right, $fh is already a filehandle. in fact, that wasn't the problem.

Image::Magick::Read has no return value, so any code like:

       $th->Read( file => $fh ) or die ....

will fail, because the LHS will never get set to 1.

this stumped me for a couple days, until i started thinking about why $! wasn't set. that was the clue as to why things didn't work.