From Sonic Retro

Surely the number of colours possible on the Megadrive is somewhat less than 1536? That number assumes that every shadow/highlght hue is distinct from a regular hue, but following the formulae on this page the colour 048C when shadowed would be 0246, which is not a novel colour assuming you start with the initial 512 and then apply shadowing/highlighting as appropriate. Quickman 15:45, 15 March 2010 (UTC)

Yes, it's less than 1536. I once tried to work out the real amount, but I gave up after a while. Maybe I'll try again later, or perhaps someone should run the "1536 colors demo" on Gens/GS with the proper palette scaling and take a screenshot. Then with any graphic editor (e.g. Paint Shop Pro) you can easily count the number of colours from there. Nineko 16:22, 15 March 2010 (UTC)
The palette diagram has 1471 unique colours, assuming it's accurate. - Hivebrain 17:23, 15 March 2010 (UTC)
No, it's not, I took it ages ago with plain old Gens, which is why I recommended someone to re-run the "1536 colors demo" on Gens/GS, since GerbilSoft implemented the proper colour values. Nineko 17:51, 15 March 2010 (UTC)
However the latest public version of Gens/GS doesn't implement the proper behaviour yet so I guess we'll have to wait a bit more. Just saying, in case someone went ahead and took a screenshot with it. Nineko 18:03, 15 March 2010 (UTC)
The diagram is accurate inasmuch as it represents the correct number of level changes for 9-bit colour. (There's no 100% accurate mapping of Megadrive colour onto a 24-bit colourspace. Oscilloscope measurements of the VDP's output give 0V for 0000, and 4.7V for 0EEE, with more-or-less-equal steps between adjacent colour levels.) I measure 512 unique colours in the central column, and 1471 colours in the whole thing. (Incidentally, we might want to replace these colour-gamut screenshots with the images from this page - the 6-bit RGB image corresponds with the Master System gamut, the 9-bit RGB image with the Megadrive gamut and the 12-bit RGB image with the Game Gear gamut.) Quickman 13:16, 26 March 2010 (UTC)