JP3790484B2 - Color conversion method, color conversion apparatus, color conversion system, and color conversion program - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides (L^*, a^*, b^*), (X, Y, Z), (R, G, B), etc., and three-dimensional input color signals (C, M, Y, K), etc. used in color printers, printing systems, etc. The present invention relates to a color conversion method, a color conversion device, a color conversion system, and a color conversion program for converting into a three-dimensional output color signal. In particular, the present invention relates to a technique for generating an output profile that requires color conversion of a three-dimensional input color signal to a four-dimensional output color signal.
[0002]
[Prior art]
Output color signals used in a color printer, a printing system, and the like are not CMY three colors but CMYK four colors with K added thereto. For this reason, L^*a^*b^*It is necessary to convert a three-dimensional input color signal such as XYZ and RGB into a four-dimensional output color signal of CMYK.
However, even if a combination of three components is given as a three-dimensional input color signal, there are an infinite number of corresponding four-dimensional output color signals, that is, CMYK combinations. For this reason, it is necessary to fix any one of the CMYK components of the four-dimensional output color signal (reducing the relationship among the three variables) to obtain one CMYK combination from a certain combination of input color signals. There is. Such conventional techniques are disclosed in, for example, Japanese Patent Laid-Open Nos. 10-816 and 10-136218.
[0003]
Hereinafter, the prior art 1 described in Japanese Patent Laid-Open No. 10-816 and the prior art 2 described in Japanese Patent Laid-Open No. 10-136218 will be briefly described with reference to FIG. Prior art 1 and prior art 2 are roughly composed of a maximum black amount Kmax calculation technology and an output black amount Kout determination technology.
[0004]
[Maximum ink amount Kmax calculation technology]
First, as shown in step S1001 of FIG. 10A, the conventional technique 1 uses the input color signal L from the known output color signal CMYK.^*a^*b^*The mapping relationship is obtained (S12 in FIG. 4 of JP-A-10-816). Next, as shown in step S1002 of FIG. 10A, the related art 1 fixes the K component in the output signal (S13 in FIG. 4 of the same publication). Next, as shown in step S1003 of FIG. 10A, the conventional technique 1 solves the inverse transformation formula of the mapping relation from the fixed component K of this output signal and a certain input signal, and corresponds to a certain input signal. The remaining component CMY of the output signal is obtained (S14 in FIG. 4 of the same publication). Next, as shown in step S1004 of FIG. 10A, the conventional technique 1 determines whether or not the obtained output signal exists in the entire color reproduction region that can be reproduced by the output color signal (same as the above). S15 in FIG. Next, as shown in S1004 of FIG. 10A, the related art 1 has a fixed component K of the output signal when the obtained output signal does not exist in the entire color reproduction region that can be reproduced by the output color signal. Is reduced by ΔK (S17 in FIG. 4). Next, the related art 1 repeats steps S1003 to S1005 in FIG. 10A until the obtained output signal exists in the entire color reproduction region that can be reproduced by the output color signal, thereby fixing the output signal. Kmax (corresponding to Ksol in the same publication) that maximizes the component K is calculated (S16 in FIG. 4 of the publication). In this case, since the prior art 1 employs a method of sequentially changing the fixed component K of the output signal (an iterative calculation method), each time the fixed component K is changed, the inverse relationship of the mapping relationship is repeated several times. May also be solved. For this reason, the prior art 1 has a problem that Kmax cannot be calculated efficiently.
[0005]
In order to solve this problem, as shown in step S1006 and step S1007 in FIG. 10B, the conventional technique 2 previously divides the entire color reproduction region that can be reproduced by the output color signal into three color reproduction regions, The number of times of solving the mapping inverse transformation is reduced. That is, as shown in S1006 and S1007 of FIG. 10B, the conventional technique 2 fixes the C component, M component, and Y component of the output signal to 0, respectively, and these fixed components of the output signal and a certain input The inverse transformation formula of the mapping relation is solved from the signal three times to obtain three output signals corresponding to a certain input signal (Japanese Patent Laid-Open No. 10-136218, S101 in FIG. 5). Next, as shown in step S1008 of FIG. 10B, the related art 2 calculates the K component of the output signal as Kmax (corresponding to Kp in the publication) based on the obtained three output signals ( S103 in FIG. 5 of the same publication, paragraph 27 of the publication. As described above, the conventional technique 2 can calculate Kmax more efficiently than the conventional technique 1 by solving the inverse transformation formula of the mapping relationship only three times.
[Technique for determining the output black amount Kout] Next, as shown in step S1009 of FIG. 10B, the related art 2 is the final output black amount in consideration of the saturation and the like based on the calculated Kmax. Kout (corresponding to Kp in the publication) is calculated (S104 in FIG. 5 of the publication). Next, as shown in step S1010 of FIG. 10A, the prior art 1 also uses Kout (Ksol · P in Japanese Patent Laid-Open No. 10-816) as the final output black amount based on the calculated Kmax. (S32 in FIG. 10 of the same publication). Next, as shown in S1011 of FIG. 10 (a) and S1012 of FIG. 10 (b), the related art 1 and the related art 2 are related to the mapping relation from the fixed component Kout of the determined output signal and a certain input signal. The inverse conversion equation is solved to calculate the remaining component CoutMoutYout of the output signal corresponding to a certain input signal (S35 in FIG. 10 of the same publication and S106 in FIG. 10 of JP-A-10-136218). As described above, the prior art 1 and the prior art 2 convert a three-dimensional input color signal into a CMYK four-dimensional output color signal.
[0006]
[Problems to be solved by the invention]
However, the prior art 1 and the prior art 2 described above have the following problems.
[0007]
[Maximum ink amount Kmax calculation technology]
Conventional technique 2 can calculate Kmax more efficiently than conventional technique 1, but has a problem that an error occurs in color reproduction. That is, in general, the output signal of an output signal of (C, M, Y, K) = (0, 0, 0, 100) is an ideal true black color (achromatic color, lightness Is not 0). For this reason, when this output device cannot output an ideal true black color, an output signal of (C, M, Y, K) = (0, 0, 0, 100) is output by this output device, The output signal of (C, M, Y, K) = (5, 10, 15, 100) is different from the color output by this output device. Therefore, even when the color of a certain input signal is a color that can be reproduced by this output device with an output signal of (C, M, Y, K) = (5, 10, 15, 100), It is determined that the color of this input signal does not exist in the color reproduction area divided into three in advance. This means that it is determined that the color of a certain input signal does not exist in an area that can be reproduced by the output color signal. Accordingly, the color of a certain input signal is once subjected to color gamut compression so as to exist in the color reproduction region divided into three, and Kmax is calculated based on the input signal subjected to the color gamut compression. Next, the output signal (C, M, Y, K) = (5,10,15,100) that should be determined cannot be obtained, and (C, M, Y, K) = (0, 0,0,100) is determined. As described above, since the color gamut compression of the input signal exists, there is a problem that an error occurs in the color reproduction of the output signal.
[0008]
[Technology for determining the output ink amount Kout]
Since prior art 1 and prior art 2 reduce Kmax to Kout, as shown in FIG. 7A, the color reproduction area that can be reproduced by KoutCMY (area surrounded by the solid line in the figure) can be reproduced by KmaxCMY. It becomes narrower than the region (region surrounded by the wavy line in the figure). Therefore, if a certain input signal (black circle in the figure) is outside the color reproduction area that can be reproduced by KoutCMY even though it exists in the area that can be reproduced by KmaxCMY, the color of a certain input signal is temporarily changed. , Color gamut compression (moved in the direction of the arrow from black circle ● to white circle ○ in the figure) so that it exists in the color reproduction area that can be reproduced by KoutCMY, and input signal (white circle ○ in the figure) that has been color gamut compressed Based on this, it is conceivable to determine Kout. However, in order to determine whether or not a certain input signal exists in a color reproduction region that can be reproduced by KoutCMY, the inverse transformation formula of the mapping relationship is once solved from the determined Kout and a certain input signal, and CMY. It is necessary to determine whether or not it can be determined. Therefore, as shown in Step S1013 of FIG. 10A, the conventional technique 1 has a fixed component of the output signal when the determined output signal Kout does not exist in the entire color reproduction region that can be reproduced by the output color signal. K is increased by ΔK (S36 in FIG. 10 of JP-A-10-816). Next, the related art 1 repeats step S1013 and step S1014 of FIG. 10A until the obtained output signal exists in the entire color reproduction region that can be reproduced by the output color signal, and outputs the output signal Kout. Determine (S35 in FIG. 10 of the same publication). In this case, since the prior art 1 employs a method of sequentially changing the fixed component K of the output signal (an iterative calculation method), each time the fixed component K is changed, the inverse relationship of the mapping relationship is repeated several times. May also be solved. For this reason, the iterative calculation method has a problem that Kout cannot be calculated efficiently.
[0009]
Prior art 2 employs a method of determining Kout, which is the final output black quantity, in consideration of the saturation and lightness of the input signal based on the calculated Kmax (Japanese Patent Laid-Open No. 10-136218). (Paragraph 59 to paragraph 69 in FIGS. 5 and 6, and FIGS. 6 and 7). However, in this method, when the K color is not completely achromatic as the K component color material of the output device (for example, newspaper printing), the color material is output in the process of generating a four-dimensional LUT (lookup table). When the medium is not achromatic white (for example, newspaper printing paper), the saturation and brightness of the output signal are not considered. For this reason, there is a problem that an error occurs between Kout that should be determined and Kout that is determined by the prior art 2, and an error occurs in color reproduction of the output signal.
[0010]
Accordingly, in view of the above-described problem, the present invention provides a color conversion method capable of minimizing an error in color reproduction of an output signal and efficiently calculating the maximum black amount Kmax and determining the output black amount Kout. It is an object to provide a color conversion device, a color conversion system, and a color conversion program.
[0011]
[Means for Solving the Problems]
The invention of claim 1 is C₁in, C₂in and C_ThreeThe three-dimensional first input color signal consisting of the three components of in is represented by C₁out, C₂out, C_Threeout and C_FourIn a color conversion method for converting to a four-dimensional first output color signal composed of four components of out,
C '₁out, C '₂out, C '_Threeout and C '_FourFrom the four-dimensional second output color signal consisting of the four components of out, C ′₁in, C '₂in and C '_Threea first step of obtaining a mapping relationship to a three-dimensional second input color signal comprising three components of in;
(a) C ′ of the first input color signal and the second output color signal_Four(b) C ′ of the first input color signal and the second output color signal₁(c) C ′ of the first input color signal and the second output color signal₂(d) C ′ of the first input color signal and the second output color signal_Threea second step of obtaining the first output color signal based on the minimum value of the out components and the mapping relationship;
A color conversion method characterized by comprising:
[0012]
In the second input signal space,
C 'of the second output signal₁vC is a vector that advances from the minimum value to the maximum value of the out component.₁C ′ of the second output signal₂vC is a vector that advances from the minimum value to the maximum value of the out component.₂C ′ of the second output signal_ThreevC is a vector that advances from the minimum value to the maximum value of the out component._ThreeC ′ of the second output signal_FourvC is a vector that advances from the minimum value to the maximum value of the out component._FourWhen
Vector vC₁, VC₂And vC_ThreeAre vectors independent of each other, and the vector vC_FourIs vC_Four= A₁× vC₁+ A₂× vC₂+ A_Three× vC_ThreeThere is a relationship. However, a1, a2 and a3 are scalar quantities, respectively,₁≧ 0, a₂≧ 0, a_ThreeThe range is ≧ 0.
[0013]
The invention of claim 2 is the color conversion method according to claim 1,
The second step further includes C of the first output signal corresponding to the entire color reproduction region of the second input signal._FourC with minimum out component_Fourout The color conversion method is characterized in that the first output color signal is obtained based on a min component.
[0014]
The invention of claim 3 is the color conversion method according to claim 1,
The second step further includes (e) C ′ of the first input color signal and the second output color signal._Four(f) C ′ of the first input color signal and the second output color signal₁(g) C 'of the first input color signal and the second output color signal₂(h) C ′ of the first input color signal and the second output color signal_ThreeThe color conversion method is characterized in that the first output color signal is obtained based on the maximum value of the out components and the mapping relationship.
