COLOR PROCESSING METHOD AND APPARATUS THEREOF

Abstract

When the color gamut of a printer is further expanded, if the same gamut expansion processing as in the prior art is applied, the chroma level becomes too high beyond necessity, resulting in extremely vivid colors. Hence, less than a favorable image is obtained. To solve this problem, information of each of an input gamut and output gamut is input, an expanding method of the input gamut is set, and an expanded gamut is generated by expanding the input gamut by that expanding method. Based on the information of the expanded gamut and output gamut, conversion characteristics required to convert the color values of the expanded gamut to those of the output gamut are calculated.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an exemplary arrangement of a color processing apparatus;

FIG. 2 is a flowchart showing details of processing to be executed by an arithmetic unit of the color processing apparatus;

FIG. 3 shows an example of a gamut expansion restriction setting window;

FIGS. 4A and 4B are graphs illustrating the relationship between gamut expansion restrictions and chroma conversion functions generated based on gamut expansion restriction parameters;

FIG. 5 is a flowchart illustrating an exemplary calculation method of gamut expansion restriction parameters by the arithmetic unit;

FIG. 6 is a flowchart illustrating conversion processing by the arithmetic unit;

FIGS. 7A and 7B are graphs showing examples of chroma conversion functions; and

FIGS. 8A and 8B are graphs showing examples of lightness conversion functions.

Claims

1. A color processing method comprising: inputting information of an input gamut and an output gamut;setting an expanding method of the input gamut;generating an expanded gamut by expanding the input gamut by the expanding method; andcalculating conversion characteristics required to convert color values of the expanded gamut into color values of the output gamut based on information of the expanded gamut and information of the output gamut.

2. The method according to claim 1, wherein the information of each of the input gamut and the output gamut is information indicating a boundary of a color gamut and includes information indicating at least a lightness range of the color gamut and maximum chromas on a plurality of hue planes.

3. The method according to claim 2, wherein the expanding method includes at least one of automatic designation, user designation, and user designation for respective hues, and when the automatic designation is set, a reproduction target chroma and maximum chromas of the input gamut and the output gamut are acquired from each of the plurality of hue planes, and a maximum chroma of the expanded gamut on a hue plane of interest is set based on a relationship between the reproduction target chroma and the maximum chromas so as to generate the expanded gamut.

4. The method according to claim 3, wherein the maximum chroma of the expanded gamut is larger than the reproduction target chroma and is smaller than the maximum chroma of the output gamut or equal to the maximum gamut of the input gamut.

5. The method according to claim 2, wherein the conversion characteristics include a chroma conversion function based on the maximum chromas of the input gamut and the expanded gamut, and a lightness conversion function based on lightness ranges of the input gamut and the output gamut.

6. A color processing apparatus comprising: an input section, arranged to input information of an input gamut and an output gamut;a setting section, arranged to set an expanding method of the input gamut;a generator, arranged to generate an expanded gamut by expanding the input gamut by the expanding method; anda calculator, arranged to calculate conversion characteristics required to convert color values of the expanded gamut into color values of the output gamut based on information of the expanded gamut and information of the output gamut.

7. A computer-executable program stored on a computer-readable storage medium comprising program code causing a computer to perform a color processing method, the method comprising: inputting information of an input gamut and an output gamut;setting an expanding method of the input gamut;generating an expanded gamut by expanding the input gamut by the expanding method; andcalculating conversion characteristics required to convert color values of the expanded gamut into color values of the output gamut based on information of the expanded gamut and information of the output gamut.

8. A computer-readable storage medium storing a computer-executable program causing a computer to perform a color processing method, the method comprising: inputting information of an input gamut and an output gamut;setting an expanding method of the input gamut;generating an expanded gamut by expanding the input gamut by the expanding method; andcalculating conversion characteristics required to convert color values of the expanded gamut into color values of the output gamut based on information of the expanded gamut and information of the output gamut.