Convert jp2k to pnm Online: jp2k2pnm

You can use Tom's Editor to easily convert images from
JPEG 2000 .JP2K to Portable aNy Map .PNM.
Tom's Editor is a free, online image manipulation and converter program.

Go to Tom's Editor

JP2K

JPEG 2000 is an image format with extension JP2K.

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.