light and means for determining a position at which each of a plurality of color patches is positioned on the color chart, on the basis of the geometric conditions.SELECTED DRAWING: Figure 13

Description

Technical Field

[0001] The present invention relates to color conversion technology.

Background Art

[0002] In a manufacturing factory of industrial products, color inspection is performed to confirm that the produced products are painted with the same color. As one of the color inspection methods, there is a method using image data of a product captured by an imaging device. For example, by calculating the color difference between the captured image of a reference product and the captured image of the product to be inspected, it is determined whether the colors are different.

[0003] At this time, due to differences in the imaging environment, differences in characteristics between imaging devices, etc., differences may occur in the color or brightness of the image data. Since color inspection in such a state where such differences occur is difficult, it is necessary to convert the image data into image data in a color space that is independent of such differences, for example, the L*a*b* space.

[0004] As one method of converting to image data in the L*a*b* space, there is the following. First, a color chart is imaged by an imaging device to obtain the RGB values of the color chart, and the color chart is measured by a dedicated measuring instrument to obtain the XYZ values of the color chart. Then, by processing the obtained RGB values and XYZ values with a dedicated program, color conversion parameters indicating the correspondence relationship between the RGB space and the XYZ space are created. Using this color conversion parameter, the image data in the RGB space is converted into image data in the XYZ space. Then, it is converted into image data in the L*a*b* space.

[0005] When creating color conversion parameters, it is desirable that the color chart contains a color patch of a color close to the color of the product to be color-inspected, as this improves the accuracy of color conversion. Therefore, even when the product to be color-inspected contains a material having an angle dependency, it is desirable that the color chart contains a color patch of a color close to the color of the material.

[0006] However, when a color chart includes color patches with angular dependence, it becomes more susceptible to the influence of specular reflection. Patent Document 1 discloses a color chart in which a plurality of color patches with angular dependence of the same color are arranged as a technique for reducing the influence of specular reflection. In such a color chart, there is a high possibility that there are color patches with angular dependence where specular reflection does not occur. For example, by taking the average of the RGB values of a plurality of color patches with angular dependence, the influence of specular reflection can be reduced.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, in Patent Document 1, when a color patch with angular dependence is arranged in a color chart, in some positions, the light of illumination may be reflected in the captured image, and in such a case, accurate color conversion parameters cannot be created.

[0009] Therefore, in view of the above problems, an embodiment of the present invention aims to provide a technique for creating color conversion parameters for performing high-precision conversion when using color patches with angular dependence.

Means for Solving the Problems

[0010] An embodiment of the present invention includes an acquisition unit that acquires information regarding geometric conditions when imaging a color chart irradiated with light, and a determination unit that determines the positions where a plurality of color patches are arranged in the color chart based on the geometric conditions. having, wherein the plurality of color patches include two or more color patches of the same color, and the determining means determines the arrangement positions of the two or more color patches of the same color It is an information processing apparatus characterized by the above.

Effects of the Invention

[0011] According to an embodiment of the present invention, when using a color patch having angular dependence, it becomes possible to create color conversion parameters for performing highly accurate conversion.

Brief Description of the Drawings

[0012]

Figure 1

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Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments do not necessarily limit the present invention. Also, not all combinations of features described in this embodiment are essential for the solution means of the present invention.

[0014] [First Embodiment] [Configuration of Color Conversion Parameter Creation System] FIG. 1 is a diagram showing the configuration of a color conversion parameter creation system. The color conversion parameter creation system includes an information processing device 1, an information processing device 2, a display device 3, a printing device 4, an imaging device 5, a color chart 6, illumination 7, a measuring instrument 8, and an input device 110. In this color conversion parameter creation system, user input is received via the input device 110, and the content based on the input is displayed on the display device 3.

[0015] Also, in the color conversion parameter creation system, the printing device 4 executes a printing process based on the data of the color chart created by the information processing device 1 to create the color chart 6. The color chart 6 is imaged by the imaging device 5 while being irradiated with the illumination 7. It is desirable that the geometric conditions at this time and the characteristics of the imaging device 5 and the illumination 7 be close to those used in color inspection. Note that the geometric conditions during imaging by the imaging device 5 include the relative positional relationship between the imaging device 5, the color chart 6, and the illumination 7, and the respective orientations of the imaging device 5, the color chart 6, and the illumination 7.

[0016] Also, in the color conversion parameter creation system, the measuring instrument 8 measures the color chart 6. Note that FIG. 1 shows a form in which the imaging device 5 and the measuring instrument 8 are arranged side by side, but it is desirable that the geometric conditions during imaging and the imaging conditions during measurement be the same. Therefore, when using the measuring instrument 8, it is desirable to replace the measuring instrument 8 with the imaging device 5 at the position of the imaging device 5.

[0017] [Hardware Configuration of Information Processing Device] FIG. 2 is a block diagram showing the hardware configuration of the information processing apparatus 1. The information processing apparatus 1 includes a CPU 101, a ROM 102, and a RAM 103. The information processing apparatus 1 also includes a VC (video card) 104, a general-purpose I / F (interface) 105, a SATA (Serial ATA) I / F 106, and a NIC (network interface card) 107.

[0018] The CPU 101 uses the RAM 103 as a work memory to execute an OS (operating system) and various programs stored in the ROM 102, an HDD (hard disk drive) 112, and the like. The CPU 101 also controls each component via the system bus 108. Note that the processing according to the flowchart described later is executed by the CPU 101 executing the program code developed in the RAM 103 from the program code stored in the ROM 102, the HDD 112, and the like.

