Ink amount calculation system for calculating ink amount set, method, and computer program

Abstract

To provide a technique capable of determining an ink amount set without making a processing time of optimization processing excessive even in a case where a designated color is present out of a gamut.SOLUTION: An ink amount calculation system comprises: a constraint condition designation section which receives a designation of a constraint condition relating to an ink amount set; a gamut generation section for generating a gamut representing a range of a color which can be reproduced under the constraint condition; a gamut determination processing section which determines whether or not a target color is within the gamut; and an ink amount calculation section which calculates an ink amount set for reproducing the target color by executing optimization processing under the constraint condition. The ink amount calculation section changes a condition of the optimization processing and executes the optimization processing in a case where the target color is out of the gamut.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an ink amount calculation system, method, and computer program for determining an ink amount set. [Background technology]

[0002] A printing device prints various printed materials using a plurality of inks of different colors. Since there is a considerable degree of freedom in the ink amount set for reproducing the same color, various methods have been proposed for determining the ink amount set for reproducing a target color. Patent Document 1 discloses a technique for calculating the ink amount for reproducing a designated color value designated by a user using an ink amount data conversion means for converting the ink amount into a color value. In this conventional technique, a candidate ink amount for reproducing the designated color value is given to the ink amount data conversion means to calculate the color value, the color difference between the obtained color value and the designated color value is evaluated, and an optimization process is performed to correct the ink amount until the evaluation criterion is satisfied, thereby calculating the ink amount for reproducing the designated color value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-334945 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, there are cases where constraints on the ink amount are imposed, limiting the gamut, which is the range of reproducible colors. In the conventional technology, when a specified color is outside the gamut, the search loop of the optimization process does not converge, resulting in excessive processing time. [Means for solving the problem]

[0005] According to a first aspect of the present disclosure, there is provided an ink amount calculation system for determining an ink amount set of a plurality of ink colors for reproducing a target color. The ink amount calculation system includes a constraint condition specification unit that accepts specification of constraint conditions related to the ink amount set, a gamut generation unit that generates a gamut that represents a range of colors reproducible under the constraint conditions, a gamut determination processing unit that determines whether the target color is within the gamut, and an ink amount calculation unit that performs an optimization process under the constraint conditions to determine the ink amount set that reproduces the target color. If the target color is outside the gamut, the ink amount calculation unit changes the conditions of the optimization process and performs the optimization process.

[0006] According to a second aspect of the present disclosure, there is provided a method for determining an ink amount set of a plurality of ink colors for reproducing a target color. The method includes the steps of (a) accepting a designation of a constraint condition related to the ink amount set, (b) generating a gamut representing a range of colors reproducible under the constraint condition, (c) determining whether the target color is within the gamut, and (d) executing an optimization process under the constraint condition to determine the ink amount set for reproducing the target color. The step (d) includes a step of changing the conditions of the optimization process and executing the optimization process when the target color is outside the gamut.

[0007] According to a third aspect of the present disclosure, there is provided a computer program for determining an ink amount set of a plurality of ink colors for reproducing a target color. The computer program causes a computer to execute the following processes: (a) accepting a designation of a constraint condition related to the ink amount set; (b) generating a gamut that represents a range of colors reproducible under the constraint condition; (c) determining whether the target color is within the gamut; and (d) performing an optimization process under the constraint condition to obtain the ink amount set that reproduces the target color. The process (d) includes a process of changing the conditions of the optimization process and performing the optimization process when the target color is outside the gamut. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram showing the configuration of a printing system. [Diagram 2] FIG. 1 is an explanatory diagram showing an example of the configuration of an image processing apparatus. [Diagram 3] 10 is a flowchart showing the procedure for determining an ink amount set that reproduces a target color. [Figure 4] FIG. 13 is an explanatory diagram showing an example of a window for specifying constraint conditions. [Diagram 5] FIG. 4 is an explanatory diagram showing an example of a gamut defined by constraints. [Figure 6] 11 is a flowchart showing the processing procedure of step S30. [Figure 7] 13 is a flowchart showing the processing procedure of step S39. [Figure 8] FIG. 11 is an explanatory diagram showing a second method for changing the conditions of the optimization process. [Figure 9] 11 is a flowchart showing the processing procedure of step S130. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 1 is an explanatory diagram showing the configuration of a printing system 500 according to an embodiment. The printing system 500 includes an image processing device 100, an input device 200, a display device 300, and a printing device 400. However, the printing device 400 is optional. The image processing device 100 functions as the "ink amount calculation system" of the present disclosure.

