Computer color matching device, computer color matching system, computer color matching method and program

Abstract

To provide a computer color matching method, computer color matching device, computer color matching system and program that reduce a difference between a target color being a desired color and a color created using CCM.SOLUTION: There is provided a computer color matching method which is executed by an arithmetic circuit accessible to a storage device and calculates a blending ratio of a plurality of reference color materials to tone a target color The storage device previously stores learning data containing at least combination data associated with a prescribed target color and a prescribed created color obtained on the basis of a blending ratio thereof. The method comprises the steps of: acquiring the target color; calculating an adjustment amount of adjusting the target color on the basis of the learning data; determining the adjusted target color on the basis of the target color and the adjustment amount; and calculating a blending ratio of the adjusted target color. The adjustment amount is determined on the basis of a difference in reflectivity between the prescribed target color and the prescribed created color in each wavelength.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] This disclosure relates to a computer color matching apparatus, a computer color matching system, a computer color matching method, and a program. [Background technology]

[0002] Conventionally, computer color matching (hereinafter referred to as "CCM") is known, which uses a computer to calculate the mixing ratio of colorants in order to obtain a desired color by combining multiple colorants. For example, Patent Document 1 describes a color matching method that uses a neural network to determine the mixing ratio of basic colorants to obtain a mixed color equivalent to a sample color. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-341297 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, even if the mixing ratio of colorants necessary to create the desired color is calculated using CCM and the colorants are mixed according to that ratio, a color different from the desired color may still be produced. The difference between the desired target color and the produced color can occur due to various factors. Therefore, it is difficult to design a CCM to prevent this difference from occurring when calculating the mixing ratio to create the target color.

[0005] This disclosure aims to provide a computer color matching method, computer color matching apparatus, computer color matching system, and program that reduce the difference between a target color (a desired color) and a color created using CCM. [Means for solving the problem]

[0006] The computer color matching method relating to this disclosure is a computer color matching method that calculates the mixing ratio of a plurality of reference colorants for toning a target color, performed by an arithmetic circuit that can access a storage device, wherein the storage device has pre-stored learning data, and the learning data includes at least combination data associated with a predetermined target color and a predetermined created color obtained based on the mixing ratio calculated to tonify the predetermined target color, and the computer color matching method includes the steps of acquiring a target color, calculating an adjustment amount to adjust the target color based on the learning data, determining an adjusted target color based on the target color and the adjustment amount, and calculating a mixing ratio to tonify the adjusted target color, wherein the target color, predetermined target color, predetermined created color, and adjusted target color are each represented by the reflectance for each wavelength, and the adjustment amount is determined based on the difference between the reflectance of the predetermined target color and the reflectance of the predetermined created color at each wavelength.

[0007] The program relating to this disclosure is a program that causes a computer's arithmetic circuit to execute the computer color matching method relating to this disclosure.

[0008] The computer color matching apparatus according to this disclosure comprises: a calculation circuit that calculates the mixing ratio of reference colorants for creating a target color; and a storage device that stores learning data including at least combination data associated with a predetermined target color and a predetermined created color obtained based on the mixing ratio calculated for coloring the predetermined target color. The calculation circuit acquires the target color, calculates an adjustment amount to adjust the target color based on the learning data, determines an adjusted target color based on the target color and the adjustment amount, calculates a mixing ratio to color the adjusted target color, and the target color, predetermined target color, predetermined created color, and adjusted target color are each represented by the reflectance for each wavelength, and the adjustment amount is determined based on the difference between the reflectance of the predetermined target color and the reflectance of the predetermined created color at each wavelength.

[0009] The computer color matching system according to the present disclosure includes a computer color matching device and a color measuring device for measuring color, and the target color is obtained by measuring with the color measuring device.

Advantages of the Invention

[0010] According to the present disclosure, it is possible to provide a computer color matching method, a computer color matching device, a computer color matching system, and a program that reduce the difference between a target color, which is a desired color, and a color created using CCM.

Brief Description of the Drawings

[0011] [Figure 1] Diagram showing a schematic configuration of the computer color matching system 1 according to Embodiment 1 and Embodiment 2 [Figure 2] Flowchart of a process for executing CCM by a conventional method [Figure 3] Flowchart of a process for executing CCM by the computer color matching method according to Embodiment 1 [Figure 4] Schematic diagram of a method for calculating an adjusted target color by the computer color matching method according to Embodiment 1 [Figure 5] Diagram showing an example of an application of the computer color matching device [Figure 6] Diagram showing an example of an application of the computer color matching device [Figure 7] Flowchart of a process for executing CCM by the computer color matching method according to Embodiment 2 [Figure 8] Graph showing an example of the reflectance of a predetermined target color having parameters similar to the target color and the reflectance of a predetermined created color [Figure 9] Graph showing the reflectance difference ratio between the reflectance of the predetermined target color shown in FIG. 8 and the reflectance of the predetermined created color [Figure 10]A graph showing an example of the reflectance of the target color and the reflectance of the adjusted target color calculated by the computer color matching method according to Embodiment 2. [Modes for carrying out the invention]

[0012] The embodiments relating to this disclosure will be described below with reference to the drawings. However, the configurations described below are merely examples of this disclosure, and this disclosure is not limited to the embodiments described below. Various modifications are possible in addition to these embodiments, as long as they do not depart from the technical concept relating to this disclosure, depending on the design, etc.

[0013] (Embodiment 1) Figure 1 is a diagram showing a schematic configuration of the computer color matching system 1 according to Embodiment 1 of the present disclosure.

[0014] As shown in Figure 1, the computer color matching system 1 according to Embodiment 1 of the present disclosure comprises a computer color matching device 10 and a colorimeter 20. The computer color matching device 10 comprises an arithmetic circuit 11, a storage device 12, an input / output device 13, and a communication circuit 14. The computer color matching device 10 is, for example, a computer.

[0015] The arithmetic circuit 11 is a control unit that controls the operation of the computer color matching device 10. The arithmetic circuit 11 includes a general-purpose processor such as a CPU or MPU that realizes predetermined functions by executing a program. The arithmetic circuit 11 realizes various processes in the arithmetic circuit 11, such as the process of calculating the blending ratio described later, by calling and executing an arithmetic program stored in the memory device 12, for example. The arithmetic circuit 11 is not limited to a form in which hardware resources and software cooperate to realize predetermined functions, but may also be a hardware circuit specifically designed to realize predetermined functions. In other words, the arithmetic circuit 11 can be realized with various processors other than CPUs and MPUs, such as GPUs, FPGAs, DSPs, and ASICs. Such an arithmetic circuit 11 may be composed of, for example, a signal processing circuit which is a semiconductor integrated circuit.

[0016] The storage device 12 is a storage medium capable of storing various types of information. The storage device 12 can be implemented as, for example, memory such as DRAM, SRAM, or flash memory, an HDD, an SSD, or other storage devices, or a combination thereof as appropriate. As described above, the storage device 12 stores programs for implementing various processes performed by the arithmetic circuit 11. In addition, as will be described later, the storage device 12 stores learning data for the arithmetic circuit 11 to calculate the adjustment amount for the target color.

[0017] The input / output device 13 functions as an input device for receiving information from the user and as an output device for outputting information to the user. The input / output device 13 is equipped with one or more human-machine interfaces. The human-machine interface includes, for example, input devices such as a keyboard, pointing device (mouse, trackball, etc.), and touchpad, and output devices such as a display and speaker. The human-machine interface also includes input / output devices such as an in-cell touch panel display (e.g., a liquid crystal panel or an organic EL panel).

[0018] The communication circuit 14 is an interface device for connecting to a device or system via a communication line, either wired or wirelessly. This interface device is capable of communication compliant with wired communication standards such as USB® or Ethernet®. Furthermore, the interface device is capable of communication compliant with wireless communication standards such as Wi-Fi®, Bluetooth®, or cellular networks.

[0019] The colorimeter 20 is, for example, a spectrophotometer. The colorimeter 20 can measure the color of an object by shining light onto the object and receiving the reflected light.

[0020] The computer color matching method according to Embodiment 1 is performed by an arithmetic circuit 11 that can access a storage device 12 and calculates the mixing ratio of a plurality of reference colorants for coloring a target color. The storage device 12 has pre-stored learning data, which includes at least combination data of either a predetermined target color or a mixing ratio of a predetermined target color, and either a predetermined created color obtained based on the mixing ratio calculated to color the predetermined target color, or the color difference of the predetermined target color to the predetermined created color. The computer color matching method includes the steps of acquiring a target color, calculating an adjustment amount to adjust the target color based on the learning data, determining an adjusted target color based on the target color and the adjustment amount, and calculating a mixing ratio for coloring the adjusted target color.

[0021] According to this method, the computer color matching system 1 that performs the method can calculate the mixing ratio to obtain a color closer to the target color than conventional color matching methods.

[0022] First, with reference to Figure 2, we will explain the method for calculating the mixing ratio of standard colorants using conventional methods with CCM. Figure 2 is a flowchart of an example of the process performed by the calculation circuit 11 to execute CCM using the conventional method. CCM using the conventional method can be performed by a system having a configuration equivalent to the computer color matching system 1 described above.

[0023] First, the calculation circuit 11 of the computer color matching device 10 acquires a target color, which is the color to be matched (S10). The target color can be acquired, for example, by a colorimeter 20 measuring an object (fabric, paper, etc.) that has the target color and transmitting the measurement to the computer color matching device 10 via the communication circuit 14. Alternatively, the target color may be acquired by the calculation circuit 11 displaying one or more colors pre-stored in the storage device 12 on a display, which is one of the input / output devices 13, and the user selecting one of the displayed colors using a mouse, which is one of the input / output devices 13.

