TIFF 6.0 Specification
Final—June 3, 1992
This Field points to a list of point transform values, one per component. This Field
is relevant only for lossless processes.
If the point transformation value is nonzero for a component, a point transforma-
tion of the input is performed prior to the lossless coding. The input is divided by
2**Pt, where Pt is the point transform value. The output of the decoder is rescaled
to the input range by multiplying by 2**Pt. Note that the scaling of input and
output can be performed by arithmetic shifts.
See the JPEG Draft International Standard (ISO DIS 10918-1) for more details.
The default value of this Field is 0 for each component (no scaling).
JPEGQTables
Tag
= 519 (207.H)
Type = LONG
N
= SamplesPerPixel
This Field points to a list of offsets to the quantization tables, one per component.
Each table consists of 64 BYTES (one for each DCT coefficient in the 8x8 block).
The quantization tables are stored in zigzag order.
See the JPEG Draft International Standard (ISO DIS 10918-1) for more details.
It is strongly recommended that, within the TIFF file, each component be assigned
separate tables. This Field is mandatory whenever the JPEGProc Field specifies a
DCT-based process (no default).
JPEGDCTables
Tag
= 520 (208.H)
Type = LONG
N
= SamplesPerPixel
This Field points to a list of offsets to the DC Huffman tables or the lossless
Huffman tables, one per component.
The format of each table is as follows:
16 BYTES of “BITS”, indicating the number of codes of lengths 1 to 16;
Up to 17 BYTES of “VALUES”, indicating the values associated with
those codes, in order of length.
See the JPEG Draft International Standard (ISO DIS 10918-1) for more details.
It is strongly recommended that, within the TIFF file, each component be assigned
separate tables. This Field is mandatory for all JPEG processes (no default).
JPEGACTables
Tag
= 521 (209.H)
Type = LONG
N
= SamplesPerPixel
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