.PNM File Extension
File TypePortable Any Map Image
What is a PNM file?
Bitmap image created in the Portable Any Map format, which was designed to handle several types of portable monochrome, grayscale, and color images; may include raster graphic data in a .PBM, .PGM, or .PPM format; may be stored using binary data or ASCII text.
PNM files store one image and do not use compression.