| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a variable length encoding method and variable length decoding method with which improvement of encoding efficiency in image encoding is attained. <P>SOLUTION: A variable length coding method is comprised of: a coefficient value scanning step in which an RL sequence generation unit 201, a reordering unit 202 and a binarization unit 203 scan coefficient values within a block in a predetermined scanning order starting at a high-frequency component toward a low-frequency component; and an arithmetic coding step in which an arithmetic coding unit 205 and a table storage unit 204 perform arithmetic coding on the absolute values of the coefficient values according to the scanning order used in the coefficient value scanning step, by switching between probability tables 1-4 for use, wherein, in the arithmetic coding step, a probability table to be used is switched to another probability table in one direction, when the arithmetic-coded absolute values of the coefficient values include an absolute value exceeding a predetermined threshold value. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
