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Old 4th March 2014, 22:57   #24253  |  Link
madshi
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Join Date: Sep 2006
Posts: 9,140
Quote:
Originally Posted by DigitalLF View Post
MadShi: i got a ATI 5750 and I'm about to get my self a 4k projektor and i think i need a new GPU for MadVR mostly for 1080p processing. What card would you recommend? is it still at the red team? or have you joined the darkside green team (nvidia)?
This question is asked a lot, and there's no simple answer. It all depends on which algorithms you want to use, which input/output resolutions need to be supported and which movie framerate and display refresh rate etc. Just as an example: If you need support for 60p, the GPU has to be almost 2.5x as fast as it would have to be if you limited yourself to 24p. So that shows clearly how much all of this depends on your exact requirements.

AMD and NVidia have their own set of advantages and disadvantages, so I can't give a clear recommendation for either one, either. If you decide to get something from AMD, you should definitely get a 7xxx series GPU.

Quote:
Originally Posted by Shiandow View Post
That's a shame, although I suspected it wasn't possible yet (since it is very rarely useful). Anyway, I have been able to show that, in principle, you can 'gamma correct' the dithering by changing the input of the dithering algorithm. And I've confirmed that this correction generally doesn't affect the first 16 bits, although for very dark colours it could in theory affect the 10th bit, but this doesn't seem to be very noticeable.
Ok, but does this improve overall image quality? Last time I tried, linear light dithering looked worse than gamma light dithering. I think the answer to this question might depend on the output bitdepth. At very low bitdepths, using gamma light is so wrong that any sort of linear light hack will probably improve things. But at higher bitdepths (say 5bit+) using gamma light dithering is probably good enough to avoid obvious gamma problems, and the dithering patterns might look better than when using linear light. This is just a guess, though...

Quote:
Originally Posted by Shiandow View Post
I'm also pretty sure that you should use the same 'gamma correction' for smooth motion and dithering otherwise you can get the 'blinking' effect, but I haven't been able to confirm this.
I'm not convinced about this. Smooth motion blending could in theory mix a black pixel from frame A together with a white pixel from frame B, regardless of bitdepth. Obviously doing this in linear light will result in dramatically different results compared to doing it in gamma light. However, if we're talking about dithering, we're dealing with mixing two neighbor shades in the output bitdepth. The general position of these two shades on the overall gamma curve are not changed by the dithering process. Using linear light will only slightly change how many pixels are drawn with shade 1 and how many with shade 2. Because of that I don't think that smooth motion FRC and dithering would have to use the same gamma function. But I've not tested any of this, so I'm just brainstorming here...
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