Takuma Murakami wrote:
I have tried to fix the wmaker problem but get stuck
since I don't know how to debug DLLs...
Although I don't know much about TIFF files, I ran
tiffinfo on two systems. The target TIFF file is
/usr/X11R6/share/WINGs/Images.tiff in cygwin
WindowMaker distribution.
On the problematic cygwin (WindowMaker-0.80.2-1,
tiff-3.6.0-5) the output is:
TIFFReadDirectory: Warning, /usr/X11R6/share/WINGs/Images.tiff:
unknown field wi
th tag 317 (0x13d) encountered.
...
Compression Scheme: LZW
...
Predictor: horizontal differencing 2 (0x2)
The 'Compression Scheme' field indicates LZW.
Is this relevant to the problem?
Yes. LZW support is not included in and has never been included in any
cygwin distribution of libtiff. This is because LZW is patented by
Unisys and they do not allow the algorithms to be used without royalty
payments.
Now, the patent did expire in September 2003 in the US, but the patent
is still valid in several other countries. Therefore, we STILL do not
include LZW support in the binary distributions of libtiff.
(Of course, this makes me wonder: (a) there were reports that "this used
to work -- or still works -- with cygtiff3. But THAT dll did not
provide LZW support either. See below for random speculation. (b) Why
is WindowMaker distributing TIFFs that cannot be read by free (as in
speech) software without violating patents in some countries? Do they
only care about the US? This is an issue that should be raised on the
relevant WindowMaker lists)
IF you want to test this proposition, the tiff -src package distributed
by cygwin provides the source code and instructions for rebuilding
cygtiff4 wiht LZW for your own personal use, if you happen to live in a
country where the UniSys patent has lapsed -- like the US -- or if you
have purchased a license from UniSys.
Then you could see if rebuilding cygtiff4 WITH LZW fixes the problem.
(Random speculation: perhaps the person who reported success by copying
their cygtiff3 onto cygtiff4 did exactly that -- rebuilt cygtiff3 with
LZW, but so long ago that they forgot. That would explain all of the
reported behaviors...)
--
Chuck