SMS vs Genesis color palette

[Joe Redifer]

So I've been wondering this for a while but was never 100% sure. Does the SMS color palette exist within the Genesis palette? On one hand it would certainly seem so since the Genesis can run SMS games and they don't look wrong. But on the other hand, some SMS games like Donald Duck and this indie port of the TMNT arcade looks to have a few brighter colors than are available on the Genesis (especially in the intro scenes to stage 1). How? Why are Genesis games so damn dark and muddy in comparison?

[Black_Tiger]

I haven't bothered comparing because I only play SMS games on a Sega Master System and Mark III SMS, but I have noticed a wide range of picture quality between Genesis consoles.

Last time I tested out a PBC before selling it, Wonderboy did look like the color temperature was off (through RGB transcoded to component), but not like what I've seen in comparisons of SG-1000 games running on a Mark III.

That TMNT video didn't state whether or not it was emulation, but the color doesn't feel right and everything blends too well. It looks more like a Game Gear game.

[Silanda]

AFAIK roughly, though I'm uncertain whether factors like different DACs come into play. I suspect it's just the case that as the Master System had a smaller palette available, artists would lean towards using colours that "popped" more. That was often the case with 8-bit systems. With the MD/Genesis's larger overall palette and the ability to display more colours at once, using vivid colours was likely eschewed by many artists in favour of choosing ones that blended better and looked more subtle. That's likely to be especially true on the Mega Drive/Genesis given that artists often used dithering to simulate halftones (mainly) because of a lack of sub-palette entries.

Then there's the other factor: colours not bright enough? Use the saturation control. I know that's certainly what I did because the outputs from different sources could vary significantly. It was almost expected for the user to do that. Of course, that leads to debate over what the intended look of a game was. The intended appearance of the Commodore 64's palette is a massive can of worms, for example (especially given that the NTSC and PAL systems output different colour levels).

[axel]

AFAIK roughly, though I'm uncertain whether factors like different DACs come into play. I suspect it's just the case that as the Master System had a smaller palette available, artists would lean towards using colours that "popped" more. That was often the case with 8-bit systems. With the MD/Genesis's larger overall palette and the ability to display more colours at once, using vivid colours was likely eschewed by many artists in favour of choosing ones that blended better and looked more subtle. That's likely to be especially true on the Mega Drive/Genesis given that artists often used dithering to simulate halftones (mainly) because of a lack of sub-palette entries.

Then there's the other factor: colours not bright enough? Use the saturation control. I know that's certainly what I did because the outputs from different sources could vary significantly. It was almost expected for the user to do that. Of course, that leads to debate over what the intended look of a game was. The intended appearance of the Commodore 64's palette is a massive can of worms, for example (especially given that the NTSC and PAL systems output different colour levels).

I agree this sounds like the most plausible explanation. Mathematically there is no reason the Genesis couldn't store the same color value as the Master System. The Genesis uses 3 bits per channel and the Master system uses 2, in the same order BGR, so if you just zero the first bit on each channel (and leave off shadow/highlight) it should look exactly the same to the VDP, at least as I understand it.

[TheMole]

I agree this sounds like the most plausible explanation. Mathematically there is no reason the Genesis couldn't store the same color value as the Master System. The Genesis uses 3 bits per channel and the Master system uses 2, in the same order BGR, so if you just zero the first bit on each channel (and leave off shadow/highlight) it should look exactly the same to the VDP, at least as I understand it.

Not sure if that's entirely correct

Let's just consider one channel, e.g. the Green channel:

On the SMS, you have 2 bits, which allows you to turn on the green channel at the following levels:

0% (00)
33%(01)
66%(10)
100%(11)

On the MD, on the other hand, you have three bits, which results in the following percentages:

0% (000)
14%(001)
29%(010)
43%(011)
57%(100)
71%(101)
86%(110)
100%(111)

So, any SMS color that is relies on at least one RGB channel value of 33% or 66% will have to mapped to the closest possible color of the MD palette (so probably 29% and 71% respectively). This means that most colors the SMS can produce cannot be reproduced accurately by the MD.

The above is of course assuming a linear relationship between the bit values and the analog color outputs.

[axel]

Not sure if that's entirely correct

Let's just consider one channel, e.g. the Green channel:

On the SMS, you have 2 bits, which allows you to turn on the green channel at the following levels:

0% (00)
33%(01)
66%(10)
100%(11)

On the MD, on the other hand, you have three bits, which results in the following percentages:

0% (000)
14%(001)
29%(010)
43%(011)
57%(100)
71%(101)
86%(110)
100%(111)

So, any SMS color that is relies on at least one RGB channel value of 33% or 66% will have to mapped to the closest possible color of the MD palette (so probably 29% and 71% respectively). This means that most colors the SMS can produce cannot be reproduced accurately by the MD.

The above is of course assuming a linear relationship between the bit values and the analog color outputs.

I see what you mean, yeah if it's linear then you're right you couldn't get the exact same values.

[Silanda]

The above is of course assuming a linear relationship between the bit values and the analog color outputs.

AFAIK it's not quite linear. https://plutiedev.com/vdp-color-ramp

[axel]

AFAIK it's not quite linear. https://plutiedev.com/vdp-color-ramp

Thank you for posting that. I had seen those numbers in the MAME driver (megadriv.cpp) for the palette but never understood where they came from or why it didn't follow an obvious pattern.

[Joe Redifer]

So in Master System mode are games using the Genesis color palette that has had each color mapped to a similar one on the Master System, or is there a separate palette of colors on the chip just for Master System games?

[TapamN]

So in Master System mode are games using the Genesis color palette that has had each color mapped to a similar one on the Master System, or is there a separate palette of colors on the chip just for Master System games?

According to here, it's actually a unique set of colors, with dedicated SMS-mode hardware to generate the DAC voltages.

[Black_Tiger]

According to here, it's actually a unique set of colors, with dedicated SMS-mode hardware to generate the DAC voltages.

It's nice to know exactly what the values are.

That's definitely a noticeable difference that would feel off.

[turboxray]

Not to purposefully complicate matters, but SMS: https://www.smspower.org/forums/1823...ndingsByBfbiii

[Sanjo]

wow never knew about the TMNT Arcade game port.
was hoping some one would make a homebrew for the Genesis
but pleasanty surprised some one is making one for the SMS! it looks amazing!
had I saw this on the SMS back in the days, I would have quickly sold all my NES games to get it!

[Joe Redifer]

According to here, it's actually a unique set of colors, with dedicated SMS-mode hardware to generate the DAC voltages.

Cool. So of course there's no way to turn both palettes on at the same time for a mindblowing 576 colors to choose from, right?

[Alianger]

That TMNT video didn't state whether or not it was emulation, but the color doesn't feel right and everything blends too well. It looks more like a Game Gear game.

No that looks correct, it just uses the palette well. The real hardware values based on the link above are only slightly different too.

A GG port could use pretty much the same shades as the arcade original, just a lot fewer of them (less than a third of the original game's in that level).