You can create a chroma key in Final Cut Pro X, but the options to make it a perfect key are limited. That’s not the case with Red Giant Software’s Primatte Keyer, the chroma key technology used in major films like Lord of the Rings, The Matrix, Harry Potter, King Kong and Spider-Man, which finally became available for Final Cut Pro X. I took Primatte Keyer 5.1 for a test drive.
A chroma key is a matte — or alpha channel — created by “cutting out” a background colour. It’s mostly used with subjects standing in front of a blue or green screen, but Primatte Keyer 5.1 can handle any colour. However, if you’ve ever tried to key other colours, you’ll know that green or blue screens are chosen for a reason. These two colours are the best to cut out most subjects, especially those with human skin…
Primatte Keyer 5.1 is a complete compositing solution, not just a keyer, because it includes two controls that allow it to seamlessly match colour and lighting between the cut out subject and the background. A new Auto Compute algorithm in Primatte Keyer 5.1 will enable you to automatically cut out the foreground and immediately place it in another scene without the need for much fine-tuning afterwards. The only conditions for the auto-pilot to work is an evenly lit scene and good contrast between subject and background.
The first step in a Primatte Keyer workflow is to set a Deartifacting method. There are four of them, including “None”. Deartifacting smoothens the background, getting rid of pixel blocks that show up as a result of compression algorithms. The method depends on the camera type which the scene was shot with, hence the choice between four methods.
While trying out the different parameters, I could easily see why working with Primatte Keyer 5.1 in Final Cut Pro X is going to be dead easy for anyone who’s used to creating composites. For novices like me or people who only occasionally work with chroma keys, Primatte Keyer comes with a good Help guide while Red Giant also provides for a couple of excellent online video tutorials.
I tried Primatte Keyer with myself standing in front of a white wall for lack of a proper screen. I found that most of the work you’ll need to do with the plug-in will revolve around the button group that is promintently grouped together in the top half of the plug-in. In fact, if you have perfect lighting and contrast between the background and a fairly simple subject, you can get an almost perfect key using only these buttons. Even if that is not the case, the button group will get you 90% into the process.
Most of your time will be spent on getting rid of colour spills, and there is a button for every conceivable spill or imperfection in the selection of the colour. You can speed up the process in the beginning by sampling colour using a rectangle, and later refine the results with selections based on pixel sampling.
Once you’ve finished cutting out the foreground based on pushing out the background colour as much as possible, there’s little else that needs to be done about the actual matte. Most of the work that follows is fine-tuning. For example, you can end up with a razor-sharp matte, but that will look all but natural when placing your subject in front of a different background. Primatte Keyer therefore lets you add some edge fringing so that, when the subject moves, the edges seem to blend naturally into the background. This defocusing capability can in turn be refined by setting different parameters.
What makes Primatte Keyer the keyer of choice is that it has not only the tools to fix for example transparent and semi-transparent areas in the subject, but also the features to view the results of your actions in different ways and version 5.1 adds another two View modes to the already impressive array of viewing methods.
Further capabilities that make Primatte Keyer more a compositing tool than a simple keying plug-in are the ability to load an image into the plug-in and use that image — which should really be a still of the new background — for colour matching and light wrapping. These two features will make it seem as if your cut out foreground really belongs to the new scene/background.