[0015]
The invention of claim 4 provides C₁in, C₂in and C_ThreeThe three-dimensional first input color signal consisting of the three components of in is represented by C₁out, C₂out, C_Threeout and C_FourIn a color conversion method for converting to a four-dimensional first output color signal composed of four components of out,
C '₁out, C '₂out, C '_Threeout and C '_FourFrom the four-dimensional second output color signal consisting of the four components of out, C ′₁in, C '₂in and C '_Threea first step of obtaining a mapping relationship to a three-dimensional second input color signal comprising three components of in;
C of the first output signal corresponding to the entire color reproduction region of the second input signal_FourC with maximum out component_Fourout a second step of obtaining a max component;
C of the first output signal corresponding to the color reproduction divided area obtained by dividing a part of the entire color reproduction area of the second input signal._FourC with minimum out component_Fourout a third step to obtain the min component;
The first input signal, the C_Fourout max component, said C_Fourout a fourth step of obtaining the first output color signal based on the min component and the mapping relationship;
A color conversion method characterized by comprising:
[0016]
The invention of claim 5 provides C₁in, C₂in and C_ThreeThe three-dimensional first input color signal consisting of the three components of in is represented by C₁out, C₂out, C_Threeout and C_FourIn a color conversion method for converting to a four-dimensional first output color signal composed of four components of out,
C '₁out, C '₂out, C '_Threeout and C '_FourFrom the four-dimensional second output color signal consisting of the four components of out, C ′₁in, C '₂in and C '_Threea first step of obtaining a mapping relationship to a three-dimensional second input color signal comprising three components of in;
C of the first output signal corresponding to the entire color reproduction region of the second input signal_FourC with maximum out component_Fourout a second step of obtaining a max component;
C_Fourout (e) C ′ of the first input color signal and the second output color signal_Four(f) C ′ of the first input color signal and the second output color signal₁(g) C 'of the first input color signal and the second output color signal₂(h) C ′ of the first input color signal and the second output color signal_Threea third step of obtaining the first output color signal based on the maximum value of the out components and the mapping relationship;
A color conversion method characterized by comprising:
[0017]
The invention of claim 6 provides C₁in, C₂in and C_ThreeThe three-dimensional first input color signal consisting of the three components of in is represented by C₁out, C₂out, C_Threeout and C_FourIn a color conversion method for converting to a four-dimensional first output color signal composed of four components of out,
C 'input to the output device₁out, C '₂out, C '_Threeout and C '_Fourobtaining a four-dimensional second output color signal comprising four components of out;
The output device outputs each of the second output color signals as a color, and the color measurement device measures each of the colors and corresponds to the second output color signal, C ′₁in, C '₂in and C '_Threeobtaining a second input color signal output from the colorimetric device after obtaining a second input color signal comprising three components of in;
A first step of obtaining a mapping relationship from the second output color signal to the second input color signal;
The entire color reproduction region of the second input color signal corresponding to the second output color signal is expressed as follows: (a) Among the second output color signals, C ′_Fourout = 100, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100 and 0 ≦ C ′_Threea first color reproduction region of a second input color signal corresponding to an output color signal of out ≦ 100; and (b) C ′ of the second output color signal.₁out = 0, 0 ≦ C ′₂out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and C ′_Foura second color reproduction region of the second input color signal corresponding to the output color signal of out ≦ 100, and (c) C ′ of the second output color signal.₂out = 0, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and 0 ≦ C ′_Foura third color reproduction region of the second input color signal corresponding to the output color signal composed of out100, and (d) C ′ of the second output color signal._Threeout = 0, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100 and 0 ≦ C ′_FourAfter the output color signal of out ≦ 100 is divided into four color reproduction regions consisting of the fourth color reproduction region of the corresponding second input color signal, the first input color signal is divided into the four color reproduction regions. A second step of determining whether it exists in the color reproduction region;
As a result of the second step, when the first input color signal does not exist in the four color reproduction regions, the first input color signal exists in the four color reproduction regions. And a third step to compress,
Based on the first input color signal after the third step, C of the first output signal corresponding to the four color reproduction regions is obtained._FourC with maximum out component_Fourout C to find max component_Fourout max calculation step;
C_Fourout Based on the max component, C of the first output signal_FourC to determine the out component_Fourout decision step;
The first input color signal after the third step and the C_FourC after out decision step_FourFrom the out component, the inverse transformation formula of the mapping relation is solved, and the first output signal C₁out, C₂out and C_ThreeC to determine the out component₁C₂C_Threeout decision step and
With
C '₁out, said C ′₂out, said C ′_Threeout and C ′_FourEach component of out is 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and 0 ≦ C ′_FourIn the range of out ≦ 100, 0 is a minimum value at which the output device can output each component of the second output color signal as a color, and 100 is the second output color signal. It is the maximum value that can output each component of as a color
This is a color conversion method characterized by the above.
[0018]
The invention according to claim 7 is the color conversion method according to claim 6, wherein the color conversion method further includes the C conversion method._FourBefore the out determination step, based on the first input color signal before the third step, C of the first output signal corresponding to the entire color reproduction region of the second input color signal_FourC with minimum out component_Fourout C for min component_Fourout with a min calculation step
C_FourThe out determination step further includes the C_Fourout Based on the min component, C of the first output signal_FourDetermine the out component
This is a color conversion method characterized by the above.
[0019]
According to an eighth aspect of the present invention, in the color conversion method according to the sixth aspect, the color conversion method further includes: (e) ) C ′ of the second output color signals_Fourout = 0, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100 and 0 ≦ C ′_Threea fifth color reproduction region of the second input color signal corresponding to the output color signal of out ≦ 100, and (f) C ′ of the second output color signal.₁out = 100, 0 ≦ C ′₂out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and C ′_Foura sixth color reproduction region of the second input color signal corresponding to the output color signal of out ≦ 100, and (g) C ′ of the second output color signal.₂out = 100, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and 0 ≦ C ′_Foura seventh color reproduction region of the corresponding second input color signal, and (h) among the second output color signals, C ′_Threeout = 100, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100 and 0 ≦ C ′_FourAfter dividing the output color signal consisting of out ≦ 100 into the second four color reproduction areas consisting of the eighth color reproduction area of the corresponding input color signal, the first color before the third step is divided. A fourth step of determining whether or not an input signal exists in the second four color reproduction regions; and a result of the fourth step is that the first input signal before the third step is The first output signal corresponding to the second four color reproduction regions based on the first input signal before the third step when present in the second four color reproduction regions C_FourC with minimum out component_Fourout C for min component_Fourout min calculation step,
C_FourThe out determination step further includes the C_Fourout Based on the min component, C of the first output signal_FourDetermine the out component
This is a color conversion method characterized by the above.
[0020]
The invention of claim 9 provides C₁in, C₂in and C_ThreeThe three-dimensional first input color signal consisting of the three components of in is represented by C₁out, C₂out, C_Threeout and C_FourIn a color conversion method for converting to a four-dimensional first output color signal composed of four components of out,
C 'input to the output device₁out, C '₂out, C '_Threeout and C '_Fourobtaining a four-dimensional second output color signal comprising four components of out;
The output device outputs each of the second output color signals as a color, and the color measurement device measures each of the colors and corresponds to the second output color signal, C ′₁in, C '₂in and C '_Threeobtaining a second input color signal output from the colorimetric device after obtaining a second input color signal comprising three components of in;
A first step of determining a mapping relationship from the second output color signal to the second input color signal;
A second step of determining whether the first input color signal is present in the entire color reproduction region of the second input color signal corresponding to the second output color signal;
As a result of the second step, when the first input color signal does not exist in the entire color reproduction region of the second input color signal, the first input color signal is changed to the second input color signal. A third step of compressing to be present in the entire color reproduction region of the color signal;
Based on the first input color signal after the third step, C of the first output signal corresponding to the entire color reproduction region of the second input color signal._FourC with maximum out component_Fourout C to find max component_Fourout max calculation step;
After dividing a part of the entire color reproduction area of the second input color signal corresponding to the second output color signal into color reproduction divided areas, the first input signal before the third step is the A fourth step of determining whether or not the color reproduction division region exists;
As a result of the fourth step, when the first input signal before the third step is present in the color reproduction divided region, based on the first input signal before the third step, the C of the first output signal corresponding to the color reproduction region_FourC with minimum out component_Fourout C for min component_Fourout min calculation step and
C_Fourout max component and C_Fourout Based on the min component, C of the first output signal_FourC to determine the out component_Fourout decision step;
The first input color signal after the third step and the C_FourC after out decision step_FourFrom the out component, the inverse transformation formula of the mapping relation is solved, and the first output signal C₁out, C₂out and C_ThreeC to determine the out component₁C₂C_Threeout decision step and
With
C '₁out, said C ′₂out, said C ′_Threeout and C ′_FourEach component of out is 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and 0 ≦ C ′_FourIn the range of out ≦ 100, 0 is a minimum value at which the output device can output each component of the second output color signal as a color, and 100 is the second output color signal. It is the maximum value that can output each component of as a color
This is a color conversion method characterized by the above.
[0021]
The invention of claim 10 provides C₁in, C₂in and C_ThreeThe three-dimensional first input color signal consisting of the three components of in is represented by C₁out, C₂out, C_Threeout and C_FourIn a color conversion method for converting to a four-dimensional first output color signal composed of four components of out,
C 'input to the output device₁out, C '₂out, C '_Threeout and C '_Fourobtaining a four-dimensional second output color signal comprising four components of out;
The output device outputs each of the second output color signals as a color, and the color measurement device measures each of the colors and corresponds to the second output color signal, C ′₁in, C '₂in and C '_Threeobtaining a second input color signal output from the colorimetric device after obtaining a second input color signal comprising three components of in;
A first step of determining a mapping relationship from the second output color signal to the second input color signal;
A second step of determining whether the first input color signal is present in the entire color reproduction region of the second input color signal corresponding to the second output color signal;
As a result of the second step, when the first input color signal does not exist in the entire color reproduction region of the second input color signal, the first input color signal is changed to the second input color signal. A third step of compressing to be present in the entire color reproduction region of the color signal;
Based on the first input color signal after the third step, C of the first output signal corresponding to the entire color reproduction region of the second input color signal._FourC with maximum out component_Fourout C to find max component_Fourout max calculation step;
The entire color reproduction region of the second input color signal corresponding to the second output color signal is represented by (a) C ′ of the second output color signal._Fourout = 0, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100 and 0 ≦ C ′_Threea first color reproduction region of a second input color signal corresponding to an output color signal of out ≦ 100; and (b) C ′ of the second output color signal.₁out = 100, 0 ≦ C ′₂out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and C ′_Foura second color reproduction region of the second input color signal corresponding to the output color signal of out ≦ 100, and (c) C ′ of the second output color signal.₂out = 100, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and 0 ≦ C ′_Foura third color reproduction region of the second input color signal corresponding to the output color signal composed of out100, and (d) C ′ of the second output color signal._Threeout = 100, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100 and 0 ≦ C ′_FourAfter being divided into four color reproduction regions consisting of an output color signal consisting of out ≦ 100 and a fourth color reproduction region of the corresponding input color signal, the first input signal before the third step is A fourth step of determining whether or not the four color reproduction divided areas exist;
As a result of the fourth step, when the first input signal before the third step exists in the four color reproduction divided regions, based on the first input signal before the third step. , C of the first output signal corresponding to the four color reproduction regions_FourC with minimum out component_Fourout C for min component_Fourout min calculation step and
C_Fourout max component and C_Fourout Based on the min component, C of the first output signal_FourC to determine the out component_Fourout decision step;
The first input color signal after the third step and the C_FourC after out decision step_FourFrom the out component, the inverse transformation formula of the mapping relation is solved, and the first output signal C₁out, C₂out and C_ThreeC to determine the out component₁C₂C_Threeout decision step and
With
C '₁out, said C ′₂out, said C ′_Threeout and C ′_FourEach component of out is 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and 0 ≦ C ′_FourIn the range of out ≦ 100, 0 is a minimum value at which the output device can output each component of the second output color signal as a color, and 100 is the second output color signal. It is the maximum value that can output each component of as a color
This is a color conversion method characterized by the above.
[0022]
The invention of claim 11 is the color conversion method according to any one of claims 7 to 10,
C_FourThe out determination step includes the C_Fourout From max component, C_FourUsing the out amount generation curve formula, C of the first output signal_FourThe out component is obtained, and the C_FourThe out component is the C_Fourout When the value is smaller than the min component, the C_Fourout Said C using min component_FourDetermine the out component
This is a color conversion method characterized by the above.
[0023]
The invention of claim 12 is the color conversion method according to any one of claims 7 to 10,
C_Fourout The max calculation step is based on the first input signal after the third step, and the C_Fourout C together with max component_Fourout C of output signal corresponding to max₁out with component, C₂out with component and C_ThreeIngredient out with with, said C_FourThe out determination step includes the C_Fourout max component, said C₁out with component, C₂out with component and C_Threeout From component, C_FourUsing the out amount generation curve formula, C of the first output signal_FourThe out component is obtained, and the C_FourThe out component is C_Fourout When the value is smaller than the min component, the C_Fourout Said C using min component_FourDetermine the out component
This is a color conversion method characterized by the above.
[0024]
The invention of claim 13 is the color conversion method according to any one of claims 1 to 12,
C ′ of the second output color signal_FourThe color corresponding to the out component is black
C ′ of the second output color signal₁The color corresponding to the out component is indigo,
C ′ of the second output color signal₂The color corresponding to the out component is red,
C ′ of the second output color signal_ThreeThe color corresponding to the out component is yellow
This is a color conversion method characterized by the above.
[0025]
The invention of claim 14 provides C₁in, C₂in and C_ThreeThe three-dimensional first input color signal consisting of the three components of in is represented by C₁out, C₂out, C_Threeout and C_FourIn the color conversion device that converts to the four-dimensional first output color signal consisting of the four components of out,
C '₁out, C '₂out, C '_Threeout and C '_FourFrom the four-dimensional second output color signal consisting of the four components of out, C ′₁in, C '₂in and C '_Threea first means for obtaining a mapping relationship to a three-dimensional second input color signal comprising three components of in;
(a) C ′ of the first input color signal and the second output color signal_Four(b) C ′ of the first input color signal and the second output color signal₁(c) C ′ of the first input color signal and the second output color signal₂(d) C ′ of the first input color signal and the second output color signal_Threesecond means for obtaining the first output color signal based on the minimum value of the out components and the mapping relationship;
A color conversion device comprising:
[0026]
The invention of claim 15 is the color conversion apparatus according to claim 14,
The second means further includes (e) C ′ of the first input color signal and the second output color signal._Four(f) C ′ of the first input color signal and the second output color signal₁(g) C 'of the first input color signal and the second output color signal₂(h) C ′ of the first input color signal and the second output color signal_ThreeThe color conversion apparatus is characterized in that the first output color signal is obtained based on the maximum value of the out components and the mapping relationship.
