Chroma Key Lighting
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One of the most often asked questions is, “How do I get all of these little jaggies off of the edges of my Chroma-keyed subject?”

And the popular cure-all seems to be the proper lighting of your Chroma-key blue wall (or back-drop). Not just a wimpy little 100 watt light aimed somewhere in the general direction of the background, but a host of lights that literally flood the background.

We’re talking a minimum of two 250 watt quartz halogens aimed at the backdrop from high and off to each side so that they will not inadvertently cast any shadows from your key subject (who should be standing at least three feet out from the backdrop).

The key subject should be illuminated with it’s own key light (another 250 watt plus) that is preferably diffused with either an umbrella or a diffusion filter.

If your camera and Panasonic MX-50 video mixer will not recognize your background as a solid, evenly lit blue, then the Chroma Keying will go crazy trying to determine where the background ends and the key subject begins.

Hence, the “jaggies.”

Every now and then, the background color of blue will reflect back onto the key subject. And this, of course, will cause background video to be keyed in onto the key subject, which you don’t want to do.

This reflected blue can be mostly eliminated by placing light colored amber gels over your background lights (the two lights that flood your backdrop). More specifically, ask for “bastard amber” at your local photo shop when purchasing these gels. They’ll know what you’re talking about.

As for the key subject light, place it about three or four feet off to one side or the other of the camera so as not to cast any direct shadows onto the background.

Once you have adjusted your “hue” and “slice” control on the Panasonic WJ-MX50 for optimum Chroma-key effect that you view on your monitor, slight adjustments of the angle and location of all of your lights will make the effect that much better.

Chroma Key Lighting Techniques Revisited

In an earlier issue of MX (above) we discussed the lack of lighting on your blue background which often resulted in “the jaggies”. Be aware that too much lighting (i.e. two or three 1200 watt lights) could cause problems as well.

Over-lighting the background could turn perceived blue into an almost white color, which of course won’t work properly with the Chroma Key section of the Panasonic MX-50 or the Videonics MX-1.

Obviously, lighting distances and other factors like ambient light will vary from one person’s studio to another. So, experiment with various lights, gels, diffusers, and distances until you obtain the perfect combination.

Remember, Chroma Key is much more than just a “turn it on - turn it off” feature on a digital mixer. It is an art form and a science in itself that requires a lot of work on your part to perform effectively. And don’t forget to white balance the Chroma key camera. If it doesn’t see true Chroma key blue, neither will your digital video mixer.

Learn more about the Panasonic MX-50, MX-30 and AVE-7. Check out our instructional videos in our Online Catalog.

Chroma Key Tricks

What if you want to key yourself in front of a very large background, such as a skyscraper or mountain, and your blue or green backdrop is only about 8 feet by 6 feet?

Well, you could get a larger backdrop that would dwarf you in comparison. Or you could just miniaturize yourself electronically.

Begin by creating a Picture-In-Picture (about 1/9th size) with you and your blue backdrop inside of the P-I-P. On the outside of the P-I-P, select Background Color as the image that surrounds the P-I-P. Referring to the instruction manual, create a “custom” background color that identically matches the color of the backdrop in your P-I-P. What you’ll see on the screen is a little tiny you in front of a very large backdrop.

Now record this image onto a video tape and take that tape out and put it into your playback (source) VCR. With that tape now playing as the incoming source, set up your Chroma Key and let that gigantic backdrop be filled in with Mount Everest or the Empire State Building.

Shifting Backgrounds

Since most video mixers can lock onto virtually any background color as a backdrop, try setting up a multitude of colors on your studio wall and set up the Chroma Key to reveal the keyed image through all of the color (by moving the cursor about the screen and pressing “OK”).

Now, with someone in front of the multi-colored wall, begin panning your camera from left to right and back again. What you will see is portions of the background image revealing and un-revealing itself (even though it will not appear to be moving). What you’re doing is deliberately confusing the video mixer  setup so that it will only reveal a background when it’s right on axis with the pre-registered color. Truly a bizarre effect.

Kill the “Jaggies”

If you’re picking up jagged edges off of your keyed in subject, it’s usually because the backdrop color is somehow bleeding onto your subject.

The first thing to do is move your subject away from the backdrop. Then make sure that your diffused lights illuminating the backdrop are not creating shadows out of your foreground subject. And then make sure that you are not trying to key in a shinny object, such as a silver-colored model airplane (which will allow your backdrop to “bleed” all over it causing jaggies). For shinny things, such as metallic objects or bald heads, try some of the matting sprays available from art supply stores (i.e. Glare-Away) which should take out most of the shinny objects reflective qualities.

Another “color bleeding” problem solver for Chroma Key is the use of amber-colored gels over your backdrop illumination lights. These gels will have a tendency to absorb the bleeding characteristics of the color blue (which is the color most people use for Chroma Key backdrops).

Play around with the Chroma Key section. See if you can come up with a few effects and tricks of your own

Please Note:  We DO NOT sell or provide support for video mixers.
We offer instructional videos on the Panasonic MX-50, MX-30 and AVE-7.
Click here for Instructions Videos.