Decoding CREW (Compression with Reversible Embedded Wavelets) codestreams

As the applications of digital imagery expand in resolution and pixel fidelity there is a greater need for more efficient compression and extraction of images and subimages. No longer is it sufficient to compress and decompress an image for a specific target device. The ability to handle many types of image data, extract images at different resolutions and quality, lossless and lossy, zoom and pan, and extract regions-of-interest are the new measures of image compression system performance. CREW is a high quality image compression system that is progressive from high compression to lossless, and pyramidal in resolution. CREW supports regions-of-interest, and multiple image types, such as bi-level and continuoustone. This paper describes the CREW system and format, shows how the correct data can be quickly extracted from a CREW file to support a variety of target devices, describes the mechanisms needed for panning, zooming, and fixed-size compression, and explains the superior performance on bilevel and graphic images.