Convert ism to pnm Online: ism2pnm

You can use Tom's Editor to easily convert images from
Image System .ISM to Portable aNy Map .PNM.
Tom's Editor is a free, online image manipulation and converter program.

Go to Tom's Editor

ISM

Image System is an image format with extension ISM.

PNM

PNM images are uncompressed 24 bit RGB images. Can cannot store Alpha channel. PNM images come in 2 types: binary and text. Especially popular on Linux.