COLOR REDUCTION PROCESSING APPARATUS, PRINTER CONTROL DEVICE, COLOR REDUCTION METHOD, AND PRINTER CONTROL METHOD

A color reduction processing apparatus and method reduce an original image containing many colors to a printable image containing few colors according to human color sensation. A conversion processing unit converts the pixel data for each pixel in an RGB color image (original image) to HLS data. A color reduction processor then generates print image data (the reduced-color image) reduced to a first color, second color, and a non-printing color by calculating the hue H, lightness L, and saturation S values of the HLS data based on specific parameters. These parameters can be set from an operating screen presented on a display. The original image and reduced-color image are presented on the display for verification by the user.