I installed the GD library and downloaded the gdtest script. Everything looked great in the output with the output. files created, but the output.jpg file is the only readable file.... The test script says all is OK....
Have you looked at netpbm (you can easily use this even if you don't have root access with it installed locally and a path) or maybe ImageMagick?
I mean the output file is not readable as an image file and doesn't display anything..... Plus if you try to open the output file in image software you get a "not readable filetype" error.....