Irrelevance Reduction

If a higher compression rate is required than achievable by redundancy reduction, a decrease in quality cannot be avoided. Appropriate technologies are available especially for graphic, audio or video coding. The main characteristic of those technologies is the attempt to evaluate the relevance of a particular part of the contents. In a step by step process the most irrelevant parts will be removed. With a higher compression rate more and more relvant contents will be lost.

Irrelvance reduction is not reversible because information will be lost during the encoding process. According to the particular technology encoding and decoding cycles cannot be repeated frequently because compression artefacts could be accumulated.

Most of the technologies belonging to irrelevance reduction as MPEG or JPEG also use methods of redundancy reduction. But the main characteristics are driven by their internal basic algorithms like DCT.

Examples for corresponding formats:

mpeg - jpeg - mjpeg - fif - png - AC-3

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