Image processing apparatus

摘要

Regarding a color difference between a color of an original image on a pixel other than a connection pixel set in a rectangular area that is an inside area of a rectangle circumscribed to the connection pixel set and a color of the original image on a pixel in the connection pixel set, the binary image generating unit (a) identifies whether the connection pixel set is a character or non character by comparing a value of an index that indicates unevenness of the color differences with a color difference threshold value, (b) identifies whether a size of the rectangular area is small or large on the basis of a threshold value, and (c) sets the color difference threshold value as a value if the size of the rectangular area is small and as another different value if the size of the rectangular area is large.

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 by colors and generate respective character images which are binary images corresponding to the 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 regarding a color difference that is a difference between a color of the original image on a pixel other than the connection pixel set in a rectangular area that is an inside area of a rectangle circumscribed to the connection pixel set and a color of the original image on a pixel in the connection pixel set, the binary image generating unit is further configured (a) to identify whether the connection pixel set is a character or non character by comparing a value of a predetermined index that indicates unevenness of the color differences with a color difference threshold value, (b) to identify whether a size of the rectangular area is small or large on the basis of a predetermined threshold value, and (c) to set the color difference threshold value as a value if the size of the rectangular area is small and as another different value if the size of the rectangular area is large.