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2017.04.28 20:38 "Interesting change/problem in LibTiff 4.0.7 with unsupported compressions", by <massoft@massoftware.com>
2017.05.02 12:56 "Re: Interesting change/problem in LibTiff 4.0.7 with unsupported compressions", by Michael Shiels
2017.05.02 14:33 "Re: Interesting change/problem in LibTiff 4.0.7 with unsupported compressions", by Charles Auer

2017.05.02 14:33 "Re: Interesting change/problem in LibTiff 4.0.7 with unsupported compressions", by Charles Auer

In the meantime, if you need to explore tags, AsTiffTagViewer is a free TIFF
Tag Viewer application for Windows.

.

http://www.awaresystems.be/imaging/tiff/astifftagviewer.html

.

Charles

.

AsTiffTagViewer - AWare
Systems<http://www.awaresystems.be/imaging/tiff/astifftagviewer.html>
www.awaresystems.be
AsTiffTagViewer, a freeware TIFF Tag Viewer for Windows, download page





________________________________
From: tiff-bounces@lists.maptools.org <tiff-bounces@lists.maptools.org> on
behalf of Michael Shiels [ MaS Software Inc ] <MaSSoft@massoftware.com>
Sent: Tuesday, May 2, 2017 12:56 PM
To: tiff@lists.maptools.org
Subject: Re: [Tiff] Interesting change/problem in LibTiff 4.0.7 with
unsupported compressions


Just wondering if anyone has thoughts on this problem.  Once I posted it
doesnítí seem to have made it into the archive which means maybe it didnít
get through at all??



This is a interesting situation since most people donít expect an error just
from enumerating the directory and reading the tags.  Maybe a warning would
be more appropriate specifically for an inability to detail out the
compression specific tags maybe??



Thanks.

Mike



From: tiff-bounces@lists.maptools.org
[mailto:tiff-bounces@lists.maptools.org] On Behalf Of Michael | Shiels [ MaS
\ Software \ Inc ]
Sent: Friday, April 28, 2017 4:38 PM
To: tiff@lists.maptools.org
Subject: [Tiff] Interesting change/problem in LibTiff 4.0.7 with unsupported
compressions



I found a decent change in the behavior of Libtiff Ė after I updated from
the 3.5.6/3.5.7 era to the most recent (yes 15 year jump!!)



Specifically this piece of code Ė basically ends up tripping an error if the
compression is not compiled/activated in the code.  So you canít even
peruse/move through a file without tripping an error.



               /*

               * An opportunity for compression mode dependent tag fixup

               */

               (*tif->tif_fixuptags)(tif);





Our engine specifically watches for errors and assumes itís pretty fatal Ė
when really itís kinda benign Ė UNLESS I want to extract the image data
itself, right??



Surely that should be pretty benign to just enumerate through a TIFF Ė even
if you donít support the compression of each page??



Mike