This is the display format associated with the broadcast of slow-scan television. This legacy format was used to transmit a static image given limited bandwidth through the use of specialized software.
This format was used for storing databases on the Pegasus and Palm PDA devices. Besides images, PDB allowed you to store tables, maps, e-books, and other data in a structured way. Today it has become obsolete and has been replaced by more flexible formats with DRM protection.