Gallery Remote 1.5.1b32 on Ubuntu Feisty.
When selecting an image that you don't have read access to (for example when your camera gets mounted as the wrong user) Gallery Remote emits a totally bogus error message telling you that Image Magick isn't installed.
I would suggest doing a simple check for file access by doing open/close on the file in the Gallery Remote application before calling external programs in order to verify that you have read access to the file.