I finally fixed it. My problem was the srgb gamma part. After I added a pow(capturedARImageColor.rgb,2.2) in my frag shader it works as intended now. But the documentation team really could do some examples specially with ARKit/SceneKit interactions, it is a rabbit hole with no exit. Also the normal documentation pages are quite bare. Microsoft (as much as I dislike their company policies) did a very good job with theirs, they provide for everything a small example. For example the attributes of vertex descriptors. To find out that they are already prefilled arrays (I still don't know how many entries they have, didn't bother to check) you have to dive deep. Such things are quite unusual, but you still don't point it out in your documentation. Here, a small example would have saved me approx 1 hour, because I would've seen you just accessing the array entries without creating the objects. At least it would have made me think, why do you do it that way and I would have examined this particularly.