Luminance
Luminance keying is typically used for titles that are on a copy-stand against a black card. This makes it easy to replace the brightness value of the black with another image, known as the background plate. Since live video can have a varying range of shades, Luma keying can be more difficult. If keying out that same black tone on a set, the talent may have shadows across clothing that cause an undesired 'hole' cut through them to the background plate. A white key could have problems leaving in white collars or the whites of the talent's eyes.

Chromamance
Chroma keying replaces the value of a particular color (typically a pure blue or green) with the background plate. This is slightly easier to set up since fashion-conscious people don't wear bright, pure, blue or green. Lighting still is an important consideration, since light levels against the backdrop must remain evenly-lit.
For greatest flexibility, Video Toaster [2] offers real time keying of either luma or chroma signals.
The Pacifica Keyer can eliminate either white or black data from the frame in real time, and replace that with an image from another camera, a still graphic or even with video in a recorded clip. With a simple mouse-drag, you can adjust tolerance and smoothing. Tolerance is how close to the selected value will be keyed out and smoothing affects how hard or soft the edge value is. Clicking in the Pick Color selector allows you to next click on any color on screen, whether from the desktop, Color Picker, or even directly in the Toaster Vision window. Video Toaster's Linear keying means you will have an easier time getting a smooth edge between the object and the background, and all settings can be saved and recalled later.

Cross Keyer
Now, real-time chroma keying is quite useful for compositing and special effects, but it is not always easy to make convincing keys. One of the problems is going back after the shoot and trying to pull a key out of something not initially intended for that.

Paint Your key
The Video Toaster [2] Cross Keyer can make a difficult key easier to accomplish since it does not rely on one color or value, but instead allows you to 'paint' out the color you wish to be transparent. It's so simple, because painting can be directly into Cross Keyer's vectorscope display, or, just like the Pacifica Keyer, you can click in the Toaster Vision display to select. The power of the Cross Keyer is in its ability to choose multiple colors as a key reference.

Here is a shot from a Toaster user who is keying an uncompressed toaster clip over 16:9 DV footage and notice how the translucent values of the key remain across the background plate.
Whether you wish to key with live camera sources, taped footage, still images, or a combination, Video Toaster [2] is the Key to Success.