Abstract: An image processing method is used to converting a color within a first color reproduction range that is a device-independent color space into a color within a second color reproduction range that is a color reproduction range of an output device. The image processing method includes defining, within the first color reproduction range, a third color reproduction range of a color that is estimated to be input; defining, within the second color reproduction range, a fourth color reproduction range that is smaller than the second color reproduction range; and, in performing the color conversion, compressing a color within the third color reproduction range into a color within the fourth color reproduction range and compressing a color within the first color reproduction range and outside the third color reproduction range into a color within the second color reproduction range and outside the fourth color reproduction range.

Abstract: The gamut of a printer has poor saturation reproducibility in a low-lightness region, often has a shape from which the gamut is cut away, and sometimes locally forms a part having extremely low color reproducibility. Hence, upon converting colors on a first gamut onto those on a second gamut, a third gamut is generated by transforming the second gamut for the purpose of the conversion, and the colors on the first gamut are mapped onto the third gamut. The colors on the first gamut are converted into those on the second gamut based on the mapping result.

Abstract: In order to implement satisfactory color reproduction which effectively uses the gamut of an output device without causing any tone burning-out in only a specific gamut, a gamut that can attain colorimetrically approximate mapping must be set in consideration of the characteristics of colors and gamuts. Hence, upon converting a first gamut onto a second gamut, a third gamut having a shape according to the characteristics of the color or gamut is set inside the second gamut. The first gamut included in the third gamut is mapped onto the second gamut which is colorimetrical matching or approximate to the first gamut. The first gamut outside the third gamut is mapped onto the second gamut outside the third gamut.

Abstract: Three primary color points are defined to determine a working color space such that the working color space includes all colors in the color reproduction range of a printer. In addition, the luminance of a white point and a standard light source is defined. A transformation matrix is determined on the basis of these points. The transformation matrix associates an RGB working color space with a color space in the XYZ color system to define the RGB working color space. Thus, when compression gamut mapping is performed on the working color space, colors in the working color space can be mapped to any colors in the color reproduction range of a printer, without dropping any colors reproducible by the printer.