[0027]
The invention of claim 16 provides C₁in, C₂in and C_ThreeThe three-dimensional first input color signal consisting of the three components of in is represented by C₁out, C₂out, C_Threeout and C_FourIn the color conversion device that converts to the four-dimensional first output color signal consisting of the four components of out,
C '₁out, C '₂out, C '_Threeout and C '_FourFrom the four-dimensional second output color signal consisting of the four components of out, C ′₁in, C '₂in and C '_Threea first means for obtaining a mapping relationship to a three-dimensional second input color signal comprising three components of in;
C of the first output signal corresponding to the entire color reproduction region of the second input signal_FourC with maximum out component_Fourout a second means of obtaining a max component;
C_Fourout (e) C ′ of the first input color signal and the second output color signal_Four(f) C ′ of the first input color signal and the second output color signal₁(g) C 'of the first input color signal and the second output color signal₂(h) C ′ of the first input color signal and the second output color signal_Threea third means for obtaining the first output color signal based on the maximum value of the out components and the mapping relationship;
A color conversion device comprising:
[0028]
The invention of claim 17 provides C₁in, C₂in and C_ThreeThe three-dimensional first input color signal consisting of the three components of in is represented by C₁out, C₂out, C_Threeout and C_FourIn the color conversion device that converts to the four-dimensional first output color signal consisting of the four components of out,
C 'input to the output device₁out, C '₂out, C '_Threeout and C '_FourC ′ output from the measurement color device from the four-dimensional second output color signal comprising the four components of out.₁in, C '₂in and C '_Threea first means for obtaining a mapping relation to a second input color signal comprising three components of in
The entire color reproduction region of the second input color signal corresponding to the second output color signal is expressed as follows: (a) Among the second output color signals, C ′_Fourout = 100, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100 and 0 ≦ C ′_Threea first color reproduction region of a second input color signal corresponding to an output color signal of out ≦ 100; and (b) C ′ of the second output color signal.₁out = 0, 0 ≦ C ′₂out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and C ′_Foura second color reproduction region of the second input color signal corresponding to the output color signal of out ≦ 100, and (c) C ′ of the second output color signal.₂out = 0, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and 0 ≦ C ′_Foura third color reproduction region of the second input color signal corresponding to the output color signal composed of out100, and (d) C ′ of the second output color signal._Threeout = 0, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100 and 0 ≦ C ′_FourThe output color signal of out ≦ 100 is divided into four color reproduction regions consisting of the fourth color reproduction region of the corresponding second input color signal, and the first input color signal is divided into the four color reproduction regions. A second means for determining whether or not the color reproduction area exists;
When the second means determines that the first input color signal does not exist in the four color reproduction regions, the first input color signal exists in the four color reproduction regions. A third means of compression,
Based on the first input color signal after passing through the third means, C of the first output signal corresponding to the four color reproduction regions_FourC with maximum out component_Fourout C to find max component_Fourout max calculation means,
C_Fourout Based on the max component, C of the first output signal_FourC to determine the out component_Fourout determination means;
The first input color signal after passing through the third means and the C_FourC after out decision step_FourFrom the out component, the inverse transformation formula of the mapping relation is solved, and the first output signal C₁out, C₂out and C_ThreeC to determine the out component₁C₂C_Threewith out decision means
With
C '₁out, said C ′₂out, said C ′_Threeout and C ′_FourEach component of out is 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and 0 ≦ C ′_FourIn the range of out ≦ 100, 0 is a minimum value at which the output device can output each component of the second output color signal as a color, and 100 is the second output color signal. It is the maximum value that can output each component of as a color
This is a color conversion device characterized by that.
[0029]
According to an eighteenth aspect of the present invention, in the color conversion device according to the seventeenth aspect, the color conversion device further includes an entire color reproduction region of the second input color signal corresponding to the second output color signal as (e ) C ′ of the second output color signals_Fourout = 0, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100 and 0 ≦ C ′_Threea fifth color reproduction region of the second input color signal corresponding to the output color signal of out ≦ 100, and (f) C ′ of the second output color signal.₁out = 100, 0 ≦ C ′₂out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and C ′_Foura sixth color reproduction region of the second input color signal corresponding to the output color signal of out ≦ 100, and (g) C ′ of the second output color signal.₂out = 100, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and 0 ≦ C ′_Foura seventh color reproduction region of the corresponding second input color signal, and (h) among the second output color signals, C ′_Threeout = 100, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100 and 0 ≦ C ′_FourThe output color signal composed of out ≦ 100 is divided into the second four color reproduction regions composed of the eighth color reproduction region of the corresponding input color signal, and the output color signal before passing through the third means. A fourth means for determining whether or not a first input signal is present in the second four color reproduction regions;
When it is determined that the first input signal before the fourth passes through the third means exists in the second four color reproduction regions, the first input signal before passing through the third means C of the first output signal corresponding to the second four color reproduction regions based on one input signal_FourC with minimum out component_Fourout C for min component_Fourout min calculating means,
C_FourThe out determination means further includes the C_Fourout Based on the min component, C of the first output signal_FourDetermine the out component
This is a color conversion device characterized by that.
[0030]
The invention of claim 19 provides C₁in, C₂in and C_ThreeThe three-dimensional first input color signal consisting of the three components of in is represented by C₁out, C₂out, C_Threeout and C_FourIn the color conversion device that converts to the four-dimensional first output color signal consisting of the four components of out,
C 'input to the output device₁out, C '₂out, C '_Threeout and C '_Fourmeans for obtaining a four-dimensional second output color signal comprising four components of out;
The output device outputs each of the second output color signals as a color, and the color measurement device measures each of the colors and corresponds to the second output color signal, C ′₁in, C '₂in and C '_Threemeans for obtaining the second input color signal output from the colorimetric device after obtaining the second input color signal comprising the three components of in;
A first means for obtaining a mapping relationship from the second output color signal to the second input color signal;
Second means for determining whether or not the first input color signal is present in the entire color reproduction region of the second input color signal corresponding to the second output color signal;
When the second means determines that the first input color signal does not exist in the entire color reproduction region of the second input color signal, the first input color signal is changed to the second input color signal. A third means for compressing the input color signal so that it exists in the entire color reproduction region of the input color signal;
Based on the first input color signal after passing through the third means, C of the first output signal corresponding to the entire color reproduction region of the second input color signal._FourC with maximum out component_Fourout C to find max component_Fourout max means,
The entire color reproduction region of the second input color signal corresponding to the second output color signal is represented by (a) C ′ of the second output color signal._Fourout = 0, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100 and 0 ≦ C ′_Threea first color reproduction region of a second input color signal corresponding to an output color signal of out ≦ 100; and (b) C ′ of the second output color signal.₁out = 100, 0 ≦ C ′₂out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and C ′_Foura second color reproduction region of the second input color signal corresponding to the output color signal of out ≦ 100, and (c) C ′ of the second output color signal.₂out = 100, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and 0 ≦ C ′_Foura third color reproduction region of the second input color signal corresponding to the output color signal composed of out100, and (d) C ′ of the second output color signal._Threeout = 100, 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100 and 0 ≦ C ′_FourThe output color signal consisting of out ≦ 100 is divided into four color reproduction regions consisting of the fourth color reproduction region of the corresponding input color signal, and the first color before passing through the third means A fourth means for determining whether or not an input signal exists in the four color reproduction divided regions;
When it is determined that the first input signal before the fourth means passes through the third means exists in the four color reproduction divided areas, the first input signal before passing through the third means C of the first output signal corresponding to the four color reproduction regions based on one input signal_FourC with minimum out component_Fourout C for min component_Fourout min calculating means and C_Fourout max component and C_Fourout Based on the min component, C of the first output signal_FourC to determine the out component_Fourout determination means;
The first input color signal after passing through the third means and the C_FourC after going through out decision means_FourFrom the out component, the inverse transformation formula of the mapping relation is solved, and the first output signal C₁out, C₂out and C_ThreeC to determine the out component₁C₂C_Threeout decision step and
With
C '₁out, said C ′₂out, said C ′_Threeout and C ′_FourEach component of out is 0 ≦ C ′₁out ≦ 100, 0 ≦ C ′₂out ≦ 100, 0 ≦ C ′_Threeout ≦ 100 and 0 ≦ C ′_FourIn the range of out ≦ 100, 0 is a minimum value at which the output device can output each component of the second output color signal as a color, and 100 is the second output color signal. It is the maximum value that can output each component of as a color
This is a color conversion device characterized by that.
[0031]
The invention of claim 20 is the color conversion device according to claim 18 or claim 19, wherein
C_Fourout determining means is the C_Fourout From max component, C_FourUsing the out amount generation curve formula, C of the first output signal_FourThe out component is obtained, and the C_FourThe out component is the C_Fourout When the value is smaller than the min component, the C_Fourout Said C using min component_FourDetermine the out component
This is a color conversion device characterized by that.
[0032]
The invention of claim 21 is the color conversion device according to claim 18 or claim 19, wherein
C_Fourout max calculating means is based on the first input signal after passing through the third means, the C_Fourout C together with max component_Fourout C of output signal corresponding to max₁out with component, C₂out with component and C_Threeout The with component is calculated and the C_Fourout determining means is the C_Fourout max component, said C₁out with component, C₂out with component and C_Threeout From component, C_FourUsing the out amount generation curve formula, C of the first output signal_FourThe out component is obtained, and the C_FourThe out component is the C_Fourout When the value is smaller than the min component, the C_Fourout Said C using min component_FourA color conversion device that determines an out component.
[0033]
The invention of claim 22 is the color conversion device according to any one of claims 14 to 21,
C ′ of the second output color signal_FourThe color corresponding to the out component is black
C ′ of the second output color signal₁The color corresponding to the out component is indigo,
C ′ of the second output color signal₂The color corresponding to the out component is red,
C ′ of the second output color signal_ThreeThe color corresponding to the out component is yellow
This is a color conversion device characterized by that.
[0034]
The invention of claim 23 provides C₁in, C₂in and C_ThreeThe three-dimensional first input color signal consisting of in is C₁out, C₂out, C_Threeout and C_Foura color conversion device for converting into a four-dimensional first output color signal composed of out;
An output device for outputting the second output color signal data input from the color conversion device as a color chart;
Each color constituting the color chart is measured, and the second input color signal corresponding to the second output color signal data is output to the color conversion device. With color device
In a color conversion system consisting of
The color conversion device further includes C ′.₁out, C '₂out, C '_Threeout and C '_FourFrom the four-dimensional second output color signal consisting of the four components of out, C ′₁in, C '₂in and C '_Threea first means for obtaining a mapping relationship to a three-dimensional second input color signal comprising three components of in;
(a) C ′ of the first input color signal and the second output color signal_Four(b) C ′ of the first input color signal and the second output color signal₁(c) C ′ of the first input color signal and the second output color signal₂(d) C ′ of the first input color signal and the second output color signal_Threesecond means for obtaining the first output color signal based on the minimum value of the out components and the mapping relationship;
A color conversion system characterized by comprising:
[0035]
The invention of claim 24 is the color conversion system according to claim 23,
The second means further includes (e) C ′ of the first input color signal and the second output color signal._Four(f) C ′ of the first input color signal and the second output color signal₁(g) C 'of the first input color signal and the second output color signal₂(h) C ′ of the first input color signal and the second output color signal_ThreeThe color conversion system is characterized in that the first output color signal is obtained based on the maximum value of the out components and the mapping relationship.
[0036]
The invention of claim 25 provides C₁in, C₂in and C_ThreeThe three-dimensional first input color signal consisting of the three components of in is represented by C₁out, C₂out, C_Threeout and C_FourIn a color conversion program for causing a color conversion device to execute a step of converting into a four-dimensional first output color signal composed of four components of out,
C '₁out, C '₂out, C '_Threeout and C '_FourFrom the four-dimensional second output color signal consisting of the four components of out, C ′₁in, C '₂in and C '_Threea first step of obtaining a mapping relationship to a three-dimensional second input color signal comprising three components of in;
(a) C ′ of the first input color signal and the second output color signal_Four(b) C ′ of the first input color signal and the second output color signal₁(c) C ′ of the first input color signal and the second output color signal₂(d) C ′ of the first input color signal and the second output color signal_Threea second step of obtaining the first output color signal based on the minimum value of the out components and the mapping relationship;
Is a color conversion program that causes a color conversion device to execute.
[0037]
The invention of claim 26 is the color conversion program according to claim 25,
The second step further includes (e) C ′ of the first input color signal and the second output color signal._Four(f) C ′ of the first input color signal and the second output color signal₁(g) C 'of the first input color signal and the second output color signal₂(h) C ′ of the first input color signal and the second output color signal_ThreeA color conversion program characterized in that the first output color signal is obtained based on a maximum value of out components and the mapping relationship.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of an example of a color conversion system that executes operations of respective steps of the color conversion method of the present invention.
