@asdecret
I attached a screenshot of my material setup. Looking at the different solutions in this thread, my setup works, but is not that advanced as other methods. I get it to work, but in my setup i only have 3 different leaf bitmaps. And i change these leafs with color correction per tree. For me this is enough for now. It is visible to see difference per tree, and on closeups the difference between leafs is visible. But i will give the other methods explained also a try.