In normal rendering without antialiasing areas with sharp edges or high frequency textures will exhibit "jaggies," or aliasing.

Each pixel will have eight neighbors raytraced and taken into account as its color is being determined. So really a 640x480 image is internally computed at 1920x1440... It's the same as linearly raytracing a 1920x1440 image and then with cubic oversampling reducing that down to a clean 640x480. This is quite time-consuming, but gives a good image quality.

Uses a randomly jittered, 16x16, global antialiasing algorithm for the finest possible raytraced image. This mode can be four to sixteen times slower than the normal mode, but the result is really pretty.