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COPYRIGHT NOTICE:
read_tiff.c - based strongly on...
TIFF software, by Sam Leffler . This is
a nice portable library for reading and writing TIFF files, plus
a few tools for manipulating them and reading other formats. It
is available via FTP as ucbvax.berkeley.edu:pub/tiff/*.tar.Z or
uunet.uu.net:graphics/tiff.tar.Z.
Permission to use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby granted,
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in
supporting documentation.
This file is provided AS IS with no warranties of any kind. The author
shall have no liability with respect to the infringement of copyrights,
trade secrets or any patents by this file or any part thereof. In no
event will the author be liable for any lost revenue or profits or
1) It has not been tested on a wide range of TIFF file types.
On the International AVS Center's anonymous ftp site
(avs.ncsc.org), in the subdirectory AVS_SAMP_DATA/TIFFS
there are a few sample TIFF files that have been tested.
2) This module has at this time (3/16/92) only been tested on
an IBM RS/6000.
3) In its current form, it is a bit "klugy" in that it first
reads in a TIFF file, converts it to an AVS .x format file
stored in "/tmp/tempAVS.x", then reads in this file again and
sends it to the output port. So you need (in its current form)
to have some space available in /tmp for read_tiff to work.
SAMPLE NETWORK:
read_tiff
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This is the README file created by Sam Leffler, to go along
with his tiff manipulation software. This software was used to create
this read_tiff AVS module. Sam Leffler's software is available
via anonymous ftp as ucbvax.berkeley.edu:pub/tiff/*.tar.Z
For more information specific to this module, check the file
read_tiff.txt, also in this directory.
$Header: /usr/people/sam/tiff/libtiff/RCS/README,v 1.9 91/08/23 16:45:25 sam Exp $
Configuration Comments:
----------------------
Aside from the compression algorithm support, there are 3
configuration-related defines that you can set in the Makefile:
SUBFILE_COMPAT if this is defined in tif_dir.c, an entry will be
included in the tag table to support short SubFileType
tags, as (incorrectly) generated by earlier versions
of this library
JPEG_SUPPORT if this is defined, support for the JPEG-related
tags will be compiled in. Note that at the present
time the JPEG compression support is not included.
MMAP_SUPPORT if this is set, and OS support exists for memory
mapping files, then the library will try to map
a file if it is opened for reading. If mmap does
not exist on your system, or the mmap call fails
on the file, then the normal read system calls are
used. It is not clear how useful this facility is.
By default, the above are not defined.
Portability Comments:
--------------------
I run this code on SGI machines (big-endian, MIPS CPU, 32-bit ints,
IEEE floating point). Makefiles exist for other platforms that the
code runs on -- this work has mostly been done by other people.
I've also been told that the code runs on Macintosh and PC-based
systems, although I don't know the particulars.
In general, I promise only that the code runs on SGI machines.
I will, however, gladly take back fixes to make it work on other
systems -- when the changes are reasonable unobtrusive.
I've tried to isolate as many of the UNIX-dependencies as possible in
two files: tiffcompat.h and tif_compat.c. There are still some problems
with the use of lseek(). I personally don't care to devote
much effort to making the code work (untouched) on lots of non-UNIX
platforms.
Machine dependencies such as byte order are specified in the
file machdep.h. You DO NOT need to define the floating point
related stuff for the library to compile! This may be needed
in the future if/when floating point data formats are supported.
Three general portability-related defines are:
USE_VARARGS define as 0 or 1 to select between the
use of varargs.h and stdarg.h; i.e.
-DUSE_VARARGS=0 means use stdarg.h
USE_PROTOTYPES define as 0 or 1 to select function
declarations with parameter types
BSDTYPES define this if your system does NOT
define the usual 4BSD typedefs
If you compile the code with prototypes (USE_PROTOTYPES=1), then
you must have USE_VARARGS=0.
Beware that if __STDC__ is defined and the USE_* symbols are
NOT defined, then compat.h defines:
USE_PROTOTYPES 1
USE_VARARGS 0
General Comments:
----------------
The library is designed to hide as much of the details of TIFF as
possible. In particular, TIFF directories are read in their entirety
into an internal format. This means that only the tags known by the
library are available to a user and that certain tag data may be
maintained that a user doesn't care about (e.g. color response
curves).
To add support for a new directory tag the following changes will be
needed:
1. Define the tag in tiff.h.
2. Add a field to the directory structure in tiffioP.h and define a
FIELD_* bit.
3. Add an entry in the FieldInfo array defined at the top of tiff_dir.c.
4. Add entries in TIFFSetField() and TIFFGetField1() for the new tag.
5. (optional) If the value associated with the tag is not a scalar value
(e.g. the array for GrayResponseCurve), then add the appropriate
code to TIFFReadDirectory() and TIFFWriteDirectory(). You're best
off finding a similar tag and cribbing code.
6. Add support to TIFFPrintDirectory() in tiff_print.c to print the
tag's value.
To add support for a compression algorithm:
1. Define the tag value in tiff.h.
2. Edit the file tiff_compress.c to add an entry to the
CompressionSchemes[] array.
3. Create a file with the compression scheme code, by convention files
are named tif_*.c (except perhaps on System V where the tif_ prefix
pushes some filenames over 14 chars.
4. Edit the Makefile to include the new source file.
A compression scheme, say foo, can have up to 10 entry points:
TIFFfoo(tif) /* initialize scheme and setup entry points in tif */
fooPreDecode(tif) /* called once per strip, after data is read,
but before the first row in a strip is decoded */
fooDecode*(tif, bp, cc, sample)/* decode cc bytes of data into the buffer */
fooDecodeRow(...) /* called to decode a single scanline */
fooDecodeStrip(...) /* called to decode an entire strip */
fooDecodeTile(...) /* called to decode an entire tile */
fooPreEncode(tif) /* called once per strip/tile, before the first row in
a strip is encoded */
fooEncode*(tif, bp, cc, sample)/* encode cc bytes of user data (bp) */
fooEncodeRow(...) /* called to decode a single scanline */
fooEncodeStrip(...) /* called to decode an entire strip */
fooEncodeTile(...) /* called to decode an entire tile */
fooPostEncode(tif) /* called once per strip/tile, just before data is written */
fooSeek(tif, row) /* seek forwards row scanlines from the beginning
of a strip (row will always be >0 and