[0019] A display device 3 is connected to the VC 104. Input devices 110 such as a mouse and a keyboard and an imaging device 5 are connected to the general-purpose I / F 105 via a serial bus 109. A general-purpose drive 113 that reads and writes an HDD 112 and various recording media is connected to the SATA I / F 106 via a serial bus 111. The NIC 107 inputs and outputs information to and from an external device. The CPU 101 uses various recording media mounted on the HDD 112 and the general-purpose drive 113 as storage locations for various data. The CPU 101 displays a GUI (graphical user interface) provided by a program on the display device 2 and receives inputs such as user instructions that can be received via the input device 110.

[0020] The information processing apparatus 2 also has the same hardware configuration as the information processing apparatus 1. Note that the information processing apparatus 1 and the information processing apparatus 2 do not necessarily have to be different hardware, and the same hardware may be shared.

[0021] <Functional Configuration of Information Processing Apparatus> FIG. 3 is a block diagram showing the functional configuration of the image processing apparatus 1. The CPU 101 reads and executes a program stored in the ROM 102 or the HDD 112 using the RAM 103 as a work memory, thereby realizing each functional module shown in FIG. 3. Note that not all of the processes shown below need to be executed by the CPU 101, and the information processing apparatus 1 may be configured such that part or all of the processes are performed by one or a plurality of processing circuits other than the CPU 101.

[0022] As shown in FIG. 3, the information processing apparatus 1 includes an acquisition unit 11, a display control unit 12, an estimation unit 13, a determination unit 14, and a print control unit 15. Further, the information processing apparatus 2 includes an imaging control unit 16, a measurement control unit 17, and a color conversion parameter creation unit 18.

[0023] The acquisition unit 11 is an acquisition means for acquiring information regarding geometric conditions when imaging a color chart. In the present embodiment, the acquisition unit 11 is used to acquire the reflected light characteristics on the surface of the color chart 6. FIGS. 4 and 5 show examples of geometric conditions when imaging a color chart.

[0024] FIG. 4 shows the positional relationship between the light source 7 and the color chart 6 in a three-dimensional orthogonal coordinate system with the installation position of the imaging device 5 as the origin. Let the coordinates of the light source 7 be (x0, y0, z0). As shown in FIG. 4, the color chart 6 is composed of 12 (= 3 in the vertical direction × 4 in the horizontal direction) color patches. The 12 color patches are each square, and the center points of the respective color patches are denoted as a1, a2,..., a12. Also, let the coordinates of the center points of the respective color patches (referred to as the center coordinates of the color patches) be (x1, y1, z1), (x2, y2, z2),... (x12, y12, z12).

[0025] FIG. 5 shows the geometric conditions when imaging a color chart in a spherical coordinate system. Here, it is assumed that the camera 5 and the color chart 6 face each other directly. Also, in FIG. 5, the geometric conditions for the center point ai of the i-th color patch are shown. As shown in FIG. 5, an angle φi is defined as the angle between the axis x on the same plane as the color chart 6 and the vector obtained by orthogonally projecting the vector from the center point ai to the light source 7 onto the same plane, and an angle θi is defined as the angle between the axis passing through the imaging device 5 starting from the center point ai and the vector from the center point ai to the light source 7.

[0026] The display control unit 12 displays, for example, a GUI on the display device 3 and receives a user instruction input via the input device 110. In the present embodiment, as an example, the GUI 600 shown in FIG. 6 is used. As shown in FIG. 6, the GUI 600 includes text boxes indicated by reference numerals 601, 602, 603, 605 and buttons indicated by reference numerals 604, 606.

[0027] The user inputs the numerical value of the vertical frame of the color chart into the text box 601 which is the setting means for the number of color patches arranged. Similarly, the user inputs the numerical value of the horizontal frame of the color chart into the text box 602 which is the setting means for the number of color patches arranged. Also, the user inputs the path to the file of the color patch table in which the information of the color patches is described into the text box 603 which is the file path input means. In this path input, software such as a file explorer may be used to refer to the path. In that case, the user presses the reference button 604 to start the file explorer. The color patch table is, for example, a table as shown in FIG. 7 and is saved in a file format such as csv. In the table of FIG. 7, the value of the color patch ID corresponding to the type of color patch is held in the first column. The RGB values in the captured image are held in the second column. Information regarding the specular reflection characteristics of the color patch is held in the third column. Here, as the information regarding the specular reflection characteristics, the angle near the specular reflection is adopted. The reflected light of the light incident on the color patch is the sum of a diffuse reflection component having the same reflection intensity in various directions and a specular reflection component having a high reflection intensity in the vicinity centered on the specular reflection angle. Such specular reflection characteristics can be calculated using, for example, a bidirectional reflectance distribution function (BRDF). For example, the specular reflection component is measured in advance for each color patch, and the angle at which its intensity becomes equal to or greater than the threshold value is described in the color patch table as the angle near the specular reflection. In the fourth column, a combination of values of cyan, magenta, yellow, and black (referred to as CMYK values) corresponding to the ink amount when printing with the printing device 4 is held. In addition, when using special inks such as metallic ink in the printing device 4, the value is also held. Based on the user input via the GUI 600, the information processing device 1 and the information processing device 2 execute the following processing, whereby a color chart is created.

