There might be an error in this palette, but yeah, types 1, 3, 7, 8 use Research palette, while types 2, 4, 5, 6 use Battlescape (Tactical) palette minus last 16 colors.
Nah they don't work at all. It seems like your software is cutting out the "unused" colors from every picture, which ruins everything. Hmm instead of using the files from the internets (I've tried them and these palettes don't seem to be very good), maybe you could try extracting the pallette from working pictures found in some mods? Or - I've modified one of your pictures to fit the research palette, you can try it. Also disable that dithering (although with such low-intesity dithering, sometimes a dithered conversion does look better than a smooth one).@Ivan: nah I couldn't help, I'm an user, not a guru, I don't know a heck about graphic formats, graphic soft (except working knowledge how to use MS paint & photoshop) etc.
Could you post the original images here? I have a thing to try out.
Converted them for you:
When an image converts poorly, it means it relies too much on colors which have no equivalent in XCOM's palette.It's possible to improve the result by tuning the image's colors beforehand : push the saturation for everything that's not greyscale, and be sure that the largest surfaces use exactly the hue of the available color ranges.
I'll suggest to the OP to put Paint.NET in the list of not recommended until I find if it is possible to save the pictures in a way that doesn't screw the color code or a way to fix the palette within the program (in case it is that which I doubt).
In the meantime I've been tackling mtpaint (which seems good but I haven't got the skills yet) and graphics gale, which has a free edition and was recommended in a pixel artist web for beginners.
Also, out of a sudden fear. Does the aircraft weapons use a different palette ?