[0024] The computer color matching device 10 can define the target color as a coordinate and numerical value represented in a predetermined color space. The predetermined color space includes, but is not limited to, CIE1976Lab, CIE1994, CIE2000, CIE1976LUV, CMC, etc. In the present invention, it is preferable to use CIE1976Lab, which can calculate color difference with high accuracy. In this specification, the computer color matching device 10 that performs CCM using a conventional method, and the computer color matching device 10 according to this embodiment 1, perform CCM using CIE1976Lab as the color space. Similarly, the computer color matching device 10 according to embodiment 2, which will be described later, can perform CCM using CIE1976Lab as the color space. In CIE1976Lab, any color is represented by a parameter that includes L, which is a component representing lightness, and a and b, which are components representing hue and saturation. In this specification, when we refer to a color, such as a target color, a calculated color, or a created color, we mean the coordinates or parameters (i.e., the values ​​of L, a, and b) that represent that color in the color space.

[0025] When the arithmetic circuit 11 obtains a target color, it calculates the mixing ratio of multiple reference colorants to produce that target color (S11). Reference colorants are colorants having predetermined colors that are used to produce any color. For example, multiple colorants such as indigo, vermilion, yellow, white, and black may be used as reference colorants. Depending on the target color to be produced, multiple reference colorants suitable for producing that target color may be selected. The storage device 12 has parameters for each reference colorant (for example, the values ​​of L, a, and b when the color of the reference colorant is represented in the color space), and the arithmetic circuit 11 can use these parameters to calculate a calculated color, which is the color that should be expressed when the reference colorants are mixed in any ratio. The arithmetic circuit 11 can calculate the mixing ratio of the reference colorants to create the target color by determining the ratio such that the calculated color and the target color match or substantially match.

[0026] When the computer color matching device 10 calculates the mixing ratio of reference colorants for matching the target color, the reference colorants are mixed according to the calculated ratio. This mixing may be done manually by the user or automatically by a machine. Depending on the object to which the color is to be added, the mixed colorants can be used to express a color based on the mixing ratio of the reference colorants by printing on paper or dyeing fabric. In this specification, the color applied to an object according to the mixing ratio calculated to match a predetermined target color is referred to as the "created color." The calculation circuit 11 may be configured to calculate the mixing ratio by adjusting it for each object to which the color is to be applied (e.g., paper, fabric, etc.) so that the color expressed when the color is applied to the object shows the desired color development. The calculation circuit 11 may also be configured to calculate the mixing ratio by adjusting it for each method of applying color (e.g., offset printing, gravure printing, etc.).

[0027] When a predetermined object is given a created color using a mixing ratio calculated by conventional CCM methods, and the colorimeter 20 measures the created color applied to the object, parameters different from those of the target color may be obtained. Such differences can occur due to, for example, human factors by the user who mixed the color, or environmental factors such as temperature or humidity at the time of mixing. One example of a human factor by the user is when the ratio of the mixed standard colorants differs slightly from the calculated distribution ratio. In addition, such differences can occur due to various factors other than those mentioned above, such as when there is a difference between the parameters of the standard colorants used by the calculation circuit 11, which are stored in the memory device 12, and the colorants used for mixing. Furthermore, changes in the colorants themselves over time can also affect these factors.

[0028] The computer color matching system 1 according to this embodiment 1 can improve the difference between the target color and the created color that occurred in conventional CCMs as described above. The computer color matching system 1 according to embodiment 1 and the computer color matching method using this system will be described below.

[0029] The computer color matching system 1 according to Embodiment 1 performs CCM (Color Coding Modulation) by executing a predetermined process before the conventional computer color matching system calculates the mixing ratio, so that the color created by mixing according to the calculated mixing ratio becomes closer to the target color. Figure 3 is a flowchart of an example of the process executed by the arithmetic circuit 11 to execute the computer color matching method according to Embodiment 1.

[0030] First, the calculation circuit 11 of the computer color matching device 10 acquires the target color (S20). As described above, the target color can be acquired, for example, by the colorimeter 20 measuring an object (fabric, paper, etc.) that has the target color and transmitting it to the computer color matching device 10 via the communication circuit 14. Alternatively, the target color may be selected and acquired from colors pre-stored in the storage device 12.

[0031] Next, the arithmetic circuit 11 determines a predetermined target color having parameters close to the parameters representing the target color in color space (S21). The predetermined target color is a target color for which CCM has been performed in the past by the computer color matching system 1. This CCM may be a conventional CCM performed by any system. The storage device 12 stores the learning data as described above. The learning data includes combination data of the predetermined target color and the predetermined created color, which is a created color corresponding to the predetermined target color. The predetermined created color means a created color created based on the mixing ratio calculated by the arithmetic circuit 11 to adjust the predetermined target color. The predetermined target color can be selected from the learning data stored in the storage device 12.

[0032] When the arithmetic circuit 11 determines a predetermined target color, it acquires the gap between the predetermined target color and the predetermined created color corresponding to the predetermined target color (S22). The arithmetic circuit 11 can use this gap as an adjustment amount to adjust the target color. The gap can be represented, for example, as the difference (L2-L1, a2-a1, b2-b1) between the parameters of the predetermined target color (L1, a1, b1) and the parameters of the predetermined created color (L2, a2, b2) in the color space. This gap may be stored in the memory device 12 in advance as learning data, or it may be acquired by the arithmetic circuit 11 calculating it from the predetermined target color and the predetermined created color as needed. Note that when the gap is stored as learning data, the predetermined created color itself does not need to be stored. The learning data may be any of the following patterns: a combination of the predetermined target color and the predetermined created color, a combination of the mixing ratio of the predetermined target color and the predetermined created color, or a combination of the predetermined target color and the gap. The learning data may also be a combination of the mixing ratio of the predetermined target color and the gap.

[0033] If the learning data stores combination data of a predetermined target color mixing ratio and a predetermined created color, the calculation circuit 11 can calculate and use the predetermined target color based on the predetermined target color mixing ratio.

[0034] The learning data may include a plurality of combination data. The arithmetic circuit 11 can use the plurality of combination data that may be included in the learning data to determine a predetermined target color. Therefore, the arithmetic circuit 11 may extract two or more combination data for the target color from the learning data and calculate an adjustment amount based on the extracted two or more combination data.

[0035] When the arithmetic circuit 11 calculates a gap, that is, an adjustment amount, it determines an adjustment target color considering the target color and the adjustment amount (S23). For example, the arithmetic circuit 11 subtracts the adjustment amount from the parameters (L a 、a a 、b a ) of the target color represented in the color space to calculate the parameters of the adjustment target color (L b 、a b 、b b ). For example, the arithmetic circuit 11 can calculate the L component L b of the adjustment target color as L b = L a - (L2 - L1). The a component a b and b component b b of the adjustment target color can be calculated similarly.

[0036] When the arithmetic circuit 11 determines the adjustment target color, it calculates the blending ratio of the reference colorants for adjusting the adjustment target color (S24). As described above, the storage device 12 has parameters regarding each reference colorant. Therefore, the arithmetic circuit 11 can calculate an adjustment calculation color, which is the color that should be expressed when the reference colorants are blended at an arbitrary ratio, using the parameters regarding each reference colorant. The adjustment calculation color is the calculation color corresponding to the adjustment target color.

[0037] The above describes the computer color matching method using the computer color matching device 10 of the computer color matching system 1 according to this embodiment 1. Similar to when CCM is performed using a conventional method, when a color is created by mixing the reference colorants at the calculated mixing ratio, the colorimeter 20 measures the color and obtains the parameters of the adjusted color. This allows a user attempting to create a target color using CCM to confirm whether the created color matches the desired target color. The adjusted color is the color created that corresponds to the adjusted target color. When the computer color matching system 1 obtains the parameters of the adjusted color, it can associate the adjusted color with the adjusted target color used in CCM to create the adjusted color and store it further as learning data in the storage device 12. This allows the computer color matching system 1 to increase the amount of learning data available for determining the adjustment amount, enabling it to perform more accurate CCM. The computer color matching system 1 may also associate the adjusted color with the mixing ratio for toning the adjusted target color and store it further as learning data in the storage device 12. The computer color matching system 1 may further store the target color for adjustment and the gap between the target color for adjustment and the adjusted color as learning data in the memory device 12. The computer color matching system 1 may further store the mixing ratio for toning the target color for adjustment and the gap between the target color for adjustment and the adjusted color as learning data in the memory device 12.

[0038] Figure 4 is a schematic diagram illustrating the method for calculating the target color using the computer color matching method described above. Referring to Figure 4, the method for calculating the mixing ratio for creating a color close to the target color using the computer matching method according to Embodiment 1 will be explained. Figure 4 shows the target color A, a predetermined target color B, a predetermined created color B', and the adjusted target color C determined based on each of the colors A, B, and B', plotted on the color space coordinates. As described above, the target color A is the parameter (L a a a , b aThe predetermined target color B has parameters (L1, a1, b1). The predetermined created color B' has parameters (L2, a2, b2). The adjusted target color C has parameters (L b a b , b b ) has.

