As shown in the examples in Figure 2.2, the noise levels of the red and blue channels in the green screen shot are much higher than for the green channel. Combining these three color channels together provides a composite of RGB and gives a color image. When these chan nels are separated out independently, you can see the image data contained in that color space. Look at the compression artifacts above the model's head in the red and blue chan nels. These can cause problems when you're trying to pull a matte from the image or video footage. The original footage was shot with an HD camera with a 4:2:2 sensor.