Stack-run coding for low bit rate image communication

We describe a new wavelet image coding approach in which a 4-ary symbol set with two contexts is used to represent significant coefficient values and the lengths of zero runs between coefficients. This algorithm works by raster scanning within subbands, and therefore involves much lower addressing complexity than other algorithms such as zerotree coding that require the creation and maintenance of intersubband dependencies across different decomposition levels. Despite its simplicity, and the fact that these dependencies are not explicitly utilized, the algorithm presented here is competitive with the recent refinements of zerotree coding. Stack-run coding can also be applied in the absence of entropy coding, resulting in an even lower complexity coder which in many cases performs within 1 dB PSNR of the entropy coded version.