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Green Screen Issues

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Jamie McGeeGreen Screen Issues
by on Jul 31, 2015 at 4:56:12 pm

Hi All,
I have some experience with Green Screens, and my usual method is
Copy of keyed layer minus keylight filter underneath
Curves on bottom layer basic CC.

I have received some 4k footage from a SONY fs7 in an mxf format.
My initial thoughts were the footage looks a little milky.
When I try to key using my normal method, the key is very noisy and not very solid.
I am assured the camera guy was experienced in shooting green screen, and I am wondering if its something I should be doing with the footage prior to keying?
As its the first time I have worked with footage from this camera I want to be sure I am doing everything right.

I had some footage from a BlackMagic cinema camera the same day, different camera guy different shoot and I could have keyed it with my eyes closed, so I dont think I should be jumping through hoops if the footage is right.
Hopefully I have attached some stills and if you are quick enough some sample footage:

If I could get your thoughts on it, I would be greatly appreciative.
I am sure I am doing something wrong and am a little embarrassed about calling the camera guy out on it to be honest!
Any tips on workflows with the format would be great.

Jamie McGee

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Dave LaRondeRe: Green Screen Issues
by on Jul 31, 2015 at 10:37:16 pm

Wow, that's pretty low-contrast footage. It's like the photog didn't know enough to open the iris.

You might try putting the footage in a nested comp, messing with brighness/contrast/saturation until it looks better, then opening the main comp and using Keylight on the nested comp.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA

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Blaise DourosRe: Green Screen Issues
by on Jul 31, 2015 at 11:06:42 pm

This footage looks as though it was shot in the slog3 color space, which is a flat color profile that allows the FS7 to capture higher dynamic range. You'll need to check with your camera guy to be sure he was shooting in slog3 vs slog2, but what you need to do is apply a LUT to the footage. slog3 to Rec709 is probably the one to use.

After that, the contrast and saturation should pop to the correct level, and be much easier to key. Because it's log footage, you'll have plenty of dynamic range for color correction after the key is pulled.

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Blaise DourosRe: Green Screen Issues
by on Jul 31, 2015 at 11:12:11 pm
Last Edited By Blaise Douros on Jul 31, 2015 at 11:15:12 pm

Here's what the shot looks like with the standard slog3 to rec709 LUT applied in Premiere, no other color correction.

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Jamie McGeeRe: Green Screen Issues
by on Aug 1, 2015 at 4:53:46 pm

Thanks Guys, I will check with the camera Op.
I am getting a better key out of the CU, after using the LUT filter in Premiere but the wide isnt giving me anything usable.
Also the LUT doesnt go across with the clip if I send to AE from Premiere, I have to render the clip out, is that right? Is there a better way of doing it? Batch render in AME with the LUT active?
Should I transcode to something else at the same time? Pro Res is my goto.

I am also using a lot of additional filters, Precomps with CURVES and CC, SPILL SUPPRESSION, KEY CLEANER.
It seems like its a lot harder to pull than it should be! Or maybe I have been lucky with my previous footage!! :)

Thanks again for the help.

Jamie McGee

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Blaise DourosRe: Green Screen Issues
by on Aug 3, 2015 at 4:05:00 pm

Apply the LUT in After Effects. If you want to make changes to the brightness, it's probably best to apply them above (i.e. before) the LUT in the effects order. After the LUT has been applied, you can do your fine-tuning and pull the key.

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