Questions and postings pertaining to the development of ImageMagick, feature enhancements, and ImageMagick internals. ImageMagick source code and algorithms are discussed here. Usage questions which are too arcane for the normal user list should also be posted here.
We can reproduce the problem you posted and will have a patch in ImageMagick 6.3.0-6 Beta within a few days. Your image sets samples per pixel to 1 when in fact it should be two (1 grayscale value and 1 alpha value). Can you check the TIFF specification and see if your image is encoded improperly? In the mean-time, ImageMagick needs to account for the possibility of an incorrect samples-per-pixel value.
