2009.02.13 17:36 "Re: [Tiff] TIFFReadRGBAImage w/ 8bit-gray + aplha", by Bob Friesenhahn

On Fri, 13 Feb 2009, Joris Van Damme (AWare Systems) wrote:

I've tested with current beta of LibTiff 4. Low-level LibTiff (TIFFReadEncodedXxx) does not get into trouble. However, the LibTiff RGBA interface does crash and burn, access violation style, even in version 4.0. At first examination, there's nothing that much out of the ordinary to this image, except that the two channels (MinIsBlack grayscale channel and the pre-calculated alpha channel) are stored planar, not chunky (in LibTiff speak, the tag TIFFTAG_PLANARCONFIG has the value PLANARCONFIG_SEPARATE) which is not all that common but certainly is perfectly legit.

The crash is likely due to an error in error handling. Via GraphicsMagick, libtiff returns this error:

  "Compression algorithm does not support random access."

I see such errors whenever libtiff tries to read a floating point TIFF (written by Photoshop CS2) which uses LZW compression. However, this file is not floating point. This suggests a problem with reading LZW compressed files written by recent Photoshop.

Bob
======================================
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/