TIFF 6.0 Specification
Final—June 3, 1992
FreeByteCounts
For each string of contiguous unused bytes in a TIFF file, the number of bytes in
the string.
Tag
= 289 (121.H)
Type = LONG
Not recommended for general interchange.
See also FreeOffsets.
FreeOffsets
For each string of contiguous unused bytes in a TIFF file, the byte offset of the
string.
Tag
= 288 (120.H)
Type = LONG
Not recommended for general interchange.
See also FreeByteCounts.
GrayResponseCurve
For grayscale data, the optical density of each possible pixel value.
Tag
= 291 (123.H)
Type = SHORT
N
= 2**BitsPerSample
The 0th value of GrayResponseCurve corresponds to the optical density of a pixel
having a value of 0, and so on.
This field may provide useful information for sophisticated applications, but it is
currently ignored by most TIFF readers.
See also GrayResponseUnit, PhotometricInterpretation.
GrayResponseUnit
The precision of the information contained in the GrayResponseCurve.
Tag
= 290 (122.H)
Type = SHORT
N
=1
Because optical density is specified in terms of fractional numbers, this field is
necessary to interpret the stored integer information. For example, if
GrayScaleResponseUnits is set to 4 (ten-thousandths of a unit), and a
GrayScaleResponseCurve number for gray level 4 is 3455, then the resulting
actual value is 0.3455.
Optical densitometers typically measure densities within the range of 0.0 to 2.0.
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