Project Scope - aheckmann/gm GitHub Wiki

ImageMagick/GraphicsMagick Detection

gm assumes ImageMagick or GraphicsMagick is already installed on the current system. gm assumes the developer uses the appropriate graphics library. gm will not gracefully handle any errors due to the developer not installing or not using the appropriate graphics library.

An easy way to test whether a graphics library installed is by executing convert -version or gm -version in a child process. See this relevant stackoverflow question: http://stackoverflow.com/a/16977899/927092