Convert a PBM image to an encapsulated PostScript style preview bitmap. More information: https://netpbm.sourceforge.net/doc/pbmtoepsi.html.
pbmtoepsi path/to/image.pbm > path/to/output.bmp
pbmtoepsi -dpi 144 path/to/image.pbm > path/to/output.bmp
pbmtoepsi -dpi 72x144 path/to/image.pbm > path/to/output.bmp
pbmtoepsi -bbonly path/to/image.pbm > path/to/output.bmp