TIFF 6.0 Specification
Final—June 3, 1992
In a TIFF ColorMap, all the Red values come first, followed by the Green values,
then the Blue values. The number of values for each color is 2**BitsPerSample.
Therefore, the ColorMap field for an 8-bit palette-color image would have 3 * 256
values.
The width of each value is 16 bits, as implied by the type of SHORT. 0 represents
the minimum intensity, and 65535 represents the maximum intensity. Black is
represented by 0,0,0, and white by 65535, 65535, 65535.
See also PhotometricInterpretation—palette color.
No default. ColorMap must be included in all palette-color images.
Compression
Compression scheme used on the image data.
Tag
= 259 (103.H)
Type = SHORT
N
=1
1 = No compression, but pack data into bytes as tightly as possible leaving no unused
bits except at the end of a row.
If
Then the sample values are stored as an array of type:
SHORT
LONG
BYTE
BitsPerSample = 16 for all samples
BitsPerSample = 32 for all samples
Otherwise
Each row is padded to the next BYTE/SHORT/LONG boundary, consistent with
the preceding BitsPerSample rule.
If the image data is stored as an array of SHORTs or LONGs, the byte ordering
must be consistent with that specified in bytes 0 and 1 of the TIFF file header.
Therefore, little-endian format files will have the least significant bytes preceding
the most significant bytes, while big-endian format files will have the opposite
order.
If the number of bits per component is not a power of 2, and you are willing to give up
some space for better performance, use the next higher power of 2. For example, if
your data can be represented in 6 bits, set BitsPerSample to 8 instead of 6, and then
convert the range of the values from [0,63] to [0,255].
Rows must begin on byte boundaries.
(SHORT boundaries if the data is stored as
SHORTs, LONG boundaries if the data is stored as LONGs).
Some graphics systems require image data rows to be word-aligned or double-word-
aligned, and padded to word-boundaries or double-word boundaries. Uncompressed
TIFF rows will need to be copied into word-aligned or double-word-aligned row
buffers before being passed to the graphics routines in these environments.
2 = CCITT Group 3 1-Dimensional Modified Huffman run-length encoding. See
Section 10. BitsPerSample must be 1, since this type of compression is defined
only for bilevel images.
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