A system and process for encoding and later decoding of bi-level images that
does
not use arithmetic coding, but whose performance is close to that of state-of-the-art
coders such as JBIG, JBIG-2, and JB2. In general, the present bi-level coder (BLC)
uses two context-based adaptive modules: 1) an adaptive predictor controlled by
low-resolution probability estimates that is used to map the original pixels explicitly
into prediction error pixels, and 2) a backward-adaptive Run-Length-Rice (RLR)
coder that encodes the prediction error pixels. 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 other current coders.