TIFF Tag JPEGTables
IFD | Image |
---|---|
Code | 347 (hex 0x015B) |
Name | JPEGTables |
LibTiff name | TIFFTAG_JPEGTABLES |
Type | UNDEFINED |
Count | N = number of bytes in tables datastream |
Default | None |
Description
JPEG quantization and/or Huffman tables.
This field is the only auxiliary TIFF field added for new-style JPEG compression (Compression=7). It is optional.
The purpose of JPEGTables is to predefine JPEG quantization and/or Huffman tables for subsequent use by JPEG image segments. When this is done, these rather bulky tables need not be duplicated in each segment, thus saving space and processing time. JPEGTables may be used even in a single-segment file, although there is no space savings in that case.
When the JPEGTables field is present, it shall contain a valid JPEG "abbreviated table specification" datastream.