To determine which component keyer will give you the best key, try creating a sample matte for each keyer.
To create a sample matte for each keyer:
The softness for each model is set automatically to 50, which helps you to quickly gauge the model that will create the best key for your clip.
The average colour sampled by the colour picker appears in the Average Colour pot. In each channel of the colour model, the channel value of the average colour appears as a white line. All pixels in the key-in clip with the selected colour value are keyed out.
The yellow lines in the colour model channels indicate the limits of the softness range. The pixels in the front clip with colour values at the centre of the range are black (transparent) in the matte. As you move away from the centre, the pixels become more opaque.
After you have selected a colour model and set the average colour, set the softness range.