Image encoding apparatus and method with both lossy and lossless means

Abstract

This invention is to generate encoded data within a target amount. A first encoding unit generates lossy encoded data of each pixel block by using a quantization matrix Qi specified by a parameter i. A second encoding unit generates lossless encoded data of each pixel block. Let Lx be the lossless encoded data length, and Ly be the lossy encoded data length. A control unit determines, using a nonlinear boundary function fi,j( ) specified by the parameters i and j, whether condition: Ly<fi,j(Lx) is satisfied and stores the determination result as history information in a history memory unit. One of the two encoded data is stored in a memory based on the determination result. If the encoded data amount stored in the memory has exceeded the target amount, the control unit updates at least one of the encoding parameters i and j on the basis of the history information.

Dependencies are inferred from the claim text.