Re: wmaker TIFF (actually libtiff4) problem

[Charles Wilson <cygwin at cwilson dot fastmail dot fm>]

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