📄 rfc1314.txt
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architecture or visual characteristics of an image. The following
Basic Fields should be included in a TIFF image file:
FIELD NAME
(TAG in hex, TYPE) VALUE DESCRIPTION
------------------ ----- -----------
BitsPerSample 1 Number of bits
(0102, SHORT) per pixel (bi-level for
now, but may allow
more later)
Compression 4 Type of Compression
(0103, SHORT) (could also be 1 = Uncompressed
1 or 3) 3 = G3 (MH or MR)
4 = G4 (MMR)
Use 4 if possible
ImageLength <image's length> Length of the Image
(0101, SHORT in scan lines
or LONG)
ImageWidth <image's width> Width of the Image
(0100, SHORT in pixels
Katz & Cohen [Page 12]
RFC 1314 Image Exchange Format April 1992
or LONG)
NewSubFileType 0 usually Flag bits indicating
(00FE, LONG) bit 0: 1 if the kind of image.
reduced (see the TIFF
resolution of reference [3])
another image
bit 1: 1 if
single page of a
multi-page image
bit 2: 1 if
image defines a
transparency
mask
Photometric- 0 for positive
Interpretation image (0 imaged
(0106, SHORT) as white, 1 as
black)
1 means reverse
black and white
RowsPerStrip <Number of Rows> Number of Rows in
(0116, SHORT Each Strip. Each
or LONG) page should be a
single strip.
SamplesPerPixel 1 (since are Bi-level
(0115, SHORT) images)
StripByteCounts count1, count2... Number of Bytes in
(0117, SHORTs each strip of the
or LONGs) images. (The Value
is an offset which
points to a series
of counts, each of
which is the same
Type, LONG or SHORT.
The Length is the
same as the number
of strips.)
StripOffsets off1, off2,... Pointers to the strips
(0111, SHORTs of the image (remember,
or LONGs) one strip per page).
(The Value is an offset
which points to a
series of offsets,
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RFC 1314 Image Exchange Format April 1992
each of which points
to the actual image
data for the strip.)
ResolutionUnit 2 | 3 Units of Resolution
(0128, SHORT) See Below, 3.C.6 2: Inches
3: Centimeters
XResolution See Below, 3.C.6 Resolution in the X
(011A, RATIONAL) direction in pixels
per ResolutionUnit
(we suggest 400 dots
per inch when possible)
YResolution See Below, 3.C.6 Resolution in the Y
(011B, RATIONAL) direction in pixels
per ResolutionUnit
(we suggest 400 dots
per inch when possible)
3.C.2. Informational Fields (Optional)
The following Informational Fields are optional. They provide
useful information to a user. All Field values are ASCII strings.
NAME (TAG in hex) DESCRIPTION
---------------- -----------
Artist (013B) Person Who Created the Image
DateTime (0132) Date and Time of Image Creation
HostComputer (013C) Name of Computer Image was Created On
ImageDescription A Short Text Description
(010E)
Make (010F) Manufacturer of Hardware (Scanner) Used
Model (0110) Model Number of Hardware (Scanner) Used
Software (0131) Software Package that Created the Image
3.C.3. Facsimile Fields (Optional, Mandatory for G3 Compression)
In addition to the above, the Facsimile Fields below should be
used. The TIFF document recommends that they not be used for
interchange between applications, but they are now in wide enough
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RFC 1314 Image Exchange Format April 1992
use for just that. These fields are optional and default to 0
(all bits off).
FIELD NAME
(TAG in hex, TYPE) VALUE DESCRIPTION
------------------ ----- -----------
Group3Options bit 0: 1 for Flag bits indicating
(0124, LONG) 2-dimensional Options for G3
coding
(i.e., MR with
k > 1)
bit 1: 1 if
uncompressed
mode MAY be used,
0 if uncompressed
mode IS NOT used.
bit 2: 1 if fill (As allowed by the G3
bits have been protocol, fill bits
added may be added between
each line of data
and the EOL. Since
fill bits are used to
"byte-align" G3 image
files, bit 2 should be
set to 1 for these
images.)
