Color conversion definition creating method, color conversion definition creating apparatus, and color conversion definition creating program storage medium

• US 7,403,315 B2
• Filed: 04/04/2003
• Issued: 07/22/2008
• Est. Priority Date: 04/04/2002
• Status: Expired due to Fees

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Tsuji, Tetsuya, Tamagawa, Kiyomi
• Primary Examiner(s): Nguyen; Madeleine A
• Application Number:
  US10/406,549
• Publication Number:
  US 20030189716A1
• Time in Patent Office: 1,936 Days
• Field of Search: 358/1.9, 358/523, 358/518, 358/520, 358/522, 358/534, 358/539, 358/1.16, 382/167, 382/162
• US Class Current: 358/523
• CPC Class Codes: H04N 1/6008 with primary colour signals, e.g. RGB or CMY(K)
• CPC Class Codes: H04N 1/6011 with simulation on a subsidiary picture reproducer H04N1/622 takes precedence; matching two or more picture reproducers H04N1/6052
• CPC Class Codes: H04N 1/6022 Generating a fourth subtractive colour signal, e.g. under colour removal, black masking
• CPC Class Codes: H04N 1/6027 Correction or control of colour gradation or colour contrast H04N1/6058 takes precedence
• CPC Class Codes: H04N 1/6052 Matching two or more picture signal generators or two or more picture reproducers
• CPC Class Codes: H04N 1/6058 Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut

Abstract

A color conversion definition (CCD) creating method of creating CCD converting coordinate points within a color reproduction area (CRA) of 1st device mediating between an image and image data, in 1st RGB color space, depending on 1st device, into coordinate points within CRA of printing in CMYK color space for printing, has 1st CCD creating step of creating 1st CCD for converting the coordinate points within CRA of 1st device in 1st RGB color space into coordinate points within CRA of 2nd device mediating between an image and image data, in 2nd RGB color space, depending on 2nd device, CRA of 2nd device being closer to CRA of the printing than 1st device, and 2nd CCD creating step of creating 2nd CCD for converting the coordinate points within CRA of 2nd device in 2nd RGB color space into coordinate points within CRA of printing in CMYK color space.

Claims

1. A color conversion definition creating method of creating a color conversion definition converting coordinate points within a color reproduction area of a first device mediating between an image and image data, in a first RGB color space, depending on the first device, into coordinate points within a color reproduction area of printing in a CMYK color space for printing, the color conversion definition creating method comprising:

a first color conversion definition creating step of creating a first color conversion definition for converting the coordinate points within the color reproduction area of the first device in the first RGB color space into coordinate points within a color reproduction area of a second device mediating between an image and image data, in a second RGB color space, depending on the second device, the color reproduction area of the second device being closer to the color reproduction area of the printing than the first device; and

a second color conversion definition creating step of creating a second color conversion definition for converting the coordinate points within the color reproduction area of the second device in the second RGB color space into coordinate points within a color reproduction area of printing in a CMYK color space,

wherein the first color conversion definition creating step is a step of creating a color conversion definition defining an association between the coordinate points in the first RGB color space and the coordinate points in the second RGB color space via a first coordinate conversion step, a second coordinate conversion step, and a third coordinate conversion step,

the first coordinate conversion step converting coordinate points within the color reproduction area of the first device in the first RGB color space depending on the first device into the coordinate points within the color reproduction area of the first device transferred to a common color space of device non-dependence,

the second coordinate conversion step converting the coordinate points within the color reproduction area of the first device transferred to the common color space, which is obtained by the first coordinate conversion step, into the coordinate points within the color reproduction area of the second device transferred to the common color space, and

the third coordinate conversion step converting the coordinate points within the color reproduction area of the second device transferred to the common color space, which is obtained by the second coordinate conversion step, into the coordinate points within the color reproduction area of the second device in the second RGB color space, and

wherein when a first coordinate point within the color reproduction area of the first device transferred to the common color space is converted into a second coordinate point within the color reproduction area of the second device transferred to the common color space, the second coordinate conversion step includes a first step of;

determining a first reference coordinate point in the color reproduction area of the first device transferred to the common color space, in accordance with the first coordinate point;

determining a second reference coordinate point associated with the first reference coordinate point, in the color reproduction area of the second device transferred to the common color space, in accordance with a first algorithm including a coordinate operation in at least either one of the first RGB color space and the second RGB color space; and

determining the second coordinate point associated with the first coordinate point in accordance with a second algorithm using a basic difference vector that is representative of a difference between the first reference coordinate point and the second reference coordinate point.

