How do I prevent losing contrast when compositing semi-transparent images? I have a scene with an object and a mirror object, simulating a mirror floor. If I fully composite the image and save it with a white background from blender, the mirror image looses a lot of contrast and detail. However, if I save it as a transparent image and add a white background in Photoshop, is is much clearer. How can I get this result straight out of Blender?

My .blend: https://www.dropbox.com/s/38xzr2y717cjygk/mirror_trans01.blend?dl=0
You can get a better result by using the Mix node's Multiply blend mode instead of the Alpha Over node.



Here's the node setup (you first need to create a unified mask to use as a factor for the mix node):