XBM file format
XBM is an image format with the source containing image data in the form of plain binary text. The bitmap image's pixels support different shades of a single color. They were created as a format for storing images of icons and cursors displayed on the Graphical User Interface of the UNIX-based X Windows System. As an extension of the C programming language, XBM can be directly integrated into a graphics application code. The image data is stored as comma-separated strings of 4-character length, with each 4-character portion representing an 8-bit memory space.
Quite similar to PBM files, the XBM format strictly supports monochrome bitmap images. Though several single color shades can be stored as XBM, most XBM images come in black and white. Some files in the XBM format use the .bm extension instead of .xbm. XBM format lost popularity, and the XPM format – an extended version of the former replaced it. XBM, however, still finds use in the Graphical User Interface of some software programs for storing cursors, icons, and selection buttons. XBM files can be read directly by a C-language decoding program, compared to other image files that require a graphical viewer or editing program to access their data content.