I wonder if there is any way to crop a image based on alpha data like this:
The reason I want to do this is that I want to crop the White area of another image (of the same dimension to the Alpha image above), then stretch it to fill the whole area, or fit to other expected dimension. And this has to be done in Compositor.
For example, this is a MANUAL way to crop then fit to expected dimension:
However, to decide the value in Crop node is not so easy in order to get rid of unwanted part. So I wonder if there is any way (math or something?) that can be smart enough to save that work.