Convert ithmb to pnm Online: ithmb2pnm
You can use Tom's Editor to easily convert images from
.ITHMB to Portable aNy Map .PNM.
Tom's Editor is a free, online image manipulation and converter program.
Go to Tom's Editor
ITHMB are thumbnails used by various Apple devices. At first these images were used by iPhods but now can be found on iPhones and iPads.
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.