[0039] The predetermined target color B is a color whose mixing ratio has been calculated in the past using CCM, and the predetermined created color B' is a color that has been toned based on the mixing ratio calculated by CCM to create the predetermined target color B. The predetermined target color and predetermined created color are selected by the arithmetic circuit 11 from the learning data stored in the storage device 12. The gap G is calculated from the predetermined target color B and predetermined created color B'. In the computer color matching method according to Embodiment 1, the gap G is represented as (L2-L1, a2-a1, b2-b1). As will be described later, it is estimated that if the parameters of the target color are close, similar gaps will occur between the target color and the created color. Therefore, it is estimated that when the arithmetic circuit 11 calculates the mixing ratio by CCM to create the target color A, and the colorimeter 20 measures the created color created based on that mixing ratio, a created color A' having a difference of gap G from the target color A will be measured. Therefore, in the computer color matching method according to Embodiment 1, the calculation circuit 11 sets a color that has a gap G difference with respect to the target color A as the adjustment target color C, and calculates the mixing ratio of the reference colorants using CCM to create the adjustment target color C.

[0040] When the mixing ratio is calculated by CCM using the computer color matching method according to Embodiment 1, the user mixes the color based on the mixing ratio and applies it to an object to create an adjusted color C'. As described above, the adjusted color C' is created taking into account the gap G. Therefore, the adjusted color C' may have parameters closer to the target color A than the created color A' which is estimated to have a gap G with respect to the target color A. Thus, with CCM using the computer color matching method according to Embodiment 1, it is possible to create a color that is closer to the target color than the created color created by CCM using conventional methods.

[0041] The created adjusted color C' can be measured by the colorimeter 20. When the colorimeter 20 measures the adjusted color C', it transmits the measurement result to the storage device 12 of the computer color matching device 10 via the communication circuit 14. The calculation circuit 11 also transmits the adjusted target color C to the storage device 12. Therefore, the storage device 12 can further store combinations of the adjusted target color C and the adjusted color C' created based on the adjusted target color C. The calculation circuit 11 can determine whether the adjusted color C' is close to the target color A by comparing the target color A and the adjusted color C'. For example, the calculation circuit 11 may determine that a color corresponding to the target color A has been created if the adjusted color C' is within a predetermined Euclidean distance range from the target color A in the color space. If the adjusted color C' is not within that range from the target color A, the calculation circuit 11 may perform CCM again. In this case, the calculation circuit 11 may create an adjusted target color by adding a gap between the target color A and the adjusted color C' to the adjusted target color C, and then calculate the mixing ratio.

[0042] As described above, with conventional CCM methods, the created color A', which is toned based on the mixing ratio calculated by the calculation circuit 11 to create the target color A, may have some gap with respect to the target color A. However, with the computer color matching method according to Embodiment 1, CCM can be performed by setting an adjusted target color C, which is a target color that takes into account the occurrence of such a gap. Therefore, when toning is performed using the mixing ratio of the reference colorants calculated by CCM, the created adjusted color C' will have a gap G' with respect to the adjusted target color C, which corresponds to the gap G between a predetermined target color B and a predetermined created color B', and can be toned to be close to the target color A. Thus, with CCM using the computer color matching method according to Embodiment 1, it is possible to tonify colors so that the gap with respect to the target color is smaller compared to CCM using conventional methods. In other words, it is possible to tonify colors so that the gap between the target color and the adjusted color is smaller than the gap between the target color and the created color. In the above calculation method, the gap is calculated using one of the combination data of a predetermined target color and a predetermined created color, but it is not limited to this, and the gap may be calculated based on multiple combination data. For example, the gap may be the average of multiple gaps obtained from each of the multiple combinations of data.

[0043] Next, an example of the operation of the computer color matching device 10 of the computer color matching system 1 according to Embodiment 1 will be described. Figure 5 shows an application 30 displayed on a display, which is one of the input / output devices 13 of the computer color matching device 10. This application 30 is an example of a means for executing CCM by the computer color matching device 10 according to Embodiment 1, and is not limited thereto. The user can execute CCM by the arithmetic circuit 11 by operating the application 30. The application 30 is stored in the storage device 12 and can be read by the arithmetic circuit 11 as needed and displayed on the input / output device 13. The application 30 can be controlled by the arithmetic circuit 11 when the user operates a mouse or keyboard, which is one of the input / output devices 13.

[0044] As shown in Figure 5, the application 30 has multiple areas for displaying predetermined information on the display of the input / output device 13. These areas include area 31, area 32, area 33, area 34, and area 35.

[0045] Application 30 can select a reference colorant to be used in area 31. For example, Figure 5 shows black, ochre, brown, and white, which are examples of reference colorants. In this embodiment, Application 30 calculates the mixing ratio for color matching the target color using the reference colorants shown in area 31. In this embodiment, area 31 is labeled with color names such as black for simplicity, but is not limited to these; for example, symbols indicating specific colors may also be used.

[0046] Area 32 displays the acquired target color. In Figure 5, the target color is set to a color close to orange. As described above, the target color can be acquired and set by the calculation circuit 11, for example, by measuring an arbitrary color with the colorimeter 20.

[0047] Region 33 displays information about one or more predetermined target colors among the learning data stored in the storage device 12 that have parameters close to the target color shown in Region 32. For example, Region 33 displays the reference colorants shown in Region 31, the mixing ratios of each reference colorant, the parameters of a predetermined calculated color (i.e., a predetermined target color) calculated based on the mixing ratios, and the parameters of a predetermined created color based on the mixing ratios. Region 33 may also display other information, such as the difference between the parameters of the predetermined target color and the predetermined created color.

[0048] Region 34 shows an arbitrary range of the color space relating to the a and b components of the parameters, with the horizontal axis representing the a component and the vertical axis representing the b component. Region 34 displays the gaps relating to the a and b components of the parameters, calculated based on the combination data of a predetermined target color and a predetermined created color corresponding to that predetermined target color, for each predetermined target color shown in Region 33. The starting point of the arrow shown in Region 34 indicates the predetermined target color. The ending point of the arrow indicates the predetermined created color corresponding to that predetermined target color. The arrow indicates the gap calculated from the predetermined target color and the predetermined created color. In this way, Region 34 can show the distribution of the gaps relating to the a and b components of the parameters for at least a portion of the combination data of predetermined target colors and predetermined created colors contained in the learning data stored in the storage device 12.

[0049] Region 35 represents an arbitrary range of the color space with respect to the L component of the parameter. Region 35 displays each gap in the L component of the parameter, calculated based on the combination data of the predetermined target color and the predetermined created color corresponding to the predetermined target color, for each predetermined target color shown in Region 33. In this way, Region 35 can display the distribution of each gap in the L component of the parameter for at least a portion of the combination data of predetermined target colors and predetermined created colors contained in the learning data stored in the storage device 12.

[0050] Application 30 may also include a function for determining the Euclidean distance to a target color, which is the range for searching for neighboring colors used in the combination data used to calculate the adjustment amount, as described later. Furthermore, Application 30 may include a function for determining parameters for excluding combination data with different color difference tendencies.

[0051] Figure 6, like Figure 5, shows application 30 displayed on a display, which is one of the input / output devices 13 of the computer color matching device 10. Figure 6 further shows the target color and the gap corresponding to the adjustment amount to be applied to the target color in area 34. The gap corresponding to the adjustment amount is indicated by a dashed arrow in area 34 of Figure 6. The starting point of the dashed arrow indicates the target color. The ending point of the dashed arrow indicates the created color that is presumed to be created when CCM is performed on the target color. An example of a computer color matching method according to Embodiment 1 will be described with reference to Figure 6.

[0052] As described above, the target color can be obtained by measuring the color with the colorimeter 20. The adjustment amount can be obtained based on the gap, which is the color difference between a predetermined target color and a predetermined created color. For example, the adjustment amount may be selected based on the gap of a predetermined target color that has parameters closest to those of the target color. The calculation circuit 11 may select the predetermined target color with the smallest Euclidean distance between the parameters of the target color and the parameters of the predetermined target color as the closest predetermined target color. Region 34 in Figure 6 shows predetermined target colors that have parameters close to those of the target color. The gaps of each predetermined target color shown by solid arrows in region 34 of Figure 6 have similar orientations and sizes. In other words, it is estimated that the created color created from the calculated mixing ratio after performing CCM on target colors with similar parameters will have similar gaps. Therefore, as in the computer color matching method according to Embodiment 1, if CCM is performed to create an adjusted target color having a difference equal to the gap of a predetermined target color with parameters similar to the target color, an adjusted created color with a color close to the target color can be obtained.

[0053] In the computer color matching method described above, the arithmetic circuit 11 obtains an adjustment amount based on the gap for the predetermined target color that has the smallest Euclidean distance between the parameter of the target color and the parameter of the predetermined target color, but is not limited to this. For example, the arithmetic circuit 11 may search for a predetermined target color that is near the parameter of the target color as a neighbor color from the learning data stored in the memory device 12. By searching for a neighbor color of the target color, the arithmetic circuit 11 can extract two or more predetermined target colors and extract two or more combination data corresponding to each of the two or more predetermined target colors. The arithmetic circuit 11 may extract a predetermined target color that is within a predetermined Euclidean distance range from the parameter of the target color as a neighbor color of the target color. In searching for a neighbor color of the target color, the arithmetic circuit 11 can set any value as the predetermined Euclidean distance, such as 1, 2, 5, or 10. By setting it in this way, the arithmetic circuit 11 can, more specifically, extract combination data for arrows displayed near the target color in the arrow (i.e., gap) shown in region 34 of Figure 6.

