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Final Cut Pro Quick Tip #23

Smoothing keyed edges By Stephen Schleicher
Its been a fun couple of weeks playing with Final Cut Pro 4.0 looking for all of those new features and of course doing actual work with the new upgrade. While we have touched on keying in Final Cut Pro before in our Final Cut Pro Quick Tips, this time we look at a new filter and how it aids in your keying process.

If you need a quick refresher on how to key in Final Cut Pro 4.0, go ahead and read Final Cut Pro Quick Tip #5: Keying Explained.

One of the great things about Final Cut Pro is how easy it is to edit DV footage, one of the bad things about DV footage is it can be a real pain to pull a decent key. As I have shown in previous articles and Quick Tips elsewhere on the DMN sites, keying with DV is not only possible, but also can generate great results. However, there is one underlying problem with DVs 4:1:1 compression scheme that being the fact that DV is compressed in the blue and red channels causing artifacting and general chunky edges around your keyed subject.

There are some work arounds namely using the edge feathering and edge smoothing features in the keying filters that come with Final Cut Pro. In Final Cut Pro 4.0, two new filters that have been added in the Keying section is Color Smoothing 4:1:1 and Color Smoothing 4:2:2. Since our discussion is focused on DV and DVCAM, well discuss Color Smoothing 4:1:1. If you are editing D1, D5, DigiBeta, or DVCPRO50, you can use this same information but instead use Color Smoothing 4:2:2.

As you might have already guessed, Color Smoothing 4:1:1 smoothes the color of DV footage. Or to be more precise, the Color Smoothing filter compares the edges of areas of color change (say between a blue screen and the subject), and instead of making an abrupt change, it smoothes the color transition to keep more of the subject in tact.

This is readily apparent in figures 1 and 2 below. In the first image, you can see color and detail loss along the tip of my nose and lips where the sampled area of the frame looses color information with the blue backdrop. After applying Color Smoothing 4:1:1, the detail is restored. You might also be able to see that some of the compressed colors return (the red values in my face get brighter).

The image has been enlarged to 200% so you can see the loss in detail

With the Color Smoothing filter applied, detail once lost is recovered for a smoother key.

Now it should be pointed out that Color Smoothing 4:1:1 is NOT a true deartifacting filter. It is not going to remove compression artifacts that appear due to the medium. It does however smooth the transitions between colors causing details to stand out more.

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Related Keywords:final cut pro 4.0, color smoothing, compressed, dv, dvcpro, keying, schleicher


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