APPARATUS AND METHOD FOR COLOR IMAGE PROCESSING

PROBLEM TO BE SOLVED: To obtain a color reproducing range of a maximum limit by allowing a total toner quantity limit to be compatible without a color saturation decrease in a low density part by permitting a color removal of 100% of a gray color in a color image processing unit. SOLUTION: An apparatus for color image processing includes a color image signal conversion means having a color image signal converting means for converting input image signals of three colors of cyan, magenta and yellow, or four colors of cyan, magenta, yellow and black. The color image signal conversion means has a means 22 for selecting the minimum value k of the input image signals of the three colors to a black output image signal; and means 26-31 for subtracting the minimum value k from the input image signals of the three colors, and multiplying the subtracted result by a multiplier f(k) determined depending upon the minimum value k to the output image signals of the cyan, the magenta and the yellow. The multiplier f(k) is given by f(k)≤Amaxfor a positive constant Amaxof Amax