The prune command was designed to be scripted against directories of files to determine which files were blank or contained only null values. As an example, large areas can get output as geographic or image based tiles. When operating on projected imagery it is possible that many of the individual tiles will contain only null values. The prune utility can be run against the images to determine those cases.
OSSIM can produce tiled output on geographic or pixel boundaries. prune can test for null or empty tiles.