[0010] The image processing device 100 includes a processor 101, a memory 102, an input / output interface 103, and an internal bus 104. The processor 101, the memory 102, and the input / output interface 103 are connected via the internal bus 104 to enable bidirectional communication. The memory 102 includes a volatile memory including a main memory and a video memory, and a non-volatile memory such as a hard disk and an SSD (Solid State Drive). The input device 200, the display device 300, and the printing device 400 are connected to the input / output interface 103 of the image processing device 100 by wired communication or wireless communication. The input device 200 is, for example, a keyboard or a mouse, and the display device 300 is, for example, a liquid crystal display. The input device 200 and the display device 300 may be integrated as a touch panel. The printing device 400 is, for example, an inkjet printer, and prints an image on a printing medium PM using multiple types of ink.

[0011] As will be described below, the image processing apparatus 100 executes a process for determining an ink amount set that reproduces a specific target color, such as a logo or corporate color, in order to print the target color with the printing apparatus 400.

[0012] 2 is an explanatory diagram showing an example of the configuration of the image processing device 100. The image processing device 100 includes a constraint condition specification unit 110, a gamut generation unit 120, a color value calculation unit 125, an ink amount calculation unit 130, a gamut determination processing unit 140, a notification unit 150, and a color replacement table creation unit 160. The functions of each of these units are realized in software by the processor 101 executing a computer program PG pre-stored in the memory 102. However, some of the functions of each unit may be realized by hardware circuits.

[0013] The constraint condition specification unit 110 accepts the specification of constraint conditions CC related to the optimization process for determining the ink amount set that reproduces the target color TC. The gamut generation unit 120 generates a gamut GM that represents the range of colors that can be reproduced under the constraint conditions CC. Examples of the constraint conditions CC and the gamut GM will be described later.

[0014] The color value calculation unit 125 uses the color prediction model CM to obtain color values ​​from the ink amount set. The color prediction model CM uses a color prediction model CM that predicts the spectral reflectance of a printed matter reproduced with the ink amount set from the value of the ink amount set. The color prediction model CM can be configured as, for example, a color prediction model based on a known spectral Neugebauer model, or a regression model of a multidimensional output configured by a neural network. As a color prediction model based on a spectral Neugebauer model, the printing model disclosed in Japanese Patent Application Laid-Open No. 2006-334945 disclosed by the present applicant can be used. The color value calculation unit 125 further calculates color values ​​from the spectral reflectance. The color values ​​are, for example, colorimetric values ​​Lab of the CIE-L*a*b* color system, or tristimulus values ​​XYZ of the CIE-XYZ color system. The color values ​​obtained by the color value calculation unit 125 are used by the gamut generation unit 120 and the ink amount calculation unit 130. The gamut generation unit 120 and the ink amount calculation unit 130 call the color value calculation unit 125 as necessary to execute a process of converting the ink amount set into a color value, and execute their respective processes using the obtained color value. Note that the gamut generation unit 120 and the ink amount calculation unit 130 may each be configured to have the functions of the color value calculation unit 125.

[0015] The ink amount calculation unit 130 executes optimization processing under the constraint conditions CC to determine the ink amount set IAS for reproducing the target color TC. The gamut determination processing unit 140 determines whether the target color TC is within the gamut GM defined by the constraint conditions CC. The notification unit 150 displays various notifications on the display device 300 to present to the user.

[0016] The color replacement table creation unit 160 creates a color replacement table CRT for the printing device 400 using the ink amount set IAS determined by the ink amount calculation unit 130. The color replacement table CRT is a lookup table used for color conversion from an input color space or a device-independent color space to an output color space for the printing device 400. The input color space is, for example, the RGB color space or the CMYK color space. The device-independent color space is, for example, the CIE-L * a * b * color space or CIE-XYZ color space. As the output color space for the printing device 400, various ink color spaces such as the CMYK color space or the CMYKRB color space can be used. The "CMYKRB color space" is a color space consisting of six ink color components: C (cyan), M (magenta), Y (yellow), K (black), R (red), and B (blue). When printing a target color TC using the printing device 400, a color conversion is performed from the input color space or the device-independent color space to the output color space for the printing device 400 using a color conversion table CRT. The color conversion table creation unit 160 can be omitted.

