| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus of arithmetic decoding capable of processing binary images and multivalued images at low cost. SOLUTION: In the apparatus, four prediction state memories 181 to 184 enabling to be accessed independently and an arithmetic calculation part 106 are equipped, when decoding 4 bits image data, perfect four suites of pairs of prediction values 113 and 114, state values 115 and 116 or estimated probability values 133 and 134 corresponding to object pixels of four bit planes of the 4 bits image data are stored respectively in each bit plane of the four memories 181 to 184, and when decoding image data of less than 4 bits, the perfect suites of pairs of the prediction values 113 and 114, the state values 115 and 116, and the estimated values 133 and 134 corresponding to object pixels of each bit plane of the image data are divided to store into at least a part of the four memories 181 to 184. The suites corresponding respectively to the object pixels are read out sequentially from the four memories 181 to 184 so that the sequential pixels are decoded based on the values 113, 114 and 115, 116 or 133, 134 which are read out.
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