Like Nigel says, one would need to get the picture file format decoded into a properly sized array or table data file to be used by the micro and glcd. So knowledge of a scripting language would be necessary along with the requirements of the microprocessor language/compiler and the glcd. Part one of the project would be to get familiar with something like Python and PyPIL (Python Imaging Library) or Java or? The PyPIL library can decode all the different image formats, resize them, and otherwise manipulate them into a file that could be downloaded to an SD and read as a micro language header file.
You might be lucky, and the micro picked out would have a built in library to decode an image to a header file, and you could skip step one? Supposedly Microchip has a TIFF file converter, although I have not verified that. Also there is a Hackaday project that converts monochrome BMP files for an AVR, and a glcd.
EDIT: This looks easier if pre-canned vendor routines are used, such as the Microchip c30, c32 graphics library. Decodes BMP, JPEG, images and SD support.