Image Quality

These two cards offer so much performance that many gamers will wonder if there is any point in buying them. A high-end 7900 GTX will render all games at well playable frame rates, so why even bother getting this card today? The answer to that is NVIDIA's new Coverage Sampling Anti-Aliasing.


This is a comparison of the different AA modes available.

In the past there were two ways how to do anti-aliasing.

Supersampling is the easiest method to implement. Instead of the native resolution you render the image at a higher resolution and scale down the final image. So instead of 800x600 you would render at 1600x1200, and then shrink (downsample) the image down. As you can imagine at higher resolutions this has a huge performance hit.
Multisampling is an optimization of this. You sample textures and shaders only once and then apply the lighting effects once as well. This still gives you the benefit of rendering the triangles at a higher resolution while keeping memory bandwidth consumption at lower levels. When the image is complete you scale it down to the final framebuffer size like in Supersampling.


NVIDIA optimizes the memory bandwidth requirements even further with their Coverage Sampling. It compresses the color information. Even though this compression is not lossless, the image quality differences are barely noticeable.


If you are looking for the maximum quality, you can enable the CSAA Q mode which does not use the lossy compression, giving you even better image quality. However, this comes at the cost of performance, usually without any visible quality improvements.

NVIDIA's CSAA implementation basically gives you the quality of 16x AA with the performance hit of only 4x AA. So it is safe to say that you will be able to enjoy your games at 16x AA, without any loss of performance. This technique works even with HDR enabled and is available on all rendering APIs.


Here you can see the differences between NVIDIA's "old" 4xAA and the new 16x CSAA. Especially the edges are a lot more smoother.