Convert pnm to htm Online: pnm2htm
You can use Tom's Editor to easily convert images from
Portable aNy Map .PNM to HTML Table Image
Tom's Editor is a free, online image manipulation and converter program.
Go to Tom's Editor
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.
This is a very simple format where every pixel is saved as a cell in HTML table. You can view such files in every web browser, for eg. Firefox or Chrome.