TIFF 6.0 Specification
Final—June 3, 1992
Section 4: Grayscale Images
Grayscale images are a generalization of bilevel images. Bilevel images can store
only black and white image data, but grayscale images can also store shades of
gray.
To describe such images, you must add or change the following fields. The other
required fields are the same as those required for bilevel images.
Differences from Bilevel Images
Compression = 1
or
32773 (PackBits).
In Baseline TIFF, grayscale images can
either be stored as uncompressed data or compressed with the PackBits algorithm.
Caution: PackBits is often ineffective on continuous tone images, including many
grayscale images. In such cases, it is better to leave the image uncompressed.
BitsPerSample
Tag
= 258 (102.H)
Type = SHORT
The number of bits per component.
Allowable values for Baseline TIFF grayscale images are
4
and
8,
allowing either
16 or 256 distinct shades of gray.
Required Fields for Grayscale Images
These are the required fields for grayscale images (in numerical order):
TagName
ImageWidth
ImageLength
BitsPerSample
Compression
PhotometricInterpretation
StripOffsets
RowsPerStrip
StripByteCounts
XResolution
YResolution
ResolutionUnit
Decimal Hex
256
257
258
259
262
273
278
279
282
283
296
100
101
102
103
106
111
116
117
11A
11B
128
Type
SHORT or LONG
SHORT or LONG
SHORT
SHORT
SHORT
SHORT or LONG
SHORT or LONG
LONG or SHORT
RATIONAL
RATIONAL
SHORT
Value
4 or 8
1 or 32773
0 or 1
1 or 2 or 3
Baseline TIFF grayscale images were called TIFF Class G images in earlier ver-
sions of the TIFF specification.
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