Opening Pgm File
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
Opening methods of Pgm file
Irfan View, Acdsee
Links to opening Pgm file