Page 5 - Improved image quality

Improved Image Quality

Not only did ATI improve improved HQ anisotropic filtering, we can also open up a large can of AA modes which makes you sick to your stomach.

Hey! You can do 24x AA with this card. Yes, the quest for the biggest e-peen between ATI and NVIDIA has always been a large struggle. Hey, for me a good high quality 8xAA mode is enough, really. But we went from 2 to 4,6,8,12,16 and we now have 24xAA for a single card.

And obviously you can combine those AA modes of the R600-based ATI Radeon HD 2900 with 128-bit HDR rendering. But as stated; AMD has also upped the ante on anti-aliasing support. The ATI Radeon HD 2900-series supports up to 24x anti-aliasing and introduces a set of new AA modes (actually available on the entire 2000 series if you have enough memory).

The first standard one is one we have known for a long time now, 8x Multi Sample AA. Multi Sample AA is the old way of doing it, but it has debuted in hardware. More interesting is the new AA mode is called CFAA, which in short means "Custom Filter Anti-Aliasing", which allows up-to 24x AA. The new Anti Aliasing supports programmable sample patterns, programmable resolve filters and it is upgradeable via driver updates. Yes, programmable sample patterns and programmable resolve filters. Yes; this new AA "filter" is complex. Basically it runs an edge detection filter on the rendered image, then applies a lot of samples, does its math and then the result is a really nice smooth jaggy free edge. The thing is, this filter is applied in the image where it's needed the most. So the most ugly jagged lines are dealt with while the less intrusive once can be left alone. A little weird if you think about it, but I do have to admit ... CFAA is looking great. We have however been unable to enable the new 12x and 24x AA modes despite a new alpha driver and patch ATI delivered. Ah well, they have an excellent driver team that'll fix this soon. I will show you some examples some of the CFAA modes though.

CFAA benefits according to ATI:

• excellent edge smoothing where it's needed the most
• reduces texture shimmering
• avoids blurring of fine detail
• provides better quality per sample over supersampling, with better performance.

CFAA benefits according to Hilbert:

• works with HDR
• more samples per pixels = always good
• less blurry images as AA is applied where it's needed
• CFAA is software upgradeable through the Catalyst drivers

So, what do you need to remember: the good news is that the existing functionality is still here including HDR+AA, Adaptive SSAA/MSAA, Temporal AA, Super AA and Gamma correct modes.

At driver level you need to enable this mode manually though, look for this:

Could this be any more confusing to the end-user? Hmm ... no. Now, I took a couple of screenshots with a nice selection of CFAA applied. Later on in the benchmarks we'll also look at performance by the way. But for now, here's CFAA applied:

no AA

4xAA  Narrow tent

 
4xAA  Wide tent

 
8xAA  Narrow tent

 
8xAA  Wide tent

As you can see it's really hard to spot the differences between Narrow and Wide tent AA modes. You'd really need to zoom in 300%, but since you don't do that in a game, what's the real-life point to that ?

As our benchmarks will show, performance is also the same between these modes. A bug? Anyway, once we see some finalized drivers we'll touch this topic a little deeper and analyze then. CFAA is definitely looking good though, and offers a not too big performance hit, which is what the compromise is always about; the best possible IQ with the best possible performance.