CCITT Group 3
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{{FormatInfo | {{FormatInfo | ||
|formattype=electronic | |formattype=electronic | ||
| − | |subcat= | + | |subcat=Compression |
|extensions={{ext|g3}} | |extensions={{ext|g3}} | ||
| + | |mimetypes={{mimetype|image/g3fax}} | ||
|pronom={{PRONOM|x-cmp/14}} | |pronom={{PRONOM|x-cmp/14}} | ||
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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. | ||
== Related formats == | == Related formats == | ||
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| + | 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. | In a [[TIFF]] file, compression codes 2, 3, and 32771 are varieties of CCITT Group 3 compression. | ||
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== Software == | == Software == | ||
| + | * [[Konvertor]] | ||
* [[Netpbm]]: g3topbm, pbmtog3 | * [[Netpbm]]: g3topbm, pbmtog3 | ||
* [[ImageMagick]] (format named "FAX") | * [[ImageMagick]] (format named "FAX") | ||
| − | [[Category: | + | == Links == |
| + | * RFC 1494: Equivalences between 1988 X.400 and RFC-822 Message Bodies | ||
| + | * RFC 2159: A MIME Body Part for FAX | ||
| + | |||
| + | [[Category:Graphics]] | ||
[[Category:Fax]] | [[Category:Fax]] | ||
Revision as of 19:34, 2 July 2016
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
- TIFF 6.0 Specification, Section 10: Modified Huffman Compression
Software
- Konvertor
- Netpbm: g3topbm, pbmtog3
- ImageMagick (format named "FAX")
