Convert a PPM image to an AutoCAD database or slide. More information: https://netpbm.sourceforge.net/doc/ppmtoacad.html.
ppmtoacad path/to/file.ppm > path/to/file.acad
ppmtoacad -dxb path/to/file.ppm > path/to/file.dxb
ppmtoacad -8 path/to/file.ppm > path/to/file.dxb