The Atari 8-bit computer line had some notorious issues with video output. Colors are muddy and dull thanks to poor design on the video circuit. Some years ago I took my 130xe and applied the Super Video mod to try to improve the clarity and color depth. At the same time I built an S-Video interface cable to take full advantage of the machine’s output.

Detailed instructions for the mod are here: http://www.oldcomputers.it/parts/atari/130xe/docs/sv130-1.html

This was a great mod, the parts are cheap and working on the 1980s board was nice. I didn’t even own my solder station at the time and did all the work with a blunt Radio Shack iron, but it still all worked out just fine.