Convert a PNM file to a Sun rasterfile. More information: https://netpbm.sourceforge.net/doc/pnmtorast.html.
pnmtorast path/to/input.pnm > path/to/output.rast
RT_STANDARD
or RT_BYTE_ENCODED
form for the output:pnmtorast -standard|rle path/to/input.pnm > path/to/output.rast