Convert a PPM file to an Atari Spectrum 512 image.
Convert a PPM file to an Atari Spectrum 512 image
ppmtospu path/to/input.ppm > path/to/output.spu
Use a dithering matrix of the specified size (0 means no dithering)
ppmtospu -d0|2|4 path/to/input.ppm > path/to/output.spu