A lossy compression method used for color images and video. Instead of compressing small blocks of 8x8 pixels (64 bits) as in JPEG and MPEG, the wavelet algorithms compress the entire image with ratios of up to 300:1 for color and 50:1 for gray scale.Wavelet compression also supports nonuniform compression, where specified parts of the image can be compressed more than others. There are several proprietary methods based on wavelet mathematics, which are available in products from companies such as Summus, Ltd. (www.summus.com) and Algo Vision LuraTech GmbH (www.luratech.com). See lossy compression and JPEG 2000.
A technique for video compression that uses wavelet transforms to compress data. Wavelet compression treats the entire image as a series of small waveforms, or signals, known as wavelets, with one per color channel, e.g., red, green, and blue. A wavelet transform is applied that quantizes the wavelets by measuring the distances between the zero line and points along each wavelet and records theses distances as coefficients, with one coefficient for each pixel in the image.The coefficients of adjacent images are averaged to produce a simplified version of the wave, which process effectively halves the size of the image description. The process is repeated again and again and so on, producing progressively smaller waves, therefore, and smaller data files in a process known as decomposition. At each step of the averaging process, the difference between the coefficients is noted.Wavelet compression is used effectively to compress transient images, such as twinkling stars in a night sky.The U.S. Federal Bureau of Investigation (FBI) uses wavelet compression to store fingerprints. Smooth, periodic images are best compressed using other methods.Wavelet compression can be either lossless or lossy in nature. See also compression, lossy compression, transform, and video.