Storing coding image data in storage of fixed memory size

This patent specification contains material that is subject to copyright protection. The copyright owner has no objection to the reproduction of this patent specification or related materials from associated patent office files for the purposes of review, but otherwise reserves all copyright whatsoever. An apparatus includes a DCT unit for transforming blocks of pixels into respective blocks of transform coefficients, entropy encoders for encoding respective partitions of the DCT blocks where at least one partition comprises bit-plane data from each block of transform coefficients, and a scan output manager for storing the entropy encoded partitions in a buffer of fixed memory size. The manager manages the storing of the coded partitions in the buffer whereby during the storing of the coded partitions if it is determined the buffer is full, a coded least perceptually significant partition currently stored in the buffer is overwritten by data from a coded more perceptually significant partition.