Photoshop Elements >

Anti-aliasing

Photographs, as you know, are made from square pixels.

In a photograph, where there's an edge that isn't perfectly vertical or horizontal, the pixels jut out.

Look at the S on the left side, below.

You can see that it doesn't look sharp.

The S on the right side has had anti-aliasing applied.

Anti-aliasing adds tones and colors to make the edges appear to be smoother.