Convert jp2 to pnm Online: jp22pnm

You can use Tom's Editor to easily convert images from
JPEG-2000 JP2 File Format Syntax .JP2 to Portable aNy Map .PNM.
Tom's Editor is a free, online image manipulation and converter program.

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JP2

JPEG-2000 JP2 File Format Syntax is an image format with extension JP2.

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.