I just found this on the net after a little search around..
Gamers like you know that a game run without anti-aliasing introduces aliasing, or “jaggies,” onto the edges of objects in the game world. These jaggies are ugly and we all know it, so we went ballistic on them with an advanced form of anti-aliasing that combines supersampling and compute-accelerated post-processed AA.
First, supersampling is a technique that renders the game in a higher resolution than the user has selected, then resizes the rendered frame back down to the proper resolution before it is displayed on the screen. This obliterates jaggies because the number of pixels in an aliased edge is reduced by the SSAA factor when the frame is resized and shown to you. That might be confusing, so allow me to give you a living example that better explains this effect:
You, as the user, have configured your game to run at 1920×1080, and you’ve selected 4xSSAA as your anti-aliasing method. These settings tell the graphics card to render the game’s content at a 4x larger resolution of 3840×2160 (ultra-high definition), then resize that frame back down to 1920×1080 before display on the monitor. At 3840×2160, the game might have a hard edge with 16 pixels that are obviously jagged. After the resize to 1920x1080p, however, these pixels are reduced by our SSAA factor (4x in our example), leaving you with a considerably smaller jagged edge of just four pixels. This effect is applied across the entire scene, hiding visual artifacts in the same way shrinking a picture in an image editor can hide flaws in a photo.
As we did with HDAO, however, we take AA one step further in Sleeping Dogs. The “Extreme” anti-aliasing setting uses the compute horsepower of Graphics Core Next to do another anti-aliasing pass on the final frame, which will smooth out those last four pixels of aliasing we described in the example above. The resources required to drive the extreme setting are quite intense, so users of HD 7800 and HD 7700 Series GPUs might try the “high” preset (2.25x SSAA, no post AA) or the “normal” preset (post AA only).
When all is said and done, though, Sleeping Dogs’ extreme preset offers the highest possible anti-aliasing quality available to a graphics card.
http://icrontic.com/discussion/96315/very-low-framerate-on-sleeping-dogs-and-csgo-beta
