A bi-level image coder for providing reduced bit rate arithmetic codes is disclosed, wherein each page of image to be coded is divided into a plurality of areas such as line groups, blocks, and an arithmetic coder codes each of input pixels (the pixel si) by using a predicted value of MPS (most probable symbol) and a predicted probability of LPS (least probable symbol) occurrence which are generated with a template and a LPS predicted probability table. The pixel attributes of the pixel si is determined to one of a character image attribute, a dither/dot image attribute and a halftoned image attribute based on statistical properties of the area of the pixel si. One of predetermined LPS predicted probability tables and one of predetermined templates are selected for each of the areas in operation. The coder may be so arranged as to following the JBIG standard. In one embodiment, a specific pixel of the template used for context data generation is moved to a position highly correlated with the pixel to be coded. <IMAGE>
Image coding method and system for providing reduced bit rate artihmetic codes