Quantization (signal processing): Difference between revisions

Revision as of 05:04, 10 June 2005

Revision as of 13:25, 13 June 2005

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One example of a lossy compression scheme that uses quantization is [[JPEG]] image compression.

During JPEG encoding, the data representing an image (typically 8-bits for each of three color components per pixel) is processed using a [[discrete cosine transform]] and is then quantized and [[entropy encoding|entropy coded]]. By reducing the precision of the transformed values using quantization, the number of bits needed to represent the image can be reduced substantially.

For example, images can often be represented with acceptable quality using JPEG at less than 3 bits per pixel (as opposed theto the typical 24 bits per pixel needed prior to JPEG compression).

Even the original representation using 24 bits per pixel requires quantization for its [[pulse-code modulation|PCM]] sampling structure.