| 摘要 |
PURPOSE:To obtain a compressed picture with a desired compression ratio or error automatically by setting the compression ratio or the error as a parameter and obtaining an optimum Q factor corresponding to the set parameter through convergence calculation processing. CONSTITUTION:Initial values QU, QD are set for initial value setting processing 302 for a Q factor. The set Q factors QU, QD are used to apply compression processing to an interleaved picture 322 to obtain the corresponding compression ratios PU, PD. Two points (QU, PU) and (QD, PD) obtained by compression processing 306 are used to approximate the relation between the compression ratio and the Q factor by a linear equation and to calculate a coefficient of the equation. Then the Q factor Qi corresponding to the compression ratio P set by using the linear equation is calculated. A new Q factor using compression processing 312 is calculated in this way. The new Q factor is used to apply compression processing to the interleaved picture 322 and the compression ratio pi when the Q factor is Qi is obtained. |