[0017] The target color TC is specified by the user using, for example, the colorimetric value Lab of the CIE-L*a*b* color system or the tristimulus value XYZ of the CIE-XYZ color system. Values ​​that represent colors in device-independent color spaces, such as the colorimetric value Lab or the tristimulus value XYZ, are also called "color values." The target color TC may be specified using data that represents spectral reflectance instead of color values. This spectral reflectance can be obtained by performing spectral measurement of a color patch of the target color TC. The target color TC may also be specified using a color name associated with the spectral reflectance.

[0018] 3 is a flowchart showing the procedure for the process of determining the ink amount set that reproduces the target color.In step S10, the constraint condition specification unit 110 accepts the specification of the constraint condition CC.

[0019] 4 is an explanatory diagram showing an example of a window W1 for specifying the constraints CC. In this example, the constraints CC include the following items: (1) Whether or not each ink that can be used by the printing device 400 can be used. (2) Duty limits of ink that can be used. (3) Duty limit for secondary colors. (4) Total ink volume TIA duty limit.

[0020] The duty is a ratio of the amount of ink, and a duty of 100% means an amount equivalent to a solid ink application. The duty of a secondary color is the sum of the duties of the two types of ink that reproduce the secondary color. The lower limit of the duty is set in consideration of graininess. For example, when a light gray color can be reproduced using either light gray ink or black ink, reproducing it using black ink reduces graininess, so it is preferable to set the lower limit of the duty for light gray in order to use light gray preferentially. However, the lower limit of the duty may be omitted. Also, the duty limit of the secondary color may be omitted. The user can arbitrarily specify these constraint conditions CC according to the target color TC. In the example of FIG. 4, it is specified that three types of ink, cyan, magenta, and yellow, can be used. The ink amount calculation unit 130 searches for an ink amount set that is a combination of ink amounts that satisfies this constraint condition CC.

[0021] In step S20, the gamut generator 120 generates a gamut GM according to the constraints CC.

[0022] 5 is an explanatory diagram showing an example of a gamut GM defined under constraint condition CC. The gamut generation unit 120 selects a number of representative ink amount sets that satisfy constraint condition CC, calls color value calculation unit 125 to calculate the color values ​​Lab of each ink amount set, and generates boundary information that indicates the outline of the gamut GM using these color values ​​Lab. In the example of FIG. 5, the outline of the gamut GM in the CIE-L*a*b* color space is displayed, and some of the color values ​​Lab of a number of representative ink amount sets are indicated by white circles. Gamut information that indicates the gamut GM under the representative constraint condition CC may be generated in advance and stored in memory 102.

[0023] In step S30 of FIG. 3, the ink amount calculation unit 130 determines the ink amount set IAS for reproducing the target color TC through optimization processing.

[0024] 6 is a flowchart showing the processing procedure of step S30. In step S31, the ink amount calculation unit 130 determines whether or not the target color TC is within the gamut GM. If the target color TC is within the gamut GM, the process proceeds to step S32, where the ink amount calculation unit 130 searches for the ink amount set IAS by executing an optimization process under the constraint condition CC. However, when step S32 is executed for the first time, an initial value of the ink amount set IAS is selected.

[0025] In step S33, the ink amount calculation unit 130 calls the color value calculation unit 125 to calculate the color value of the ink amount set IAS, and calculates the objective function using this color value. For example, the colorimetric value Lab is calculated as the color value. It is preferable to use an objective function that includes the color difference between the color reproduced by the ink amount set IAS and the target color TC. The process of calculating the color difference can be performed as follows. The colorimetric value Lab of the color reproduced by the ink amount set IAS can be obtained by predicting the spectral reflectance from the ink amount set IAS using the color prediction model CM, calculating the tristimulus values ​​XYZ under the observation conditions using a specific light source such as a D50 light source using the spectral reflectance, and converting the tristimulus values ​​XYZ into the colorimetric value Lab. Even when the target color TC is specified using the spectral reflectance, the colorimetric value Lab is calculated in a similar manner. The color difference is calculated by applying these two colorimetric values ​​Lab to a color difference formula such as CIE DE2000.

[0026] In step S34, the ink amount calculation unit 130 determines whether the ink amount set IAS has been sufficiently optimized. Specifically, if the objective function is equal to or less than a preset target value, it is determined that sufficient optimization has been achieved. On the other hand, if the objective function is greater than the target value, it is determined that sufficient optimization has not been achieved. If sufficient optimization has been achieved, in step S36 the ink amount calculation unit 130 selects one optimal ink amount set IAS, and the processing of step S30 ends.

