Convert esm to pnm Online: esm2pnm
You can use Tom's Editor to easily convert images from
Enhanced Simplex .ESM to Portable aNy Map .PNM.
Tom's Editor is a free, online image manipulation and converter program.
Go to Tom's Editor
Enhanced Simplex is an image format with extension ESM.
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.