[0054] The calculation circuit 11 can calculate the adjustment amount for the target color based on two or more extracted combination data. The calculation circuit 11 may also calculate the adjustment amount by averaging the gaps obtained from each of the two or more combination data.

[0055] Furthermore, the arithmetic circuit 11 may exclude some combination data from two or more combination data. The arithmetic circuit 11 can exclude combination data with different gap trends with respect to the gaps obtained from each combination data. For example, the arithmetic circuit 11 may calculate the standard deviation σ of the gaps based on two or more gaps obtained from two or more combination data and exclude combination data with gaps that are not included in the predetermined value. The arithmetic circuit 11 can set any value as the predetermined value, for example, 1σ, 2σ, or 3σ. By setting it in this way, the arithmetic circuit 11 can more specifically exclude combination data relating to arrows (i.e., gaps) with clearly different directions in the arrows (i.e., gaps) shown in region 34 of Figure 6.

[0056] According to the computer color matching method disclosed herein, the calculation circuit 11 of the computer color matching device 10 can calculate a mixing ratio to obtain a color closer to the target color than conventional color matching methods. As described above, this method is performed by modifying the target color to an adjusted target color before performing conventional color matching. Therefore, users can have the computer's calculation circuit execute the computer color matching method disclosed herein without creating a new program to calculate the mixing ratio to obtain the target color, by using a program for performing conventional color matching.

[0057] (Embodiment 2) This document describes a computer color matching system according to Embodiment 2 of the present disclosure, and a computer color matching method using the system. Embodiment 2 primarily describes the differences from Embodiment 1. In Embodiment 2, components identical or equivalent to those in Embodiment 1 are denoted by the same reference numerals. Furthermore, in Embodiment 2, descriptions that overlap with those in Embodiment 1 may be omitted. The computer color matching system 1 according to Embodiment 2 has the same configuration as the computer color matching system 1 according to Embodiment 1. The computer color matching method according to Embodiment 2 can be performed by the computer color matching system 1.

[0058] The computer color matching method according to Embodiment 2 is performed by an arithmetic circuit 11 that can access a storage device 12 and calculates the mixing ratio of a plurality of reference colorants to colorize a target color. The storage device 12 has pre-stored learning data, which includes at least combination data associated with a predetermined target color and a predetermined created color obtained based on the mixing ratio calculated to colorize the predetermined target color. The computer color matching method includes the steps of acquiring a target color, calculating an adjustment amount to adjust the target color based on the learning data, determining an adjusted target color based on the target color and the adjustment amount, and calculating the mixing ratio to colorize the adjusted target color. The target color, predetermined target color, predetermined created color, and adjusted target color are each represented by their reflectance for each wavelength. The adjustment amount is determined based on the difference between the reflectance of the predetermined target color and the reflectance of the predetermined created color at each wavelength. In this embodiment, the adjustment amount is determined based on the difference ratio between the reflectance of the predetermined target color and the reflectance of the predetermined created color at each wavelength. The combination data may include a combination of a predetermined target color, the reflectance of the predetermined target color, or the mixing ratio of the predetermined target color, and a combination of the mixing ratio of a predetermined created color, the predetermined created color, the reflectance of the predetermined created color, or the difference ratio of the reflectance of the predetermined target color to the reflectance of the predetermined created color at each wavelength.

[0059] According to this method, the computer color matching system 1 that performs the method can calculate mixing ratios to obtain a color closer to the target color than conventional color matching methods. Furthermore, the color created with the mixing ratios obtained by this method can be closer to the target color than conventional color matching methods, regardless of the light source.

[0060] In the computer color matching method according to Embodiment 1, the calculation circuit 11 performs a predetermined process to execute CCM before performing the process of calculating the mixing ratio. Specifically, as a predetermined process, the calculation circuit 11 calculates the difference (i.e., gap) between the parameters of a predetermined target color and a predetermined created color, and adjusts the parameters of the target color based on this gap. The computer color matching method according to Embodiment 2 differs from the computer color matching method according to Embodiment 1 in that, as will be described later, the calculation circuit 11 adjusts the reflectance of the target color based on the difference ratio of the reflectances of the predetermined target color and the predetermined created color.

[0061] The target color is defined as the result of combining light of various wavelengths, i.e., colors determined by wavelength. A predetermined target color, a predetermined created color, and an adjusted target color are similarly defined as the result of combining light of various wavelengths. The computer color matching apparatus 10 according to Embodiment 2 can define the target color as the reflectance for each wavelength. The wavelength range defined for the reflectance of the target color includes a predetermined wavelength range, and the predetermined wavelength range may include at least the visible light region. Specifically, the predetermined wavelength range may include, for example, 400 nm to 700 nm. The wavelength range is not limited to this and may also include 360 ​​nm to 780 nm. Furthermore, the predetermined wavelength range may also include the infrared region or the ultraviolet region. In addition to CCM using CIE1976Lab, the computer color matching apparatus 10 according to Embodiment 2 can perform CCM using reflectance. The reflectance can be calculated, for example, at multiple wavelengths within a predetermined wavelength range. In the computer color matching apparatus 10 according to Embodiment 2, the reflectance can be calculated at 16 different wavelengths within a predetermined wavelength range, but is not limited to this. The reflectance may be calculated using 10 different wavelengths, or it may be calculated using 30 different wavelengths. The wavelengths used to calculate the reflectance may be determined not only by the number of wavelengths, but also by the wavelength intervals. For example, the reflectance may be calculated using wavelengths from 400 nm to 700 nm, at 10 nm intervals. Specifically, the reflectance may be calculated using wavelengths of 400 nm, 410 nm, ..., 700 nm. The wavelength interval is not limited to 10 nm, and can be any interval such as 5 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc.

[0062] In Embodiment 2, the storage device 12 of the computer color matching device 10 holds data on the reflectance of each reference colorant. Based on this reflectance, the calculation circuit 11 can calculate a calculated color, which is the color that should be expressed when the reference colorants are mixed in any ratio. The calculation circuit 11 can calculate the mixing ratio of the reference colorants to create the target color by determining the ratio such that the reflectance of the calculated color matches or substantially matches the reflectance of the target color.

[0063] Figure 7 is a flowchart of an example of the process performed by the arithmetic circuit 11 in order to execute the computer color matching method according to Embodiment 2.

[0064] First, the calculation circuit 11 of the computer color matching device 10 acquires target color data (S30). As described above, the target color data is acquired, for example, by the colorimeter 20 measuring an object (fabric, paper, etc.) that has the target color, and transmitted to the computer color matching device 10 via the communication circuit 14. This allows the calculation circuit 11 to acquire the target color data. Alternatively, the target color data may be acquired by the user selecting from colors pre-stored in the storage device 12.

[0065] Next, the arithmetic circuit 11 determines a predetermined target color having parameters close to the parameters representing the target color in color space (S31). As described above, the predetermined target color is a target color for which CCM has been performed in the past by the computer color matching system 1. This CCM may be a conventional CCM performed by any system. The storage device 12 stores the learning data as described above. The learning data includes combination data of the predetermined target color and the predetermined created color, which is a created color corresponding to the predetermined target color. The predetermined created color means a created color created based on the mixing ratio calculated by the arithmetic circuit 11 in order to colorize the predetermined target color. The predetermined target color can be selected from the learning data stored in the storage device 12.

[0066] When the calculation circuit 11 determines a predetermined target color, it obtains the reflectance of the predetermined target color for each wavelength, and the reflectance of the predetermined creation color corresponding to the predetermined target color. These reflectances are stored in the storage device 12, for example, in association with the predetermined target color and predetermined creation color, and the calculation circuit 11 can obtain them by reading them from the storage device 12. Alternatively, the calculation circuit 11 may obtain the reflectances at each wavelength by calculating them from the information of the predetermined target color and predetermined creation color stored in the storage device 12 (for example, the parameters of these colors).

[0067] The calculation circuit 11 obtains the reflectance for each wavelength of each color and then obtains the difference ratio between the reflectance of a predetermined target color and the reflectance of a predetermined created color at each wavelength (S32). Specifically, the calculation circuit 11 calculates the difference between the reflectance of the predetermined target color and the reflectance of the predetermined created color at each wavelength and obtains it as a difference ratio. The difference ratio at a predetermined wavelength indicates the percentage by which the reflectance of the predetermined created color at that wavelength deviates from the reflectance of the predetermined target color at that wavelength. Thus, the difference ratio at a predetermined wavelength is determined based on the difference between the reflectance of the predetermined target color and the reflectance of the predetermined created color at each wavelength. The calculation circuit 11 can use the difference ratio at each wavelength as an adjustment amount for adjusting the target color. The adjustment amount can be determined based on the difference ratio between the reflectance of the predetermined target color and the reflectance of the predetermined created color at each wavelength. In this specification, the difference ratio at each wavelength may be collectively referred to as the "reflectance difference ratio" or more simply as the "difference ratio" as appropriate. The reflectance difference ratio includes the difference ratio between the reflectance of a predetermined target color and the reflectance of a predetermined created color for each wavelength within a predetermined wavelength range. In this embodiment, the predetermined wavelength range includes, but is not limited to, the wavelength range of 400 nm to 700 nm.

