Lossless JPEG (original)
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The original '''lossless JPEG''' (sometimes called '''lossless JPEG-1''') refers to the original [[JPEG]] format when used with lossless compression, instead of the usual lossy compression. It is a standard type of JPEG file, defined in the original JPEG standard (ITU-T Rec. T.81). Few applications support it, though it has found some use in the medical industry, such as in [[DICOM]] files. Note that this format is distinct from [[JPEG-LS]]. | The original '''lossless JPEG''' (sometimes called '''lossless JPEG-1''') refers to the original [[JPEG]] format when used with lossless compression, instead of the usual lossy compression. It is a standard type of JPEG file, defined in the original JPEG standard (ITU-T Rec. T.81). Few applications support it, though it has found some use in the medical industry, such as in [[DICOM]] files. Note that this format is distinct from [[JPEG-LS]]. | ||
| − | A lossless JPEG image may have any bit depth from 2 to 16 bits per sample. | + | A lossless JPEG image may have any bit depth from 2 to 16 bits per sample. The compression scheme uses [[Huffman coding]] or [[arithmetic coding]]. |
== Identification == | == Identification == | ||
Revision as of 17:05, 21 November 2013
- See Lossless JPEG for other uses of the term.
The original lossless JPEG (sometimes called lossless JPEG-1) refers to the original JPEG format when used with lossless compression, instead of the usual lossy compression. It is a standard type of JPEG file, defined in the original JPEG standard (ITU-T Rec. T.81). Few applications support it, though it has found some use in the medical industry, such as in DICOM files. Note that this format is distinct from JPEG-LS.
A lossless JPEG image may have any bit depth from 2 to 16 bits per sample. The compression scheme uses Huffman coding or arithmetic coding.
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Identification
A lossless JPEG file is identified by the presence of an SOF3, SOF7, SOF11, or SOF15 segment. Refer to JPEG for a discussion of JPEG segments.
Specifications
- ITU-T Rec. T.81: The JPEG standard
Software
- Thomas Richter's libjpeg
- ljpeg-6b.tar.gz: Lossless JPEG patch for IJG libjpeg 6b (presumably by Ken Murchison)
- Lossless JPEG Codec (Cornell University): pnmtoljpg, ljpgtopnm
- Stanford PVRG JPEG
Sample files
- ljpeg-6b.tar.gz → testimgl.jpg
- ljpg.tar.Z → F-18.ljpg