[0039]
This color conversion system generally includes a color measurement device 1, a color conversion device 2, and an output device 3. The color conversion device 2 generally includes an arithmetic device 4 such as a CPU and a storage device 5 including a magnetic recording medium such as a magnetic disk, a semiconductor memory, and other recording media. Furthermore, a color conversion program for causing the color conversion device to execute each step of the color conversion method of the present invention is recorded on the recording medium of the storage device 5.
Here, the color measurement device 1 measures each color (color patch) constituting the color chart corresponding to the second output color signal input to the output device 3 to obtain a color measurement signal. In addition, the colorimetric device 1 converts the colorimetric signal of each color patch that has been measured into L^*a^*b^*, Converted into a second input color signal such as RGB, and the second input color signal is output to the color conversion device 2.
In addition, the color conversion device 2 generates second output color signal data constituting the color chart by the arithmetic device 4 and outputs the second output color signal data to the output device 3. On the other hand, the color conversion device 2 receives the second input color signal output from the color measurement device 1. Next, the color conversion device 2 generates a mapping relationship from the second output color signal to the second input color signal by the arithmetic device 4 and controls each step of the present invention described later. In addition to the second output color signal, the second input color signal, and the mapping relationship, the storage device 5 stores various data necessary for the control of each step of the present invention described later.
Further, the output device 3 receives the second output color signal output from the color conversion device 2 and outputs a color chart corresponding to the second output color signal data.
[0040]
(First embodiment)
Next, FIG. 2, FIG. 3 and FIG. 4 are examples of flowcharts for implementing the color conversion method of the present invention.
First, according to the first embodiment, based on the Kmax calculated according to the operation of FIG. 2, according to the operation of FIG. The output color signals Cout, Mout, Yout and Kout are determined.
As shown in FIG. 5, the operation principle of the first embodiment is as follows: (1) Kstart, MAX, KMAX, γ, which are approximately obtained in advance from the inherent black amount generation curve of the output device. (2) Steps S100 to S130 for obtaining a mapping relationship, and (3) whether the first input color signal is within the color reproduction region of the second output color signal CMYK. Steps S200 to S230 for determining, (4) Steps S300 to S350 for calculating Kmax when the first input color signal is present in the color reproduction region of the second output color signal CMYK, Step S400 for compressing the color gamut of the first input color signal when one input color signal does not exist in the color reproduction region of the second output color signal CMYK, and (6) unique ink of the output device A scan for determining the first output color signal Kout from the quantity generation curve. Steps S800 to S830 and (7) Step S910 for determining the remaining first output color signals Cout, Mout and Yout.
Here, Kstart (0 ≦ Kstart <100) is a start position for generating black in the black generation curve of the output device. MAX (MAX = 100) is the maximum output signal value of the output device. KMAX (0 ≦ KMAX ≦ 100) is the maximum black generation value in the output device. Γ (0 ≦ γ) represents the curvature of the black generation curve. Then, the respective values of Kstart, MAX, KMAX, and γ are set so as to approximate the black generation amount curve corresponding to the output device as shown in FIG. Kmax (Kstart ≦ Kmax ≦ MAX) is the generation of black when the first input color signal given by a certain value exists in the color reproduction region divided into four in this embodiment. This is the value of K (black) in the region where the amount is maximum.
Incidentally, in the present embodiment, L defined by the International Lighting Commission as the first input color signal or the second input signal.^*a^*b^*And CMYK (C: deep blue, M: red, Y: yellow, K: black) as the first output signal or the second output signal, the second output signal to the second second signal. The mapping relationship to the input signal and the color conversion from the first input color signal to the first output signal will be described. However, the input color signals are XYZ, L^*u^*v^*The same applies to the case of using RGB, etc.
[0041]
In the second input signal space,
VC is a vector that advances from the minimum value to the maximum value of the C ′ component of the second output signal.₁age,
VC is a vector that advances from the minimum value to the maximum value of the M ′ component of the second output signal.₂age,
VC is a vector that advances from the minimum value to the maximum value of the Y ′ component of the second output signal._Threeage,
VC is a vector that advances from the minimum value to the maximum value of the K ′ component of the second output signal._FourThe vector vC₁, VC₂And vC_ThreeAre vectors independent of each other, and the vector vC_FourIs vC_Four= A₁× vC₁+ A₂× vC₂+ A_Three× vC_ThreeThere is a relationship. However, a1, a2 and a3 are scalar quantities, respectively,₁≧ 0, a₂≧ 0, a_ThreeThe range is ≧ 0.
This vC₁, VC₂, VC_ThreeAnd vC_FourAs long as the above relationship is satisfied (FIG. 9B), the present invention does not limit the K component of the output signal to black. That is, this vC₁, VC₂, VC_ThreeAnd vC_FourAs long as the above relationship is satisfied, the combination of output signals is not limited to indigo, red, yellow, and black.
[0042]
The first embodiment will be specifically described below with reference to FIG. First, in step S10, Kstart, MAX, KMAX, and γ previously obtained are input.
Next, in order to obtain the mapping relationship from the second output color signal to the second input color signal, in step S100, a combination of the second output color signals (C ′, M ′, Y ′, K ′). Is generated. Next, in step S110, the second output color signal is output as a CMYK color chart by the output device.
Here, each of C ′, M ′, Y ′ and K ′ is in the range of 0 ≦ C ′ ≦ 100, 0 ≦ M ′ ≦ 100, 0 ≦ Y ′ ≦ 100, 0 ≦ K ′ ≦ 100. The combination of the second output color signals (C ′, M ′, Y ′, K ′) is generated within this range. A preferable combination of the second output color signals (C ′, M ′, Y ′, K ′) is obtained by regularly increasing or decreasing each C′M′Y′K ′ component. For example, by setting each C′M′Y′K ′ component to 0, 10, 20, 30,..., 80, 90, 100, a preferable second output color signal combination can be obtained. Note that if the number of combinations of the second output color signals is increased, the amount of calculation for obtaining the mapping relationship from the second output color signal to the second input signal increases. In view of the processing capability, the combination of the second output color signals is determined. In view of the processing capability of the arithmetic unit 4 at the time of filing of the present invention, the combination of the second output color signals is usually preferably 200 to 1000 color patches.
[0043]
In step S120, each color patch of the color chart obtained in this way is measured by the colorimetric device 1 such as a spectrophotometer or a scanner that can obtain the same signal as the first input color signal, and the second color patch is obtained. Get the input signal. Here, for example, the unit of the first input color signal is L^*a^*b^*The second input signal is L using a spectrophotometer.^*a^*b^*Get in units. For example, when the unit of the first input color signal is RGB, the second input signal is obtained in RGB units using a scanner. In step S130, the second input signal L 'of each color measured from the second color output color signals C'M'Y'K' of the CMYK color chart.^*a '^*b '^*The mapping relationship is generated and stored in the storage device 5 as a determinant or a lookup table.
[0044]
At this time, from the second output signal C′M′Y′K ′ to the second input signal L ′.^*a '^*b '^*The mapping relationship to can be expressed by the following equation (1) using the function F.
(L '^*, A '^*, B '^*) = F (C ′, M ′, Y ′, K ′) (1)
Furthermore, the inverse function F of the function F^-1Can be expressed by the following equation (2).
(C, M, Y) = F^-1(L^*, A^*, B^*, K) (2)
Using this relationship, the first input signal L^*a^*b^*Is converted into the first output signal CMYK, an appropriate first output color signal Kout is determined, and then the first input color signal L^*a^*b^*The remaining first output color signals Cout, Mout and Yout can be determined.
[0045]
Next, the first input color signal L^*a^*b^*Is the second input signal L ′ corresponding to the second output color signal C′M′Y′K ′.^*a '^*b '^*In order to determine whether or not it exists in all the color reproduction regions, (a) C′M′Y ′ (0 ≦ C ′ ≦ 100, 0 ≦ M) where K ′ = 100. (B) M′Y′K ′ (0 ≦ M ′ ≦ 100, 0 ≦ when C ′ = 0), and a first color reproduction region that is reproduced with “≦ 100, 0 ≦ Y ′ ≦ 100) (C) C'Y'K '(0≤C'≤100, 0≤ when M = 0), a second color reproduction area that is reproduced with Y'≤100, 0≤K'≤100) A third color reproduction region reproduced at Y ′ ≦ 100, 0 ≦ K ′ ≦ 100), and (d) C′M′K ′ (0 ≦ C ′ ≦ 100, 0 ≦ when Y = 0) M ′ ≦ 100, 0 ≦ K ′ ≦ 100), and the fourth color reproduction region is divided into four color reproduction regions. The first input color signal L^*a^*b^*Is present in these four color reproduction regions divided into four.
Here, for example, whether or not the first input color signal exists in an area reproduced by C′M′Y ′ when K ′ = 100 (hereinafter also referred to as a color reproduction area at K = 100). Can be determined by the following method.
[0046]
First, a microcube composed of eight different colors is generated in the color reproduction region at K = 100, and is composed of the first input color signal using the normal vector of the surface constituting the surface of the microcube. To determine whether the color is outside or inside the surface. At this time, if it is on the inner side with respect to all the surfaces, it is determined that it exists in the color gamut constituted by the minute cube, that is, in the color reproduction region at K = 100.
When this operation is performed in step S200 and it is determined that the color constituted by the first input color signal is present in the color reproduction region at K = 100, the process proceeds to step S300. On the other hand, when the entire color reproduction region at K = 100 is covered and the color constituted by the first input color signal does not exist in the color gamut constituted by any minute cube, K = 100 Is determined not to exist in the color reproduction region at step S210, and the process proceeds to step S210.
[0047]
Similarly, a region reproduced with M′Y′K ′ when C ′ = 0 in step S210, a region reproduced with C′Y′K ′ when M ′ = 0 in step S220, and a step In S230, it is determined whether or not there is a color composed of the first input color signal in the region reproduced by C′M′K ′ when Y ′ = 0 in S230. At that time, the process proceeds to one of steps S310, S320, and S340, and if it does not exist in any of the four color reproduction regions, the process proceeds to step S400.
In addition, in each area divided into four, since it takes time to construct a microcube comprehensively, it becomes a target from the mapping relationship from the second output color signal generated in advance to the second input signal. In the color reproduction region of the second output color signal, a color near the coordinates corresponding to the second input color signal is searched, and the first input color is configured by preferentially constructing a microcube composed of them. It is possible to efficiently determine whether the signal is within the color reproduction region.
[0048]
Next, in steps S300 to S340, Kmax when the first input color signal is present in the entire color reproduction region of the second input signal corresponding to the second output color signal C′M′Y′K ′. Ask for.
First, step S300 is a case where the first input signal exists in the region reproduced by C′M′Y ′ when K ′ = 100, and the first obtained by solving equation (3). The K value (= 100) of the output signal is set to Kmax.
(C, M, Y) = F^-1(L^*, A^*, B^*, K = 100) (3)
[0049]
In step S301, it is determined whether or not there is a solution of K (K = 100) of the first output signal in step S300. If there is a solution of K (K = 100) of the first output signal, the process proceeds to step S302 and proceeds to step S500. If there is no solution for K (K = 100) of the first output signal, the process proceeds to step S340.
[0050]
Step S310 is a case where the first input signal exists in a region reproduced by M′Y′K ′ when C ′ = 0, and the first output signal obtained by solving Equation (4). The K value of is assumed to be Kmax.
(M, Y, K) = F^-1(L^*, A^*, B^*, C = 0) (4)
[0051]
In step S311, it is determined whether or not a solution of K (C = 0) of the first output signal exists in step S310. If there is a solution of K (C = 0) of the first output signal, the process proceeds to step S312 and proceeds to step S500. If there is no solution for K (C = 0) of the first output signal, the process proceeds to step S320.
[0052]
Step S320 is a case where the first input signal exists in the region reproduced by C′Y′K ′ when M ′ = 0, and the first output signal obtained by solving Equation (5). The K value of is assumed to be Kmax.
(C, Y, K) = F^-1(L^*, A^*, B^*, M = 0) (5)
[0053]
In step S321, it is determined whether or not a solution of K (M = 0) of the first output signal exists in step S320. If there is a solution of K (M = 0) of the first output signal, the process proceeds to step S322 and proceeds to step S500. If there is no solution for K (M = 0) of the first output signal, the process proceeds to step S330.
[0054]
Step S330 is a case where the first input signal exists in a region reproduced by C′M′K ′ when Y ′ = 0, and the first output signal obtained by solving Equation (6). The K value of is assumed to be Kmax.
(C, M, K) = F^-1(L^*, A^*, B^*, Y = 0) (6)
[0055]
In step S331, it is determined whether or not there is a solution of K (Y = 0) of the first output signal in step S330. If there is a solution of K (Y = 0) of the first output signal, the process proceeds to step S332 and proceeds to step S500. If there is no solution of K (Y = 0) of the first output signal, the process proceeds to step S300.
[0056]
Step S340 is processing when there is an error in the determination of the color reproduction region in steps S200 to S230 and a solution cannot be obtained in the calculations in steps S300 to S330. (Note that, in the steps S200 to S230, when a microcube having eight different colors is generated, if the microcube is generated inappropriately, the first input signal does not exist in the color reproduction region. Nevertheless, there may be an error that steps S200 to S230 are erroneously determined to exist in the color reproduction region.)
