Method for printing a color image which includes black ink

Abstract

In color printing, for example, a color image is generally picked up by a color camera, image scanner and is processed by an image processor and a processing result is obtained as a full color image by a color printer. Some color printers use three different color inks of yellow, magenta and cyan and other printers use black in addition to those inks. Black ink is outputted to print a black area of the colored image and allotment of yellow, magenta or cyan inks is formed on at least part of the black area. Allotment and output of each of the color inks onto the black ink is determined by a color matrix table which defines a color ink output rule. The color matrix table also contains matrix elements for not outputting any of the color of inks. The black ink is output in accordance with a dither matrix table which is an array of thresholds defining where to form the black ink dots in the black area of the color image dependently of the color density levels of colors in the colored image so that the double output of the black ink and the level magenta or cyan inks determined by the color matrix is carried out in accordance with the color density levels of the colors in the colored image. In addition the colored inks can be applied onto the black ink dots not only in a color matrix table but also by the use of random numbers, that is by random selection of the colored inks.