TIFF 6.0 Specification
Final—June 3, 1992
dimensionally coded line. That is, RowsPerStrip should be a multiple of “Param-
eter K,” as documented in the CCITT specification.
Bit 1
is 1 if uncompressed mode is used.
Bit 2 is 1 if fill bits have been added as necessary before EOL codes such that
EOL always ends on a byte boundary, thus ensuring an EOL-sequence of 1 byte
preceded by a zero nibble: xxxx-0000 0000-0001.
Default is 0, for basic 1-dimensional coding. See also Compression.
T6Options
Tag
= 293 (125.H)
Type = LONG
N
=1
See
Compression = 4.
This field is made up of a set of 32 flag bits. Unused bits
must be set to 0. Bit 0 is the low-order bit. The default value is 0 (all bits 0).
bit 0
bit 1
is unused and always 0.
is 1 if uncompressed mode is allowed in the encoding.
In earlier versions of TIFF, this tag was named Group4Options. The significance
has not changed and the present definition is compatible. The name of the tag has
been changed to be consistent with the nomenclature of other T.6-encoding appli-
cations.
Readers should honor this option tag, and only this option tag, whenever T.6-
Encoding is specified for Compression.
For T.6-Encoding, each segment (strip or tile) is encoded as if it were a separate
image. The encoded string from each segment starts a fresh byte.
There are no one-dimensional line encodings in T.6-Encoding. Instead, even the
first row of the segment’s pixel array is encoded two-dimensionally by always
assuming an invisible preceding row of all-white pixels. The 2-dimensional pro-
cedure for encoding the body of individual rows is the same as that used for 2-
dimensional T.4-encoding and is described fully in the CCITT specifications.
The beginning of the encoding for each row of a strip or tile is conducted as if
there is an imaginary preceding (0-width) white pixel, that is as if a fresh run of
white pixels has just commenced. The completion of each line is encoded as if
there are imaginary pixels beyond the end of the current line, and of the preceding
line, in effect, of colors chosen such that the line is exactly completable by a code
word, making the imaginary next pixel a changing element that’s not actually
used.
The encodings of successive lines follow contiguously in the binary T.6-Encoding
stream with no special initiation or separation codewords. There are no provisions
for fill codes or explicit end-of-line indicators. The encoding of the last line of the
pixel array is followed immediately, in place of any additional line encodings, by
a 24-bit End-of-Facsimile Block (EOFB).
000000000001000000000001.B.
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