GAMGI uses the file extension to automatically determine the file format. To export a standard .ppm file of the whole graphic area of a GAMGI window, just give the filename the extension .ppm. These files start with an header:

P3
#Made with GAMGI 0.12.8
750 402
255

where the first line indicates the type of file, the second line is a comment, the third line is the number of columns (750) and lines (402) and the fourth line is the maximum color value (255).

After the header, the number of lines and columns in the file is the same as in the graphic area (from top to bottom), each position describing a pixel as a triplet of rgb colors, ranging from 0 to 255 (the maximum allowed value).

This format produces notoriously large files, although very simple, without loss of information and well supported by most graphics applications, such as the GIMP and XV.