[0068] The difference ratio at a given wavelength can be calculated, for example, by dividing the difference between the reflectance of a given target color and the reflectance of a given created color by the reflectance of the given created color, as shown in equation (1) below. The difference ratio at a given wavelength, as shown in equation (1), represents a value relative to the reflectance of the given created color. In other words, the difference ratio at a given wavelength indicates the magnitude of the difference between the reflectance of the given created color and the reflectance of the given target color relative to the reflectance of the given created color. The calculation circuit 11 can obtain the difference ratio between the reflectance of the given target color and the reflectance of the given created color at each wavelength by performing the calculation shown in equation (1) for each wavelength.

[0069]

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[0070] In the computer color matching method according to Embodiment 2, the calculation circuit 11 of the computer color matching device 10 adjusts the difference in reflectance for each wavelength using relative values ​​rather than absolute values. As a result, the calculation circuit 11 can perform equivalent adjustments for wavelengths with high reflectance and wavelengths with low reflectance within a predetermined wavelength range.

[0071] The reflectance difference ratio may be pre-stored in the storage device 12 as learning data, associated with a predetermined target color or predetermined created color corresponding to the reflectance difference ratio, or it may be obtained by the calculation circuit 11 from the predetermined target color and predetermined created color as needed. Note that when the reflectance difference ratio is stored as learning data, the predetermined created color itself does not need to be stored. The learning data may also include combination data associated with the predetermined target color and the predetermined created color. The combination data stored as learning data may be a combination of the predetermined target color, the reflectance of the predetermined target color or the orientation ratio of the predetermined target color, and the mixing ratio of the predetermined created color, the predetermined created color, the reflectance of the predetermined created color or the reflectance difference ratio.

[0072] If the learning data stores combination data of a predetermined target color mixing ratio and a predetermined created color, the calculation circuit 11 can calculate and use the predetermined target color based on the predetermined target color mixing ratio.

[0073] The training data may include multiple combination data. The arithmetic circuit 11 can use multiple combination data that may be included in the training data to determine a predetermined target color. Therefore, the arithmetic circuit 11 may extract two or more combination data for the target color from the training data and calculate an adjustment amount based on the two or more extracted combination data. The adjustment amount may be, for example, the average value of the reflectance difference ratio in the two or more combination data calculated for each wavelength. In this way, the adjustment amount can be calculated by averaging the values ​​calculated based on the reflectance difference in the two or more combination data.

[0074] The calculation circuit 11 calculates the adjustment amount, then calculates the reflectance of the adjusted target color based on the reflectance of the target color and the adjustment amount, and determines the adjusted target color (S33). The reflectance of the adjusted target color indicates the reflectance of the adjusted target color. The calculation circuit 11 can calculate the reflectance of the adjusted target color at each wavelength by subtracting the product of the reflectance of the target color and the adjustment amount from the reflectance of the target color for each wavelength, for example, as shown in the following formula (2).

[0075] Reflectance of the target color = Reflectance of the target color (1 - amount of adjustment) (2)

[0076] Once the arithmetic circuit 11 determines the target color for adjustment, it calculates the mixing ratio of the reference colorants to achieve that target color (S34). As described above, the memory device 12 has parameters for each reference colorant. Therefore, the arithmetic circuit 11 can use the parameters for each reference colorant to calculate the calculated color for adjustment, which is the color that should be expressed when the reference colorants are mixed in any ratio. As described above, the calculated color for adjustment is the calculated color that corresponds to the target color for adjustment.

[0077] The above describes the computer color matching method using the computer color matching device 10 of the computer color matching system 1 according to this second embodiment. Similar to when CCM is performed using a conventional method, when a color is created by mixing the reference colorants at the calculated mixing ratio, the colorimeter 20 measures the color and obtains the parameters of the adjusted color. This allows a user attempting to create a target color using CCM to confirm whether the created color matches the desired target color. As described above, the adjusted color is a color created that corresponds to the adjusted target color. When the computer color matching system 1 obtains the parameters of the adjusted color, it can associate the adjusted color with the adjusted target color used in CCM to create the adjusted color and store it further in the storage device 12 as learning data. In other words, the parameters of the adjusted target color and the parameters of the adjusted color can be further stored in the storage device 12 as learning data.

[0078] Furthermore, as described above, the computer color matching device 10 can obtain the reflectance of a color by measuring the mixed color with the colorimeter 20. When the computer color matching system 1 obtains the reflectance of the adjusted color, it may associate the reflectance of the adjusted color with that of the adjusted target color and store this as learning data in the storage device 12.

[0079] This allows the computer color matching system 1 to increase the amount of training data available for determining the adjustment amount, enabling it to perform more accurate CCM. The computer color matching system 1 may further store in the storage device 12 as training data by associating the adjustment creation color with the mixing ratio for toning the adjustment target color. The computer color matching system 1 may further store in the storage device 12 as training data by associating the mixing ratio for toning the adjustment target color with the reflectance difference ratio between the adjustment target color and the adjustment creation color. The computer color matching system 1 may store the above data in the storage device 12 as training data by combining them. In other words, combinations having at least one of the adjustment target color, the reflectance of the adjustment target color, or the mixing ratio of the adjustment target color, and the corresponding adjustment creation color, the reflectance of the adjustment creation color, or the reflectance difference ratio between the adjustment target color and the adjustment creation color can be stored as training data.

[0080] Next, we will explain the relationship between wavelength, reflectance, and color difference. If wavelength is λ, then reflectance R(λ), light source data S(λ), and color matching function. JPEG0007884429000002.jpg525 has discrete values ​​for each wavelength. Using these values, the tristimulus values ​​X, Y, and Z are given by the following equations (3) to (5).

[0081]

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[0082]

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[0083]

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[0084] L is a parameter in the color space. * a * , b * This represents X, Y, and Z, and the X, Y, and Z values ​​of the white board. n , Y n , Z n Using these, the following equations (6) to (8) are given. Also, f(t) is given by equation (9).

[0085]

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[0086]

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[0087]

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[0088]

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[0089] Furthermore, in the CIE1976Lab color space, the color difference ΔE * ab This is given by the following equation (10): ΔL * Δa * Δb * The L in each of the two colors * a * , b * It is the difference in values.

[0090]

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[0091] The calculation circuit 11 can, for example, use the above-described formula to calculate parameters and color differences from wavelength and reflectance, or vice versa.

[0092] In the computer color matching system 1 according to Embodiment 2, the calculation circuit 11 of the computer color matching device 10 can determine a predetermined target color in the same manner as the computer color matching system 1 according to Embodiment 1. For example, the calculation circuit 11 may determine the predetermined target color for obtaining the reflectance difference ratio with respect to the target quantity as the predetermined target color that has the smallest Euclidean distance between the parameter of the target color and the parameter of the predetermined target color.

[0093] In the computer color matching device 10 according to Embodiment 2, the calculation circuit 11 may perform CCM using the application 30 shown in Figures 5 and 6 above. The calculation circuit 11 can search for neighboring colors of the target color to be used to calculate the adjustment amount through the function of the application 30 which determines the Euclidean distance to the target color, and can determine a predetermined target color to be used for CCM from said neighboring colors. For example, the calculation circuit 11 may extract predetermined target colors within a predetermined range of Euclidean distance as neighboring colors of the target color, and determine one or more of these neighboring colors as the predetermined target color to be used for CCM. In this way, the calculation circuit 11 of the computer color matching device 10 according to Embodiment 2 may calculate color differences, etc., based on parameters in the color space, as in the computer color matching method according to Embodiment 1.

[0094] The calculation circuit 11 may exclude some combination data from two or more combination data. As described in the computer color matching method according to Embodiment 1, the calculation circuit 11 can exclude combination data with different gap trends with respect to the gaps obtained from each combination data. For example, the calculation circuit 11 may calculate the standard deviation σ of the gaps based on two or more gaps obtained from two or more combination data and exclude combination data with gaps that are not included in the predetermined value. The calculation circuit 11 can set any value as the predetermined value, for example, 1σ, 2σ, or 3σ.

[0095] The following describes the method for determining the target color using the computer color matching method according to Embodiment 2. Figure 8 is a graph showing an example of the reflectance of a predetermined target color having parameters similar to the target color, and the reflectance of a predetermined created color. In Figure 8, the horizontal axis is wavelength (nm), and the vertical axis is the reflectance (%) at each wavelength. In Figure 8, the solid line A req This indicates the reflectance of a predetermined target color stored in the training data. In Figure 8, dashed line A mea This indicates the reflectance of the predetermined created color corresponding to the predetermined target color, which is stored in the learning data. As described above, the predetermined target color means a color for which CCM was performed in the past by the computer color matching system 1 and the mixing ratio was calculated. The predetermined created color means a color that has been toned based on the mixing ratio calculated by CCM to create the predetermined target color. The predetermined target color and the predetermined created color are selected by the arithmetic circuit 11 from the learning data stored in the memory device 12. As is clear from Figure 8, there is a difference ratio for each wavelength between the reflectance of the predetermined target color and the reflectance of the predetermined created color. Therefore, for example, if a user mixes a reference colorant with the mixing ratio calculated to create the predetermined target color, a color shifted by that difference ratio (i.e., an adjusted created color) will be created for each wavelength.

