(http://www.faximum.com/technotes/071)
TITLE: #071 - Information on TIFF File Compatibility
KEYWORDS: tiff tiff-f fax image file compatibility
RELEASE: All
CLASSIFICATION: All
PROBLEM: User reports difficulty generating TIFF files using other (i.e.
non-Faximum) software that are compatible with Faximum.
CAUSE: The TIFF standard permits an extremely wide varation in files that
adhere to the standard. In order to be fully compliant with Faximum
the TIFF files must be of Class F (see below).
SOLUTION: The TIFF standard is an extremely flexible and extensible standard
for formatting image files. Images from the simplest uncompressed
black and white to the high-resolution compressed 24-bit colour can
be encoded as TIFF files. In order to limit the burden on software
that must interprete TIFF files, TIFF files are divided into
different "classes" depending on the type of image that is to be
encoded. Class F TIFF (or TIFF-F) files are used to store fax
images. In order for a TIFF file to be a valid Class F TIFF file
it must contain the following tags.
In simple English, Faximum will handle most uncompressed or
compressed black and white TIFF images with a resolution of
around 200 dpi.
In detail, the following lists the TIFF tags and permitted values
for TIFF-F files. (Note that this list is for information only.
Users requiring detailed knowledge of TIFF-F files ought to refer
to the TIFF specification itself, available from Aldus Corporation
at +1 (206) 628-6593. A PostScript version of the TIFF specification
may be obtained from ftp://ftp.faximum.com/pub/documents/TIFF6.ps).
A flat-text version of the TIFF-F extensions to the base TIFF spec
may be obtained from ftp://ftp.faximum.com/pub/documents/tiff_f.txt).
BitsPerSample [Optional]
If present, value must be 1.
Compression [Optional]
3 - CCITT T.4 encoding - Recommended
Faximum will also usually accept images with compression
tag values of 1, 2, or 32773.
If you need support for other compression levels these may
be available by special arrangement for customers who have
technical support contracts.
Otherwise you are recommended to configure the software you
are using to produce the TIFF files so that they use one
of the supported compression methods.
FillOrder [Optional]
1 or 2
Group3Options [Optional]
If present, value must be 0 or 4. (i.e. 1-Dimensional
compression only; byte-aligned EOLS optional.)
ImageLength [Required]
A normal letter sized page has approx. 1100 scan lines in
standard resolution and roughly 2200 scan lines in
fine resolution. Numbers significantly higher or lower
than this either mean the image is in a resolution that
in not compatible with faxing or the image is larger or
smaller than a normal letter sized page.
ImageWidth [Required]
1728 - Recommended
Faximum will accept images that are narrower. Faximum will
truncate images that are wider. Extremely wide images may,
however, cause Faximum to overflow its internal buffers.
Again, images with an ImageWidth significantly larger than
1728 are probably either at a higher resolution than is
supported by most fax machines and/or a size that is wider
than the normal fax machine supports. Either will likely
cause the resulting faxed image to differ in appearance
from what is expected.
NewSubFileType [Optional]
If present, value must be 0 or 2.
Orientation [Optional]
If present, value must be 1.
PageNumber [Optional]
Value not significant (Faximum processes the pages of a
multiple-page TIFF file in the order they appear within
the TIFF file, not in PageNumber order.)
PhotometricInterpretation [Optional]
If present, value must be 0 or 1.
PlanarConfiguration [Optional]
If present, value must be 1.
Resolution Unit [Optional]
2 - Recommended
RowsPerStrip [Optional]
SamplesPerPixel [Optional]
If present, value must be 1.
StripByteCounts [Required]
Actual value must be correct for the file but is not, of
itself, significant.
StripOffsets [Required]
Actual value must be correct for the file but is not, of
itself, significant.
SubFileType [Optional]
If present, value must be 1 or 3.
XResolution [Required]
If X resolution is not 200 d.p.i. (+/- 5%) then the image
may not appear correctly when faxed or used as an
overlay.
YResolution [Required]
If Y resolution is not 100 or 200 d.p.i. (+/- 5%) then the
image may not appear correctly when faxed or used as an
overlay.
As an aside, the normal width of a TIFF fax image is 1728 pixels.
Images narrower than that are fine, images wider than that will
be truncated. The normal length of a TIFF fax image will depend
on the Y resolution (usually 100 or 200) and the page length.