[0028] <Explanation of Color Patches with Angle Dependence> A description of the color patch having angular dependence in the present embodiment will be given. The angular dependence is the ratio of the intensity in the specular reflection direction to the intensity in the diffuse reflection direction of the color patch. A color patch having angular dependence refers to one having a relatively large magnitude of this angular dependence. As a color patch having angular dependence, for example, a color patch of a metallic color can be cited.

[0029] <Process executed by the information processing apparatus> FIG. 8 is a flowchart showing the processes executed by the information processing apparatus 1 and the information processing apparatus 2. Hereinafter, each step (process) is represented by prefixing S to a numerical value.

[0030] In S801, the acquisition unit 11 acquires the geometric conditions when imaging the color chart. The geometric conditions acquired in this step include information on the coordinates (x0, y0, z0) of the light source 7 and information on the coordinates (x1, y1, z1), (x2, y2, z2), ···, (x12, y12, z12) of the center points a1, a2, ···, a12 of the color patches. As a method for acquiring this information, for example, values measured using a measuring instrument such as a measurer are stored in advance in the ROM 102 or the like, and the acquisition unit 11 acquires the stored values.

[0031] In S802, the display control unit 12 receives a user input regarding the setting of the color chart. Here, the state transition when the display control unit 12 uses the GUI shown in FIG. 6 will be described with reference to FIG. 9.

[0032] In Fig. 9, reference numerals 901 to 904 each indicate a state, and reference numerals 601 to 606 each indicate an input by the operation elements shown in Fig. 6. First, in the input reception state 901, input from the user is received. The user inputs the number of vertical frames of the color chart into text box 601 and the number of horizontal frames into text box 602. For example, when arranging 12 color patches, the user inputs 3 into text box 601 and 4 into text box 602. Also, the user inputs the path of the color patch table file pre-stored in the HDD 112 etc. into text box 603. Further, the user inputs the number of color patches having angular dependence into text box 605. When the display control unit 12 receives the input via these text boxes, as shown in Fig. 9, it is a self-transition from the input reception state 901 to the input reception state 901. Incidentally, in inputting the path, by pressing the reference button 604, a transition is made to the reference state 902, and the user may refer to one or more paths. Also, when the user presses the chart creation button 606, a transition is made from the input reception state 901 to the input check state 903.

[0033] In the reference state 902, for example, a file explorer is launched and the path is referred to. When the user selects one path and the reference is completed, a transition is made from the reference state 902 to the input reception state 901, and the selected path is automatically input into text box 603.

[0034] In the input check state 903, checks are made as to whether the user's input is correct, specifically, whether there are any deficiencies in the input information, whether a file exists at the destination specified by the path input into text box 603, etc. If the user's input is incorrect, a transition is made from the input check state 903 to the error output state 904. On the other hand, if the user's input is correct, the process of S803 (see Fig. 8) is executed.

[0035] In the error output 904, error details, for example, the details of items that were incorrect in the input by the user, are displayed in a pop-up or the like. After displaying the error details, the process returns to the input acceptance 901, and the display control unit 12 resumes accepting the input by the user. The information input by the user is stored in the ROM 102, the HDD 112, etc., and is read and used as needed hereafter.

[0036] In S803, the estimation unit 13 creates a reflected light intensity ranking indicating the rank for each of the frames in which the color patches are arranged within the color chart. The reflected light intensity due to the direct light of the light source 7 can be expressed by Equation (1), using the coordinate information of the light source 7 acquired in S801 and the coordinate information of the center point of each frame in the chart. Let the intensity of the direct light of the light source 7 be V.

[0037]

Equation

[0038] Here, cosθi is obtained from Equation (2).

[0039]

Equation

[0040] Assuming that the intensity of the direct light is constant at each point regardless of the position, the ranking of the height of the reflected light intensity is the same as the ranking of the magnitude of cosθi calculated by Equation (2). Incidentally, the ranking of the reflected light intensity may be obtained by measurement. For example, a mirror may be placed at the position of the color chart as an object where approximately total reflection occurs, this mirror may be observed from the position of the imaging device 5, and the ranking of the reflected light intensity may be created by visually confirming the reflected light intensity. Also, actually, the mirror may be imaged by the imaging device 5, and the ranking of the reflected light intensity may be created based on the image data acquired by the imaging.

[0041] In S804, the determination unit 14 selects one type of color patch from the color patch table. As will be described later, the selection process in this step is repeatedly executed. When repeatedly selecting color patches, they are selected in order from the one with the widest angle near specular reflection. Let the selected color patch be color patch X.

[0042] In S805, the determination unit 14 arranges color patch X. Using the specular reflection intensity ranking obtained in S803, color patch X selected in the most recent S804 is arranged in the frame with the lowest specular reflection intensity among the frames where color patches have not yet been arranged.

[0043] In S806, the determination unit 14 determines whether the arrangement in S805 has been completed for all types of color patches whose information is held in the color patch table. If the determination result in this step is true, proceed to S807. On the other hand, if the determination result in this step is false, return to S804. Note that if the arrangement of color patches is completed for the number of color patches with angle dependence input via the text box 605, the remaining color patches may be arranged appropriately and proceed to S807. In this case, color patches other than those with angle dependence may be arranged, for example, randomly or considering color proximity.

