Line based reduced memory, wavelet image compression

Abstract

In this work we propose a novel algorithm for wavelet based image compression with very low memory requirements. The wavelet transform is performed progressively and we only require that a reduced number of lines from the original image be stored at any given time. The result of the wavelet transform is the same as if we were operating on the whole image, the only difference being that the coefficients of different subbands are generated in an interleaved fashion. We begin encoding the (interleaved) wavelet coefficients as soon as they become available. We classify each new coefficient in one of several classes, each corresponding to a different probability model, with the models being adapted on the fly for each image. Our scheme is fully backward adaptive and it relies only on coefficients that have already been transmitted. Our experiments demonstrate that our coder is still very competitive with respect to similar state-of-the-art coders. It is noted that schemes based on zero trees or bit plane encoding basically require the whole image to be transformed (or else have to be implemented using tiling). The features of the algorithm make it well suited for a low memory mode coding within the emerging JPEG2000 standard.