Alexander Keith

Decoding compression with reversible embedded wavelets (CREW) 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. Compression with reversible embedded wavelets (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 continuous-tone. 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 bi-level and graphic images.

Next Generation Image Compression And Manipulation Using CREW

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 sub-images. 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, zoom and pan, and to extract regions-of-interest are the new measures of image compression systems. CREW (compression with reversible embedded wavelets) is a high quality image compression system that is progressive from high compression to lossless, pyramidal, and supports regions-of-interest and multiple image types. 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 bi-level and graphic images.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 sub-images. 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, zoom and pan, and to extract regions-of-interest are the new measures of image compression systems. CREW (compression with reversible embedded wavelets) is a high quality image compression system that is progressive from high compression to lossless, pyramidal, and supports regions-of-interest and multiple image types. 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 bi-level and graphic images.

Compression with reversible embedded wavelets with an enhanced binary mode

Compression with reversible embedded wavelets (CREW) is a unified lossless and lossy continuous-tone still image compression system. Wavelet coefficients are encoded in a bit-significance embedded order, allowing lossy compression by truncating the compressed data after encoding. CREWs context-based coding, called Horizon coding, takes advantage of the spatial and spectral information available in the wavelet domain and adapts well to the lessor significant bits. CREWs capabilities have been enhanced to include a binary mode for compression of binary and graphic images. This also improves compression on some images that do not use the full dynamic range. The binary mode encodes bit-planes of the image without using the transform. This JBIG-like system uses the resources already available in the CREW system. This paper introduces some basic concepts of CREW and describes the binary mode in detail.

Device selective quantization for reversible wavelets

Compression with reversible embedded wavelets (CREW) consists of three major parts: a wavelet transform, an embedded context model, and a binary entropy coder. The wavelet transform is a special implementation of high quality wavelet which provides perfect reconstruction with finite precision coefficients. The context model describes the wavelet coefficients in a particular order with conditional probability estimates. Finally the FSM-coder, a binary entropy coder with functionality similar to the QM-coder, is used to generate the final code stream.