[0044] Note that after S806, the determination unit 14 may select an existing color chart that is close to the color chart determined by the processing in S804 to S806. For example, select the closest one from existing Macbeth color charts or color charts created previously. Regarding the proximity used in this selection, for example, calculate the count of how many color charts are made from the same color materials, and the larger the calculated count, the closer it is considered. Or, it may be considered that the closer the count of the angles near specular reflection described in the color chart table is, the closer it is. Or, it may be considered that the closer the number of color patches with angle dependence is, the closer it is.

[0045] In S807, the print control unit 15 creates a color chart using the printing device 4. In creating the color chart, first, data for the color chart is generated. For example, based on the arrangement of color patches determined by the processing up to S806, image data is generated in which the pixel values corresponding to the respective color patches are the CMYK values read from the color patch table. Then, the print control unit 15 causes the printing device 4 to execute printing based on the image data of the color chart. Here, the configuration of the printing device 4 will be described with reference to FIG. 10.

[0046] The head cartridge 1001 has a recording head composed of a plurality of ejection ports and an ink tank that supplies ink to this recording head, and is also provided with a connector for receiving signals for driving each ejection port of the recording head. The ink tank can be equipped with inks of CMYK colors and metallic ink. The head cartridge 1001 is mounted on the carriage 1002 in a positionally fixed and replaceable manner, and the carriage 1002 is provided with a connector holder for transmitting drive signals and the like to the head cartridge 1001 via a connector.

[0047] The carriage 1002 is capable of reciprocating movement along the guide shaft 1003. Specifically, the carriage 1002 is driven via a drive mechanism such as a motor pulley 1005, a driven pulley 1006, and a timing belt 1007 using the main scanning motor 1004 as a drive source, and its position and movement are controlled. Incidentally, the movement of the carriage 1002 along the guide shaft 1003 is referred to as "main scanning", and the movement direction of the carriage 1002 is referred to as the "main scanning direction".

[0048] The recording medium 1008 for printing is placed on an auto sheet feeder (hereinafter referred to as "ASF") 1010. During printing, the pickup roller 1012 rotates via a gear by driving the paper feed motor 1011, and the recording medium 1008 is separated one by one from the ASF 1010 and fed. Further, the recording medium 1008 is conveyed to a recording start position facing the discharge port surface of the head cartridge 1001 on the carriage 1002 by the rotation of the conveyance roller 1009. The conveyance roller 1009 is driven via a gear using the line feed (LF) motor 1013 as a drive source. The determination of whether the recording medium 1008 has been fed and the determination of the position at the time of paper feeding are made when the recording medium 1008 passes through the paper end sensor 1014. The head cartridge 1001 mounted on the carriage 1002 is held such that the discharge port surface protrudes downward from the carriage 1002 and is parallel to the recording medium 1008. The control unit 1020 controls the operations of the respective parts of the printing apparatus 4. For simplicity of explanation, the printing apparatus 4 in the present embodiment will be described as a binary printer that controls whether to discharge ink at a predetermined resolution. Also, in the printing apparatus 4, a method capable of modulating the size of the discharged ink droplets may be adopted.

[0049] The image formation operation will be described below. First, when the recording medium 1008 is conveyed to a predetermined recording start position, the carriage 1002 moves on the recording medium 1008 along the guide shaft 1003, and ink is ejected from the ejection port of the recording head during the movement. When the carriage 1002 moves to one end of the guide shaft 1003, the conveyance roller 1009 conveys the recording medium 1008 by a predetermined amount in a direction perpendicular to the scanning direction of the carriage 1002. This conveyance of the recording medium 1008 is referred to as "paper feed" or "sub-scanning", and the conveyance direction of the recording medium 1008 is referred to as the "paper feed direction" or "sub-scanning direction". When the conveyance of the predetermined amount of the recording medium 1008 is completed, the carriage 1002 moves again along the guide shaft 1003. In this way, by repeating the scanning by the carriage 1002 of the recording head and the paper feed, an image is formed on the recording medium 1008. Incidentally, when using metal ink, as long as the metal ink application area and the colored ink application area do not overlap, the order of applying the ink may be either one first. Also, when applying metal ink 100% on the substrate, it is desirable to apply colored ink after applying white ink to the colored ink application area.

[0050] Incidentally, the recording medium used in this embodiment may be any medium that can support printing by the recording head. Also, in this embodiment, the recording method of the printing apparatus 4 is the inkjet method, but other recording methods may be adopted as the recording method of the printing apparatus 4.

[0051] Incidentally, it is not always necessary to create a color chart by printing. For example, a color chart may be created by manually cutting out existing color materials to create color patches and attaching them to a plate or the like. Also, it may be used as a color chart by displaying it on a display device such as a display.

[0052] Returning to the description of FIG. 8. In S808, the imaging control unit 16 images the color chart using the imaging device 5. Then, the color signal values (R C , G C , BC ) is obtained. For example, by averaging the color signal values of the regions of each color patch in the captured image, color signal values (R C , G C , B C ) as imaging data for each of the plurality of color patches are obtained. Incidentally, the color signal values (R C , G C , B C ) are device-dependent color signal values.

[0053] In S809, the measurement control unit 17 measures a color chart using the measuring instrument 8. By this step, color signal values (X, Y, Z) as measurement data for each of the plurality of color patches are obtained. Incidentally, the color signal values (X, Y, Z) are device-independent color signal values.

