Effective Chroma Key Shots

Nov 17, 2011 BY Administrator
Entering the World of Compositing

Chroma keying compositing is a technique in which two images are layered together. A color range in the top layer is made transparent, revealing the layer below it. You might have heard of it as just “special effects,” but it’s one of the video industry’s techniques that allow a meteorologist to read off of a map or place an actor into a land of fantasy. During a previous project, our team at Planet Vox found some helpful aids in achieving that ideal key for their subject.

The footage was recorded in 720p resolution at 60 frames per second using the Panasonic HPX500. For getting the full body shots of the subject, the Planet Vox team decided to rotate the camera to a vertical orientation. What this does is take the 1280x720 footage and instead make it 720x1280, nearly doubling the lines of resolution for the subject.

Recording with the camera on its side is no easy task and must be done very carefully. To give the camera more stability on its side, a Glidetrack Shooter HD was used on top of a tripod, followed by a second tripod head mounted on top of the Glidetrack Shooter HD. Finally, the HPX is placed on the second tripod head where it is properly leveled and no longer at risk of falling and breaking. This elaborate setup can be seen here.

It takes the right software to attain a good-looking chroma key. Red Giant’s Keying Suite 11 has been found to allow more precision and control for separating the subject from the background. Key Correct 1.2 does a good job removing the artifacts and noise, while matching the foreground to the background. The Warp 1.1 toolset from the Red Giant suite gives a realistic shadow for the talent that was shot on a green screen.