If the calculation (steps S300, S310, S320, S330) has been completed for all the color gamuts and the K solution (steps S301, S311, S321, S331) of the first output signal has not been obtained, step S340 is performed. In steps S200 to S230, it is determined that an out-of-gamut color has been erroneously brought into steps S300 to S330, and the process proceeds to step S400. On the other hand, if the calculation has not been completed for the entire color gamut, the process proceeds to step S310 to perform the calculation for another color gamut.
[0057]
Next, step S400 is an operation for obtaining Kmax when the first input color signal does not exist in any of the four color reproduction regions divided into the four, and the color of the first input color signal The gamut is compressed using the gamut compression method into an area that can be reproduced by the second output color signal C′M′Y′K ′. Here, as a color gamut compression operation, as a method standardized by the International Commission on Illumination, a color that maps an input color signal outside the output color signal reproduction region onto the closest reproduction region of the output color signal is used. A domain compression method is known. In addition, “Div.8 TC8-03” of the International Lighting Commission discusses the color gamut compression method. For example, as quoted in paragraph 18 of JP-A-2000-134490, “To Develop A Universal Gamut Mapping Algorithm-Literature survey, Design Research Center, University of Derby, (1997)” by J. Morovic. According to the above, there is a Chord Clipping method as an example of a high-performance color gamut compression method. Examples of the color gamut compression method are disclosed in Japanese Patent Laid-Open Nos. 9-98298, 2000-165687, 11-540237, and the like.
[0058]
In step S401, it is determined whether there is a solution for color gamut compression in step S400. If this solution exists, the process proceeds to step S500. On the other hand, if this solution does not exist, it is determined that there has been a determination error due to an error in the color gamut determination in steps S200 to S230, and the process proceeds to step S310 to perform calculation for each color gamut to obtain Kmax. (Note that, in the steps S200 to S230, when a microcube having eight different colors is generated, if the microcube is generated inappropriately, the first input signal exists in the color reproduction region. Nevertheless, there may be an error that steps S200 to S230 mistakenly determine that the color reproduction area does not exist, and it is determined that there is a determination error due to an error in the color gamut determination of steps S200 to S230. (Instead of step S300, it is also possible to first move to any one of steps S320, S330, and S310 and perform calculations for each remaining color gamut to obtain Kmax.)
[0059]
Next, in step S500, it is determined whether or not Kmin, which is a value of K in a region where the amount of black generation is minimized, is determined. In the first embodiment, since the optimum first output color signals Cout, Mout, Yout, and Kout are obtained without obtaining Kmin, the process proceeds to step S800.
[0060]
Next, in steps 800 to S820, the optimum value of the first output color signal K (= Kout) using Kmax obtained by the above operation and the stored Kstart, MAX, KMAX, γ. Is calculated using the following equation (7) or (8).
First, in step S800, Kmax and Kstart are compared. When Kmax <Kstart,
Kout = 0 (7)
(Step S810), the process proceeds to step S900.
[0061]
Furthermore, in step S800, when Kmax ≧ Kstart,
Kout = ((Kmax−Kstart) / (MAX−Kstart)) γ × KMAX (8)
(Step S820), it is determined in step S830 that the value of Kmin does not exist, and the value of the first output signal Kout is determined. Then, the process proceeds to step S900.
[0062]
In step S900, it is determined whether or not the first input signal is present in the color gamut using the color gamut determination results in steps S200 to S230 and step S400. If it is within the color gamut, the process moves to step S910. On the other hand, if it is out of the color gamut, the process moves to step S930.
[0063]
In step S910, Kout obtained from the above method and the first input signal L^*a^*b^*From the above, by solving the inverse transformation formula of the mapping relation to the second output signal CMYK, that is, the following relational expression (9), the optimum first output signals Cout, Mout and Yout can be obtained. it can.
(Cout, Mout, Yout) = F^-1(L^*, a^*, b^*, Kout) ... (9)
[0064]
In step S920, it is determined whether or not the solution in step S910 exists. If this solution exists, Cout, Mout and Yout, which are solutions in S910, are determined as the first output signal. On the other hand, if this solution does not exist, the first input signal L^*a^*b^*Is outside the color reproduction region of the second output signal at K = Kout, and the process proceeds to step S930.
[0065]
Step S930 is mapped to the color reproduction region of the second output signal represented by K ≦ Kout using the same color gamut compression method as in Step S400. The mapped result is determined as the first output signal.
[0066]
Thus, in the first embodiment, in order to obtain the first output color signal CMYK from the first input color signal, the black generation amount is maximized in the four divided color reproduction regions. The value Kmax of K in the region was obtained, and then Kout, Cout, Mout and Yout were determined. In particular, in the first embodiment, it is determined whether or not the first input signal is present in the first color reproduction region reproduced by C′M′Y when K ′ = 100. is doing. For this reason, when the first input signal is present in the first color reproduction region, it is not necessary to gamut compress the first input signal in step S400. Thus, when the input signal is not subjected to color gamut compression, there is an advantage that an error in color reproduction of the output signal can be minimized.
[0067]
(Second embodiment)
Next, as a second embodiment, a K value Kmin in a region where the amount of black generation is minimized can be obtained, and Kout, Cout, Mout, and Yout can be determined using Kmax and Kmin.
Specifically, the method for obtaining Kmin will be described with reference to FIG. 3. First, based on the result determined in S200 to S230 or S400 of the first embodiment in step S510, the first input signal is within the color reproduction region. It is determined whether or not. If it is within the color reproduction region, the process proceeds to step S600. If it is outside the color reproduction region, the process proceeds to step S520.
[0068]
In step S520, the determination of Kmin outside the color gamut corresponds to the same processing as in S400 of the first embodiment, so that the overlapping color gamut compression processing is not performed and Kmin = Kmax is set, and the process proceeds to step S800.
[0069]
Next, in step S600, it is determined whether or not the color constituted by the first input color signal exists in the area reproduced by C'M'Y 'when (e) K' = 0. Similarly, in step S610, (f) an area reproduced with M'Y'K 'when C' = 100, and in step S620, (g) C'M'K when M '= 100. In step S630, it is determined whether or not it exists in the area reproduced in C′M′K ′ when (h) Y ′ = 100.
[0070]
In steps S600 to S630, as a method for determining whether or not the color constituted by the first input color signal is within the color reproduction region of the divided output color signals C′M′Y′K ′, Similarly to the above steps S200 to S230 (FIG. 2), a microcube composed of eight different colors is generated in the color reproduction region, and whether or not it exists inside all the surfaces constituting the surface of the microcube. A method for discrimination can be used.
In the operations in steps S600 to S630, it was confirmed that the color constituted by the first input color signal is present in the color reproduction region of the output color signal C′M′Y′K ′ divided. At that time, the process proceeds to one of steps S700, S710, S720, and S740, respectively.
[0071]
First, Step S700 is a case where the first input signal exists in the region reproduced by C′M′Y ′ when K ′ = 0, and the first input obtained by solving Equation (10) is shown in FIG. The K value (= 0) of the output signal is defined as Kmin.
(C, M, Y) = F^-1(L^*, A^*, B^*, K = 0) (10)
[0072]
In step S701, it is determined whether or not a solution of K (K = 0) of the first output signal exists in step S700. If there is a solution of K (K = 0) of the first output signal, the process proceeds to step S702 and proceeds to step S800. If there is no solution for K (K = 100) of the first output signal, the process proceeds to step S740.
[0073]
Step S710 is a case where the first input signal exists in the region reproduced by M′Y′K ′ when C ′ = 100, and the first output signal obtained by solving Equation (11). Let Kmin be the K value.
(M, Y, K) = F^-1(L^*, A^*, B^*, C = 100) (11)
[0074]
In step S711, it is determined whether or not a solution of K (C = 100) of the first output signal exists in step S710. When there is a solution of K (C = 100) of the first output signal, the process proceeds to step S712 and proceeds to step S800. If there is no solution of K (C = 100) of the first output signal, the process proceeds to step S720.
[0075]
Step S720 is a case where the first input signal exists in the region reproduced by C′Y′K ′ when M ′ = 100, and the first output signal obtained by solving Equation (12). Let Kmin be the K value.
(C, Y, K) = F^-1(L^*, A^*, B^*, M = 100) (12)
[0076]
In step S721, it is determined whether or not a solution of K (M = 100) of the first output signal exists in step S720. If there is a solution of K (M = 100) of the first output signal, the process proceeds to step S722 and proceeds to step S800. If there is no solution of K (M = 100) of the first output signal, the process proceeds to step S730.
[0077]
Step S730 is a case where the first input signal exists in the region reproduced by C′M′K ′ when Y ′ = 100, and the first output signal obtained by solving Equation (13). Let Kmin be the K value.
(C, M, K) = F^-1(L^*, A^*, B^*, Y = 100) (13)
[0078]
In step S731, it is determined whether or not there is a solution of K (Y = 100) of the first output signal in step S730. If there is a solution of K (Y = 100) of the first output signal, the process proceeds to step S732 and proceeds to step S800. If there is no solution of K (Y = 100) of the first output signal, the process proceeds to step S700.
[0079]
Next, in steps S800 to S850, the optimum value of the first output color signal K (= Kout) is obtained using Kmax and Kmin obtained by the above operation and the stored Kstart, MAX, KMAX, γ. ) Is calculated using the previous equation (7) or (8).
First, in step S800, Kmax and Kstart are compared. When Kmax <Kstart,
Kout = 0 (7)
(Step S810).
On the other hand, in step S800, when Kmax ≧ Kstart,
Kout = ((Kmax−Kstart) / (MAX−Kstart)) γ × KMAX (8)
Is given (step S820).
[0080]
Further, in step S830, it is determined that Kmin exists. In step S840, Kout obtained by equation (8) is compared with Kmin. If the condition of Kout <Kmin is not satisfied, Kout is left as it is and step S900 is performed. If it is satisfied, the process proceeds to step S900 after setting Kout = Kmin in step S850.
[0081]
Finally, in step S900, it is determined whether or not the first input signal exists in the color gamut using the color gamut determination results in steps S200 to S230 and step S400. If it is within the color gamut, the process moves to step S910. On the other hand, if it is out of the color gamut, the process moves to step S930.
[0082]
In step S910, the optimum first output signals Cout, Mout, and Yout can be obtained by solving the relational expression (9) using Kout obtained from the above method.
[0083]
In step S920, it is determined whether or not the solution in step S910 exists. In the second embodiment, since Kout = Kmin in S850, a solution always exists. Accordingly, Cout, Mout, and Yout are determined as the first output signal.
[0084]
Step S930 is mapped to the color reproduction region of the second output signal represented by K ≦ Kout using the same color gamut compression method as in Step S400. The mapped result is determined as the first output signal.
[0085]
In the first embodiment, Kmax may be calculated based on the first input signal that has undergone color gamut compression (S400), while in the second embodiment, the first color that is not always color gamut compressed. Kmin may be calculated based on the input signal (S600, S610, S620, S630). Therefore, if Kmin exists, Kout may not be determined based on Kmax (S820), and Kout may be determined based on Kmin (S850). Referring to FIG. 7B, for example, if Kmin (region of Kmin ≦ 50) exists, Kout is not determined based on Kmax (region of Kmax ≧ 75) (from the black circle ● to the arrow tip. Kout may be determined based on Kmin (region where Kmin ≦ 50) (the position of the black circle ● remains). In this way, when the input signal is not subjected to color gamut compression, there is an advantage that an error in color reproduction of the output signal can be minimized as compared with the first embodiment.
[0086]
In the second embodiment, the determination as to whether or not the first input signal exists in the color reproduction region that can be reproduced by KoutCMY is (f) C′M when K ′ = 0. A fifth color reproduction area that can be reproduced with 'Y' and (g) a sixth color reproduction area that can be reproduced with M'Y'K 'when C' = 100 and (h) when M '= 100 A seventh color reproduction area that can be reproduced with C'Y'K 'and (i) an eighth color reproduction area that can be reproduced with C'M'K' when Y '= 100 Judgment is made based on whether or not there is one color reproduction region. As described above, by dividing a part of the entire color reproduction region into the second four color reproduction regions, there is an advantage that Kout can be efficiently calculated as compared with the conventional iterative calculation method.
In FIGS. 2 to 4, if the gist of the invention is not changed by changing the order of operations, it is arbitrary to change the order. For example, when it is determined whether or not a certain input color signal exists in an area divided into four (steps S200, S210, S220 and S230 or steps S600, S610, S620 and S630), which area comes first (For example, the order of steps S230, S220, S210, and S200, the order of steps S630, S620, S610, and S600).
[0087]
(Third embodiment)
Next, as a third embodiment, replacing the previous formulas (7) and (8) of the black amount generation curve in the first embodiment with the following formulas (7 ′) and (8 ′), The present invention can also be implemented.
First, in step S800, Kmax and Kstart are compared. When Kmax <Kstart,
Kout = 0 ... (7 ')
(Step S810 ′).
On the other hand, in step S800, when Kmax ≧ Kstart,
Kout = ((Kmax + min × w−Kstart) / (MAX−MAX × w−Kstart)) γ × KMAX (8 ′)
Is given (step S820).
Note that min is the minimum value among the Cwith, Mwith, and Ywith values of the first output signal obtained together with Kmax for a certain first input signal. Here, Cwith, Mwith and Ywith of the first output signal obtained together with Kmax with respect to a certain first input signal are C components obtained by solving equations (3) to (6) and Kmax, M component and Y component. W (0 <w <1) is a weighting factor.
