4XS Antialiasing

A new breed of antialiasing technology comes in the form of NVIDIA's Accuview™ Technology was introduced with the launch of the GeForce4 family of video cards. This new Accuview engine improves upon NVIDIA's multisampling technique by providing improved 2X, Quincunx, 4X, and their all new 4XS antialiasing modes. The advanced technology of the GeForce4 GPU and nVIDIA's Accuview Antialiasing subsystem will offer 2X AA and Quincunx AA on the GeForce4 at speeds of the GeForce2 with antialiasing turned off. It is almost like getting Antialiasing for "free". So how do the new GeForce4 GPU's and the Accuview Antialiasing subsystem work together to provide improved antialiased images with higher performance? Read on to find out!

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Quincunx Revisited

NVIDIA's Quincunx AA first stepped into the gaming scene with the advent of the GeForce3 family of video cards. Quincunx is a multisampling technique that can almost be considered the happy medium between the 2X and 4X antialiasing modes. Quincunx offers quality comparable to the 4X mode with performance levels similar to the 2X mode. Quincunx AA alleviates memory bandwidth as well as reduces the amount of GPU processes by taking data samples from neighboring pixels instead of requiring the GPU to create additional samples for each pixel in the initial rendering step. By using these samples from neighboring pixels, Quincunx AA balances the image quality without having to write numerous amounts of samples per pixel to the frame buffer.

The Quincunx approach above was revolutionary in its ability to offer high quality res screens with acceptable performance. Although, NVIDIA's Accuview AA subsystem on the new GeForce4 GPUs, takes this technology one step further by shifting the point at where the subpixel samples are taken, resulting in lower counts of color error thanks to a more accurate sampling pattern. Thus, the user is left with a better antialiased image. Accuview is a suite of antialiasing techniques that includes 2X AA, Quincunx AA, 4X AA, and 4XS AA modes.

4XS AA mode delivers improved subpixel coverage and a higher level of texture quality. By offering more texture samples per pixel, 4XS AA produces a higher quality graphic image. With 50 percent more subpixel coverage than previous modes, 4XS AA has finer gradation in final pixel color values at the edge of an object. The final result yields a smoother, more refined edge.

The GeForce4 GPU family integrates the NVIDIA Accuview antialiasing subsystem, which provides wider internal data paths. In fact, the GeForce4 GPUs can compute sampled pixels, or additional samples, at full speed with no reduction in engine performance whatsoever. The wider data paths also enable the GeForce4 GPUs to use the same texture data for all of the samples in the pixel, significantly reducing the memory bandwidth required to texture all of the AA samples.