Okay the premise of this tutorial is that I have an image in photoshop (image 1), and my render in max (image 2) that I want to composite over the top.
If I save the render as a BMP or a JPG and open in photoshop, the only way I can really do it is to cut out the ship from the white background. Easiest way to do this is magic wand right?
Problem is when I do that I get really rough edges around the ship (image 3).
So heres what I do to avoid that.
When you save your render for compositing, save it as a TGA file. They contain a premultiplied alpha-channel. When you open it in photoshop and click on the channels list you will see it there (image 4).
How we use this by CTRL+Click on the thumbnail of the alpha-channel (image 5). This will create a selection, and because of the anti-aliasing that max did, they edges are slightly transparent. Click back on the Layers list and CTRL+C to copy the selection.
Now paste into the other image and you're done (image 6).
I hope you guys find this useful. It is also much easier than saving out a bitmap and a separate alpha bitmap, I've seen some people do that too.
     
Matt
http://theprophetmoses.deviantart.com |
Didn't know that.
