Compression artifact
A compression artifact (or artefact) is a deliberate visible change in media (including images, audio, and video). It is caused by lossy compression. Lossy data compression removes some of the media's data. This way the data becomes small enough to be stored in the desired disk or transmitted inside the available bandwidth. If the compressor cannot store enough data in the compressed form, the result is a loss of quality, or introduction of artifacts.
The most common digital compression artifacts are DCT blocks. This is caused by the discrete cosine transform (DCT) compression algorithm used in many digital media, such as JPEG image compression, MP3 digital audio, and MPEG video coding formats.[1][2]
These compression artifacts appear when heavy compression is applied. It occurs often in common digital media, such as DVDs, common computer file formats such as JPEG, MP3 and MPEG files. It also occurs in some other alternatives to the compact disc like the as Sony's MiniDisc format. Uncompressed media (such as on Laserdiscs and WAV files) or losslessly compressed media (such as FLAC or PNG) do not suffer from compression artifacts.
Compression Artifact Media
Original image, with good text edges and color grade
Loss of edge clarity and tone "fuzziness" in heavy JPEG compression
Illustration of the effect of JPEG compression on a slightly noisy image with a mixture of text and whitespace. Text is a screen capture from a Wikipedia conversation with noise added (intensity 10 in Paint.NET). One frame of the animation was saved as a JPEG (quality 90) and reloaded. Both frames were then zoomed by a factor of 4 (nearest neighbor interpolation).
Block coding artifacts in a JPEG image. Flat blocks are caused by coarse quantization. Discontinuities at transform block boundaries are visible.
Example of image with artifacts due to a transmission error
Video glitch art (epilepsy warning)
- DATAMOSHSTREET
An example of a "deep fried" image made from a photo of a can of Diet Pepsi
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References
- ↑ Bovik, Alan C. (2009). The essential guide to image processing. London: Academic Press. ISBN 978-0-08-092251-5. OCLC 429896570.
- ↑ "POSTmatter - Beyond resolution: Rosa Menkman's glitch art". postmatter.merimedia.com. Archived from the original on 2019-10-19. Retrieved 2021-05-08.