[0027] On the other hand, if optimization has not been achieved sufficiently, the process proceeds to step S35, where the ink amount calculation unit 130 determines whether or not the termination condition for the optimization process has been met. Specifically, if the number of searches or the search time has reached its upper limit, the termination condition is determined to be met, and if the number of searches or the search time has not reached its upper limit, the termination condition is determined to be not met. If the termination condition has not been met, the process returns to step S32, and the processes from step S32 onwards are executed again. If the termination condition has been met, the process of step S30 is aborted. Note that if the termination condition has been met, the initial value of the ink amount set IAS may be reset, and the optimization process from step S32 onwards may be executed again.

[0028] If it is determined in step S31 that the target color TC is outside the gamut GM, the process proceeds to step S37, where the notification unit 150 notifies the user that the color is outside the gamut GM. At this time, the user may be notified of a diagram showing the shape of the gamut GM and the position of the target color TC in the device-independent color space. The user may also be notified of the distance between the boundary of the gamut GM and the target color TC. Furthermore, if the target color TC is an important image element such as a corporate mark, the position of the target color TC may be visibly indicated in an image including that image element.

[0029] In step S38, the user specifies whether or not to continue the processing of step S30. If the processing is not to be continued, the processing of step S30 is terminated. On the other hand, if the processing is to be continued, the conditions for the optimization processing are changed in step S39, and the optimization processing from step S32 onwards is then executed. The purpose of continuing the processing is to find an ink amount set IAS for reproducing a color close to the target color TC when the target color TC itself cannot be reproduced by the printing device 400.

[0030] 7 is a flowchart showing the processing procedure of step S39. In step S100, a method for changing the optimization process conditions is selected. This selection may be made by the user, or may be made automatically by the ink amount calculation unit 130 in accordance with preset rules. As this change method, for example, it is possible to select one of the following three methods:

[0031] <First method M1 for changing the optimization process conditions> In the first method M1, at least one of the following is performed in step S110. (1) Relaxing the target value of the objective function of the optimization process. (2) Reducing the number of searches or the search time that defines the termination condition of the optimization process. The relaxed target value and the shortened number of searches or search time may be specified by the user, or may be set according to preset rules by the ink amount calculation unit 130. In this first method M1, by relaxing the target value and shortening the number of searches or search time, it is possible to prevent the search from taking an excessively long time.

[0032] <Second method M2 for changing optimization process conditions> In the second method M2, in step S120, a color on the boundary of the gamut GM that exists near the target color TC is set as a new target color.

[0033] Fig. 8 is an explanatory diagram showing an example of a method for setting a new target color in the second method M2. In this example, a straight line SL is used to connect the representative point RP in the gamut GM and the target color TC, and the intersection CP between the straight line SL and the boundary of the gamut GM is calculated. The color at this intersection CP is adopted as the new target color TCn. As the representative point RP in the gamut GM, for example, any of the following can be used. (a) Fixed values ​​such as L*a*b*=(50,0,0). (b) Center of gravity of gamut GM. (c) A color that is a combination of one or two values ​​selected from the L*, a*, and b* values ​​of the Lab color values ​​of the target color TC and a fixed value. Specifically, for example, the following colors can be used. Lightness-priority color = (L*, 0, 0). However, if the L* value of the target color TC is outside the gamut GM, the L* value may be the maximum or minimum L* value of the gamut GM. Hue / saturation priority color = (50, a*, b*). However, if the a* or b* value of the target color TC is outside the gamut, the a* or b* value may be set as the maximum or minimum value of the L* value of the gamut GM. The user may specify which of the above points is to be the representative point RP, or the ink amount calculation section 130 may select it according to preset rules.

[0034] <Third method M3 for changing optimization process conditions> In the third method M3, the constraint CC is relaxed in step S130.

