PATTERN MATCHING CODING DEVICE USING PATTERN MATCHING AND CODING METHOD THEREFOR

Image data is separated to character region and image region in a character/image separating portion (102). A mark is cut off from the character region by a mark cut-off portion (103). The image region is inputted to both the mark cut-off portion and an image period determining portion (104). The image period determining portion determines the period of grid image and dither image in the image region and notifies that period information to the mark cut-off portion. The mark cut-off portion cuts off the mark from an image in accordance with the period information. The mark cut-off by the mark cut-off portion is accumulated in an accumulating portion (106) for use as a library and it is determined whether or not there is a match library in old libraries by a match determining portion (105). If the match determining portion determines that there is a match library, it sends both the mark and match library to a coding portion (107). The coding portion carries out arithmetic coding by using a template for referring to the mark and reference match library at the same time.