For example, a standard resolution letter page will be 11" x 100 dpi
or about 1100 scan lines long. A fine resolution legal page will
be about 14" x 200 or 2800 lines long.
If you have a TIFF image and wish to determine the values of the
tags in its TIFF header, use the "tiffls -l" command. Tiffls is
a utility shipped as part of the Faximum software. (Depending on
the platform and version of your software look in one of the
following directories:
/usr/fax/bin
/opt/FAXserver/bin
/opt/faximum/bin
The following is an example of the output of "tiffls -l " on a valid
TIFF-F image produced using the Faximum ASCII to TIFF conversion
utility.
==================================================================
1.tif: Intel format Version: 42
1:
NewSubfileType (254) Long 2
ImageWidth (256) Short 1728
ImageLength (257) Short 1056
BitsPerSample (258) Short 1
Compression (259) Short 3
PhotometricInterpretation (262) Short 0
FillOrder (266) Short 1
ImageDescription (270) ASCII
StripOffset (273) Long 362
Orientation (274) Short 1
SamplesPerPixel (277) Short 1
RowsPerStrip (278) Short 65535
StripByteCounts (279) Long 6166
XResolution (282) Rational 204/1
YResolution (283) Rational 98/1
PlanarConfig (284) Short 1
T4Options (292) Long 4
ResolutionUnit (296) Short 2
PageNumber (297) Short 0 1
Software (305) ASCII
DateTime (306) ASCII <2002:11:01 17:39:44>
Artist (315) ASCII
HostComputer (316) ASCII
FaxImageType (34200) Long 0
Barcode (34203) ASCII <...>
DID (34204) ASCII < >
ReceiveTime (34206) Long 0
ReceiveDuration (34207) Short 0
Annotation (34208) ASCII <...>
Offset of next ifd: 0
==================================================================
Note that the text fields shown above are for information only
and their content is not material.
The following is another example of the output of "tiffls -l " on
a valid TIFF-F image produced using GhostScript.
==================================================================
out.tif: Intel format Version: 42
1:
NewSubfileType (254) Long 2
ImageWidth (256) Long 1728
ImageLength (257) Long 2200
BitsPerSample (258) Short 1
Compression (259) Short 3
PhotometricInterpretation (262) Short 0
FillOrder (266) Short 2
StripOffset (273) Long 338
Orientation (274) Short 1
SamplesPerPixel (277) Short 1
RowsPerStrip (278) Long 2200
StripByteCounts (279) Long 42205
XResolution (282) Rational 200/1
YResolution (283) Rational 200/1
PlanarConfig (284) Short 1
T4Options (292) Long 4
ResolutionUnit (296) Short 2
PageNumber (297) Short 0 0
Software (305) ASCII
DateTime (306) ASCII <2002:11:01 17:34:07>
Offset of next ifd: 0
==================================================================
The following is an example of the output of "tiffls -l " on a
TIFF image that is not in a format that can be faxed.
==================================================================
1:
NewSubfileType (254) Long 2
ImageWidth (256) Short 396
ImageLength (257) Short 612
BitsPerSample (258) Short 8
Compression (259) Short 1
PhotometricInterpretation (262) Short 1
FillOrder (266) Short 1
DocumentName (269) ASCII
ImageDescription (270) ASCII < Image generated by GNU ...>
StripOffset (273) Long 8 7928 15848 23768 31688 ...
Orientation (274) Short 1
SamplesPerPixel (277) Short 1
RowsPerStrip (278) Short 20
StripByteCounts (279) Long 7920 7920 7920 7920 ...
PlanarConfig (284) Short 1
Software (305) ASCII
Offset of next ifd: 0
==================================================================
The biggest problem with the file above is that it is not black and
white but grayscale (i.e. BitsPerSample is not 1).
If you cannot determine the reason for the incompatibility, please
fax the output of the "tiffls -l" to Faximum Technical Support for
analysis.
Tech Note: 071 - Copyright 2002 Faximum Software Inc., All Rights Reserved.
Last Updated: Fri Nov 1 18:49:34 PST 2002
The complete set of Faximum TechNotes are available on the Internet at
http://www.faximum.com/TechSupport
© Copyright 2001 Faximum Software Inc. All Rights Reserved.