Color conversion matrix forming method, color conversion table forming method, and program

• US 20050073707A1
• Filed: 09/13/2004
• Published: 04/07/2005
• Est. Priority Date: 10/01/2003
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Yamazoe, Manabu
• Granted Patent: US 7,414,754 B2
• Time in Patent Office: Days
• US Class Current: 358/1.900
• CPC Class Codes: H04N 1/6033 using test pattern analysis H04N1/6055 takes precedence

Abstract

A method of easily obtaining a color conversion matrix serving as a foundation of color reproduction at a high speed irrespective of its degree is provided. The method has: a step of constructing nth-degree matrix coefficients regarding a first color space of a plurality of color patch data sets and obtaining a pseudo inverse matrix to the obtained matrix; and a step of forming a color conversion matrix from a product of a matrix constructed by color data regarding a second color space of the color patch data sets and the pseudo inverse matrix.

Claims

1. A method of calculating a color conversion matrix for allowing color data in a first color space regarding a plurality of color patch data to correspond to color data in a second color space, comprising the steps of:

forming a pseudo inverse matrix of a matrix constructed by the color data in said first color space when the number of said color patch data does not coincide with the total number of components of said color conversion matrix; and

calculating said color conversion matrix by using said pseudo inverse matrix and a matrix constructed by the color data in said second color space.

2. A method according to claim 1, wherein the color data in said first color space is device color data of an input device and the color data in said second color space is CIEXYZ data.

3. A method according to claim 1, wherein the color data in said first color space is CIEXYZ data and the color data in said second color space is device color data of an output device.

4. A method according to claim 1, wherein the matrix constructed by the color data in said first color space includes a higher-degree term of the color data in said first color space.

5. A method according to claim 1, wherein in the matrix constructed by said color data, the number of row components of the matrix regarding the color patch data to which importance should be attached is increased to a value larger than the number of row components of the matrix regarding the other color patch data.

6. A method of forming a color conversion table of a color profile for defining a device color from an optimum color conversion matrix for allowing color data in a first color space regarding a plurality of color patch data to correspond to color data in a second color space, comprising the steps of:

forming a pseudo inverse matrix of a matrix constructed by the color data in said first color space when the number of said color patch data does not coincide with the total number of components of said color conversion matrix;

calculating said color conversion matrix by using said formed pseudo inverse matrix and a matrix constructed by the color data in said second color space; and

forming said color conversion table by using said color conversion matrix.

7. A program, stored on a computer readable medium, for obtaining a color conversion matrix for allowing color data in a first color space regarding a plurality of color patch data to correspond to color data in a second color space, comprising:

a code for forming a pseudo inverse matrix of a matrix constructed by the color data in said first color space when the number of said color patch data does not coincide with the total number of components of said color conversion matrix; and

a code for calculating said color conversion matrix by using said formed pseudo inverse matrix and a matrix constructed by the color data in said second color space.