Color separation into a plurality of ink components including primary color ink and spot color ink

Abstract

Utilizing an ink set that includes a plurality of chromatic primary color inks that, when used in combination, can reproduce achromatic color, and at least one spot color ink of hue different from any of the plurality of chromatic primary color inks. Color to be reproduced on a print medium according to any one input color is termed “reproduction color”, and the combination of ink quantities in the ink set for reproducing the reproduction color on the print medium is termed the “color separation ink quantity set.” The ink quantity of the spot color ink included in the color separation ink quantity set is adjusted in accordance with a lightness parameter value which is correlated to lightness of reproduction color, so as to reduce ink quantity at a rate of change greater than the rate of change of the lightness parameter in the direction of increasing brightness.

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of U.S. patent application Ser. No. 10 / 773,087, filed on Feb. 4, 2004, the disclosure of which is hereby incorporated by reference in its entirety.BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to a color printing technique employing a plurality of inks.

[0004] 2. Description of the Related Art

[0005] In recent years, color ink jet printers have come to enjoy widespread use as image output devices. A typical color ink jet printer employs, in addition to black (K) ink, several kinds of ink of the hues cyan C, magenta M, and yellow Y. Any color in a color image can be reproduced using these several kinds of ink.

[0006] In a printer of this kind, ink amounts of each useable ink are determined according to an arbitrary color of the color image. Herein, the process of determining ink amount of each ink used in printing for color reproduction in this manner will be referred to ...

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