[0035] FIG. 9 is a flowchart showing the processing procedure of step S130. In step S131, the constraint condition CC is relaxed. For example, in the constraint condition CC of FIG. 4, the availability of use of each ink color and the duty limit of each ink color can be changed. The content of the relaxation of the constraint condition CC may be specified by the user, or may be set by the ink amount calculation unit 130 according to a rule set in advance. In step S132, the gamut generation unit 120 generates a gamut GM according to the changed constraint condition CC. In step S133, the ink amount calculation unit 130 determines whether the target color TC is within the gamut GM. If the target color TC is outside the gamut GM, the process returns to step S131, the constraint condition CC is relaxed again, and the process from step S132 onward is executed again. On the other hand, if the target color TC is within the gamut GM, the process proceeds to step S134, and the notification unit 150 notifies the user of the relaxed constraint condition CC. In step S135, the user is asked whether to proceed to the optimization process. At this time, the user may reconsider the relaxed constraint conditions CC and select not to execute the optimization process. If the optimization process is not executed, the process is terminated in step S136. If it is determined that the optimization process is executed, the process of step S130 and step S39 in FIG. 6 is terminated, and the optimization process from step S32 onward is executed.

[0036] Note that if a color is set as the target color TC that does not fall within the gamut GM even if the constraint CC is relaxed, relaxing the constraint CC is meaningless. Therefore, it is possible to first determine whether the target color TC is within the maximum gamut using the maximum gamut without the constraint CC, and only if it is within the maximum gamut, to attempt to relax the constraint CC. The "maximum gamut without the constraint CC" is a gamut that indicates the entire range of colors that can be reproduced by the printing device 400.

[0037] In step S40 in Fig. 3, it is determined whether or not the processing of steps S10 to S30 has been completed. If there are multiple target colors TC, if the processing of steps S10 to S30 has been completed for all target colors TC, the processing is determined to be completed. If the processing is not completed, the processing of steps S10 to S30 is executed again. In step S50, the color replacement table creation unit 160 creates a color replacement table CRT for the printing device 400 using the ink amount set IAS and the target color TC. However, step S50 may be omitted.

[0038] As described above, in this embodiment, when the target color TC is outside the gamut GM, the optimization process conditions are changed and the optimization process is executed, so it is possible to prevent an excessive amount of time being spent searching for the ink amount set IAS.

[0039] In the embodiment described above, whether or not the target color TC is within the gamut GM is determined and notified before the ink amount set IAS is calculated, but it is also possible to notify that the target color TC is outside the gamut GM after the ink amount set IAS is calculated. Even in this case, it is preferable to change the conditions of the optimization process and execute the optimization process again, similar to the process in FIG.

[0040] Other forms: The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various forms without departing from the spirit of the present disclosure. For example, the present disclosure can be realized in the following forms. The technical features in the above-mentioned embodiments corresponding to the technical features in each form described below can be appropriately replaced or combined in order to solve some or all of the problems of the present disclosure, or to achieve some or all of the effects of the present disclosure. Furthermore, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

[0041] (1) According to a first aspect of the present disclosure, there is provided an ink amount calculation system for determining an ink amount set of a plurality of ink colors for reproducing a target color. The ink amount calculation system includes a constraint condition specification unit that accepts specification of constraint conditions related to the ink amount set, a gamut generation unit that generates a gamut that represents a range of colors reproducible under the constraint conditions, a gamut determination processing unit that determines whether the target color is within the gamut, and an ink amount calculation unit that performs an optimization process under the constraint conditions to determine the ink amount set that reproduces the target color. If the target color is outside the gamut, the ink amount calculation unit changes the conditions of the optimization process and performs the optimization process. According to this ink amount calculation system, by changing the conditions of the optimization process when the target color is out of gamut, it is possible to prevent an excessive amount of time being spent searching for an ink amount set.

[0042] (2) In the ink amount calculation system, the constraint conditions may include one or more of the availability of each of the ink colors, a duty limit for each ink color, and a duty limit related to a total ink amount. According to this ink amount calculation system, the ink color and its duty used to reproduce the target color can be set as constraints.

[0043] (3) In the ink amount calculation system described above, changing the conditions of the optimization process may include at least one of relaxing a target value of an objective function of the optimization process, and shortening the number of searches or the search time that defines an end condition of the optimization process. According to this ink amount calculation system, by relaxing the target value and shortening the number of searches or the search time, it is possible to prevent an excessive amount of time being spent searching for an ink amount set.

[0044] (4) In the above ink amount calculation system, changing the conditions of the optimization process may include setting a color at an intersection of a line connecting a representative point in the gamut and the target color with a boundary of the gamut as a new target color. According to this ink amount calculation system, a color on the boundary of the gamut is set as the new target color, so it is possible to prevent excessive time being spent searching for an ink amount set.

