ASUS GeForce EN8800GTX/HTDP/768M Video Card Review :: Lumenex Engine

NVIDIA's new architecture brings a new form of image quality enhancing features. They have trademarked Lumenex for their IQ enhancing features on the G80. Lumenex brings 16x Coverage Sampling Anti-Aliasing (CSAA), 16x near perfect angle independent anisotropic filtering, 16-bit and 32-bit floating point texture filtering, fully orthogonal 128-bit High Dynamic Range rendering with all the above features and a full 10-bit display pipeline.

The GeForce 8800 supports supersampling, multisampling and transparency adaptive antialiasing. Antialiasing helps alleviate artifacts in a scene caused by pixel lines being thinner than a pixel wide. Transparency Anti-aliasing adds either SS or MS to transparent textures like a chain-link fence or dense vegetation. Four new AA modes are supported by the G80, 8X, 8XS, 16x and 16xQ. The G80 can use up to four subsamples in a clock AA, with two clocks; the card can do 8X AA. A new kind of AA called Coverage Antialiasing is supported by the G80.

Traditional MSAA requires 4x the storage and ROP bandwidth as standard rendering due to the fact that the samples are taken four times from the same pixel. NVIDIA cards like the 7900GTX can render this fast as the chip was designed to do high resolution 4x MSAA with minimal performance hit. MSAA takes 4 samples from a pixel, which doesn't alleviate the requirements.

The problem with the 7xxx and earlier card's MSAA was it was limited to four sample AA (2 clocks). For higher image quality more samples are necessary. CSAA adds a number of coverage samples to traditional MSAA. Coverage sampling does not work correctly with apps that use Stencil/Z data at sub-pixel locations like F.E.A.R. Extraction Point, 8XQ AA is probably the best mode for FEAR XP. The new modes of AA are 8X, 8XQ, 16X and 16XQ modes. The older GeForce graphics cards did mixed mode Multi-Sample AA+SuperSample AA. This has been replaced by the new coverage AA. 8x is 4 sample MSAA+4 coverage samples. 8XQ is true 8 sample AA. 16x is 4 sample MSAA+8 coverage samples. 16xQ is 4x Multi-sample AA+ 12 coverage samples.

The 16x mode is CSAA. In applications, the combination of CSAA+Transparency Anti-Aliasing gives the absolute best image quality and performance combination possible on the 8800 series cards as it offers better AA than 4x or 8XS but similar performance to 4x.. The 16xQ mode is the maximum mode available on the 8800GTX. It looks absolutely stunning, but performance is a factor with this mode as we'll see in the performance section.

Here are three screenshots from Oblivion, one with 16xQ FSAA+no HDR, one with 16xQ FSAA+Bloom and one with 16xQ FSAA+HDR. The no HDR pic is rather dull looking, due to the fact that the range of contrasts in this mode is limited to 255:1. Blooming is the effect of walking out into the bright sun from a dark cave, where everything in the scene is bright. The third pic is much more natural looking to the eye. The sky is an appropiate color and brightness.

The GeForce 7900GTX and earlier Shader Model 3.0 cards were capable of 16-bit Floating Point blending and texturing. The 8800GTX is the first commercial video card to feature support for 32-bit Floating Point blending. This allows 128-bit precision High Dynamic Range rendering, a requirement of Shader Model 4 hardware. HDR allows the application to have a higher contrast ratio of the darkest and brightest areas of a scene. Higher precision hardware means a wider range of HDR.

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