[0088]
In the first embodiment, equations (7) and (8) can be expressed as Kout = f (Kmax), and Kout is calculated based on Kmax, while in the third embodiment, the equation (7) 7 ′) and (8 ′) can be expressed as Kout = f (Kmax, Cwith, Mwith, Ywith), and Kout is calculated based on Kmax, Cwith, Mwith, and Ywith. 8A, in the first embodiment, the first color reproduction that can be reproduced by C′M′Y ′ when the first input signal is K ′ = 100. The first color reproduction area that can be reproduced by C′M′Y ′ when K ′ = 100 when the area is present in the area (halftone dot area in the figure) or the first input signal after color gamut compression is set to K ′ = 100 (The halftone dot area in the figure), the gradation of the black ink on the shadow side is impaired (a horizontal part appears at Kout in the figure). On the other hand, with reference to FIG. 8B, in the third embodiment, the first input signal can be reproduced with C′M′Y ′ when K ′ = 100. The first color that can be reproduced by C'M'Y 'when it exists in the color reproduction area (halftone area in the figure) or when the first input signal after color gamut compression is K' = 100 When it exists in the reproduction area (halftone area in the figure), the black gradation of the shadow side appears (Kout in the figure changes smoothly). As described above, the use of the black amount generation curve based on Kmax, Cwith, Mwith, and Ywith has an advantage that the gradation of the black ink on the shadow side appears. In addition, since Kout is determined based on min (minimum value of CMY), that is, determined according to the amount of ink overlap of CMYK, the point where ink overlap is maximum (C = M = Y = K). = 100), there is an advantage that the black generation amount is maximized.
[0089]
(Fourth embodiment)
Further, as a fourth embodiment, the previous formulas (7) and (8) of the black amount generation curve in the second embodiment are replaced by the formulas (7 ′) and (8 ′). The invention can also be implemented. In other words, the present invention can be implemented by adapting the third embodiment to the second embodiment.
[0090]
In the fourth embodiment, if Kmin exists, Kout becomes Kout = Kmin instead of the equations (7 ′) and (8 ′). That is, in the fourth embodiment, Kout = f (Kmax, Cwith, Mwith, Ywith, Kmin) can be expressed, and Kout is calculated based on Kmax, Cwith, Mwith, Ywith, and Kmin. Referring to FIG. 9A, in the fourth embodiment, the color gamut unique to the output device (the entire color reproduction region of the second input signal corresponding to the second output signal) is maximized. You can make use of it. This has the advantage that the error in color reproduction of the output signal can be minimized.
[0091]
According to the first to fourth embodiments described above, the three-dimensional first input signal can be color-converted into a four-dimensional first output signal. Therefore, the color conversion device 2 can color-convert a certain first input signal to a first output signal and output the first output signal to the output device 1. Also, the color conversion device 2 uses this color conversion method to obtain a new mapping relationship from the three-dimensional first input signal to the four-dimensional first output signal, and creates a determinant or a lookup table. can do. As a result, the first input signal becomes L^*a^*b^*In the case of a unit such as a common color space (CCS) corresponding to human visual characteristics, a printer, a printer, etc. in a color management system supported at the OS level of a personal computer or the like An output profile corresponding to the output device 3 can be created. When the first input signal is in RGB units, a device link profile between the color measuring device 1 such as a scanner and the output device 3 can be created.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an example of a color conversion system of the present invention.
FIG. 2 is a diagram related to calculation of Kmax in a flowchart of an example for carrying out the color conversion method of the present invention.
FIG. 3 is a diagram related to calculation of Kmin in an example of a flowchart for implementing the color conversion method of the present invention.
FIG. 4 is a diagram related to determination of Kout, Cout, Mout, and Yout in an example of a flowchart for implementing the color conversion method of the present invention.
FIG. 5 is a simplified diagram of a flowchart for carrying out the first embodiment of the present invention.
FIG. 6 is a graph showing an example of a black generation amount curve (vertical axis: Kout, horizontal axis: Kmax).
FIG. 7 is a graph showing a color reproduction area.
FIG. 8 shows an example of the black generation amount curve (vertical axis: Kout, horizontal axis: L^*(a^*= 0, b^*= 0)).
FIG. 9A shows an example of a black generation amount curve (vertical axis: Kout, horizontal axis: L^*(a^*= 0, b^*= 0)). (B) It is a graph which shows the relationship of each component of the output signal in input signal space.
FIG. 10 is a simplified flowchart diagram for implementing a prior art color conversion method.

Claims (19)

A three-dimensional first input color signal composed of three components C ₁ in, C ₂ in and C ₃ in is converted into four components composed of four components C ₁ out, C ₂ out, C ₃ out and C ₄ out. In the color conversion method of converting to the first output color signal of the dimension,
From the four-dimensional second output color signal consisting of four components of C ′ ₁ out, C ′ ₂ out, C ′ ₃ out and C ′ ₄ out, C ′ ₁ in, C ′ ₂ in and C ′ ₃ in Obtaining a mapping relationship to a three-dimensional second input color signal comprising the three components of:
The entire color reproduction area of the second input color signal corresponding to the second output color signal is: (a) Among the second output color signals, C ′ ₄ out = 100, 0 ≦ C ′ ₁ out ≦ A first color reproduction region of a second input color signal corresponding to an output color signal comprising 100, 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₃ out ≦ 100, and (b) the second output. Among the color signals, the second input color corresponding to the output color signal composed of C ′ ₁ out = 0, 0 ≦ C ′ ₂ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and C ′ ₄ out ≦ 100. (C) Among the second output color signals, C ′ ₂ out = 0, 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and 0 ≦ C 'An output color signal consisting of ₄ out100, a third color reproduction region of the corresponding second input color signal, and (d) of the second output color signal, C' ₃ out = 0, 0≤C ' ₁ out ≦ 100,0 ≦ C ' the out ≦ 100 and 0 ≦ C 'output color signal consisting of ₄ out ≦ 100, the four color reproduction area composed of the fourth color reproduction area of the corresponding second input color signal, after dividing the second A determination step of determining whether one input color signal exists in the four color reproduction regions;
As a result of the determination step, when the first input color signal is not present in the four color reproduction regions, the first input color signal is present in the four color reproduction regions. A compression step to compress,
A C ₄ out_max calculation step for obtaining a C ₄ out_max component that maximizes the C ₄ out component of the first output signal corresponding to the four color reproduction regions based on the first input color signal after the compression step; ,
Based on the C ₄ out - max component, and C ₄ out determination step of determining the C ₄ out components of said first output signal,
From the first input color signal after the compression step and the C ₄ out component after the C ₄ out determination step, the inverse transformation formula of the mapping relation is solved to obtain C ₁ out, C _{2 of} the first output signal. C ₁ C ₂ C ₃ out determining step for determining out and C ₃ out components;
With
The components of the C ′ ₁ out, the C ′ ₂ out, the C ′ ₃ out, and the C ′ ₄ out are 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₂ out ≦ 100, and 0 ≦ C. ' ₃ out ≤ 100 and 0 ≤ C' ₄ out ≤ 100, where 0 is a minimum value with which the output device can output each component of the second output color signal as a color, and 100 is The output device is a maximum value that can output each component of the second output color signal as a color,
In the space of the second input signal, a vector going from the minimum value of the C ′ ₁ out component of the second output signal to the maximum value is vC _1, and the minimum value of the C ′ ₂ out component of the second output signal is maximized. The vector going to the value is vC ₂ , the vector going from the minimum value of the C ′ ₃ out component of the second output signal to the maximum value is vC _3, and the minimum value of the C ′ ₄ out component of the second output signal is the maximum Assuming that the vector going to the value is vC ₄ , the vectors vC ₁ , vC ₂ and vC ₃ are mutually independent vectors, and the vector vC ₄ is vC ₄ = a ₁ × vC ₁ + a ₂ × vC ₂ + a ₃ × A color conversion method having a relationship of vC ₃ , wherein a1, a2, and a3 are scalar amounts, and are in a range of a ₁ ≧ 0, a ₂ ≧ 0, and a ₃ ≧ 0. The color conversion method according to claim 1, wherein the color conversion method is:
Before the C ₄ out determination step, based on the first input color signal before the compression step, the C ₄ out component of the first output signal corresponding to the entire color reproduction region of the second input color signal is The C ₄ out_min calculation step for obtaining the minimum C ₄ out_min component is as follows:
In addition,
The color conversion method, wherein the C ₄ out determination step further determines a C ₄ out component of the first output signal based on the C ₄ out_min component. The color conversion method according to claim 1, wherein the color conversion method further includes:
(E) Among the second output color signals, C ′ ₄ out = 0, 0 ≦ C ′ ₁ out ≦ A fifth color reproduction region of the second input color signal corresponding to the output color signal consisting of 100, 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₃ out ≦ 100, and (f) the second output. Among the color signals, the second input color corresponding to the output color signal composed of C ′ ₁ out = 100, 0 ≦ C ′ ₂ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and C ′ ₄ out ≦ 100. (G) Among the second output color signals, C ′ ₂ out = 100, 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and 0 ≦ C _'4 into an output color signal consisting Out100, among the corresponding second seventh color reproduction area of the input color signal and (h) said second output color _{signal, C' 3 out = 100,0 ≦} C ' ₁ out ≦ 100, In an output color signal consisting of 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₄ out ≦ 100, a second four color reproduction regions consisting of an eighth color reproduction region of the corresponding input color signal, A second discriminating step for discriminating whether or not the first input signal before the third step exists in the second four color reproduction regions after the division;
As a result of the second determination step, when the first input signal before the compression step exists in the second four color reproduction regions, based on the first input signal before the compression step, A C ₄ out_min calculating step for obtaining a C ₄ out_min component that minimizes the C ₄ out component of the first output signal corresponding to the second four color reproduction regions;
With
The color conversion method, wherein the C ₄ out determination step further determines a C ₄ out component of the first output signal based on the C ₄ out_min component. A three-dimensional first input color signal composed of three components C ₁ in, C ₂ in and C ₃ in is converted into four components composed of four components C ₁ out, C ₂ out, C ₃ out and C ₄ out. In the color conversion method of converting to the first output color signal of the dimension,
From the four-dimensional second output color signal consisting of four components of C ′ ₁ out, C ′ ₂ out, C ′ ₃ out and C ′ ₄ out, C ′ ₁ in, C ′ ₂ in and C ′ ₃ in Obtaining a mapping relationship to a three-dimensional second input color signal comprising the three components of:
A determination step of determining whether or not the first input color signal is present in the entire color reproduction region of the second input color signal corresponding to the second output color signal;
As a result of the determination step, when the first input color signal does not exist in the entire color reproduction region of the second input color signal, the first input color signal is changed to the second input color signal. A compression step for compressing the image so that it exists in the entire color reproduction region of
Based on the first input color signal after the compression step, a C ₄ out_max component that maximizes the C ₄ out component of the first output signal corresponding to the entire color reproduction region of the second input color signal is obtained. C ₄ out_max calculation step;
After a part of the entire color reproduction area of the second input color signal corresponding to the second output color signal is divided into color reproduction divided areas, the first input signal before the compression step is the color reproduction. A second discriminating step for discriminating whether or not it exists in the divided area;
As a result of the second determination step, when the first input signal before the compression step is present in the color reproduction division region, the color reproduction region based on the first input signal before the compression step A C ₄ out_min calculating step for obtaining a C ₄ out_min component that minimizes the C ₄ out component of the first output signal corresponding to
Based on the C ₄ out - max component and the C ₄ out_min component, and C ₄ out determination step of determining the C ₄ out components of said first output signal,
From the first input color signal after the compression step and the C ₄ out component after the C ₄ out determination step, the inverse transformation formula of the mapping relation is solved to obtain C ₁ out, C _{2 of} the first output signal. C ₁ C ₂ C ₃ out determining step for determining out and C ₃ out components;
With
The components of the C ′ ₁ out, the C ′ ₂ out, the C ′ ₃ out, and the C ′ ₄ out are 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₂ out ≦ 100, and 0 ≦ C. ' ₃ out ≤ 100 and 0 ≤ C' ₄ out ≤ 100, where 0 is a minimum value with which the output device can output each component of the second output color signal as a color, and 100 is The output device is a maximum value that can output each component of the second output color signal as a color,
In the space of the second input signal, a vector going from the minimum value of the C ′ ₁ out component of the second output signal to the maximum value is vC _1, and the minimum value of the C ′ ₂ out component of the second output signal is maximized. The vector going to the value is vC ₂ , the vector going from the minimum value of the C ′ ₃ out component of the second output signal to the maximum value is vC _3, and the minimum value of the C ′ ₄ out component of the second output signal is the maximum Assuming that the vector going to the value is vC ₄ , the vectors vC ₁ , vC ₂ and vC ₃ are mutually independent vectors, and the vector vC ₄ is vC ₄ = a ₁ × vC ₁ + a ₂ × vC ₂ + a ₃ × A color conversion method having a relationship of vC ₃ , wherein a1, a2, and a3 are scalar amounts, and are in a range of a ₁ ≧ 0, a ₂ ≧ 0, and a ₃ ≧ 0. A three-dimensional first input color signal composed of three components C ₁ in, C ₂ in and C ₃ in is converted into four components composed of four components C ₁ out, C ₂ out, C ₃ out and C ₄ out. In the color conversion method of converting to the first output color signal of the dimension,
From the four-dimensional second output color signal consisting of four components of C ′ ₁ out, C ′ ₂ out, C ′ ₃ out and C ′ ₄ out, C ′ ₁ in, C ′ ₂ in and C ′ ₃ in Obtaining a mapping relationship to a three-dimensional second input color signal comprising the three components of:
A determination step of determining whether or not the first input color signal is present in the entire color reproduction region of the second input color signal corresponding to the second output color signal;
As a result of the determination step, when the first input color signal does not exist in the entire color reproduction region of the second input color signal, the first input color signal is changed to the second input color signal. A compression step for compressing the image so that it exists in the entire color reproduction region of
Based on the first input color signal after the compression step, a C ₄ out_max component that maximizes the C ₄ out component of the first output signal corresponding to the entire color reproduction region of the second input color signal is obtained. C ₄ out_max calculation step;
The entire color reproduction area of the second input color signal corresponding to the second output color signal is: (a) Among the second output color signals, C ′ ₄ out = 0, 0 ≦ C ′ ₁ out ≦ A first color reproduction region of a second input color signal corresponding to an output color signal comprising 100, 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₃ out ≦ 100, and (b) the second output. Among the color signals, the second input color corresponding to the output color signal composed of C ′ ₁ out = 100, 0 ≦ C ′ ₂ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and C ′ ₄ out ≦ 100. (C) Among the second output color signals, C ′ ₂ out = 100, 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and 0 ≦ C _'4 into an output color signal consisting Out100, among the corresponding second third of the color reproduction area of the input color signal and; (d) second output color _{signal, C' 3 out = 100,0 ≦} C ' ₁ out ≦ 100, After dividing the output color signal consisting of 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₄ out ≦ 100 into four color reproduction regions consisting of the fourth color reproduction region of the corresponding input color signal A second determination step of determining whether or not the first input signal before the third step exists in the four color reproduction divided regions;