[0096] Figure 9 is a graph showing the reflectance difference ratio between the reflectance of a predetermined target color and the reflectance of a predetermined created color, as shown in Figure 8. The horizontal axis of Figure 9 represents wavelength (nm), and the vertical axis represents the difference ratio at each wavelength. In Figure 9, line D shows the reflectance difference ratio between the reflectance of a predetermined target color and the reflectance of a predetermined created color, as shown in Figure 8. The reflectance difference ratio shown in Figure 9 is calculated by applying the above-mentioned formula (1) to the reflectance of the predetermined target color and the reflectance of the predetermined created color. As is clear from Figures 8 and 9, in this example, the reflectance of the predetermined created color is greater than that of the predetermined target color in the wavelength range of approximately 400 nm to approximately 600 nm. Also, in this example, the reflectance of the predetermined target color is greater than that of the predetermined created color in the wavelength range of approximately 600 nm to approximately 700 nm. Therefore, for example, if a user mixes a standard colorant with a mixing ratio to create a target color with parameters or reflectance similar to the predetermined target color, it is presumed that a color with a reflectance shifted by the reflectance difference ratio shown in Figure 9 will be mixed. Therefore, in the computer color matching method according to this disclosure, the calculation circuit 11 corrects any color discrepancies that may occur between the target color and the created color by performing a process to adjust the reflectance difference ratio before performing the process to calculate the mixing ratio for acquiring the target color.

[0097] Figure 10 is a graph showing an example of the reflectance of the target color and the reflectance of the adjusted target color calculated by the computer color matching method according to Embodiment 2. In Figure 10, the horizontal axis is wavelength (nm), and the vertical axis is the reflectance (%) at each wavelength. In Figure 10, the solid line B req This indicates the reflectance of the target color. Dashed line B adjThis indicates the reflectance of the adjustment target color. The adjustment target color is calculated based on the reflectance difference ratio calculated from a predetermined target color and a predetermined created color. As described above, in this embodiment, at wavelengths between approximately 400 nm and approximately 600 nm, the reflectance of the predetermined created color is greater than that of the predetermined target color. Also, at wavelengths between approximately 600 nm and approximately 700 nm, the reflectance of the predetermined created color is smaller than that of the predetermined target color. Since the adjustment created color is adjusted to correct this reflectance difference ratio, as shown in Figure 10, the reflectance of the adjustment target color is smaller than that of the target color at wavelengths between approximately 400 nm and approximately 600 nm. Also, the reflectance of the adjustment target color is greater than that of the target color at wavelengths between approximately 600 nm and approximately 700 nm.

[0098] When the mixing ratio is calculated by CCM using the computer color matching method according to Embodiment 2, the user mixes the color based on the mixing ratio, applies it to an object, and creates an adjusted color. As described above, the adjusted color is created considering a predetermined reflectance difference ratio. Therefore, the adjusted color may have a reflectance closer to the target color than the created color which is estimated to have a predetermined reflectance difference ratio with respect to the target color. Because the adjusted color has a reflectance closer to the target color, it may have parameters closer to the target color in various light sources with a predetermined spectral distribution compared to the created color. Thus, with CCM using the computer color matching method according to Embodiment 2, it is possible to create a color that is closer to the target color than the created color created by CCM using conventional methods.

[0099] As described above, the created adjusted color can be measured by the colorimeter 20. When the colorimeter 20 measures the adjusted color, it transmits the measurement result to the storage device 12 of the computer color matching device 10 via the communication circuit 14. The calculation circuit 11 also transmits the adjusted target color to the storage device 12. Therefore, the storage device 12 can further store combinations of the adjusted target color and the adjusted color created based on the adjusted target color. The calculation circuit 11 can determine whether the adjusted color is close to the target color by comparing the target color and the adjusted color. For example, the calculation circuit 11 may determine that a color corresponding to the target color A has been created if the adjusted color is within a predetermined Euclidean distance range from the target color in a color space to which any light source is applied. Alternatively, the calculation circuit 11 may determine that a color corresponding to the target color has been created if, for example, the average difference ratio between the reflectance of the adjusted color and the reflectance of the target color for each wavelength is below a predetermined threshold. If the adjusted color does not meet the above conditions, the calculation circuit 11 may perform CCM again. In this case, the calculation circuit 11 may create a further adjusted target color by adding a reflectance difference ratio between the target color and the adjusted color to the adjusted target color, and calculate the mixing ratio.

[0100] As described above, with conventional CCM methods, the created color, toned based on the mixing ratio calculated by the calculation circuit 11 to create the target color, may have some difference from the target color. However, with the computer color matching method according to Embodiment 2, it is possible to perform CCM by setting an adjusted target color, which is a target color that takes such differences into account. Therefore, when coloring is performed using the mixing ratio of the reference colorants calculated by CCM, the created adjusted color will have a reflectance difference ratio with respect to the adjusted target color that is equivalent to the reflectance difference ratio between the predetermined target color and the predetermined created color, and can be colored to be close to the target color. Thus, with CCM using the computer color matching method according to Embodiment 2, it is possible to colorize the color so that the reflectance difference ratio with respect to the target color is smaller compared to conventional CCM. In other words, with CCM using the computer color matching method according to Embodiment 2, it is possible to colorize the color so that the reflectance difference ratio between the reflectance of the target color and the reflectance of the adjusted created color is smaller than the reflectance difference ratio between the reflectance of the target color and the reflectance of the created color.

[0101] (Examples) Next, an example of the operation of the computer color matching device 10 of the computer color matching system 1 according to this embodiment will be described.

[0102] The mixing ratios calculated by conventional CCM methods, as well as the mixing ratios calculated by CCM using the computer color matching methods of Embodiments 1 and 2, will be explained with reference to Table 1.

[0103] [Table 1]

[0104] Table 1 shows the mixing ratios of standard colorants that can create a target color set as a predetermined sample, the mixing ratios calculated by multiple CCM methods to create the target color, and the difference between these mixing ratios. The standard colorants used to create the predetermined sample are white, black, ochre, and brown, as shown in Table 1. Column A of Table 1 shows the mixing ratio A of each standard colorant that can create the target color. Column B of Table 1 shows the mixing ratio B of the standard colorants calculated by conventional CCM methods to create the target color, and the difference between mixing ratio A and mixing ratio B. Column C of Table 1 shows the mixing ratio C of the standard colorants calculated by CCM according to Embodiment 1 to create the target color, and the difference between mixing ratio A and mixing ratio C. Column D of Table 1 shows the mixing ratio D of the standard colorants calculated by CCM according to Embodiment 2 to create the target color, and the difference between mixing ratio A and mixing ratio D. When mixing ratios B, C, and D are close to mixing ratio A, the color created based on those ratios will exhibit a color close to the target color.

[0105] The "Mixing Difference" row in column B of Table 1 represents the square root of the sum of squares calculated from the difference between mixing ratio A and mixing ratio B of each standard colorant. Similarly, the "Mixing Difference" row in column C of Table 1 represents the square root of the sum of squares calculated from the difference between mixing ratio A and mixing ratio C of each standard colorant. The "Mixing Difference" row in column D of Table 1 represents the square root of the sum of squares calculated from the difference between mixing ratio A and mixing ratio D of each standard colorant. Basically, the smaller the value of the square root of the sum of squares, the closer the resulting color created based on that mixing ratio will be to the target color. As shown in Table 1, the value in column C of the "Mixing Difference" row is smaller than the value in column B. Also, the value in column D of the "Mixing Difference" row is smaller than the value in column B and is almost the same as the value in C. Therefore, the resulting color created based on the mixing ratio of the standard colorants calculated by CCM using the computer color matching method according to Embodiments 1 and 2 may be closer to the target color than the resulting color created based on mixing ratio B.

[0106] The parameters based on the blending ratio calculated by conventional CCM methods, as well as the parameters based on the blending ratio calculated by CCM using the computer color matching methods of Embodiment 1 and Embodiment 2, will be explained with reference to Table 2.

[0107] [Table 2]

[0108] Table 2 shows the color difference for each light source with respect to the mixing ratio calculated by CCM using the conventional method, the computer color matching method according to Embodiment 1, and the computer color matching method according to Embodiment 2. Specifically, column B shows the color difference between the reflectance calculated based on mixing ratio A and the parameters (L, a, b in the CIE color space) obtained for each light source, and the reflectance calculated based on mixing ratio B and the parameters obtained for each light source. Specifically, the color difference represents the Euclidean distance in the CIE color space between two parameters (between a predetermined L, a, b and another L, a, b). Column C shows the color difference between the reflectance calculated based on mixing ratio A and the parameters obtained for each light source, and the reflectance calculated based on mixing ratio C and the parameters obtained for each light source. Column D shows the color difference between the reflectance calculated based on mixing ratio A and the parameters obtained for each light source, and the reflectance calculated based on mixing ratio D and the parameters obtained for each light source.

[0109] In Table 2, "D65" indicates the D65 light source, which simulates sunlight. Therefore, for example, the row "D65" and column "B" show the color difference between the parameters obtained based on mixing ratio A and the parameters obtained based on mixing ratio B for the D65 light source.

[0110] "A" represents light source A, which simulates an incandescent light bulb. Therefore, for example, row "A" and column "C" show the color difference between the parameters obtained based on mixing ratio A and the parameters obtained based on mixing ratio C, with respect to light source A.

[0111] "F6" indicates the F6 light source, which simulates a white fluorescent lamp. Therefore, for example, row "F6" and column "D" show the color difference between the parameters obtained based on mixing ratio A and the parameters obtained based on mixing ratio D, with respect to the F6 light source.

[0112] "F8" indicates the F8 light source, which simulates a high color rendering fluorescent lamp. Therefore, for example, row "F8" and column "D" show the color difference between the parameters obtained based on mixing ratio A and the parameters obtained based on mixing ratio D, with respect to the F8 light source.

