Convert ngg to pnm Online: ngg2pnm

You can use Tom's Editor to easily convert images from
Nokia Group Graphics .NGG to Portable aNy Map .PNM.
Tom's Editor is a free, online image manipulation and converter program.

Go to Tom's Editor

NGG

Nokia Group Graphics is an image format with extension NGG.

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.