CCITT Group 3
From Just Solve the File Format Problem
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| − | '''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 | + | '''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 machine]]s. 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. | 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. | ||
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Revision as of 21:36, 11 November 2015
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
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
- TIFF 6.0 Specification, Section 10: Modified Huffman Compression
Software
- Netpbm: g3topbm, pbmtog3
- ImageMagick (format named "FAX")
