Wikinews:Broadcast/Chroma key green screen

A digital green chroma key screen.

A chroma key green screen allows a person or object to be seamlessly composited on top of a different background image, or even another moving video.

A "digital green" screen works well for chroma keying with DV format video. This particular hue of green is saturated and bright enough that you don't have to have many thousands of watts of light to adequately expose it for your video camera.

You can purchase such a screen from a specialty camera store or over the net.

I've had good results with a Westcott 6' x 7', Digital Green screen, model number 5990. Westcott is located in Toledo, Ohio. This model flips open from a small three-foot diameter ring which comes in a handy carrying case if you need to move it about. You can find this screen for less than US$200.

Once the "key" is enabled, the green disappears from the video.

However, if you want to walk about on the virtual set as you are speaking, you'll need a roll-down unit with a stand, which will allow the green color of the screen to surround you right down to your feet. Roll-down units are a bit more expensive, and they take up a lot more room, but the results can be amazing to watch as you appear to be walking about on the set. I've seen these systems go for about US$300 to US$600 on sites like eBay and from some specialty camera stores.

There are much more expensive screens available that are made from exotic materials - some of them go for as much as US$3000. These more expensive screens, such as the ones made by Reflecmedia do an excellent job of evening out the screen's appearance to the camera, but for our purposes, such expensive screens are overkill.

Please don't make the mistake of trying to save money by buying a cheap, thin muslin screen. It will be partially translucent and reveal whatever is behind it when you turn on the lights. Also, the color can be very uneven on some of them, because they are dyed after they are woven, rather than using thread that is colored at the factory. — DV 12:48, 16 Apr 2005 (UTC)