This filter reduces alias effects (see Antialiasing) using the Scale3X edge-extrapolation algorithm.
Scale3X is derived from Scale2X, which is a graphics effect to increase the size of small bitmaps guessing the missing pixels without interpolating pixels and blurring the images.[11] Scale2X was originally developed to improve the quality of old Arcade and PC games with a low video resolution played with video hardware like TVs, Arcade monitors, PC monitors and LCD screens.[12]
The Antialias filter works as follows:
For every pixel,
the filter expands the original pixel in 9 (3x3) new pixels according to the Scale3X algorithm, using the colors of the pixel and its 8 adjacent pixels (extrapolation);
then the filter subsamples the new pixels to a weighted average pixel.
The following examples illustrate the effect on some patterns. The small squares are one pixel in size (zoom 16:1).