pgm is: Pgm extension is related to Portable Gray Map. You can try to open pgm files with Irfan View and Acdsee softwares.
Pgm extension stands for image files. These images 8-bit gray toned. The image definition consist of numbers. And every single number represents different kind of gray hue. You have chance to open pgm files with Irfan View and Acdsee softwares. To get detailed information, please take a look to following web pages: www.acdsee.com, www.irfanview.com
Pgm File format viewers or openers
Irfan View, Acdsee
Pgm File related links.