Abstract: A first image is formed with at least a first color included in a first coloring system and corresponding to first color signal data converted from second signal data corresponding to at least a second color included in a second coloring system and related to an original image. At least a color modification parameter corresponding to a difference between the first color and a third color related to the original image. The color modification parameter is optimized to calculate a first area to be modified and a first amount to be modified with respect to the original image. A second image is formed using the second color signal data on the basis of the first area and amount to be modified and another first image already formed. Next, a third image is formed using the first color signal data, the third image corresponding to the second color. And, the second and third images are synthesized to form the first image.

Abstract: Color reproducing ranges of a CRT and a printer are divided to a plurality of sector areas which extend radially from a predetermined center point on an achromatic color axis (L* axis). For each sector area, a number of maximum distances of the color reproducing ranges of the CRT and the printer are measured from the predetermined center point. This maximum distance data are used to calculate a compression or expansion ratio for compressing the color reproducing range of the CRT into the color reproducing range of the printer, or vice-versa, the color reproducing range of the printer can be expanded into the color reproducing range of the CRT. With this compression or expansion ratio, the color space data of the CRT is compressed or expanded into the color reproducing range of the printer toward or away from the predetermined center point. Thus, it is possible to convert the color reproducing ranges of the CRT to that of the printer without losing a balance of luminosity and chroma.