Convert sfw to pnm Online: sfw2pnm
You can use Tom's Editor to easily convert images from
Seattle File Works image .SFW to Portable aNy Map .PNM.
Tom's Editor is a free, online image manipulation and converter program.
Go to Tom's Editor
Seattle File Works image is an image format with extension SFW.
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.