Convert hdr to pnm Online: hdr2pnm
You can use Tom's Editor to easily convert images from
Radiance RGBE image .HDR to Portable aNy Map .PNM.
Tom's Editor is a free, online image manipulation and converter program.
Go to Tom's Editor
Radiance RGBE image is an image format with extension HDR.
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.