PHYX Keyer has several useful tools that you can adjust very simply within your NLE. If I'm doing something quick, I usually prefer to do all of the effects within Final Cut. That being said, I haven't been able to pull decent keys in Final Cut, aside from a few things that were lit perfectly. PHYX Keyer works with the same interface as every other effect in your NLE, but the difference is that, now, you will be pulling great keys very quickly and easily.
There are several useful tools within the plug in. The basic keyer has a YUV Difference, 3D, and Channel Keyer. Each one has a powerful deartifactor that reconstructs chroma channels and helps resort details that often get lost during the process, especially when working in reduced color spaces like 4:1:1 (DV) or 4:2:0 (HDV and PAL).
The Despill filter works much like other despill plug ins, but doesn't create the awful magenta or yellow fringe artifacts found in other keyers. You can see in my example the difference between trying to fix spill with the basic despill in Final Cut and the one provided with PHYX keyer. The proof is in the pudding, and we are talking about minutes, not hours of work.
Diffkeyer is a great little tool if you have the footage available. When shooting something on a greenscreen, always shoot a clean plate of the greenscreen itself. If you have that clean plate, you can use it in diffkeyer. It will find the actors based on their difference from the background plate, and create a great matte. This particular tool is VERY helpful, especially if you are shooting without a green or blue screen. You can easily pull mattes from any footage, as long as you have a clean plate of the background.
If you are unsure about your ability to light a greenscreen, Screencorrector is a great tool for you. Much like the Diffkeyer, it uses a clean plate of your greenscreen to compare to your footage with actors in frame, and auto adjusts to create the best possible greenscreen lighting to pull a matte from.
Lightwrap is a great tool to fuse your background image with the foreground. It creates a lightsource from the background image and wraps the light around the edges of the foreground image to blend and interact with it. It's a great little finishing touch that adds realism in a flash.
I love the ability to pull great mattes with PHYX in Final Cut, so that quick projects can stay within the program and aren't sliding back and forth between that and After Effects so much. With many projects speed is key, and PHYX Keyer definitely helps you accomplish quality results with less time. I didn't have any available footage with clean plates, so I wasn't able to test the Diffkeyer properly. But even just cutting out a piece of the greenscreen from a shot with actors was enough to give me a great idea for how it works. PHYX does offer some sample footage on their website for this option which works great, but I tend to want to use my own footage to test a plug in. The functionality of Phyx Keyer is very simple, which helps. Some keyers have many more adjustment possibilities, but can frustrate you with the difficulty you will go through just to pull a matte.
