An encoding device for a flow of digital images comprises:a working memory (42) for already decoded image blocks data, a pilot (40), mounted to analyze an incidental flow of data of digital images, and arranged to determine data to be decoded of a current block, said data to be decoded being of the complete data type or of the parameters-data type, to store the complete data in the working memory (42) as already decoded image blocks data, and to call a decoding unit (48) with the parameters-data, the decoding unit (48) reacting to the reception of parameters-data by: selecting some already decoded image blocks, forming an approximation base, which borders the current block according to a selected rule, calculating an approximation of the current block, based on a linear algebraic function of the approximation base data, and storing in the working memory (42), for the current block, already decoded image blocks data derived from this approximation.