From the course: VFX Keying: Master Course

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Pre-processing the clip for the keyer

Pre-processing the clip for the keyer - Nuke Tutorial

From the course: VFX Keying: Master Course

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Pre-processing the clip for the keyer

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- [Instructor] In some situations pre-processing a green screen or a blue screen with color correction can dramatically improve the key. But be careful, you can also make things worse. Now there are a million possibilities to applying pre-processing to improve your keys, so the examples here are just a few to get you thinking in the right direction. So let's start by taking a look at this over-exposed shot. If we look at the code values up here, I'm going to sample the blue screen. Look at this, 1.8. Now that blue screen should have a brightness of maybe 0.7, 0.8, 0.6, somewhere in that neighborhood. Now if we look at these whites, look at this, 2.1, 2.1, 2.68. Way over-exposed. As a result keyer produced this very nasty edge. You see, every keyer has a sweet spot where it expects the color to be, and if you go outside that sweet spot you don't get a good key. So what I did was I took the original picture, just applied this Grade node here, where I just gained it down to point five…

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