Image processing apparatus and image processing method

Abstract

A monochrome/color judgement is executed in an image processing apparatus such as a printer based upon man's visual characteristics with respect to each target pixel in an image. A reference value K is calculated based upon plural color component values in the target pixel, and then, a dispersed value a is obtained based upon the plural color component values. It is judged whether or not a color attribute of the target pixel satisfies a judging condition based upon K and α. If the judging condition is satisfied, the target pixel is judged to be a monochrome pixel, while, if the judging condition is not satisfied, the target pixel is judged to be a color pixel. When any one of pixels among a predetermined unit is a color pixel, color processing is executed, while monochrome processing is executed when all pixels constructing the predetermined unit are monochrome pixels. The judgement can be performed by referring to peripheral pixels. The judging object may be one portion of the image.