JPEG fixed image compression bit ordering method for a state word representing the state of a coefficient at the moment of entropy coding with several passes of the coefficient

摘要

The last bit N-1 indicates if the coefficient of a state word (s(c)) is significant, the value of this bit represents the sign of the word. The last but one bit N-2 of the state word is the coding bit. The indication provided by the value of the coding bit depends upon the value of the last bit of the state word. The state word indicates the coefficient has been coded at the start of the first entropy coding pass when the value of the coding bit is equal to the value of the last bit. A N bit state word (s(c)) represents the state of a coefficient (c) at the time of entropy coding with several passes of the coefficient. The state word has a bit indicating if the coefficient is significant, a bit indicating if the coefficient has been coded during the first pass and bits respectively indicating that neighboring coefficients (a-i) are significant when the value of bits is equal to 1.