[ptx] OSX-Hugin error w/ hi-qual TIFF

[Jeff Green]

I get an error when attempting to stitch a high-quality TIFF image in 
the Mac OS X version of Hugin. It returns a dialog with the error 
number of 255 (err num=2 in the terminal). The stitching of JPEG images 
works okay.

I'm using OSX Hugin version 0.5beta3.

jeff