Abstract: A document processor comprises an image reader for reading a document sheet to output digital RGB signals, a color model converter that converts the RGB signals to HSV signals and YUV signals through arithmetic operations, and then attaches the YUV signals to the HSV signals of individual pixels, a color detector for detecting pixels of those colors to be subjected to image processing; and an image processing section consisting of a color converter, a color extractor and an area recognizer. The image processing section is previously registered with a number of colors to be subjected to image processing, wherein different contents of image processing are designated to respective colors, so the color converter, the color extractor and the area recognizer can carry out designated contents of image processing simultaneously on pixels of registered colors.