Fast Adaptive Encoder for Bi-Level Images

We present a new bi-level image compression coder that does not use arithmetic encoding, but whose performance is close to that of state-of-the-art coders such as JBIG, JBIG-2, and JB2. The proposed bi-level coder (BLC) uses two simple adaptation rules: the first to compute context-dependent probability estimates that control a pixel prediction module, and the second to adjust a run-length parameter in a Run-Length-Rice (RLR) coder. That’s contrary to the usual approach where the context-dependent probability estimate controls both pixel prediction and adaptive entropy coding. Due to its simplicity, in many applications BLC may be a better choice than JBIG or JBIG-2.