Convert atk to pnm Online: atk2pnm

You can use Tom's Editor to easily convert images from
Andrew Toolkit raster object .ATK to Portable aNy Map .PNM.
Tom's Editor is a free, online image manipulation and converter program.

Go to Tom's Editor

ATK

Andrew Toolkit raster object is an image format with extension ATK.

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.