Context-based arithmetic encoding/decoding method and apparatus

摘要

An apparatus encodes a binary shape signal by using a modified context-based arithmetic encoding technique. The apparatus computes a context number of each binary pixel in the binary shape signal based on its corresponding context. Then, a probability corresponding to the context number is detected and a state of each binary pixel is determined by comparing the probability with a preset threshold value. Furthermore, a predicted pixel value corresponding to each binary pixel is decided based on the probability. The predicted pixel value is compared with an original pixel value of each binary pixel to thereby output a mapping value representing whether the predicted pixel value is identical to the original pixel value or not. The apparatus generates a first and a second sequences by rearranging the mapping values of the binary pixels in the binary shape signal according to the states of the binary pixels and assigns adaptive probability sets to the first and the second sequences, respectively. The first and the second sequences are arithmetically encoded based on the adaptive probability sets to thereby produce an encoded binary shape signal.