To solve the problem wherein a monitor and a printer become different from each other in a color gamut profile depending on hue when a color gamut is compressed, intensity and saturation may be much reduced in color reproducibility when hue is retained, a method for compressing the color gamut as hue is changed so as to improve color reproducibility as a whole is employed in the case in which the intensity and saturation are much reduced in color reproducibility, two or more color signals located on an iso-hue line before the color gamut is compressed get staying off the iso-hue line to cause a perceptive color shift after the color gamut is compressed.
The hue change value of a primary color is determined from the profiles of a first and a second color gamut so as to decide the degree of rotation of a hue (S1-S3), the L*a*b* values of input color signals are converted into an HVC color system value (S4), the hue difference of a primary color between a first and a second color gamut is calculated (S5), a hue change value HP is calculated (S6), input color signals other than the primary color in the first color gamut are changed in hue (S7), the hues of the input color signals are rotated by the use of a hue change value Hin (S8), and the color signals whose hues are rotated are converted into an L*a*b* color system value (S9).
Shiro Takayanagi
Yasuhiro Otsuka
Shuji Kimura