Abstract: An encoding and transmission method with at least two levels of quality of digital pictures, each digital picture being formed by at least one matrix of encoded picture elements, wherein each of the pictures is cut up into blocks of picture elements, a reversible mathematical transformation is applied to each of the blocks of picture elements, the coefficients of the transformed picture blocks are quantized and the quantized coefficients are encoded. The transformed coefficients are divided into at least two digital trains, the first train including basic coefficients enabling the reconstruction of a standard quality picture, and at least one second digital train including a set of complementary coefficients enabling the reconstruction of higher quality pictures, in combination with the basic coefficients of the first digital train and possibly the coefficients of other complementary digital trains, the digital trains being processed and/or used distinctly, during the encoding.

Abstract: A method for the regulation of the throughput of assistance data is provided. The assistance date assists in the reconstruction of subsampled moving electronic images. The method is particularly useful for HDTV transmission by a HMAC channel. For each elementary block of the image, an optimal processing operation is selected from first and second parallel processing operations. The second processing operation includes an image filter, and the first processing operation includes a motion compensation process. The first processing operation generates a larger data throughput rate of assistance data than the second processing operation. If the throughput rate of assistance data approaches or exceeds the maximum throughput rate permitted for a transmission unit, the second processing operation which produces a smaller data throughput rate is automatically selected.

Abstract: A method provides greater reduction in the throughput rate and, at the same time, greater fidelity to the configuration of an HD source image. The method is applied to a multiprocessing system wherein, within the picture or picture image blocks, "neutral" processing mode picture elements are determined, namely picture elements capable of accepting, without discrimination, at least two distinct sub-sampling processing modes; and it is chosen to associate, with each of the neutral processing mode picture elements, the one of the neutral processing modes that enables an optimal reduction in the throughput rate of the assistance data.