How to precisely cut texture to match alpha channel?

[Ofnuts]

(11-21-2022, 04:46 AM)remunaw12 Wrote: 1. Original game asset (PNG)
2. I want to replace arm texture (originaly metal) with a bare skin by using another image.
3. Trying to cut the arm from the image to match the shape of metal texture from original asset.

Basically do that, or am I just make things more complicated?

* Add a new layer
* Paste a piece of skin that totally overlays the metal part and is even a bit larger
* On the layer with skin: right click in layer list, then Composite mode ➤ Clip to backdrop