Group4Options bit 0: unused Flag bits indicating
(0125, LONG) bit 1: 1 if Options for G4
uncompressed
mode MAY be used,
if this bit is 0
it means that
uncompressed mode
IS NOT used.
3.C.4. Storage and Retrieval Fields (Optional)
The following fields are optional and may be useful for document
storage and retrieval.
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RFC 1314 Image Exchange Format April 1992
FIELD NAME
(TAG in hex, TYPE) DESCRIPTION
------------------ -----------
DocumentName Name of the Document
(010D, ASCII)
PageName Name of the Page
(011D, ASCII)
PageNumber Page Number in a Multi-Page Document
(0129, SHORTs) Two SHORT Values are specified, the
first is the page number and the
second is the total number of pages
in the document. The first page
is page 0. (NOTE: This does not
necessarily correspond to page
numbers which may be printed
in the image.)
XPosition X Offset of the Left Side of
(011E, RATIONAL) the Image, in ResolutionUnits
YPosition Y Offset of the Top of
(011F, RATIONAL) the Image, in ResolutionUnits
3.C.5. TIFF-F Fields (NOT Recommended)
TIFF-F defines the following new fields for G3 (MH) encoded
images. Since these fields are not defined in TIFF-B itself,
their use is not recommended. However, since TIFF-F files may
include these tags for image data which came from a G3 fax
machine, readers should be prepared for them.
These three fields deal with corrupted image data which is due to
the fact that G3 devices may not perform error correction on bad
data.
FIELD NAME
(TAG in hex, TYPE) DESCRIPTION
------------------ -----------
BadFaxLines Number of Bad fax scan lines
(0146, SHORT or LONG) encountered during fax reception
(but not necessarily in the file)
CleanFaxData 0 means no bad lines received
(0147, SHORT) 1 means bad lines were regenerated
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RFC 1314 Image Exchange Format April 1992
by the receiving device
2 means bad lines were detected
but not regenerated
ConsecutiveBadFaxLines The maximum number of consecutive
(0148, SHORT or LONG) bad fax lines (but not necessarily
in the file)
3.C.6. More on Representing Resolutions
The tags XResolution and YResolution are both RATIONALs, i.e., the
ratio of two LONGS. G3 fax resolutions are actually specified in
dots (or lines) per mm while G4 is in dots per inch (actually,
dots per 25.4 mm).
For example, G3 horizontal resolution is defined to be 1728 dots
per 215 mm which comes out to 80.4 dots per cm or about 203 dots
per inch. It is frequently referred to as just 200 dpi. To avoid
any possibility of problems due to round off error, this should be
represented by having XResolution = 17280/215 and ResolutionUnit =
3 (cm). However when reading, 204/1 or even 200/1 with
ResolutionUnit = 2 (inches) should be recognized as representing
the same resolution.
For G4, on the other hand, the resolution 400 dots/inch should be
represented by an XResolution of 400/1 and ResolutionUnit = 2.
The following table shows various ways of representing the
standard resolutions in order of preference:
ResolutionUnit XResolution YResolution
-------------- ----------- -----------
G3 normal 3 17280/215 3850/100
3 80/1 3850/100
3 17280/215 385/10
3 80/1 385/10
2 2042/10 9779/100
2 204/1 98/1
2 200/1 100/1
G3 fine 3 17280/215 77/1
3 80/1 77/1
2 2042/10 19558/100
2 204/1 196/1
2 200/1 200/1
Katz & Cohen [Page 17]
RFC 1314 Image Exchange Format April 1992
G4 200 dpi 2 200/1 200/1
G4 300 dpi 2 300/1 300/1
Other 300 dpi 2 300/1 300/1
G4 400 dpi 2 400/1 400/1
600 dpi 2 600/1 600/1
It is suggested that Image readers be able to handle all of the
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