Producing a compressed digital image organized into layers corresponding to increasing visual quality levels and providing rate-control of such compressed digital image

Abstract

A method for producing a compressed digital image from an input digital image is disclosed, wherein the compressed digital image is organized into layers corresponding to increasing visual quality levels. The input digital image is decomposed to produce a plurality of subbands, each subband having a plurality of subband coefficients. The plurality of subband coefficients of each subband of the decomposed input digital image are quantized to produce a quantized output value for each subband coefficient of each subband. At least one bit-plane is formed from the quantized output values of the subband coefficients of each subband. Each bit-plane of each subband in at least one pass is entropy encoded to produce a compressed bit-stream corresponding to each pass, wherein each subband is entropy encoded independently of the other subbands. A visual significance value is computed for each pass, and a visual quality table is provided that specifies a number of expected visual quality levels and corresponding visual significance values. For each expected visual quality level, a minimal set of passes and their compressed bit-streams that are necessary to achieve the corresponding visual significance value are identified. The compressed bit-streams corresponding to passes are then ordered into layers from the lowest expected visual quality level to the highest expected visual quality level specified in the visual quality table to produce a compressed digital image, wherein each layer includes the passes and their corresponding compressed bit-streams from the identified minimal set corresponding to the expected visual quality level that have not been included in any lower visual quality layers.