The Unsharp Mask effect increases the contrast between colors that define an edge.

This effect works with 8-bpc and 16-bpc color.

Original (left), and with effect applied (right)

Radius

The distance from the edge at which pixels are adjusted for contrast. If you specify a low value, only pixels near the edge are adjusted.

Threshold

The greatest difference between adjacent pixels for which contrast isn’t adjusted. A lower value produces a greater result. A value that is too low causes contrast for the entire image to be adjusted and can generate noise or cause unexpected results.