Thanks for your feedback!
To keep it quick:
- Settings are something that are on the to-do list - the app really grew in the last 12 months from mono to full color support, so there's still many polishes I'd like to do (Hence the RC "Release Candidate" label - program is good to use, but there are some rough edges). Settings being one of them.
- Stop / Cancel. Also on the to-do list.
- Scrolling: maybe the direction you mention has something to do with the OS's "natural scroll" settings. Maybe Ditherista doesn't detect those properly? I can only guess here - but you could share what OS you're using and if you have this feature enabled. That'd help me investigate.
- Selection / Partial dithering: I like that idea. I implemented a selection widget last month for something similar...
- Amiga HAM (4096 colors): I considered adding it at first, but reading into it, just adding HAM palette won't create correct looking HAM images, because the HAM mode has a few peculiar rules about which colored pixels can be next to each other. It would require writing a separate ditherer that replicates how the Amiga's hardware chooses pixel colors in HAM mode. So it's not quite as straight forward as just adding a palette. But if you say, "I don't care about accuracy" you should be able to load a Paint.NET palette with the Amiga's 4096 colors.
- more than 256 colors for reduced palettes: I need to investigate this and test this. Some of the 3rd party code I'm using doesn't support more colors... so more coding needed :P ...and then there's also the speed to consider. Also, at some point, more colors don't really give you much better results. The quality of the color dither then depends much more on color matching and the color quantization algorithms than the number of colors. The better those 2 algorithms are, the better the dither will look, even when very few colors (<32) are used.
What does this mean? The next version of Ditherista won't support more colors, but I worked on improving the accuracy and speed of color dithering (I'm testing this over the holidays...).
- Commodore Plus/4 Palette: if you have a link to a good one, I'd be happy if you can share it and I'll include it in a future release! (Doesn't have to be in Paint.NET format)
Thanks again!