Using Luminance Keys with Non-Black-and-White Images

If you are looking for some interesting video combinations and special effects, try playing around with luminance key effects on different types of source footage. What I mean is that you don't always have to use black-and-white images to get spectacular special effects. Here is an idea that I used on one of my projects. I hope it gets the ball rolling as far as some creative ideas:

1. Use any moving video footage on Video Track 1 (I used a shot of horses galloping).

2. To convey the horses' strength and intensity, I placed a shot of fire on Video Track 2.

3. I applied the Luminance Key effect to the fire, dropping out the image of the flames and keeping their shape and motion (see Figure 7.6).

   Figure 7.6. Create unusual effects by simply placing a luminance key over high-contrast moving video footage.

   

Luminance keys do not work well if the image you are trying to drop out has the same brightness (or darkness) values that are in the image you are trying to keep. You wind up dropping out portions of the image that are usually less than desirable, as shown in Figure 7.7.

Figure 7.7. Images with little contrast do not work well with luminance keys.

tip

The advantage of using a luminance key was that I could use standard video of moving flames that constantly gave me a "moving" key without having to create a key for each frame.