> Refining the Chroma Key Filter Settings
> The most effective chroma key settings are found by an iterative process of adjusting all three parameters, viewing results over time, and adjusting them again, until you are satisfied with the overall performance. Here’s a suggested pattern of refinement.
> Temporarily move your background or image clip out of the way, so that the canvas color can be used as a backdrop against your foreground image.
> Next, adjust the White Key value by dragging the slider from left to right. As the opaque area reduces, pay close attention to the edges of the foreground image. If background starts showing through, creating a shadow effect from the black (or other) background, adjust the Tolerance level to the left to eliminate the shadows around the edge.
> Then, return to the White Key parameter and completely eliminate the opaque areas so that the entire background is fully transparent.
> Work back and forth between the White Key and Tolerance sliders (with a little fudge factor in each) to strike a perfect balance as you scrub your clip.
> Finally, reduce the Angle slider value to zero, then move it to the right again until the background is completely transparent, then increase it a bit more for fudge factor.
> Scrub the clip often, to make sure the chroma key works well across the entire clip.
> Note: Sometimes a video will slightly vary color over time. Thus, you might need different keys. To add different chroma keys to a clip, you can split the source clip into several clips and then apply a slightly different key color to each one.