How does the RGB scale work exactly?

[Mister Y]

I'm a bit puzzled about what the RGB scale does, exactly.

Is the number corresponding to the number of bits in each RGB channel? If so, why is, for example, the Sega Megadrive listed as "8", when it had a 9.bit color depth with 3 bits for each color channel? Similarly, the F1 help sheet for the Shift+P Palette window says to set the RGB scale value to 16 for Amiga colors, when the Amiga had 4 bits per color component. Unless that's not how the RGB scale works, which only puzzles me further.

[Yves Rizoud]

It's probably confusing because there is only one setting, and it applies to each of the three R and G and B channels.
In order to use the Sega's color space, you pick 8 because the 3bits per channels give 8 different values (2x2x2). The sliders will go 0 to 7. Total number of possible colors : 8 x 8 x8 = 512
In order to use the Amiga's color space, you pick 16 because the 4bits per channels give 16 different values (2x2x2x2). The sliders will go 0 to 15.  Total number of possible colors : 16 x 16 x16 = 4096

It would probably have been clearer to have this setting a "number of bits per channel", but then we couldn't have the Amstrad's '3 values per channel' (empty / half / full), because 3 isn't a power of two.

Le ven. 20 déc. 2024 à 10:08, Mister Y <miste...@gmail.com> a écrit :

I'm a bit puzzled about what the RGB scale does, exactly.

Is the number corresponding to the number of bits in each RGB channel? If so, why is, for example, the Sega Megadrive listed as "8", when it had a 9.bit color depth with 3 bits for each color channel? Similarly, the F1 help sheet for the Shift+P Palette window says to set the RGB scale value to 16 for Amiga colors, when the Amiga had 4 bits per color component. Unless that's not how the RGB scale works, which only puzzles me further.

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[Mister Y]

That was on me only having partial information on how this kind of color works, thanks for the clarification!

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[Mister Y]

Then given this how would one achieve the 65,536 color palette of the CPS1, if at all possible?

[miniupnp]

Hello,

As far as I know the 16 bits colors of  CPS1 are not the usual RGB565 (32 levels of Red x 64 levels of green x 32 levels of blue)
but an unusual 12 bit RGB444 + 4 bits of brightness.
I don't know the formula to map this to the 24bit RGB888 supported by GrafX2.

Regards,

Le 16/01/2025 à 11:57, Mister Y a écrit :