Convert ihe to pnm Online: ihe2pnm
You can use Tom's Editor to easily convert images from
Interlace Hires Editor .IHE to Portable aNy Map .PNM.
Tom's Editor is a free, online image manipulation and converter program.
Go to Tom's Editor
Interlace Hires Editor is an image format with extension IHE.
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.