1. A method of processing, comprising: accepting an ordered series of quantized transform coefficients of a block of image data; classifying the accepted series into a class of a plurality of pre-defined classes according to one or more factors including the size of the block of image data; applying one of a plurality of pre-defined entropy coding methods to the accepted ordered series to form a sequence of codewords, the entropy coding method applied being according to the class of the accepted series, wherein for at least two different pre-defined classes of ordered series of different sizes, different pre-defined entropy coding methods are applied to the different pre-defined classes.