Patent ID: 8305667

Claim:
A computer implemented method for forming a target color in an image, the target color being intermediate between a spot color and a second color, the method comprising: receiving CMYK colorant recipes for the spot color and the second color, and a mixture percentage value that indicates the proportion of the spot color relative to the second color; converting the device CMYK colorant recipes for the spot color and the second color to respective base sets of color space referencing component values; calculating a desired set of color space referencing component values corresponding to the target color based on the base sets of color space referencing component values of the spot color and the second color, and the mixture percentage value that indicates the proportion of the spot color relative to the second color; determining a particular CMYK colorant recipe that produces the set of color space referencing component values for the target color; and forming an output image containing the target color, wherein: the step of determining the particular CMYK colorant recipe comprises the further steps of: fixing a K n value for the recipe according to the formula: K n =K 0 +n·(K 1 −K 0 ); and selecting C n , M n , and Y n values corresponding to K n that produce the desired color space referencing component values, where n is a mixture percentage value of the two colors, K 1 is a K colorant of the spot color, and K 0 is a K colorant of the second color.