[0113] In Table 2, "Average" represents the average value of the parameters obtained based on each light source for each blending ratio B, C, and D. Therefore, the value in the "Average" row, column "B," represents the average color difference between the parameters obtained based on blending ratio A and the parameters obtained based on blending ratio B for the four light sources. The same applies to blending ratios C and D.

[0114] In this embodiment, the light sources used to compare color differences are the four light sources described above, but are not limited to these; any other light source may be used to evaluate the color difference. As described above, mixing ratio A is a mixing ratio that can create the target color. Therefore, it is presumed that, for a given light source, the mixing ratio that calculates parameters close to those calculated based on mixing ratio A will result in a color closer to the target color when actually mixed with that light source.

[0115] Regarding the color difference between the target color and the created color (hereinafter referred to as "first color"), if the color difference is small under one light source but large under another, it can be said that conditional color matching (so-called metamerism) is occurring between the target color and the second color. In other words, the first color is essentially a different color from the target color. Conversely, regarding the color difference between the target color and the created color (hereinafter referred to as "second color"), if the color difference is small under multiple light sources, it can be said that no metamerism is occurring, or that the degree of metamerism is small, between the target color and the second color. In other words, the second color is essentially closer to the target color than the first color.

[0116] As shown in Table 2, in this embodiment, the color differences based on mixing ratios B, C, and D are each 0.00 with respect to the D65 light source. Therefore, the conventional method, the computer color matching method according to Embodiment 1, and the computer color matching method according to Embodiment 2 are all able to accurately reproduce the target color with respect to the D65 light source.

[0117] As shown in Table 2, in this embodiment, the color difference between mixing ratio A and mixing ratio B is 0.02 for light source A, 0.02 for light source F6, and 0.02 for light source F8. The color difference between mixing ratio A and mixing ratio C is 0.13 for light source A, 0.11 for light source F6, and 0.05 for light source F8. Therefore, with respect to light sources A, F6, and F8, the CCM by the computer color matching method according to Embodiment 1 has lower accuracy in handling metamerism compared to CCM by conventional methods. Consequently, in this embodiment, the color created based on the mixing ratio calculated by the CCM by the computer color matching method according to Embodiment 1 may exhibit metamerism with respect to the target color.

[0118] The color difference between mixing ratio A and mixing ratio D is 0.01 for light source A, 0.00 for light source F6, and 0.00 for light source F8. Therefore, for light sources A, F6, and F8, the CCM by the computer color matching method according to Embodiment 2 has improved accuracy in handling metamerism compared to the CCM by the method according to Embodiment 1. Thus, the CCM by the computer color matching method according to Embodiment 2 can calculate more appropriate mixing ratios than conventional methods not only for the D65 light source but also for other light sources. Therefore, the CCM by the computer color matching method according to Embodiment 2 can calculate mixing ratios that can create colors in which no metamerism occurs or the degree of metamerism occurs is small compared to the CCM by the method according to Embodiment 1.

[0119] The computer color matching method according to Embodiment 2 requires a large amount of processing by the calculation circuit 11 because it calculates the difference ratio of reflectance for each wavelength. However, with this method of CCM, the calculation circuit 11 can evaluate metamerism in a single calculation. Furthermore, in the computer color matching method according to Embodiment 1, the calculation circuit 11 adjusts the color shift using color difference, whereas in the computer color matching method according to Embodiment 2, the calculation circuit 11 adjusts the color shift using reflectance. Therefore, in the computer color matching method according to Embodiment 2, the calculation circuit 11 can evaluate each color, such as the target color and the adjustment target color, using reflectance.

[0120] As described above, according to the computer color matching method of Embodiment 2, the calculation circuit 11 of the computer color matching device 10 determines the mixing ratio of colors to be created to obtain the target color using the reflectance of each color. Therefore, according to the computer color matching method of Embodiment 2, the calculation circuit 11 can calculate a mixing ratio that can create a color close to the target color, which is the desired color, under any light source. As described above, this method is performed by performing a process to adjust the target color to an adjusted target color before performing CCM using the conventional method. Therefore, the user does not have to create a new program to calculate the mixing ratio to obtain the target color, but can use a program for performing CCM using the conventional method to have the computer's calculation circuit execute the computer color matching method of this disclosure.

[0121] (Other embodiments) In the computer color matching system 1 according to Embodiment 2 described above, the calculation circuit 11 calculates the difference ratio at each wavelength and uses the difference ratio as an adjustment amount, but is not limited to this. The calculation circuit 11 may adjust the reflectance of a predetermined target color using the difference between the reflectance of a predetermined target color and the reflectance of a predetermined creation color. For example, the calculation circuit 11 may calculate the adjustment amount from the difference in the reflectance of a predetermined target color to the reflectance of a predetermined creation color at each wavelength. The calculation circuit 11 can calculate the reflectance of the adjustment target color at each wavelength by subtracting the adjustment amount from the reflectance of the target color. The adjustment amount calculated in this way has an absolute difference from the reflectance of the predetermined creation color.

[0122] In the above-described embodiment 2, the learning data included, but is not limited to, a combination of a predetermined target color, the reflectance of the predetermined target color, or the orientation ratio of the predetermined target color, and a combination of a predetermined mixing ratio of the predetermined creation color, the predetermined creation color, the reflectance of the predetermined creation color, or the reflectance difference ratio. The learning data stored in the storage device 12 may also be a combination of a predetermined target color, the reflectance of the predetermined target color, or the orientation ratio of the predetermined target color, and a combination of a predetermined mixing ratio of the predetermined creation color, the predetermined creation color, the reflectance of the predetermined creation color, or the reflectance difference.

[0123] In the above-described embodiment 2, when the training data includes multiple combinations of data, the adjustment amount includes the average value of the reflectance difference ratio in two or more combinations of data calculated for each wavelength, but is not limited to this. For example, the adjustment amount may be the average value of the reflectance difference in two or more combinations of data calculated for each wavelength.

[0124] As described above, in the computer color matching system 1 according to Embodiment 2, the calculation circuit 11 performs the computer color matching method using the reflectance difference ratio, but is not limited to this. The calculation circuit 11 may also perform the computer color matching method using the reflectance difference instead of the reflectance difference ratio.

[0125] (Summary of the embodiments) The computer color matching apparatus, computer color matching system, computer color matching method, and program according to the embodiments described above may be configured as follows.

[0126] (Aspect 1) The computer color matching method is a computer color matching method that calculates the mixing ratio of a plurality of reference colorants for toning a target color, which is performed by an arithmetic circuit (11) that can access a memory device (12), wherein the memory device (12) has pre-stored learning data, and the learning data includes at least combination data associated with a predetermined target color and a predetermined created color obtained based on the mixing ratio calculated to tonify the predetermined target color, and the computer color matching method includes the steps of acquiring a target color, calculating an adjustment amount to adjust the target color based on the learning data, determining an adjusted target color based on the target color and the adjustment amount, and calculating the mixing ratio for toning the adjusted target color, wherein the target color, predetermined target color, predetermined created color, and adjusted target color are each represented by the reflectance for each wavelength, and the adjustment amount is determined based on the difference between the reflectance of the predetermined target color and the reflectance of the predetermined created color at each wavelength. According to this method, the arithmetic circuit (11) can determine an adjusted target color that shows a target color that takes into account the difference in reflectance that would occur between the target color and the created color tonified to produce the target color. Therefore, the calculation circuit (11) can calculate a mixing ratio that can produce a color close to the target color, which is the desired color, under any light source.

[0127] (Aspect 2) In the computer color matching method of Aspect 1, the adjustment amount is calculated from the difference in reflectance of a predetermined target color to the reflectance of a predetermined created color at each wavelength, and the reflectance of the adjusted target color at each wavelength may be calculated by subtracting the adjustment amount from the reflectance of the target color. According to this method, the calculation circuit (11) can calculate the reflectance of the adjusted target color by adjusting the absolute value of the difference in reflectance that may occur between the target color and the created color. Therefore, the calculation circuit (11) can calculate a mixing ratio that can create a color close to the target color, which is the desired color, at any light source.

[0128] (Aspect 3) In the computer color matching method of Aspect 1, the adjustment amount is calculated by dividing the difference in reflectance of a predetermined target color to the reflectance of a predetermined created color at each wavelength by the reflectance of the predetermined created color, and the reflectance of the adjustment target color at each wavelength may be calculated by subtracting the product of the reflectance of the target color and the adjustment amount from the reflectance of the target color. According to this method, the calculation circuit (11) can calculate the reflectance of the adjustment target color by adjusting the difference in reflectance that may occur between the target color and the created color using relative values ​​for each reflectance. Therefore, the calculation circuit (11) can calculate a mixing ratio that can create a color close to the target color, which is the desired color, at any light source.

[0129] (Aspect 4) In any one of the computer color matching methods from aspects 1 to 3, the target color, predetermined target color, predetermined creation color, and adjustment target color are further represented by coordinates representing a color space, and the calculation circuit (11) may select the predetermined target color that has the smallest Euclidean distance to the target color in the coordinates in the step of calculating the adjustment amount. According to this method, the calculation circuit (11) can determine the adjustment amount by using the color that is considered to be closest to the target color as the predetermined target color. Therefore, the calculation circuit (11) can calculate a mixing ratio that can create a color close to the target color, which is the desired color, under any light source.

