When to pad or extrude textures in texture atlas?

Question

In what situations is it necessary to extrude the pixels around a texture within a texture atlas, and in what situations will a padding of transparent pixels suffice when trying to prevent edge artifacts around your images?

Answer 1

Extrude --extrude TexturePacker Documentation: Extrude Extrude repeats the sprite's pixels at the border. Sprite's size is not changed.

There are two uses for this:

Reduce flickering in some cases where sprites have to be put next to each other in the final program. Check if sprite outlines are OK. E.g. if you want to use sprites to create tilemaps this allows you to see if there are semi-transparent pixels at the borders of the tiles.