NV40 doesnt support gamma-correct FSAA,does it?

[Basic]

Only if you can afford 12+ bits per colour channel.

... or have a block exponent (RGBe).

Why have I got this déjà vu feeling?

 

[pcchen]

If the bacbuffer is in linear space, 8 bits per channel gives too little precision in the low ranges/dark colours. If the backbuffer is linear like you proposed, I don't see what the DAC precision has to do with anything since the transform will be linear?

The RAMDAC uses a (non-linear) look-up table to do gamma correction, which is supported on most video cards today.

You'll lose some precision in dark colors, since most PC screen has 1.8 or 2.2 gamma, which give excess precision in dark colors. On the other hand, you get more precision in light colors. It is somewhat related to the response of human eyes, as dark colors normally need more precision than light colors.

RGBe as Basic proposed is a workaround but I think it's not likely to be widely supported. P20 is claimed to support FP16 back buffer, but how it affects the performance is not known yet.

By the way, does R3X0 support gamma corrected blending?

 

[Simon F]

I think it's enough if the RAMDAC has a 12 bits look-up table? Of course, DVI-D is limited to 8 bits...

Sorry, I meant to say "12 bpc in the framebuffer".

 

[GameCat]

Ah, sorry my brain really isn't paying attention today

Don't know where I got the idea that a linear framebuffer doesn't require gamma correction... Anyway, even the DAC being 12 bits doesn't help the fact that you'll get precision related artifacts in the framebuffer if it's 8 bits per channel and linear. I doubt having more precision in the DAC could remove the artifacts, it can't recreate signal quality that isn't there, although it certainly would improve quality to have more bits to get the actual gamma converision in higher precision.