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TIFF Tag T4Options
| IFD | | Image |
|---|---|---|
| Code | 292 (hex 0x0124) | |
| Name | T4Options | |
| LibTiff name | TIFFTAG_GROUP3OPTIONS | |
| Type | LONG | |
| Count | 1 | |
| Default | 0 (basic 1-dimensional coding) |
Description
Options for Group 3 Fax compression
This field is made up of a set of 32 flag bits. Unused bits must be set to 0. Bit 0 is the low-order bit.
The specification defines these bits:
Bit 0 is 1 for 2-dimensional coding (otherwise 1-dimensional is assumed). For 2-D coding, if more than one
strip is specified, each strip must begin with a 1-dimensionally coded line. That is, RowsPerStrip should be a
multiple of Parameter K, as documented in the CCITT specification.
Bit 1 is 1 if uncompressed mode is used.
Bit 2 is 1 if fill bits have been added as necessary before EOL codes such that EOL always ends on a byte
boundary, thus ensuring an EOL-sequence of 1 byte preceded by a zero nibble: xxxx-0000 0000-0001.
LibTiff defines these bits as follows:
GROUP3OPT_2DENCODING = 1;
GROUP3OPT_UNCOMPRESSED = 2;
GROUP3OPT_FILLBITS = 4;