JPEG-LS
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The Joint Photographic Experts Group, in addition to their well-known lossy image compression techniques, JPEG and JPEG 2000, also have three standards for lossless compression (of which JPEG-LS has a lossy mode):
Lossless JPEG was developed as a late addition to JPEG in 1993, using a completely different technique from the lossy JPEG standard. It uses a predictive scheme based on the three nearest (causal) neighbors (upper, left, and upper-left), and entropy coding is used on the prediction error. It was never widely adopted.
JPEG-LS was developed with the aim of providing a low complexity lossless image compression standard that could be able to offer better compression efficiency than lossless JPEG. Part 1 of this standard was finalized in 1999. The core of JPEG-LS is based on the LOCO-I algorithm, that relies on prediction, residual modeling and context-based coding of the residuals. Most of the low complexity of this technique comes from the assumption that prediction residuals follow a two-sided geometric distribution (also called a discrete Laplace distribution) and from the use of Golomb-like codes, which are known to be near-optimal for geometric distributions. Besides lossless compression, JPEG-LS also provides a lossy mode where the maximum absolute error can be controlled by the encoder. Compression for JPEG-LS is generally much faster than JPEG 2000 and much better than the original lossless JPEG standard.
JPEG 2000 includes a lossless mode based on a special integer wavelet filter (biorthogonal 3/5). JPEG 2000's lossless mode runs more slowly and usually has worse compression ratios than JPEG-LS. However, it is scalable and progressive, and, because its algorithm is more similar to JPEG 2000, it is more widely supported[citation needed].
[edit] External links
- JPEG 2000 still image coding versus other standards
- JPEG-LS home page
- LOCO-I home page
- Licensing terms for HP's LOCO technology in JPEG-LS (free reg. req.; not sublicensable; available only to companies)
- http://kt.ijs.si/aleks/jpeg-ls/index.htm, Links to Various Implementations.
- http://www.dclunie.com/jpegls.html, single-tone / grayscale JPEG-LS encoder algorithm.
| Multimedia compression formats | |
|---|---|
| Video compression formats | ISO/IEC: MPEG-1 | MPEG-2 | MPEG-4 | MPEG-4/AVC | ITU-T: H.261 | H.262 | H.263 | H.264 | SMPTE: VC-1 Others: AVS | Dirac | Indeo | MJPEG | RealVideo | Theora | VP7 | WMV |
| Audio compression formats | ISO/IEC MPEG: MPEG-1 Layer III (known as MP3) | MPEG-1 Layer II | AAC | HE-AAC ITU-T: G.711 | G.722 | G.722.1 | G.722.2 | G.723 | G.723.1 | G.726 | G.728 | G.729 | G.729a Others: AC3 | ATRAC | FLAC | iLBC | Monkey's Audio | Musepack | RealAudio | SHN | Speex | Vorbis | WavPack | WMA |
| Image compression formats | ISO/IEC/ITU-T: JPEG | JPEG 2000 | JPEG-LS | JBIG | JBIG2 Others: BMP | GIF | ILBM | PCX | PNG | TGA | TIFF | WMP |
| Media container formats | 3GP | ASF | AVI | FLV | Matroska | MP4 | MXF | NUT | Ogg | Ogg Media | QuickTime | RealMedia Audio only: AIFF | AU | WAV |
