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BlueBox: basic Chroma Key effects on your Casablanca
Chromakeying on CasablancaChromaKey is a process where a color (usually blue or green) is digitally subtracted from a video scene, allowing a second video scene to be inserted in its place. On Casablanca you use the 'BlueBox' found under the 'Special' button in the Edit screen.
This software effect is included as part of the Operating System (some early versions required the activation of BlueBox after you registered your Casablanca - if this is your case, please contact your Casablana reseller for assistance).
Let's walk through the process using the following two scenes ‘Actor' - a hypothetical scene of an actor in front of an evenly lit, uniformly colored background (blue and green with 50% color saturation work best).
The 2nd scene, Jelli is a scene from an aquarium with Jelli swimming around in a tank. The desired effect is to have the Actor appear as if he is in the tank with the Jelli.
In the Edit Window:
Experiment to set Color Range to a percentage that gives the best result. Click again. Repeat until you've found a value that gives a clean result, with no raggedness. Then left click OK.
You can also run a Preview to see motion.
Then click on Create to render your Bluebox effect. You could also make a scene of the result. This would insure you have this available as a clip in your clip bin with the effect permanently complete.
**The most technical aspect of using the Blue Box effect is setting the Color Range slider. By adjusting this setting, you are determining the tolerance for the color that is being keyed out (which, in my example, is green). If the percentage is too low, you will see green shadows and edges around the Actor's body. If the percentage is too high, parts of our Jellifish will become transparent. There really is no ideal or recommended setting for this option; you'll need to experiment with it on your own in order to become familiar with its range.
Also - this effect will only be truly successful when using a scene with optimum background coloring. Even using a commercial Blue or Green screen will not provide great results unless it is lit evenly. If there are ‘hotspots' from inconsistent lighting that will affect your results (and not in a good way).
For greater control and more sophisticated chroma key operations, check out BlueBox World and the Keyer functions in CB Paint/CB Paint 2.