[0054] In S810, the color conversion parameter creation unit 18 creates color conversion parameters representing the correspondence between device-dependent color signal values (R C , G C , B C ) and device-independent color signal values (X, Y, Z). Each of the color signal values (RGB values, specifically (R C , G C , B C )) acquired in S808 is converted into L*a*b* values ((L*1, a*1, b*1)) using Expressions (3) to (7). Here, the color signal values of the reference white are set as (X W , Y W , Z W ). Incidentally, the L*a*b* values are device-independent color signal values and are values expressed in a color space with L*, a*, and b* as axes respectively. Also, each of the device-independent color signal values (X, Y, Z) acquired in S809 is converted into L*a*b* values ((L*2, a*2, b*2)) using Expressions (4) to (7).

[0055]

Equation

[0056] [Number]

[0057] [Number]

[0058] [Number]

[0059] [Number]

[0060] The coefficients α0 to α8 of the matrix shown in Equation (3) are obtained by the least squares method so that the color difference ΔE shown in Equation (8) approaches 0. By obtaining the coefficients α0 to α8 of the matrix, Equation (3), which is a relational expression representing the correspondence between the device-dependent color signal values (R C , G C , B C ) and the device-independent color signal values (X, Y, Z), is obtained.

[0061] [Number]

[0062] The coefficients of the matrix in Equation (3) are output as color conversion parameters. For each of the RGB values of the captured image of the subject to be inspected and the RGB values of the reference, they are converted into L*a*b* values using Equations (3) to (7). Then, the color difference is calculated using a color difference calculation formula such as ΔE76 or ΔE94. Color inspection can be performed by using this color difference as an evaluation value.

[0063] Incidentally, instead of obtaining the color conversion parameters, a lookup table (hereinafter referred to as "LUT") may be created. In creating the LUT, for example, first, on the display device 3, the display color signal values (R D , G D , BD ) is used to display a color chart that includes a total of 729 color patches with different values of R, G, and B by 32 each from (0, 0, 0) to (255, 255, 255). Next, by measuring each of the displayed color patches with the measuring instrument 8, device-independent color signal values (X, Y, Z) are obtained. As a result, for each color patch, a correspondence table between the display color signal values (R D , G D , B D ) and the device-independent color signal values (X, Y, Z) is obtained. This correspondence table is in the LUT format, and LUT D is created.

[0064] Also, as a LUT for color conversion (referred to as a color conversion LUT), not only one that converts RGB values to XYZ values but also one that converts RGB values to RGB values may be created. For example, by gamma mapping, the correspondence between the captured color signal values (R C , G C , B C ) and the display color signal values (R D , G D , B D ) is maintained to create a color conversion LUT A . First, a color conversion LUT C that maintains the correspondence between the captured color signal values (R C , G C , B C ) and the device-independent color signal values (X, Y, Z) is created. The color conversion LUT C can be created by obtaining 729 correspondence relationships with different values of R, G, and B by 32 each from (0, 0, 0) to (255, 255, 255) for the captured color signal values (R C , G C , B C ). Next, using the created color conversion LUT C and the color conversion LUT D , by known gamma mapping, the captured color signal values (R C , G C , B C ) are converted to the display color signal values (R D , G D , B D) is converted. By this conversion, the correspondence between the imaging color signal values (R C , G C , B C ) and the display color signal values (R D , G D , B D ) is obtained, so that a color conversion LUT A can be created. This LUT A may be used instead of the color conversion parameters.

[0065] In addition, in this embodiment, as an example of the color chart, a color chart 6 composed of 12 (= 3 in the vertical direction × 4 in the horizontal direction) color patches is shown. However, the number of color patches constituting the color chart is not limited to 12 and may be any integer. Also, as the position information of each color patch, the coordinate information of the center point of the color patch is used, but the coordinate information of a position other than the center may be used. For example, the coordinate information of an end such as the upper right end of the color patch may be used.

[0066] Also, as shown in FIG. 5, although the imaging device 4 is assumed to be facing the chart 6 directly, it does not necessarily have to be facing directly. Also, the data regarding the reflected light intensity created in S803 does not necessarily have to be in a ranking format. For example, by threshold processing using a predetermined threshold value, the positions can be divided into a position with high reflected light intensity and a position with low reflected light intensity, and color patches having an angle dependency may be arranged at the low positions.

[0067] Also, in this embodiment, as shown in FIGS. 1, 4, 5, etc., the color conversion parameter creation system has one illumination 7, but the color conversion parameter creation system may have a plurality (two or more) of illuminations. In that case, the reflected light intensity is the sum of the respective illumination components.

[0068] <Effects of this Embodiment> As described above, according to this embodiment, the arrangement position of the color patch is determined based on the reflected light intensity corresponding to the position. Then, by arranging color patches having an angle dependency at positions with low reflected light intensity, the influence of specular reflection can be reduced, and accurate color conversion parameters can be created.

[0069] [Second Embodiment] In the first embodiment, a color patch having angular dependence was arranged in the color chart only once for each type. In contrast, in this embodiment, one or more color patches having angular dependence are arranged for each type. Note that since the hardware configurations of the information processing apparatus 1 and the information processing apparatus 2 in this embodiment are the same as those in the first embodiment, the description thereof is omitted. In the following, the differences between this embodiment and the first embodiment will be mainly described. Also, the same components as those in the first embodiment will be denoted by the same reference numerals and described.

