Compositing can be a very deep and complex subject, especially when dealing with animation, but here we’ll try and keep it fairly simple and straightforward. There is always talk amongst those in the industry when it comes to blue/green screen and working on an edit as to whether or not one should do their composite in whatever NLE software their working with or export to a third party software to handle the task. Unless your working with animation, the answer, like so many in post production questions is a not a simple one. Take for instance Avid, who has excellent composite tools available in their 3.0 versions ( and up ) that can do the job relatively pain free providing the ‘screen’ is a talking head or has minimal movement. Final Cut does a decent job too, providing your using the newly acquired Ultimatte software that was made available earlier this year. Both are good and most editor’s may prefer to use their NLE system to avoid the hassle of exporting and re-importing footage for what may be no difference other than minor ones no one notices.
What I’ve noticed is that any real form of compositing outside of talking heads needs to be done in a third party software that is specifically geared for such a task. Call me old fashioned, but no matter how much these company’s try to encompass and “all-in-one” type interface, it never really lives up to phrase. There is a reason why we have third party software in the first place. Having said that, I’ll repeat that I am strictly referring to a more involved composite, one perhaps that has motion and other elements working within it. But which third party software is best?
Well, I’ll let that debate rage on in forums but for now I’ll tell you what I use and what I think is best suited for the common needs. Aside from Autodesk’s Combustion (due to it’s $1000.00 price tag) I would recommend Shake as my choice for any Node based compositing . It’s smooth interface and well tuned engine can handle anything you throw at it. However the most common one amongst the majority of user’s including myself would be After Effects. It’s wealth of features and tweaks allow the common users to catch on a little more quickly than the complexity of Node based software and it’s simple integration of various formats is a plus as well.
So how does one do a proper composite? I’ll break down a quick list of things that are vital to performing a good composite with a blue/green screen, and yes, I’ll use After Effects as the choice of software given that it’s the most familiar to many. First off, I will assume that you are using a version that contains the plug-in ‘Keylight’, if your not, well, sorry but these days you should be.
1. Apply Keylight and use the pen tool to ink the color of whatever background your removing.
2. Go to Status and adjust the ‘screen gain’ and ‘balance’ to get the screen black – do NOT try and remove all the grey, you can leave this around the edges.
3. Go to Screen Matte and adjust ‘ screen pre blur’ to clean up edges ( I would go as high as “2″ ), then go to into the Screen Matte tab and adjust “clip black & white” to get the image white but still try and keep the edges soft.
4. Next, go to ‘foreground color correction’ and turn it on, then move further down into ‘suppression’ and change suppress color tab to the color of the background your removing.
5. Apply the Matte Choker effect to take away any dead pixels around the edges, use the Choke 1 tab to do this.
6. Lastly, use the Channel Blur effect and change the ‘alpha blur’ tab to adjust by .5
And there you have it, some simple but effective points to start you moving forward. Again, there are many software applications and ways to go about using them to properly composite but I thought I would share the basics in this one. Yes, it’s fairly simple, but the fundementals allow for a great composite.
There are many great tools out there to help us with our compositing, some, yes, are more complicated than others. But in the end what should matter most is quality, and of course your ability to provide a good composite in a relatively reasonable time. Remember, most producers, managers or even directors don’t understand the technical aspects of post production and why they take as long as they can, so be warry of testing your compositing skills with a client as you may end of up looking like you don’t know what your doing. But don’t let that mislead you, a complex or poorly shot blue/green screen can lead to lengthy time in the edit suite trying to clean it up. And the number one thing I’ve come to recognize is that most people don’t know how to properly shoot blue/green screen in the first place! So a seemingly simple composite can take twice as long to the incompetence of the shoot. My advice, as always, would be to practice, either at home or work in your spare time. Remember that compositing is a very serious and skillful art, especially when you start moving up to more complicated projects involving fast motion, animation or multiple persons and objects in a scene, and I’ll also mention as a side note, can dramatically increase your dollar value as an artist if your very good.