pnmtoddif
Convert a PNM image to a DDIF image file.
TLDR
Convert a PNM image to a DDIF image file
$ pnmtoddif [path/to/image.pnm] > [path/to/image.ddif]
Explicitly specify the horizontal and vertical resolution of the output image
$ pnmtoddif -resolution [horizontal_dpi] [vertical_dpi] [path/to/image.pnm] > [path/to/image.ddif]
