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Chroma Effect – Why are there wavy lines?
I’m using a green screen behind an actor standing among some crates.
I’m using Adobe Premiere 5.0’s Chroma Keying effect (under video effects) to drop different background images behind the actor.
The problem?
After applying the Chroma effect, if you look at different crates and at parts of the actor, it looks like the border lines are moving in quick, small waves. Although the waves are small, this is enough to be very distracting.
This doesn’t just occur at the borders touching the green screen, this includes the actor’s eyes, mouth, and wood lines within the crates. There is absolutely no green on set except on the green screen.
In viewing the video clip without the Chroma effect (but using Premiere Pro), the waves disappear. Everything is normal. Same thing when you view the raw footage.
How do I correct this problem?
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4 Replies
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Are you describing Premiere 5 or Premiere Pro CS 5?
It sounds like your key settings could use some adjustment.
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Sorry about that. I’m using Adobe Premiere Pro CS5.
I have tried different combinations within the Chroma Key settings (moving the Similartiy, Blend, Threshold, Cutoff around) and the waves remain. It looks like a mini heatwave over certain parts.
What other options could I try to adjust?
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It’s difficult to say without actually seeing it.
Perhaps a framegrab of the greenscreen both with and without key applied?
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If you are using CS5 then i would suggest you use the Ultra Keyer effect instead. It is far superior to chroma key.
– JB
Jon Barrie
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