XBM

XBM (X BitMap) is a raster image file format. It was one of the first image formats supported by graphical web browsers.

An XBM file is plain text, and doubles as a fragment of C programming code. The format is very inefficient in size, but it can be useful as a simple way to embed an image into a C program.

Sample files

 * http://www.fileformat.info/format/xbm/sample/index.htm
 * http://people.sc.fsu.edu/~jburkardt/data/xbm/xbm.html