A coding method for an ordered series of quantized transform coefficients of a block of image data, including a context adaptive position coding process to encode the position of clusters of non-zero-valued coefficients, e.g., a multidimensional position coder that uses one of a plurality of code mappings selected according to at least one criterion including at least one context-based criterion, and an amplitude encoding process to encode any amplitudes remaining to be coded, the amplitude coding using one or a plurality of amplitude code mappings selected according to at least one criterion, including a context-based criterion. A context-based selection criterion means a criterion that during encoding is known or derivable from one or more previously encoded items of information. Also a coding apparatus, a decoding apparatus, a computer readable medium configured with instructions that when executed implement a coding method, and another medium for a decoding method.