4.2. Antialias

4.2.1. Overview

This filter reduces alias effects (see Anti-aliasing) 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.^[8] 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.^[9]

The Antialias filter works as follows:

For every pixel,

the filter expands the original pixel in 9 (3×3) 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.

4.2.2. Activating the Filter

This filter is found in the main menu under Filters → Enhance → Antialias.

4.2.3. Examples

The following examples illustrate the effect on some patterns. The small squares are one pixel in size (zoom 16:1).

Original image (zoom 16:1)

“Antialias” applied (zoom 16:1)