CCITT Group 3

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== Related formats ==
 
== Related formats ==
  
In a [[TIFF]] file, compression type 2 is a type of 1-dimensional CCITT Group 3. Compression type 3 without T4Options bit 0 set is a slightly different type of 1-dimensional CCITT Group 3. Compression type 3 with T4Options bit 0 set is 2-dimensional CCITT Group 3.
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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]].
 
Other formats that can use CCITT Group 3 compression include [[PDF]] and [[SPIFF]].

Revision as of 18:42, 9 May 2013

File Format
Name CCITT Group 3
Ontology
Extension(s) .g3
PRONOM x-cmp/14

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.

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