[0070] <Functional Configuration of Information Processing Apparatus, GUI> The display control unit 12 displays a GUI on the display device 3, for example, and receives a user instruction input via the input device 110. In this embodiment, as an example, the GUI 1100 shown in FIG. 11 is used. As shown in FIG. 11, the GUI 1100 includes text boxes indicated by reference numerals 601, 602, 603, 605, and 1101, buttons indicated by reference numerals 604 and 606, and selection lists indicated by reference numerals 1102 and 1103.

[0071] The user inputs the path to the file of the color patch table in which the information of the color patch is described into the text box 603. The file of this color patch table is stored in advance in the HDD 112 or the like. The color patch table is, for example, a table as shown in FIG. 12. In the fifth column of this table, the number of arrangements indicating how many corresponding color patches are to be arranged is described. Note that this number of arrangements may be described in advance. When the number of arrangements is not described in the fifth column, it is determined during the process by the process described later.

[0072] <Process Executed by Information Processing Apparatus> FIGS. 13 to 15 are flowcharts showing the processes executed by the information processing apparatus 1 and the information processing apparatus 2.

[0073] In S1301, the display control unit 12 receives a user input regarding the setting of the color chart. Here, the state transition when the display control unit 12 uses the GUI shown in FIG. 11 will be described with reference to FIG. 16.

[0074] Reference numerals 901 to 904 in FIG. 16 each indicate one state, and reference numerals 601 to 606, 1101 to 1103 each indicate an input by the operation element shown in FIG. 11. In the input reception in 901, the input by the user is received. When the display control unit 12 receives an input via the text box or the selection list, as shown in FIG. 11, it is a self-transition from the input reception in 901 to the input reception in 901.

[0075] The user selects whether to make the number of color patches having angular dependence uniform or non-uniform via the selection list 1102. Here, when making it uniform, for example, the number per type of color patch having angular dependence is made 2 for all, so as to align the number per type of the color patch. Note that the user inputs the number when making it uniform into the text box 1101. Also, the user selects whether to execute the exception processing for specular reflection via the selection list 1103. Here, the exception processing for specular reflection is a specific process executed when it is estimated that specular reflection will occur at the location where the color patch is arranged.

[0076] In S1302, the determination unit 14 determines the number of color patches to be arranged. S1302 will be described in detail with reference to FIG. 14.

[0077] First, in S1401, the determination unit 14 initializes the number of color patches to be arranged for each type of color patch, that is, sets the number of arrangements to 1.

[0078] Next, in S1402, the determination unit 14 determines whether "uniform" has been selected via the selection list 1102 in S1301. If the determination result of this step is true, the process proceeds to S1403. On the other hand, if the determination result of this step is false (that is, if "non-uniform" has been selected by the user via the selection list 1102), the process proceeds to S1404.

[0079] In S1403, the determination unit 14 updates the number of arrangements of the color patches corresponding to each type of color patch having angular dependence. For example, for each type of color patch having angular dependence, the number of arrangements of the color patch is set to the value input in the text box 1101.

[0080] In S1404, the determination unit 14 selects one type of color patch having angular dependence from the color patch table. As will be described later, the selection process of this step is repeatedly executed, but when repeatedly selecting this one type of color patch, the selection is made in descending order of the angle near the specular reflection.

[0081] In S1405, the determination unit 14 adds 1 to the current value of the number of arrangements corresponding to the color patch type selected in the most recent S1404.

[0082] In S1406, the determination unit 14 determines whether the total number of arrangements for each color patch type determined so far matches the number of frames of the color chart. If the determination result of this step is true, the series of processes ends. On the other hand, if the determination result of this step is false, the process returns to S1404.

[0083] The number of arrangements for each color patch type determined by the process of FIG. 14 is held by updating the fifth column of the color patch table (see FIG. 12) stored in, for example, the HDD 112, and is read and used as needed in subsequent processes.

[0084] Return to the description of FIG. 13. After the process of determining the number of color patches to be arranged, in S804, the determination unit 14 selects one type of color patch from the color patch table. The type of color patch selected in this step is referred to as color patch X.

[0085] In S1303, the determination unit 14 arranges the color patch X. S1303 will be described in detail with reference to FIG. 15.

[0086] First, in S1501, the determination unit 14 initializes a variable indicating the number of loop iterations (let it be loop variable i), that is, sets the loop variable i to 0.

[0087] In S1502, the determination unit 14 arranges the color patch X in the color chart. Specifically, when the loop variable i = 0, the color patch X is arranged in the frame at the position with the lowest reflected light intensity. On the other hand, when the loop variable i ≠ 0, the color patch X is arranged in the frame at the position with the longest distance from the already arranged color patch X (the position farthest from the already arranged color patch X). First, by threshold processing, the frames of the color chart are classified into frames with high reflected light intensity and frames with low reflected light intensity, and the color patch X may be arranged in the frame with the longest distance from the already arranged color patch X among the frames with low reflected light intensity. Also, here, a form of arranging two color patches of the same type is shown, but three or more color patches of the same type may be arranged. In this case, when arranging the nth color patch, the distances from the positions of the first to the (n - 1)th patches already arranged are calculated, and a form in which the nth color patch is arranged in the frame where the minimum value among them is the largest can be considered.

[0088] In S1503, the determination unit 14 determines whether the setting value regarding the exception processing of specular reflection is On, that is, whether "On" is selected by the user via the selection list 1103. If the determination result in this step is true, the process proceeds to S1504. On the other hand, if the determination result in this step is false (that is, when "Off" is selected by the user via the selection list 1103), the process proceeds to S1507.

