Image processing apparatus with improved compression of image data of character images and background images using respective different compressing methods

摘要

An edge image generating unit detects edges in an original image and generates an edge image from the edges. A connection pixel extracting unit extracts connection pixel sets in the edge image. A binary image generating unit classifies colors of the connection pixel sets into a predetermined number of achromatic target colors and a predetermined number of chromatic target colors if a color mode is set as color, and classifies the colors of the connection pixel sets into a predetermined number of achromatic target colors if the color mode is set as monochrome, where the number of the achromatic target colors set in the color mode of monochrome is larger than the number of the achromatic target colors in the color mode of color.

主权项

1. An image processing apparatus, comprising:
an edge image generating unit configured to detect edges in an original image and to generate an edge image formed by the detected edges; a connection pixel extracting unit configured to extract connection pixel sets in the edge image; a binary image generating unit configured to classify the connection pixel sets into target colors by classifying colors of the connection pixel sets into the target colors and generate character images which are binary images corresponding to the target colors, each one of the character images generated on the basis of the connection pixel sets of which the colors were classified into one of the target colors; a background image generating unit configured to generate a background image of the original image on the basis of the character images; and an image compressing unit configured to compress image data of the character images and image data of the background image using respective different compressing methods; wherein the binary image generating unit is further configured to classify the colors of the connection pixel sets into a predetermined number of achromatic target colors and a predetermined number of chromatic target colors if a color mode is set as color, and classify the colors of the connection pixel sets into a predetermined number of achromatic target colors if the color mode is set as monochrome; the number of the achromatic target colors set in the color mode of monochrome is larger than the number of the achromatic target colors in the color mode of color; and wherein the binary image generating unit is further configured so that if there are only a predetermined number or less of connection pixel sets of which the colors were classified into an original target color in the achromatic target colors and the chromatic target colors and are apart by at least a predetermined amount from an average of the colors classified into the original target color, the binary image generating unit re-classifies the predetermined number or less of the connection pixel sets into another target color.