IMAGE ENCODER, IMAGE ENCODING METHOD, IMAGE DECODER, IMAGE DECODING METHOD, AND DATA RECORDING MEDIUM

摘要

An image encoder has, as shown in the figure, a block forming device (2) which divides image signals composed of a plurality of pixel values corresponding to one image display region into blocks corresponding to the blocks comprising predetermined number of pixels respectively and outputs the predetermined number of pixels each constituting the image signal of each block in units of one block, a pixel value replacing means which replaces the pixel values of unencoded pixels among peripheral pixels positioned around encoded pixels with pseudo pixel values which are obtained from the pixel values of the encoded pixels among the peripheral pixels in accordance with a predetermined rule, and an encoding device (16a) which receives image signals composed of a plurality of pixel values corresponding to the respective blocks, performs the encoding processing by which the pixel values of each block are successively encoded in accordance with the pixel values of the encoded pixels and the pseudo pixel values of the unencoded pixels, and outputs image encoding signals. By the image encoder (101) constituted like this, an adaptive encoding processing of each pixel and an encoding processing of each block can be combined without marring the correlation between the pixel values of the unencoded pixels and the pixel values of the encoded pixels, while preventing the decoding of the encoded signal. Hence, the influence of the transmission error can be converged for each block and the encoding efficiency can be improved in comparison with the efficiency of a simple encoding processing for each block. On the decoding side, the encoded signal can be decoded correctly while the deterioration of the prediction efficiency of the encoded pixels is avoided.