Patent ID: 8861028

Claim:
A color-adjusting method to be used in a color conversion which converts colors of a first device into colors of a printer as a second device having a gamut being different from a gamut of the first device, for mapping out-gamut colors outside the gamut of the second device within the gamut of the second device in the color conversion, the method comprising: using a processor of a device which performs the color conversion to perform: a first step of representing the gamut of the second device on a plane defined by a lightness axis and a chroma axis at a hue in a color system, by using values obtained by color measurement of a color chart which has been outputted by the second device; a second step of obtaining a limiting value of a total quantity of color material which determines a total quantity of color material used when the second device outputs the color chart; a third step of dividing a region outside the gamut of the second device, based on a point of maximum chroma of the gamut of the second device and a white point and a black point of the gamut of the second device on the lightness axis, into a high-lightness region wherein lightness values are higher than a lightness value of the point of maximum of chroma and a low-lightness region wherein lightness values are lower than the lightness value of the point of maximum of chroma, and further dividing the low-lightness region, based on a reference point defined according to the limiting value of the total quantity of color material, into a low-chroma region and a medium-high-chroma region wherein chroma values of the low-chroma region are lower than chroma values of the medium-high-chroma region, the reference point being set between the lightness value of the point of maximum of chroma and a lightness value of the black point both located on the lightness axis; a fourth step of defining a gamut-mapping angle for mapping the out-gamut colors within the gamut of the second device, for each of the high-lightness region, the low-chroma region in the low-lightness region and the medium-high-chroma region in the low-lightness region, the gamut-mapping angle being defined as “lightness/chroma”; and a fifth step of adjusting a lightness value and a chroma value of each of the out-gamut colors no as to shift the each of the out-gamut colors in the plane at the gamut-mapping angle corresponding to a region which is one of the high-lightness region, the low-chroma region and the medium-high-chroma region and includes the each of the out-gamut colors, to perform mapping the out-gamut colors within the gamut of the second device.