[0045] (5) In the ink amount calculation system, changing the conditions for the optimization process may include relaxing the constraint conditions. According to this ink amount calculation system, by relaxing the constraints, it is possible to widen the gamut and prevent excessive time being spent searching for an ink amount set.

[0046] (6) According to a second aspect of the present disclosure, there is provided a method for determining an ink amount set of a plurality of ink colors for reproducing a target color. This method includes the steps of (a) accepting a designation of a constraint condition related to the ink amount set, (b) generating a gamut that represents a range of colors reproducible under the constraint condition, (c) determining whether the target color is within the gamut, and (d) executing an optimization process under the constraint condition to determine the ink amount set that reproduces the target color. The step (d) includes the step of changing the conditions of the optimization process and executing the optimization process when the target color is outside the gamut.

[0047] (7) According to a third aspect of the present disclosure, there is provided a computer program for determining an ink amount set of a plurality of ink colors for reproducing a target color. This computer program causes a computer to execute the following processes: (a) accepting designation of constraint conditions related to the ink amount set; (b) generating a gamut that represents a range of colors reproducible under the constraint conditions; (c) determining whether the target color is within the gamut; and (d) performing an optimization process under the constraint conditions to obtain the ink amount set that reproduces the target color. The process (d) includes a process of changing conditions for the optimization process and performing the optimization process when the target color is outside the gamut.

[0048] The present disclosure may be realized in various forms other than an image processing device, a printing system, and a computer program, for example, an image processing method, a non-transitory storage medium on which a computer program is recorded, and the like. [Explanation of symbols]

[0049] 100... image processing device, 101... processor, 102... memory, 103... input / output interface, 104... internal bus, 110... constraint condition designation unit, 120... gamut generation unit, 125... color value calculation unit, 130... ink amount calculation unit, 140... gamut determination processing unit, 150... notification unit, 160... color replacement table creation unit, 200... input device, 300... display device, 400... printing device, 500... printing system

Claims

1. An ink amount calculation system for determining an ink amount set of a plurality of ink colors for reproducing a target color, comprising: a constraint condition specification unit that accepts specification of a constraint condition related to the ink amount set; a gamut generator for generating a gamut representing a range of colors reproducible under the constraints; a gamut determination processing unit that determines whether the target color is within the gamut; an ink amount calculation unit that determines the ink amount set that reproduces the target color by executing an optimization process under the constraint conditions; Equipped with The ink amount calculation system, wherein when the target color is outside the gamut, the ink amount calculation unit changes conditions for the optimization process and executes the optimization process.

2. 2. The ink amount calculation system according to claim 1, The constraint conditions include one or more of: availability of each of the ink colors, a duty limit for each ink color, and a duty limit related to a total ink amount.

3. 2. The ink amount calculation system according to claim 1, The change of the conditions of the optimization process includes: Relaxing the target value of the objective function of the optimization process; and shortening the number of searches or the search time that defines the termination condition of the optimization process; An ink amount calculation system comprising at least one of the above.

4. 2. The ink amount calculation system according to claim 1, An ink amount calculation system, wherein the change in the conditions of the optimization process includes setting a color at an intersection of a straight line connecting a representative point in the gamut and the target color with a boundary of the gamut as a new target color.

5. 2. The ink amount calculation system according to claim 1, An ink amount calculation system, wherein the change of the conditions of the optimization process includes relaxing the constraint conditions.

6. 1. A method for determining an ink amount set of a plurality of ink colors for reproducing a target color, comprising the steps of: (a) receiving a specification of a constraint condition related to the ink amount set; (b) generating a gamut representing the range of colors reproducible under said constraints; (c) determining whether the target color is within the gamut; (d) determining the ink amount set that reproduces the target color by performing an optimization process under the constraint conditions; and Equipped with The method, wherein step (d) includes the step of, if the target color is outside the gamut, changing conditions for the optimization process and executing the optimization process.

7. 1. A computer program for determining an ink amount set of a plurality of ink colors for reproducing a target color, comprising: (a) receiving a specification of a constraint condition related to the ink amount set; (b) generating a gamut representing the range of colors that can be reproduced under the constraints; (c) determining whether the target color is within the gamut; (d) executing an optimization process under the constraint conditions to obtain the ink amount set that reproduces the target color; Run the following on your computer: The process (d) includes a process of changing conditions for the optimization process and executing the optimization process when the target color is outside the gamut.

Images