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Started by 1zacster | | 2 answers
SSAA on windows 8 desktop?
NVIDIA advertised their new 970/980 GPUs as having "4k quality on a 1080p display" by supersample anti aliasing because of the leap in gpu power while display resolution is still relatively small. SSAA has existed for a while now and I was wondering if it could be applied to a windows 8 desktop for slightly sharper text/images.
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a b * Windows 8
September 20, 2014 11:12:38 PM

1zacster said:
NVIDIA advertised their new 970/980 GPUs as having "4k quality on a 1080p display" by supersample anti aliasing because of the leap in gpu power while display resolution is still relatively small. SSAA has existed for a while now and I was wondering if it could be applied to a windows 8 desktop for slightly sharper text/images.


SSAA or FSAA (Full Scene Anti-Aliasing) is the simplest form of Anti-Aliasing. It works by rendering the scene at a resolution that is a scalar multiple of the display resolution and then downsampling it. For example, when 2xSSAA is applied to a 1920x1080 display the render path would render the scene at 3840x2160. A downsampling filter that uses neighbour information would then be used to bring it back down to 1920x1080. The drawback of SSAA is that while it is algorithmically simple, it is very computationally demanding. In particular, it must run the pixel shaders exponentially more times than other AA methods. 2xSSAA requires 4 times as many runs, and 4xSSAA requires 16 times as many runes.

Due to the computational complexity of SSAA it has often been passed over for MSAA which is itself an optimization of SSAA that does not run the pixel shader more than once per actual output pixel. Instead, MSAA performs additional shading computations only where there is overlap between geometry (edges). However, NVidia claims that their newest GPUs can get away with 2xSSAA at 1920x1080 as there is sufficient shading power for most games. Times will tell if this is true or not.

In any case, anti-aliasing is designed to smooth out an image that is too sharp by removing the high frequency components. It is not designed to make an image more clear. The UI and overlays of various games are applied after the scene has been rendered and are themselves usually not subject to anti-aliasing techniques. A notable exception is FXAA which must be carefully implemented to avoid blurring the overlay. Applying Anti-Aliasing to an overlay or an image with a fixed position and resolution would blur the elements that the designer intended to be there.

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