If you are wanting to send images, there are already some cool ways to do that: either SSTV (https://en.wikipedia.org/wiki/Slow-scan_television) or Wenet, which sends them at a much higher speed: https://github.com/projecthorus/wenet.

I wrote some code to send SSTV because everything was either proprietary and didn't work, shareware and didn't work (and often with the original author gone Silent Key so no way to get the real version), or under some vaguely-specified licence and written with Tk widgets in Fortran or some damn thing.

I wrote it about 25 years ago and can't currently find it but it's one one of these hard disks in these here blue moving crates somewhere. It'd take less time to recreate than find, I suspect, especially if I also wanted to make it build nicely in gcc from this decade.

It just grabbed from a V4L2 source, and emitted a burst of Robot36 over the soundcard. In conjunction with a heavy-duty Tait T2000-family transceiver I used it to livestream a drive across Glasgow, slowly and noisily, sending one picture per minute which gave the poor PA transistor time to cool a bit ;-)