Compressed graphic image data files, such as Compressed ARC (Arc-second Raster Chart/map) Digitized Raster Graphics (CADRG) map files for a region of interest, are stored in blocks of memory (nodes) preferably arranged as a linked list. Portions of files containing data for an area of interest including an image of interest are decompressed before the data are sent to a frame buffer for display. Nodes that do not contain requested data are flagged as unused, but not deallocated, making the data in such nodes available for use or replacement.