CCITT Group 3
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== Specifications == | == Specifications == | ||
| − | * [ | + | * [https://www.itu.int/rec/T-REC-T.4/en ITU-T Recommendation T.4] |
| − | * [ | + | * [https://www.adobe.io/open/standards/TIFF.html Adobe TIFF standards] → TIFF6.pdf, Section 10: Modified Huffman Compression - Defines a slightly simplified form of the 1-d format |
== Software == | == Software == | ||
Revision as of 14:23, 2 December 2020
CCITT Group 3 is a lossless compressed data format for bi-level images. It is also known as T4, T.4, Fax3, Group 3, G3, or ITU-T Fax Group 3. It is one of the formats used by fax machines. It is usually embedded in another image file format such as TIFF, but can be stored in a file by itself.
It comes in two main varieties: so-called 1-dimensional and 2-dimensional (though both are used on 2-dimensional images). The 1-dimensional variety uses Modified Huffman (MH) compression, and the 2-dimensional variety uses Modified READ (MR) compression.
Contents |
Related formats
Many of the formats listed in the Fax formats article use CCITT Group 3 compression.
In a TIFF file, compression codes 2, 3, and 32771 are varieties of CCITT Group 3 compression.
Other formats that can use CCITT Group 3 compression include PDF and SPIFF.
See also
Specifications
- ITU-T Recommendation T.4
- Adobe TIFF standards → TIFF6.pdf, Section 10: Modified Huffman Compression - Defines a slightly simplified form of the 1-d format
Software
- Konvertor
- Netpbm: g3topbm, pbmtog3
- ImageMagick (format named "FAX")
- Farbfeld Utilities
