Primatte keyer problems

Hi Everyone.

I'm doing some chroma key tests in FCP and Motion and I'm having problems getting a decent key out of Motion. The footage was shot in IMX 50 format and I applied the Chroma Key effect in FCP and managed a passable key using all the usual methods and then feathering the edges of the key to tackle any "jaggies" along the edge of my subject (human).

I then tried to key the same footage in Motion using the Primatte key thinking that it would do a much better job than the FCP keyer.

Unfortunately, it looked much worse. I used the tutorial in the Apple Pro Training Series book as a guide and did everything I could to get a decent key, but had serious problems with jagged edges around my subject, noise and other things.

Now, if I were reading this post, my first thought would be that the green screen footage wasn't shot well, but I know it was because I got a usable key using FCPs keyer.

I'm not sure why the Primatte key failed, but when I did the tutorial with the tutorial footage, everything turned out fine. Is it possible that Motion has issues with the IMX 50 codec? I used it because I wanted a 4:2:2 codec. Perhaps I should have used DVC 50 instead.

Any thoughts?

Andy

Everything goes better in 4:2:2, but a decent key can be gotten in FCP if you use the Color Smoothing 4:1:1 filter. And this may be the very reason you're having problems with 4:1:1 in Motion - I'm not aware of such a filter there.

I recently evaluated all my keying assets (FCP, Motion, Shake, Boris) on some (good) 4:1:1 bluescreen footage and found that the key in Boris RED was faster and cleaner that anything Apple supplied. Frankly, I was surprised...

That's just the thing. The IMX 50 codec IS 4:2:2. That's why I was so surprised.

When I'm keying DV footage in Motion I first cut each shot into an Uncompressed 8-bit sequence in FCP, then apply the 4:1:1 smoothing filter, then export as a self-contained quictime and bring that into Motion. This way the footage retains the result of the 4:1:1 smoothing filter.