New Anti-Aliasing Modes
As we mentioned earlier, new multi-sample anti-aliasing resolve functionality in the Radeon HD 2000 series GPUs makes another new feature, Custom Filter AA, or CFAA, possible.
In addition to all of the AA features in the Radeon X1000 series GPUs (multisampling, programmable sample patterns, gamma correct resolve, temporal AA, adaptive supersampling / multisampling, and super AA), Radeon HD 2000 series GPUs support up to 8x multisampling and can now take samples from outside pixel boundaries, apply non-uniform sample weights, and filter kernels that adapt to the characteristics of each pixel. An adaptive edge detect filter is also available that performs an edge detection pass on a rendered image. Edge pixels are resolved using more samples along the direction of the edge.
Using the various custom filters results in an increase in the effective number of samples per pixel without increasing the memory footprint. CFAA filters are also software upgradeable and can be used to enhance in-game AA settings for most DirectX 9 titles. CFAA works in conjunction with all other AA features and is compatible with HDR and stencil shadows as well.