an exercise in miscellany

Compression Artifact

In technology & innovatons on January 3, 2011 at 9:49 pm

A compression artifact (or artefact) is a noticeable distortion of media – an image, audio, or video – due to the application of an overly aggressive or inappropriate lossy data compression algorithm.

These lossy data compression schemes discard some data to simplify the media sufficiently to store it in the desired space (data-rate) – if there is not enough data in the compressed version to reproduce the original with acceptable fidelity, artifacts will result. Alternatively, the compression algorithm may incorrectly determine certain distortions to be of little subjective importance, but they may in fact be objectionable to the viewer.

Compression artifacts occur in many common media such as DVDs, common computer file formats such as JPEG, MP3, or MPEG files, and Sony’s ATRAC compression algorithm. Uncompressed media (such as on Laserdiscs, Audio CDs, and WAV files) or losslessly compressed media (FLAC, PNG, etc.) do not suffer from compression artifacts.

The minimization of artifacts is a key goal in implementation of lossy compression schemes. However, artifacts are occasionally intentionally produced for artistic purposes, a style known as glitch art.

Technically speaking, a compression artifact is a particular class of data error that is usually the consequence of quantization in lossy data compression.

via Compression artifact – Wikipedia

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