JPEG-LS
JPEG-LS is an image file format and compressed data format. It supports both lossy and lossless compression. The lossy compression is often called "near-lossless", because the encoder can set a limit on the maximum error. Its compression algorithm is LOCO-I, developed by HP Labs.
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Disambiguation
JPEG-LS files are very similar in structure to JPEG, to the extent that JPEG-LS could be considered to be a kind of JPEG, or an extension of JPEG. However, given that they use different filename extensions, and that few applications that support JPEG support JPEG-LS, JPEG and JPEG-LS should probably be thought of as different and incompatible formats.
The terms "JPEG-LS" and "Lossless JPEG" do not have the same meaning(s). See Lossless JPEG for more information.
Identification
Like JPEG, JPEG-LS files begin with bytes FF D8 FF.
A JPEG-LS file will contain an 0xF7 ("SOF55" or "JPG7") segment somewhere in it. Often, the 4th byte in the file is 0xF7.
Related formats
JPEG-LS compression can be used in some other file formats, such as JPX, JPM, SPIFF, and DICOM.
Specifications
Software
- CharLS: A C++ JPEG-LS library. Includes sample files.
- Thomas Richter's libjpeg
- UBC JPEG-LS Codec
- JPEG-LS Software (David A. Clunie)
- XnView
