PPM (Portable pixmap format)

is a Portable Pixel Map, and comprises three bytes for each pixel, one for the red component, one for the green component, and one for the blue component. Hence it is a 'true colour' image, using the full 24 bit representation. Each of the single colour planes is actually grey scale image, hence a PPM file can be separated into three PGM files, or generated from three PGM files.