Abstract: A two-dimensional data array, such as an orthogonally scanned television image, is divided into a multiplicity of elemental blocks each containing a given number of PCM samples which are converted by linear transformation into a series of coefficients to be quantized for transmission to a remote receiver. The data blocks are processed one at a time by an iterative coder which allots a progressively increasing number of bits to a given block in successive operating stages, the bits being allocated to the several coefficients of the block according to the position of the barycenter of their signal energy assigning the block to one of K classes. An initial overall reconstruction error, computed from the coefficients of a block with no bits yet available for quantization, is updated with each bit allotment in the course of an iteration in which a selected coefficient is subjected to simultaneous coding with S quantizers differing from one another in their quantum steps.