2. A color conversion definition creating method of creating a color conversion definition converting coordinate points within a color reproduction area of a first device mediating between an image and image data, in a first RGB color space, depending on the first device, into coordinate points within a color reproduction area of printing in a CMYK color space for printing, the color conversion definition creating method comprising:

a first color conversion definition creating step of creating a first color conversion definition for converting the coordinate points within the color reproduction area of the first device in the first RGB color space into coordinate points within a color reproduction area of a second device mediating between an image and image data, in a second RGB color space, depending on the second device, the color reproduction area of the second device being closer to the color reproduction area of the printing than the first device; and

a second color conversion definition creating step of creating a second color conversion definition for converting the coordinate points within the color reproduction area of the second device in the second RGB color space into coordinate points within a color reproduction area of printing in a CMYK color space,

wherein the second color conversion definition creating step comprises;

a first conversion step of converting coordinate points in the second RGB color space into coordinate points within the common color space of device non-dependence in accordance with a color reproduction quality of the second device;

a second conversion step of converting the coordinate points within the common color space determined in the first conversion step into coordinate points within a CMY color space;

a first K-function creating step of setting up a first color conversion parameter and determining a first function of K from coordinate points of C=M=Y of coordinate points in the CMY color space determined in the second conversion step in accordance with a data conversion algorithm for converting the coordinate points in the CMY color space into coordinate points in the CMYK color space having a printability according to the first color conversion parameter set up;

a first association creating step of determining coordinate points within the CMYK color space bound by the first function of K determined in the first K-function creating step, associated with coordinate points of C=M=Y of the coordinate points within the CMY color space determined in the second conversion step, in accordance with a color reproduction quality of the printing, so that a first association for providing an association between the coordinate points in the CMY color space of C=M=Y and the coordinate points in the CMYK color space is determined;

a second K-function creating step of setting up a second color conversion parameter based on the first association determined in the first association creating step instead of the first color conversion parameter, on the data conversion algorithm, and determining a second function of K from the coordinate points consisting of an arbitrary combination of C, M and Y in the CMY color space determined in the second conversion step, in accordance with the data conversion algorithm on which the second color conversion parameter is set up; and

a second association creating step of determining coordinate points in the CMYK color space bound by the second function of K determined in the second K-function creating step, associated with the same coordinate points as the coordinate points in the common color space associated with the coordinate points consisting of an arbitrary combination of C, M and Y in the CMY color space determined in the second conversion step, in accordance with a color reproduction quality of the printing, so that a second association for providing an association between the coordinate points consisting of an arbitrary combination of C, M and Y in the CMY color space and the coordinate points in the CMYK color space is determined.

3. A color conversion definition creating method of creating a color conversion definition converting coordinate points within a color reproduction area of a first device mediating between an image and image data, in a first RGB color space, depending on the first device, into coordinate points within a color reproduction area of printing in a CMYK color space for printing, the color conversion definition creating method comprising:

a first color conversion definition creating step of creating a first color conversion definition for converting the coordinate points within the color reproduction area of the first device in the first RGB color space into coordinate points within a color reproduction area of an imaginary second device mediating between an image and image data, in a second RGB color space, depending on the imaginary second device, the imaginary second device having a color reproduction area that is coincident with the color reproduction area for printing; and

a second color conversion definition creating step of creating a second color conversion definition for converting the coordinate points within the color reproduction area of the second device in the second RGB color space into coordinate points within a color reproduction area of printing in a CMYK color space,

wherein the second color conversion definition creating step comprises;

a first conversion step of converting coordinate points in the second RGB color space into coordinate points within the common color space of device non-dependence in accordance with a color reproduction quality of the second device;

a second conversion step of converting the coordinate points within the common color space determined in the first conversion step into coordinate points within a CMY color space;

a first K-function creating step of setting up a first color conversion parameter and determining a first function of K from coordinate points of C=M=Y of coordinate points in the CMY color space determined in the second conversion step in accordance with a data conversion algorithm for converting the coordinate points in the CMY color space into coordinate points in the CMYK color space having a printability according to the first color conversion parameter set up;

a first association creating step of determining coordinate points within the CMYK color space bound by the first function of K determined in the first K-function creating step, associated with coordinate points of C=M=Y of the coordinate points within the CMY color space determined in the second conversion step, in accordance with a color reproduction quality of the printing, so that a first association for providing an association between the coordinate points in the CMY color space of C=M=Y and the coordinate points in the CMYK color space is determined;

a second K-function creating step of setting up a second color conversion parameter based on the first association determined in the first association creating step instead of the first color conversion parameter, on the data conversion algorithm, and determining a second function of K from the coordinate points consisting of an arbitrary combination of C, M and Y in the CMY color space determined in the second conversion step, in accordance with the data conversion algorithm on which the second color conversion parameter is set up; and

a second association creating step of determining coordinate points in the CMYK color space bound by the second function of K determined in the second K-function creating step, associated with the same coordinate points as the coordinate points in the common color space associated with the coordinate points consisting of an arbitrary combination of C, M and Y in the CMY color space determined in the second conversion step, in accordance with a color reproduction quality of the printing, so that a second association for providing an association between the coordinate points consisting of an arbitrary combination of C, M and Y in the CMY color space and the coordinate points in the CMYK color space is determined.