[0130] (Aspect 5) In any one of the computer color matching methods of aspects 1 to 3, the target color, predetermined target color, predetermined creation color, and adjustment target color are further represented by coordinates representing a color space, the learning data includes a plurality of combination data, and the method further includes a step of extracting two or more combination data for the target color from the learning data, and the step of calculating the adjustment amount may calculate the adjustment amount based on the extracted two or more combination data. According to this method, the calculation circuit (11) can determine the adjustment amount using a plurality of predetermined target colors. Therefore, the calculation circuit (11) can calculate a mixing ratio that can create a color close to the target color, which is the desired color, under any light source.

[0131] (Aspect 6) In the computer color matching method of aspect 5, the extraction step may be a step of extracting two or more combination data by searching for neighboring colors of the target color from the learning data. According to this method, the calculation circuit (11) can determine the adjustment amount using a plurality of predetermined target colors selected from colors close to the target color. Therefore, the calculation circuit (11) can calculate a mixing ratio that can create a color close to the target color, which is the desired color, under any light source.

[0132] (Aspect 7) In the computer color matching method of Aspect 6, the extraction step may exclude combination data from the retrieved combination data in which the color difference trend between a predetermined target color and a predetermined creation color is different. According to this method, the calculation circuit (11) can determine the adjustment amount by excluding predetermined target colors from among the retrieved plurality of predetermined target colors in which the color difference trend between the predetermined target color and the predetermined creation color is different from that of other predetermined target colors. Therefore, the calculation circuit (11) can calculate a mixing ratio that can create a color close to the target color, which is the desired color, under any light source.

[0133] (Aspect 8) In any one of the computer color matching methods from aspects 5 to 7, the step of calculating the adjustment amount may be to calculate the adjustment amount by averaging values ​​based on two or more differences at each wavelength obtained from two or more combination data extracted in the extraction step. According to this method, the calculation circuit (11) can determine the adjustment amount using a plurality of reflectance difference ratios based on a plurality of predetermined target colors. Therefore, the calculation circuit (11) can calculate a mixing ratio that can create a color close to the target color, which is the desired color, in any light source.

[0134] (Aspect 9) Any one of the computer color matching methods from aspects 1 to 8 may further include the step of adding combination data to the training data, which includes at least one of the following: a target color to adjust, the reflectance of the target color to adjust, or a mixing ratio of the target color to adjust, and one of the following: a created color to adjust obtained by the mixing ratio calculated to adjust the target color, the reflectance of the created color to adjust, or a value based on the difference in each wavelength between the reflectance of the target color to the reflectance of the created color to adjust. According to this method, the calculation circuit (11) can calculate a mixing ratio that can produce a color close to the target color, which is the desired color, under any light source, based on any combination data.

[0135] (Aspect 10) In any one of the computer color matching methods from aspects 1 to 9, the wavelength range in which the reflectance of the target color is obtained may include at least the visible light region. According to this method, the calculation circuit (11) can calculate a mixing ratio that can produce a color close to the target color, which is the desired color, in at least the visible light region, using any light source.

[0136] (Aspect 11) The program can cause the calculation circuit (11) to execute one of the computer color matching methods from Aspect 1 to Aspect 10.

[0137] (Aspect 12) The computer color matching device (10) includes an arithmetic circuit (11) that calculates the mixing ratio of reference colorants to create a target color, and a storage device (12) that stores learning data including at least combination data associated with a predetermined target color and a predetermined created color obtained based on the mixing ratio calculated to create the predetermined target color. The arithmetic circuit (11) acquires a target color, calculates an adjustment amount to adjust the target color based on the learning data, determines an adjusted target color based on the target color and the adjustment amount, calculates a mixing ratio to create the adjusted target color, and the target color, predetermined target color, predetermined created color, and adjusted target color are each represented by the reflectance for each wavelength, and the adjustment amount is determined based on the difference between the reflectance of the predetermined target color and the reflectance of the predetermined created color at each wavelength. With this configuration, the arithmetic circuit (11) can determine an adjusted target color that shows a target color that takes into account the difference in reflectance that would occur between the target color and the created color that has been toned to create the target color. Therefore, the calculation circuit (11) can calculate a mixing ratio that can produce a color close to the target color, which is the desired color, under any light source.

[0138] (Aspect 13) The computer color matching system (1) comprises the computer color matching device (10) of aspect 12 and a colorimeter (20) for measuring color, and the target color is obtained by measuring with the colorimeter (20).

[0139] The computer color matching apparatus and computer color matching system described in this disclosure are realized through the cooperation of hardware resources, such as a processor and memory, and software resources (computer programs). [Industrial applicability]

[0140] This disclosure provides a computer color matching method, computer color matching apparatus, computer color matching system, and program for reducing the difference between a target color (a desired color) and a color created using CCM. Therefore, it can be suitably used in this type of industrial field. [Explanation of Symbols]

[0141] 1. Computer Color Matching System 10. Computer Color Matching Device 11 Arithmetic circuit 12 Storage device 13 Input / Output Devices 14. Communication Circuit 20 Colorimetric device 30 Applications

Claims

1. A computer color matching method that calculates the mixing ratio of multiple reference colorants for matching a target color, performed by an arithmetic circuit that can access a memory device, The aforementioned storage device has pre-stored the learning data. The learning data includes at least combination data associated with a predetermined target color and a predetermined created color obtained based on a mixing ratio calculated to colorize the predetermined target color. The aforementioned computer color matching method is: The steps include obtaining the aforementioned target color, A step of calculating the adjustment amount to adjust the target color based on the aforementioned learning data, A step of determining an adjusted target color based on the aforementioned target color and the aforementioned adjustment amount, The step includes calculating the mixing ratio for adjusting the target color, The target color, the predetermined target color, the predetermined created color, and the adjusted target color are each expressed in terms of reflectance for each wavelength, and the adjustment amount is determined based on the difference between the reflectance of the predetermined target color and the reflectance of the predetermined created color at each wavelength. The aforementioned target color, the predetermined target color, the predetermined creation color, and the adjusted target color are further represented by coordinates representing a color space. The training data includes a plurality of the aforementioned combined data, The computer color matching method further includes the step of extracting two or more combination data for the target color from the learning data, The step of calculating the adjustment amount includes calculating the adjustment amount based on the two or more combination data extracted, The extraction step includes extracting two or more combination data by searching for neighboring colors of the target color from the training data. Computer color matching method.

2. The adjustment amount is calculated from the difference between the reflectance of the predetermined target color and the reflectance of the predetermined created color at each wavelength. The reflectance of the target color at each wavelength is calculated by subtracting the adjustment amount from the reflectance of the target color. The computer color matching method according to claim 1.

3. The adjustment amount is calculated by dividing the difference between the reflectance of the predetermined target color and the reflectance of the predetermined created color at each wavelength by the reflectance of the predetermined created color. The reflectance of the target color at each wavelength is calculated by subtracting the product of the target color's reflectance and the adjustment amount from the target color's reflectance. The computer color matching method according to claim 1.

4. The computer color matching method according to claim 1, wherein the calculation circuit, in the step of calculating the adjustment amount, selects the predetermined target color that has the smallest Euclidean distance to the target color in the coordinates.

5. The computer color matching method according to claim 1, wherein the extraction step involves excluding combination data from the two or more combination data that have different color difference trends with respect to the predetermined target color.

6. The computer color matching method according to claim 1, wherein the step of calculating the adjustment amount is to calculate the adjustment amount by averaging values ​​based on two or more differences at each wavelength obtained from two or more combination data extracted by the extraction step.

7. The aforementioned target color for adjustment, the reflectance of the target color for adjustment, or the mixing ratio of the target color for adjustment, The adjusted color obtained by the mixing ratio calculated to create the target color, the reflectance of the adjusted color, or a value based on the difference in each wavelength between the reflectance of the adjusted color and the reflectance of the target color, The step of further adding combination data having at least to the training data, The computer color matching method according to any one of claims 1 to 6.

8. The computer color matching method according to claim 1, wherein the wavelength range from which the reflectance of the target color is obtained includes at least the visible light region.

9. A program for causing the calculation circuit to execute the computer color matching method described in claim 1.

10. A calculation circuit that calculates the mixing ratio of standard colorants to create the target color, The system includes a storage device that stores learning data, which includes at least combination data associated with a predetermined target color and a predetermined created color obtained based on a mixing ratio calculated to colorize the predetermined target color, The aforementioned arithmetic circuit is The target color is obtained, Based on the aforementioned learning data, the adjustment amount for adjusting the target color is calculated, Based on the aforementioned target color and adjustment amount, the adjusted target color is determined. The mixing ratio for creating the aforementioned target color is calculated, The target color, the predetermined target color, the predetermined created color, and the adjusted target color are each expressed in terms of reflectance for each wavelength, and the adjustment amount is determined based on the difference between the reflectance of the predetermined target color and the reflectance of the predetermined created color at each wavelength. The aforementioned target color, the predetermined target color, the predetermined creation color, and the adjusted target color are further represented by coordinates representing a color space. The training data includes a plurality of the aforementioned combined data, The calculation circuit further extracts two or more combination data for the target color from the learning data, Calculating the adjustment amount includes calculating the adjustment amount based on the two or more combination data extracted, Extracting two or more combination data includes extracting two or more combination data by searching for neighboring colors of the target color from the training data. Computerized color matching device.

11. The computer color matching apparatus according to claim 10, It is equipped with a colorimeter that measures color, The aforementioned target color is obtained by measuring it with the aforementioned colorimeter. Computer color matching system.

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