US Patent 7262882 Distribution curve generating device

A plurality of color signals indicative of a plurality of color patterns are processed based on a first distribution curve to distribute the original color signals into color signals for normal ink and color signals for light ink. Then, the plurality of color patterns are printed by the color signals for normal ink and color signals for light ink. Then, the density of each color pattern is detected to produce a density curve. A second distribution curve is produced based on the detected density, the original color signals, and the first distribution curve so that the second distribution curve can attain a properly linearly-changing density curve. By preparing beforehand a plurality of first distribution curves dependently on a variety of usage conditions of the printer, it is possible to use a second distribution curve that is in conformity to the usage condition, under which the printer is desired to be driven, by selecting a distribution curve that corresponds to the usage condition.