[![Leaf Example][1]][1]

So, I want to make my own leaf textures for trees, but if I just make a PNG with transparent background it gets a weird white edge. So I found that usually they use this effect with an alpha mask to get rid of that issue.
I remember watching a tutorial on how could I do it time ago, but i don't remember the technique, the name of it neither the tutorial name.

Any ideas?

(Actually, I found other ways to fix the issue, but I want to be able to use this)

  [1]: https://i.sstatic.net/5jBlb.png