HTH - Hope This Helps. If you do 2 renders like you say it should work. Make sure you don't have anything like Glare or Blur on though, since they would blur your edges and give you strange edges to your transparencies. And for that matter, any level of grey will be a level of transparency, so you may be better trying a non-photorealistic setting, or a Toon setting for your render so that the leaves are 100% white and everything else is 100% black. GL! (Good luck!) ;>