[0089] In S1504, the determination unit 14 estimates whether specular reflection occurs. For example, θ is obtained from cosθi calculated by Equation (2). When θ is within the angular range near the specular reflection of the color patch X described in the color patch table, it is estimated that specular reflection occurs.

[0090] In S1505, the determination unit 14 determines whether specular reflection occurs based on the estimation result of S1504. If the determination result of this step is true, the process proceeds to S1506. On the other hand, if the determination result of this step is false (that is, when it is estimated that specular reflection does not occur), the process proceeds to S1507.

[0091] In S1506, the determination unit 14 executes exception processing for increasing the number of arrangements of the color patch X. For example, it may notify the user that specular reflection occurs, prompt the user to increase the number of arrangements of the color patch or change the geometric conditions. Also, a warning stating that specular reflection occurs may be displayed on the display device 3.

[0092] In S1507, the determination unit 14 determines whether the value of the loop variable i is greater than or equal to the value obtained by subtracting 1 from the number of arrangements corresponding to the color patch X. If the determination result of this step is true, the series of processes ends. On the other hand, if the determination result of this step is false, the process proceeds to S1508.

[0093] In S1508, the determination unit 14 increments (adds 1) the current value of the loop variable i. After this step, the process proceeds to S1502.

[0094] <Effects of this Embodiment> As described above, according to this embodiment, the number of arrangements for each type of color patch is determined, and the color patches are arranged in consideration of the reflected light intensities that vary depending on the positions within the color chart. As a result, a plurality of color patches having angular dependence are arranged at positions where the reflected light intensity is low, thereby reducing the influence of specular reflection and enabling the creation of highly accurate color conversion parameters.

[0095] [Embodiment 3] In the first and second embodiments, the arrangement of the color patches was obtained based on the reflected light intensity at the positions within the color chart. In contrast, in this embodiment, the number of color patches to be arranged is determined based on the lighting conditions. Note that since the hardware configurations of the information processing apparatus 1 and the information processing apparatus 2 in this embodiment are the same as those in the first embodiment, the description thereof is omitted. In the following, the differences between this embodiment and the first embodiment will be mainly described. Also, the same components as those in the first embodiment will be described with the same reference numerals.

[0096] <Processing executed by the information processing apparatus> FIG. 17 is a flowchart showing the processing executed by the information processing apparatus 1 and the information processing apparatus 2.

[0097] In S1701, the acquisition unit 11 acquires information on the lighting distribution as the lighting condition. Based on the information on the lighting distribution acquired in this step, the number of color patches to be arranged is determined. Here, for example, it is assumed that there are a plurality of lightings 7, and the number of lightings 7 is acquired.

[0098] In S1702, the number of color patches to be arranged is determined. Specifically, the number of arrangements corresponding to each type of color patch having angular dependence is made equal to the number of lightings 7 acquired in S1701. Note that the number of arrangements corresponding to the type of color patch having angular dependence does not necessarily have to be equal to the number of lightings 7, and the number of arrangements of the color patches having angular dependence may be increased as the number of lightings increases.

[0099] In S1703, the determination unit 14 arranges the color patch X. Note that since the arrangement process in this step is the same as that in S1303, the description thereof is omitted here.

[0100] Note that in this embodiment, the number of arrangements of the color patches having angular dependence is determined based on the number of lightings 7. However, for example, the arrangement is made according to the area of the direct light of the lighting as viewed from the position of the color chart. The number may be determined.

[0101] For example, place a mirror of the same size as the color chart at the installation position of the color chart, image the placed mirror with the imaging device 5, and check the area of the region where total reflection occurs (or the area of the region where the reflected light intensity is equal to or greater than a predetermined threshold value). Let the ratio of this area to the entire mirror be P. At this time, specular reflection will occur in the color patches to be arranged at a ratio of P. In order to reduce the influence, the number of patches arranged may be determined according to the following formula so that the region with an area larger than the ratio P is occupied by the color patches having angular dependence.

[0102]

Number

[0103] In addition, in this specification, arranging the color patches so as to satisfy formula (9) is described as "arranging two color patches at a ratio of P". At this time, it may be determined to arrange two in order from the one with the largest angle near the specular reflection.

[0104] Alternatively, an imaging device may be installed at the position of the color chart, and the number of color patches arranged may be determined based on the captured image by the installed imaging device. For example, the ratio P of the illumination pixels in the captured image may be obtained according to formula (10), and two color patches may be arranged at the obtained ratio P.

[0105]

Number

[0106] Also, the number of color patches arranged may be determined based on the occupied area of illumination as seen from the color chart position. Consider the area on the unit sphere centered on the color chart. Specifically, consider a first area with illumination and a second area without illumination on the extension line of the line connecting the color chart center and a point on the unit sphere, and determine the number of color patches arranged based on the ratio of the first area. Here, since the light behind the color chart is not considered, only the unit hemisphere on the front side of the color chart is considered. When the ratio of the first area in this unit hemisphere is P, determine the number of color patches arranged so as to arrange two color patches at the ratio P.

[0107] In addition, it is not necessarily required to measure the illumination distribution, and the user may manually input the ratio P. For example, a GUI for inputting the ratio P from 0 to 1 may be provided, and two color patches may be arranged at the ratio P input by the user. Also, it is not necessarily required to use a ratio, and inputs such as more or less illumination may be used, or an input for the occupied area of illumination may be used.

