nVidia's Quincunx AA was met with mixed
emotions when it came out with the GeForce 3. While the anti alaised image was
close to that of 4x AA, it was criticized for being much blurrier then super
sampling anti alaising. QC Anti Alaising places a sub pixel directly in the
middle of the pixel. Points 2 and 4 and points 3 and 5 are blended together to
produce the colour in point 1. The problem with this form of anti alaising is
since there is a high level of colour error, edges and lines often look very
To counter this, nVidia introduces Accuview
AA. In laymens turns, the sub pixels of each pixel have been moved into each
pixel. Thus when the blending occurs on points 2-4 and points 3-5, this way the
colour samples are not taken from the edge anymore thus reducing the colour
error. The resulting image is much cleaner and sharper.
Unfortunately the performance penalty
associated with 4xS (Accuview AA) is very high. When using 4xS AA the
performance is lower then 4x AA, thankfully not by much though.
Above is 4x4 Evolution 2. AS we can see, the
difference between no anti alaising and 2x is quite large. QC and 4x AA are very
close in terms smoothing out the jaggies although QC seems to be a little
blurrier then the rest. 4xS is obviously the sharpest of each AA, just look at
the yellow lines.