Image processing method, image processing apparatus and data recording medium

An image processing apparatus for performing block-by-block decoding of a coded image signal that is obtained by performing a coding processing including frequency transformation to a digital image signal, for each of blocks constituting a single display screen, said apparatus comprising:

• a variable-length decoding unit for performing variable-length decoding to a coded string that is obtained by performing inter-frame prediction, intra-frame prediction, frequency transformation, quantization, rearrangement, and variable-length coding to an image signal corresponding to each block;
• inverse scanning means including plural inverse scanners having different orders of rearrangement, and each rearranging quantized values which have been rearranged in coding so that the order of the quantized values is returned to the order before the rearrangement, the inverse scanning means selecting an inverse scanner to be used for rearranging the quantized values, according to a scan changing signal which is generated outside/inside a system, and inter-frame prediction information indicating the kind of inter-frame prediction and intra-frame prediction information indicating the kind of intra-frame prediction in coding;
• intra-frame prediction means for generating intra-frame predicted values of quantized values corresponding to a decoding target block from quantized values corresponding to an already decoded block located in the vicinity of the decoding target block, according to the intra-frame prediction information, and outputting the result of addition between the output of the inverse scanning means and the intra-frame predicted values;
• inter-frame prediction means for performing inter-frame prediction to the output of the intra-frame prediction means on the basis of the inter-frame prediction information, to generate an image signal corresponding to each block;
• and
• an inverse blocking unit for inverse-blocking the image signals of the respective blocks according to frequency transformation type information indicating a processing unit of frequency transformation in coding, to output a digital image signal;
• and
• said inverse scanning means being constructed so that switching is performed, on the basis of flag information indicating switching of rearrangement, which information is input together with an input signal of the decoding target block that is obtained by coding various frequency components which have been subjected to the inter-frame prediction process and the intra-frame prediction process in a prescribed order, between the first rearrangement operation in which the input signal is subjected to adaptive rearrangement in an order according to the kinds of both the prediction processes, and the second rearrangement operation in which the input signal is subjected to rearrangement in a specific order, regardless of the kinds of both the prediction processes.

A method for decoding a coded image signal obtained by coding a digital image signal on a block basis, said method comprising:

• decoding the coded image signal to obtain frequency components of a decoding target block to be subjected to decoding;
• selecting one rearrangement operation from a first rearrangement operation in which the frequency components are subjected to adaptive rearrangement and second rearrangement operation in which the frequency components are subjected to rearrangement in a specific order, on a basis of rearrangement operation selecting information;
• performing rearrangement to the frequency components of the decoding target block, based on the selected one rearrangement operation;
• generating an intra-frame predicted value for the frequency components of the decoding target block from frequency components of an already decoded block located in a vicinity of the decoding target block;
• and
• predictive decoding the frequency components of the decoding target block by using the intra-frame predicted values.