Convert dcm to pnm Online: dcm2pnm

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

Go to Tom's Editor

DCM

DICOM is an image format with extension DCM.

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.