2009.08.28 01:32 "[Tiff] tiff 3.9.0 writes bad files", by Bob Friesenhahn
Indications are that libtiff 3.9.0 is writing defective TIFF files. Please don't use or distribute it.
It seems that the StripOffset and StripByteCount for the last strip in the file are being written as zero.
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/