As a result of the second determination step, when the first input signal before the compression step exists in the four color reproduction divided regions, the four input signals are based on the first input signal before the compression step. A C ₄ out_min calculating step for obtaining a C ₄ out_min component that minimizes the C ₄ out component of the first output signal corresponding to two color reproduction regions;
Based on the C ₄ out - max component and the C ₄ out_min component, and C ₄ out determination step of determining the C ₄ out components of said first output signal,
From the first input color signal after the compression step and the C ₄ out component after the C ₄ out determination step, the inverse transformation formula of the mapping relation is solved to obtain C ₁ out, C _{2 of} the first output signal. C ₁ C ₂ C ₃ out determining step for determining out and C ₃ out components;
With
The components of the C ′ ₁ out, the C ′ ₂ out, the C ′ ₃ out, and the C ′ ₄ out are 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₂ out ≦ 100, and 0 ≦ C. ' ₃ out ≤ 100 and 0 ≤ C' ₄ out ≤ 100, where 0 is a minimum value with which the output device can output each component of the second output color signal as a color, and 100 is The output device is a maximum value that can output each component of the second output color signal as a color,
In the space of the second input signal, a vector going from the minimum value of the C ′ ₁ out component of the second output signal to the maximum value is vC _1, and the minimum value of the C ′ ₂ out component of the second output signal is maximized. The vector going to the value is vC ₂ , the vector going from the minimum value of the C ′ ₃ out component of the second output signal to the maximum value is vC _3, and the minimum value of the C ′ ₄ out component of the second output signal is the maximum Assuming that the vector going to the value is vC ₄ , the vectors vC ₁ , vC ₂ and vC ₃ are mutually independent vectors, and the vector vC ₄ is vC ₄ = a ₁ × vC ₁ + a ₂ × vC ₂ + a ₃ × A color conversion method having a relationship of vC ₃ , wherein a1, a2, and a3 are scalar amounts, and are in a range of a ₁ ≧ 0, a ₂ ≧ 0, and a ₃ ≧ 0. In the color conversion method according to any one of claims 2 to 5,
The C ₄ out determining step, the C ₄ from out_max component, by using the generated curve equation of C ₄ out amount calculates the C ₄ out components of said first output signal, the C ₄ out component the C ₄ A color conversion method, wherein the C ₄ out component is determined using the C ₄ out_min component when smaller than the out_min component. In the color conversion method according to any one of claims 2 to 5,
The C ₄ out_max calculating step, based on the first input signal after the compression step, the C ₄ with out_max component, C ₁ out_with component of the output signal corresponding to the C ₄ out_max, C ₂ out_with component and C ₃ Find out_with component,
The C ₄ out determining step, the C ₄ out - max component, said C ₁ out_with component, wherein the C ₂ out_with component and the C ₃ out_with component, by using the generated curve equation of C ₄ out amount, the first output determine the C ₄ out components of the signal, the C ₄ when out component is smaller than the C ₄ out_min component, a color conversion method characterized by determining the C ₄ out components using the C ₄ out_min component . The color conversion method according to any one of claims 1 to 7,
The color corresponding to the C ′ ₄ out component of the second output color signal is black.
The color corresponding to the C ′ ₁ out component of the second output color signal is indigo;
The color corresponding to the C ′ ₂ out component of the second output color signal is red,
A color conversion method, wherein the color corresponding to the C ′ ₃ out component of the second output color signal is yellow. The color conversion method according to any one of claims 1 to 7, wherein the step of obtaining the mapping relationship includes:
Obtaining the second output color signal input to the output device;
The output device outputs each of the second output color signals as a color, and the color measurement device measures each of the colors, and the second input color signal corresponding to the second output color signal Obtaining the second input color signal output from the colorimetric device,
Calculating a mapping relationship from the second output color signal to the second input color signal. A three-dimensional first input color signal composed of three components C ₁ in, C ₂ in and C ₃ in is converted into four components composed of four components C ₁ out, C ₂ out, C ₃ out and C ₄ out. In the color conversion device for converting to the first output color signal of the dimension,
A four-dimensional second output color signal consisting of four components C ′ ₁ out, C ′ ₂ out, C ′ ₃ out and C ′ ₄ out, which is input to the output device, is output from the measurement color device. , C ′ ₁ in, C ′ ₂ in, and C ′ ₃ in, a first means for obtaining a mapping relationship to a second input color signal composed of three components;
The entire color reproduction area of the second input color signal corresponding to the second output color signal is: (a) Among the second output color signals, C ′ ₄ out = 100, 0 ≦ C ′ ₁ out ≦ A first color reproduction region of a second input color signal corresponding to an output color signal comprising 100, 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₃ out ≦ 100, and (b) the second output. Among the color signals, the second input color corresponding to the output color signal composed of C ′ ₁ out = 0, 0 ≦ C ′ ₂ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and C ′ ₄ out ≦ 100. (C) Among the second output color signals, C ′ ₂ out = 0, 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and 0 ≦ C 'An output color signal consisting of ₄ out100, a third color reproduction region of the corresponding second input color signal, and (d) of the second output color signal, C' ₃ out = 0, 0≤C ' ₁ out ≦ 100,0 ≦ C ' the out ≦ 100 and 0 ≦ C 'output color signal consisting of ₄ out ≦ 100, the four color reproduction area composed of the fourth color reproduction area of the corresponding second input color signal is divided, the first A second means for determining whether one input color signal exists in the four color reproduction regions;
When the second means determines that the first input color signal does not exist in the four color reproduction regions, the first input color signal exists in the four color reproduction regions. A third means of compression,
Based on the first input color signal after passing through the third means, a C ₄ out_max component that maximizes the C ₄ out component of the first output signal corresponding to the four color reproduction regions is obtained. ₄ out_max calculation means,
Based on the C ₄ out - max component, and C ₄ out determination means for determining a C ₄ out components of said first output signal,
From C ₄ out components after the first input color signal and the C ₄ out determination step after via said third means, by solving the inverse conversion equation of the mapping relation, C of the first output signal C ₁ C ₂ C ₃ out determining means for determining ₁ out, C ₂ out and C ₃ out components;
With
The components of the C ′ ₁ out, the C ′ ₂ out, the C ′ ₃ out, and the C ′ ₄ out are 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₂ out ≦ 100, and 0 ≦ C. ' ₃ out ≤ 100 and 0 ≤ C' ₄ out ≤ 100, where 0 is the minimum value that the output device can output as a color each component of the second output color signal, and 100 is , The maximum value that the output device can output each component of the second output color signal as a color,
In the space of the second input signal, a vector going from the minimum value of the C ′ ₁ out component of the second output signal to the maximum value is vC _1, and the minimum value of the C ′ ₂ out component of the second output signal is maximized. The vector going to the value is vC ₂ , the vector going from the minimum value of the C ′ ₃ out component of the second output signal to the maximum value is vC _3, and the minimum value of the C ′ ₄ out component of the second output signal is the maximum Assuming that the vector going to the value is vC ₄ , the vectors vC ₁ , vC ₂ and vC ₃ are mutually independent vectors, and the vector vC ₄ is vC ₄ = a ₁ × vC ₁ + a ₂ × vC ₂ + a ₃ × A color conversion apparatus having a relationship of vC ₃ , wherein a1, a2, and a3 are scalar amounts, and are in a range of a ₁ ≧ 0, a ₂ ≧ 0, and a ₃ ≧ 0. The color conversion device according to claim 10, wherein the color conversion device further includes:
(E) Among the second output color signals, C ′ ₄ out = 0, 0 ≦ C ′ ₁ out ≦ A fifth color reproduction region of the second input color signal corresponding to the output color signal consisting of 100, 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₃ out ≦ 100, and (f) the second output. Among the color signals, the second input color corresponding to the output color signal composed of C ′ ₁ out = 100, 0 ≦ C ′ ₂ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and C ′ ₄ out ≦ 100. (G) Among the second output color signals, C ′ ₂ out = 100, 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and 0 ≦ C _'4 into an output color signal consisting Out100, among the corresponding second seventh color reproduction area of the input color signal and (h) said second output color _{signal, C' 3 out = 100,0 ≦} C ' ₁ out ≦ 100, In an output color signal consisting of 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₄ out ≦ 100, a second four color reproduction regions consisting of an eighth color reproduction region of the corresponding input color signal, A fourth means for dividing and determining whether or not the first input signal before passing through the third means exists in the second four color reproduction regions;
When it is determined that the first input signal before the fourth passes through the third means exists in the second four color reproduction regions, the first input signal before passing through the third means C ₄ out_min calculating means for obtaining a C ₄ out_min component that minimizes the C ₄ out component of the first output signal corresponding to the second four color reproduction regions based on one input signal;
With
The color conversion device, wherein the C ₄ out determining means further determines a C ₄ out component of the first output signal based on the C ₄ out_min component. A three-dimensional first input color signal composed of three components C ₁ in, C ₂ in and C ₃ in is converted into four components composed of four components C ₁ out, C ₂ out, C ₃ out and C ₄ out. In the color conversion device for converting to the first output color signal of the dimension,
Means for obtaining a four-dimensional second output color signal comprising four components of C ′ ₁ out, C ′ ₂ out, C ′ ₃ out and C ′ ₄ out, which is input to the output device;
The output device outputs each of the second output color signals as a color, and the color measurement device measures each of the colors and corresponds to the second output color signal, C ′ ₁ in, C ′. Means for obtaining the second input color signal output from the colorimetric device after obtaining the second input color signal comprising three components of ₂ in and C ′ ₃ in;
A first means for obtaining a mapping relationship from the second output color signal to the second input color signal;
A second means for determining whether or not the first input color signal exists in the entire color reproduction region of the second input color signal corresponding to the second output color signal;
When the second means determines that the first input color signal does not exist in the entire color reproduction region of the second input color signal, the first input color signal is changed to the second input color signal. A third means for compressing the input color signal so that it exists in the entire color reproduction region of the input color signal;
Based on the first input color signal after passing through the third means, the C ₄ out component of the first output signal corresponding to the entire color reproduction region of the second input color signal is maximized. C ₄ out_max means for obtaining ₄ out_max components;
The entire color reproduction area of the second input color signal corresponding to the second output color signal is: (a) Among the second output color signals, C ′ ₄ out = 0, 0 ≦ C ′ ₁ out ≦ A first color reproduction region of a second input color signal corresponding to an output color signal comprising 100, 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₃ out ≦ 100, and (b) the second output. Among the color signals, the second input color corresponding to the output color signal composed of C ′ ₁ out = 100, 0 ≦ C ′ ₂ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and C ′ ₄ out ≦ 100. (C) Among the second output color signals, C ′ ₂ out = 100, 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and 0 ≦ C _'4 into an output color signal consisting Out100, among the corresponding second third of the color reproduction area of the input color signal and; (d) second output color _{signal, C' 3 out = 100,0 ≦} C ' ₁ out ≦ 100, The output color signal consisting of 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₄ out ≦ 100 is divided into four color reproduction regions consisting of the fourth color reproduction region of the corresponding input color signal. A fourth means for determining whether or not the first input signal before passing through the third means exists in the four color reproduction divided regions;
When it is determined that the first input signal before the fourth means passes through the third means exists in the four color reproduction divided regions, the first input signal before passing through the third means. C ₄ out_min calculating means for obtaining a C ₄ out_min component that minimizes the C ₄ out component of the first output signal corresponding to the four color reproduction regions based on one input signal; the C ₄ out_max component; based on the C ₄ out_min component, and C ₄ out determination means for determining a C ₄ out components of said first output signal,
From the first input color signal after passing through the third means and the C ₄ out component after passing through the C ₄ out determining means, the inverse transformation equation of the mapping relation is solved to obtain the first output A C ₁ C ₂ C ₃ out determination step for determining C ₁ out, C ₂ out and C ₃ out components of the signal;
With
The components of the C ′ ₁ out, the C ′ ₂ out, the C ′ ₃ out, and the C ′ ₄ out are 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₂ out ≦ 100, and 0 ≦ C. ' ₃ out ≤ 100 and 0 ≤ C' ₄ out ≤ 100, where 0 is the minimum value that the output device can output as a color each component of the second output color signal, and 100 is , The maximum value that the output device can output each component of the second output color signal as a color,
In the space of the second input signal, a vector going from the minimum value of the C ′ ₁ out component of the second output signal to the maximum value is vC _1, and the minimum value of the C ′ ₂ out component of the second output signal is maximized. The vector going to the value is vC ₂ , the vector going from the minimum value of the C ′ ₃ out component of the second output signal to the maximum value is vC _3, and the minimum value of the C ′ ₄ out component of the second output signal is the maximum Assuming that the vector going to the value is vC ₄ , the vectors vC ₁ , vC ₂ and vC ₃ are mutually independent vectors, and the vector vC ₄ is vC ₄ = a ₁ × vC ₁ + a ₂ × vC ₂ + a ₃ × A color conversion apparatus having a relationship of vC ₃ , wherein a1, a2, and a3 are scalar amounts, and are in a range of a ₁ ≧ 0, a ₂ ≧ 0, and a ₃ ≧ 0. The color conversion device according to claim 11 or 12,
The C ₄ out determination means, wherein the C ₄ from out_max component, by using the generated curve equation of C ₄ out amount calculates the C ₄ out components of said first output signal, the C ₄ out component the C ₄ A color conversion device that determines the C ₄ out component using the C ₄ out_min component when the C ₄ out_min component is smaller than the out_min component. The color conversion device according to claim 11 or 12,
The C ₄ out - max calculation means, based on the first input signal after passing through the third means, together with the C ₄ out - max component, C ₁ out_with component of the output signal corresponding to the C ₄ out_max, C ₂ Find out_with component and C ₃ out_with component,
The C ₄ out determination means, wherein the C ₄ out - max component, said C ₁ out_with component, wherein the C ₂ out_with component and the C ₃ out_with component, by using the generated curve equation of C ₄ out amount, the first output determine the C ₄ out components of the signal, the C ₄ when out component is smaller than the C ₄ out_min component, the C ₄ color conversion apparatus characterized by determining the C ₄ out components using out_min component . The color conversion device according to any one of claims 10 to 14,
The color corresponding to the C ′ ₄ out component of the second output color signal is black.
