2D Modifier - Crop an image using alpha
Crop the image n pixels inward in order to cut the edges accordingly to the alpha channel of the image.
Note that you can do some kind of a border on the outward of the image by setting the Choke parameter in negative.
here is an example (the right part is alpha choked by a -8.52 px)
Choke of the alpha choker
Iterations of the alpha choker
(2D Relative Size): Size of the alpha choker
In same group: Mask
and Discard Alpha