Options/proposal for supporting over 15 colors

[pokepress]

So, while the Genesis has a technical limit of 16 (practically 15 in most cases) colors per palette, and a layer (aka plane) can only be assigned one palette, it is possible to display images that have more than 15 colors. One such method is to combine two backgrounds using transparency. You can see an example of that in the branch I've created here:

https://github.com/pokepress/sega-slides

It has some limitations due to the amount of VRAM in the Genesis, but seems to work well for real-world images.

In theory, this could be taken further via shadow/highlight and other techniques like midframe palette changes, but those would be considerably more difficult to program.

[joeyparrish]

I'm very open to this in general.

This began as an offshoot of https://github.com/joeyparrish/kinetoscope and the video encoder and player there. For video playback, the limit was bandwidth and CPU time to push frames to the VDP, so using two planes to increase color fidelity would have required me to half my framerate, which was already quite low.

But there's no such real-time restriction for showing slides, so there's no reason we can't use two planes & two palettes here.

I took a brief look at the code in your fork, and I like your approach using pillow to split a 30-color image into two based on the color index. Very elegant!

I would be happy to take a PR for this if you want to contribute. Thank you!