CREW : Compression with Reversible Embedded

abstract Compression with Reversible Embedded Wavelets (CREW) is a uniied lossless and lossy continuous-tone still image compression system. It is wavelet-based using a \reversible" approximation of one of the best wavelet lters. Reversible wavelets are linear lters with non-linear rounding which implement exact-reconstruction systems with minimal precision integer arithmetic. Wavelet coeecients are encoded in a bit-signiicance embedded order, allowing lossy compression by simply truncating the compressed data. For coding of coeecients, CREW uses a method similar to Shapiro's zerotree, and a completely novel method called Horizon. Horizon coding is a context based coding that takes advantage of the spatial and spectral information available in the wavelet domain. CREW provides state of the art lossless compression of medical images (greater than 8 bits deep), and lossy and lossless compression of 8-bit deep images with a single system. CREW has reasonable software and hardware implementations.