The color corresponding to the C ′ ₁ out component of the second output color signal is indigo;
The color corresponding to the C ′ ₂ out component of the second output color signal is red,
A color conversion apparatus, wherein the color corresponding to the C ′ ₃ out component of the second output color signal is yellow. A three-dimensional first input color signal composed of C ₁ in, C ₂ in and C ₃ in is converted into a four-dimensional first output color signal composed of C ₁ out, C ₂ out, C ₃ out and C ₄ out A color conversion device for converting to
An output device for outputting the second output color signal data input from the color conversion device as a color chart;
Each color constituting the color chart is measured, and the second input color signal corresponding to the second output color signal data is output to the color conversion device. A color device;
A color conversion system comprising: the color conversion device further comprising:
From the four-dimensional second output color signal consisting of four components of C ′ ₁ out, C ′ ₂ out, C ′ ₃ out and C ′ ₄ out, C ′ ₁ in, C ′ ₂ in and C ′ ₃ in A first means for obtaining a mapping relationship to a three-dimensional second input color signal comprising the three components of:
The entire color reproduction area of the second input color signal corresponding to the second output color signal is: (a) Among the second output color signals, C ′ ₄ out = 100, 0 ≦ C ′ ₁ out ≦ A first color reproduction region of a second input color signal corresponding to an output color signal comprising 100, 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₃ out ≦ 100, and (b) the second output. Among the color signals, the second input color corresponding to the output color signal composed of C ′ ₁ out = 0, 0 ≦ C ′ ₂ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and C ′ ₄ out ≦ 100. (C) Among the second output color signals, C ′ ₂ out = 0, 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and 0 ≦ C 'An output color signal consisting of ₄ out100, a third color reproduction region of the corresponding second input color signal, and (d) of the second output color signal, C' ₃ out = 0, 0≤C ' ₁ out ≦ 100,0 ≦ C ' the out ≦ 100 and 0 ≦ C 'output color signal consisting of ₄ out ≦ 100, the four color reproduction area composed of the fourth color reproduction area of the corresponding second input color signal is divided, the first A second means for determining whether one input color signal exists in the four color reproduction regions;
When the second means determines that the first input color signal does not exist in the four color reproduction regions, the first input color signal exists in the four color reproduction regions. A third means of compression,
Based on the first input color signal after passing through the third means, a C ₄ out_max component that maximizes the C ₄ out component of the first output signal corresponding to the four color reproduction regions is obtained. ₄ out_max calculation means,
Based on the C ₄ out - max component, and C ₄ out determination means for determining a C ₄ out components of said first output signal,
From C ₄ out components after the first input color signal and the C ₄ out determination step after via said third means, by solving the inverse conversion equation of the mapping relation, C of the first output signal C ₁ C ₂ C ₃ out determining means for determining ₁ out, C ₂ out and C ₃ out components;
With
The components of the C ′ ₁ out, the C ′ ₂ out, the C ′ ₃ out, and the C ′ ₄ out are 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₂ out ≦ 100, and 0 ≦ C. ' ₃ out ≤ 100 and 0 ≤ C' ₄ out ≤ 100, where 0 is the minimum value that the output device can output as a color each component of the second output color signal, and 100 is , The maximum value that the output device can output each component of the second output color signal as a color,
In the space of the second input signal, a vector going from the minimum value of the C ′ ₁ out component of the second output signal to the maximum value is set as vC _1, and the minimum value of the C ′ ₂ out component of the second output signal is maximized. The vector going to the value is vC ₂ , the vector going from the minimum value of the C ′ ₃ out component of the second output signal to the maximum value is vC _3, and the minimum value of the C ′ ₄ out component of the second output signal is the maximum When the vector to the value is vC ₄ , the vectors vC ₁ , vC _2, and vC ₃ are independent from each other, and the vector vC ₄ is vC ₄ = a ₁ × vC ₁ + a ₂ × vC ₂ + a ₃ × A color conversion system having a relationship of vC ₃ , wherein a1, a2, and a3 are scalar amounts, and are in a range of a ₁ ≧ 0, a ₂ ≧ 0, and a ₃ ≧ 0. The color conversion system according to claim 16, wherein the color conversion device further includes:
(E) Among the second output color signals, C ′ ₄ out = 0, 0 ≦ C ′ ₁ out ≦ A fifth color reproduction region of the second input color signal corresponding to the output color signal consisting of 100, 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₃ out ≦ 100, and (f) the second output. Among the color signals, the second input color corresponding to the output color signal composed of C ′ ₁ out = 100, 0 ≦ C ′ ₂ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and C ′ ₄ out ≦ 100. (G) Among the second output color signals, C ′ ₂ out = 100, 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and 0 ≦ C _'4 into an output color signal consisting Out100, among the corresponding second seventh color reproduction area of the input color signal and (h) said second output color _{signal, C' 3 out = 100,0 ≦} C ' ₁ out ≦ 100, In an output color signal consisting of 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₄ out ≦ 100, a second four color reproduction regions consisting of an eighth color reproduction region of the corresponding input color signal, A fourth means for dividing and determining whether or not the first input signal before passing through the third means exists in the second four color reproduction regions;
When it is determined that the first input signal before the fourth passes through the third means exists in the second four color reproduction regions, the first input signal before passing through the third means C ₄ out_min calculating means for obtaining a C ₄ out_min component that minimizes the C ₄ out component of the first output signal corresponding to the second four color reproduction regions based on one input signal;
With
The color conversion system, wherein the C ₄ out determining means further determines a C ₄ out component of the first output signal based on the C ₄ out_min component. A three-dimensional first input color signal composed of three components C ₁ in, C ₂ in and C ₃ in is converted into four components composed of four components C ₁ out, C ₂ out, C ₃ out and C ₄ out. In a color conversion program for causing a color conversion device to execute a step of converting into a first output color signal of a dimension,
From the four-dimensional second output color signal consisting of four components of C ′ ₁ out, C ′ ₂ out, C ′ ₃ out and C ′ ₄ out, C ′ ₁ in, C ′ ₂ in and C ′ ₃ in Obtaining a mapping relationship to a three-dimensional second input color signal comprising the three components of:
The entire color reproduction area of the second input color signal corresponding to the second output color signal is: (a) Among the second output color signals, C ′ ₄ out = 100, 0 ≦ C ′ ₁ out ≦ A first color reproduction region of a second input color signal corresponding to an output color signal comprising 100, 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₃ out ≦ 100, and (b) the second output. Among the color signals, the second input color corresponding to the output color signal composed of C ′ ₁ out = 0, 0 ≦ C ′ ₂ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and C ′ ₄ out ≦ 100. (C) Among the second output color signals, C ′ ₂ out = 0, 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and 0 ≦ C 'An output color signal consisting of ₄ out100, a third color reproduction region of the corresponding second input color signal, and (d) of the second output color signal, C' ₃ out = 0, 0≤C ' ₁ out ≦ 100,0 ≦ C ' the out ≦ 100 and 0 ≦ C 'output color signal consisting of ₄ out ≦ 100, the four color reproduction area composed of the fourth color reproduction area of the corresponding second input color signal, after dividing the second A determination step of determining whether one input color signal exists in the four color reproduction regions;
As a result of the determination step, when the first input color signal is not present in the four color reproduction regions, the first input color signal is present in the four color reproduction regions. A compression step to compress,
A C ₄ out_max calculation step for obtaining a C ₄ out_max component that maximizes the C ₄ out component of the first output signal corresponding to the four color reproduction regions based on the first input color signal after the compression step; ,
Based on the C ₄ out - max component, and C ₄ out determination step of determining the C ₄ out components of said first output signal,
From the first input color signal after the compression step and the C ₄ out component after the C ₄ out determination step, the inverse transformation formula of the mapping relation is solved to obtain C ₁ out, C _{2 of} the first output signal. C ₁ C ₂ C ₃ out determining step for determining out and C ₃ out components;
To the color conversion device,
The components of the C ′ ₁ out, the C ′ ₂ out, the C ′ ₃ out, and the C ′ ₄ out are 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₂ out ≦ 100, and 0 ≦ C. ' ₃ out ≤ 100 and 0 ≤ C' ₄ out ≤ 100, where 0 is a minimum value with which the output device can output each component of the second output color signal as a color, and 100 is The output device is a maximum value that can output each component of the second output color signal as a color,
In the space of the second input signal, a vector going from the minimum value of the C ′ ₁ out component of the second output signal to the maximum value is set as vC _1, and the minimum value of the C ′ ₂ out component of the second output signal is maximized. The vector going to the value is vC ₂ , the vector going from the minimum value of the C ′ ₃ out component of the second output signal to the maximum value is vC _3, and the minimum value of the C ′ ₄ out component of the second output signal is the maximum Assuming that the vector going to the value is vC ₄ , the vectors vC ₁ , vC ₂ and vC ₃ are mutually independent vectors, and the vector vC ₄ is vC ₄ = a ₁ × vC ₁ + a ₂ × vC ₂ + a ₃ × A color conversion program having a relationship of vC ₃ , wherein a1, a2, and a3 are scalar amounts, and are in a range of a ₁ ≧ 0, a ₂ ≧ 0, and a ₃ ≧ 0. The color conversion program according to claim 18,
(E) Among the second output color signals, C ′ ₄ out = 0, 0 ≦ C ′ ₁ out ≦ A fifth color reproduction region of the second input color signal corresponding to the output color signal consisting of 100, 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₃ out ≦ 100, and (f) the second output. Among the color signals, the second input color corresponding to the output color signal composed of C ′ ₁ out = 100, 0 ≦ C ′ ₂ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and C ′ ₄ out ≦ 100. (G) Among the second output color signals, C ′ ₂ out = 100, 0 ≦ C ′ ₁ out ≦ 100, 0 ≦ C ′ ₃ out ≦ 100 and 0 ≦ C _'4 into an output color signal consisting Out100, among the corresponding second seventh color reproduction area of the input color signal and (h) said second output color _{signal, C' 3 out = 100,0 ≦} C ' ₁ out ≦ 100, In an output color signal consisting of 0 ≦ C ′ ₂ out ≦ 100 and 0 ≦ C ′ ₄ out ≦ 100, a second four color reproduction regions consisting of an eighth color reproduction region of the corresponding input color signal, A second discriminating step for discriminating whether or not the first input signal before the third step exists in the second four color reproduction regions after the division;
As a result of the second determination step, when the first input signal before the compression step exists in the second four color reproduction regions, based on the first input signal before the compression step, A C ₄ out_min calculating step for obtaining a C ₄ out_min component that minimizes the C ₄ out component of the first output signal corresponding to the second four color reproduction regions;
Is further executed by the color conversion device,
The color conversion program characterized in that the C ₄ out determination step further determines a C ₄ out component of the first output signal based on the C ₄ out_min component.

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