[0108] Also, when the above-described ratio P is obtained, it is not necessarily required to arrange two color patches at the ratio P, and the number of color patches to be two may be reduced so as to fall within the range of the set number of frames. Also, two color patches may be arranged at a ratio higher than the above-described ratio P. Also, three or more color patches of the same type (that is, the same color) may be arranged.

[0109] Also, when the number of arrangements is changed, if the number of frames of the color patches is insufficient in the set color chart, the number of frames may be automatically changed so that the number of frames on the color chart is sufficient.

[0110] <Effect of this embodiment> As described above, according to this embodiment, based on the illumination conditions, the number of color patches having angular dependence and the arrangement positions are determined. By arranging a plurality of color patches having angular dependence, the influence of specular reflection can be reduced, and accurate color conversion parameters can be created.

[0111] [Other Embodiments] In addition, among the above-described processing units, for the estimation unit 13, the determination unit 14, etc., instead of them, a machine-learned learned model may be used for processing. In that case, for example, a plurality of combinations of input data and output data to the processing unit are prepared as learning data, knowledge is acquired from them by machine learning, and a learned model that outputs output data for the input data as a result based on the acquired knowledge is generated. The learned model can be configured by, for example, a neural network model. Then, the learned model operates in cooperation with a CPU or a GPU, etc. as a program for performing the same processing as the processing unit, thereby performing the processing of the processing unit. In addition, the above-described learned model may be updated after a certain process as necessary.

[0112] Also, the above-described embodiments may be used in appropriate combination.

[0113] Further, the present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

Description of Reference Numerals

[0114] 1 Information processing apparatus 11 Acquisition unit 14 Determination unit

Claims

1. An acquisition means for acquiring information regarding geometric conditions when imaging a color chart irradiated with light, A determination means for determining positions where a plurality of color patches are arranged on the color chart based on the geometric conditions, and having, The plurality of color patches include two or more color patches of the same color, The determination means determines the arrangement positions of the two or more color patches of the same color, An information processing apparatus characterized by the above.

2. The geometric conditions include the positional relationship among the imaging device, the light source, and the color chart, The information processing apparatus according to claim 1, characterized by the above.

3. The plurality of color patches arranged on the color chart include metallic color patches, The information processing apparatus according to claim 1 or 2, characterized by the above.

4. The intensity of the reflected light due to the direct light of the light source varies according to the position within the color chart, The information processing apparatus according to any one of claims 1 to 3, characterized by the above.

5. The color chart has a plurality of frames each having one color patch arranged therein, The information processing apparatus according to any one of claims 1 to 4, characterized by the above.

6. For each of the plurality of frames, by using the coordinate information of the center point of each frame acquired as information regarding the geometric conditions and the intensity of the direct light of the light source, a calculation means for calculating the intensity of the reflected light that is incident on the position of the center point and reflected in the direction of the imaging device is further provided, The information processing apparatus according to claim 5, characterized by the above.

7. A creation means for creating a reflected light intensity ranking indicating the ranking of the reflected light intensities corresponding to each of the plurality of frames of the color chart based on the intensity calculated by the calculation means is further provided, The information processing apparatus according to claim 6, characterized by the above.

8. The determination means, Selects one type of color patch from the plurality of color patches, Determines the arrangement position of the selected one type of color patch by using the reflected light intensity ranking, The information processing apparatus according to claim 7, characterized by the above.

9. The determination means, Selects the one type of color patch in order from the one with the widest angle near specular reflection, Assigns, in order from the one with the lowest reflected light intensity in the reflected light intensity ranking, the frame for arranging the selected one type of color patch, The information processing apparatus according to claim 8, characterized in that...

10. When the number of the two or more color patches of the same color is two, the determining means determines the arrangement positions of the color patches of the same color so that the distance between the color patches of the same color becomes large. The information processing apparatus according to any one of claims 1 to 9, characterized in that...

11. The number of arrangements of the two or more color patches of the same color in the color chart is determined based on the ratio of the area of a region where the reflected light intensity in the region of the color chart is equal to or greater than a predetermined threshold value. The information processing apparatus according to any one of claims 1 to 10, characterized in that...

12. The number of arrangements of the two or more color patches of the same color in the color chart is determined based on an imaging image obtained by an imaging device installed at the position of the color chart. The information processing apparatus according to any one of claims 1 to 10, characterized in that...

13. The geometric conditions include the illumination distribution of a light source. The information processing apparatus according to any one of claims 1 to 12, characterized in that...

14. The apparatus further comprises determining means for determining the number of arrangements corresponding to each type of color patch included in the plurality of color patches by using the information on the illumination distribution. The information processing apparatus according to claim 13, characterized in that...

15. Imaging control means for acquiring imaging data of the color patches by causing an imaging device to image the color chart; Measurement control means for acquiring measurement data of the plurality of color patches by causing a measuring instrument to measure the color chart; Color conversion parameter creation means for creating color conversion parameters for converting image data expressed in a first color space into image data expressed in a second color space based on the imaging data and the measurement data; further comprising... The information processing apparatus according to any one of claims 1 to 14, characterized in that...

16. A step of acquiring information on geometric conditions when imaging a color chart irradiated with light; A step of determining positions where each of a plurality of color patches is arranged in the color chart based on the geometric conditions, wherein the plurality of color patches include two or more color patches of the same color, and in the step of determining, the arrangement positions of the two or more color patches of the same color are determined. The information processing method, characterized in that...

17. ... ​ A program for causing a computer to execute the method according to claim 16.

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