When shooting for Green Screen…

[Duke Sweden]

And the answer, after MUCH google wording configurations is….shoot flat.

[Alex Udell]

Hi Duke…

I guess…

the theory would be….

why paint yourself into a corner?

Isn’t the idea of shooting flat to provide the most latitude in post?

Where as, if you try to shoot with a look, some parts of the range might be captured (clipped) in a way as to be unrecoverable to adjusted to your satisfaction?

Alex Udell
Editing, Motion Graphics, and Visual FX
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[Duke Sweden]

Hi Alex. My reasoning, and again I’m just a hack, was that once you’ve keyed out the clip there’s nothing left but the (well lit) body. Now, as an example of why I asked the question, on my latest little clip, I shot using Cineflat, the flattest profile available for Nikon. After keying out the background, when I went to tweak the exposure, brightness, etc. and do some color grading, the background reappeared and I couldn’t key it out because it was this really weird dark gray/purple color. Remember, I’m only using a Nikon D5500, h264 compression. Now that I think about it, this really wasn’t the place to ask!

But thanks for responding. Cheers!

[Tero Ahlfors]

Depends on the keyer. I’ve done a bunch of keying on stuff that had been shot/debayered flat from Alexa and Red cameras. I’ve had no problems with Keylight and Quantel/Flame keyers. But these were real movie productions with proper (or as proper that they could do on their budget) sets.

[Duke Sweden]

Well, there ya go. Mind you I don’t have a lot of problems with getting good keys, but I’m not really doing complicated keying or post production grading. In fact I’m too embarrassed to even put up any samples. Anyway, you guys, as usual, have been very helpful.
Thanks!

[Chris Wright]

i’ve read a lot about this and here comes my 2 cents…
ok, so the trick here is 8 bit vs 10 bit(i.e. professional).

remember the 8 bit log for the GH4? in the beginning, everyone was like,

wow! it’s totaly worth it to buy the log thingy, until they found it’s 8

bit.

Well guess what, all that pulling and pushing to get back to where you

need to be(with a LUT) doesn’t actual help you at all if you’re 8 bit. and

h.264 isn’t going to help much either, it’s a bitrate limited codec.

i.e. if you do want to shoot flat you need a camera with very low noise

and 10 bits and guess what keying likes? yep, low noise.

->What you are actually looking for is a “Neutral Picture Style”, not a

flat profile. although this technique is confusingly called prolost flat.

i.e. sharpness 0, contrast 0, saturation(2 notches left)

the reason saturation is not 0, if you throw it away in the camera’s
codec, then its almost impossible to get it back in 8bit, 4:2:0.

Cinestyle may give 1-2 more f-stops,but the color noise will go waaaay up.

Another important thing to save your bits from artifacting is to make
doubly sure your white balance is correct, so you’re not fighting the temp
colors in post.

[Duke Sweden]

i’ve read a lot about this and here comes my 2 cents…
ok, so the trick here is 8 bit vs 10 bit(i.e. professional).

remember the 8 bit log for the GH4? in the beginning, everyone was like,

wow! it’s totaly worth it to buy the log thingy, until they found it’s 8

bit.

Well guess what, all that pulling and pushing to get back to where you

need to be(with a LUT) doesn’t actual help you at all if you’re 8 bit. and

h.264 isn’t going to help much either, it’s a bitrate limited codec.

See, that was my original point. I said that using a flat profile removes color information that I can’t get back. Hey, I ain’t as dumb as I thought I was!

i.e. if you do want to shoot flat you need a camera with very low noise

and 10 bits and guess what keying likes? yep, low noise.

Again, Nikon D5500. h264. Total amateur. Still like to do things right.

->What you are actually looking for is a “Neutral Picture Style”, not a

flat profile. although this technique is confusingly called prolost flat.

i.e. sharpness 0, contrast 0, saturation(2 notches left)

the reason saturation is not 0, if you throw it away in the camera’s
codec, then its almost impossible to get it back in 8bit, 4:2:0.

Going back to my original point 😉

Cinestyle may give 1-2 more f-stops,but the color noise will go waaaay up.

I don’t usually use Cinestyle. Usually Flaat11 or the D5500’s “Flat” profile. I’ll try Neutral next time.

Another important thing to save your bits from artifacting is to make
doubly sure your white balance is correct, so you’re not fighting the temp
colors in post.

I ALWAYS set my white balance before each shoot, so that’s not a problem.
Thanks for your input. Cheers!

[Alex Udell]

Hey Duke…

On your first key pass, if you take a look at your matte and it’s good…

you may need to export with alpha….then grade on that…

not sure why adjusting the color post KEY would bring back the backing unless you were tweaking a filter upstream of the key….?

but I have seen some weirdness in Ppro from time to time is GPU is enabled and how it handles (or doesn’t) alpha channels.

Alex Udell
Editing, Motion Graphics, and Visual FX
Let’s Connect on Linkedin
Examples: Retail Automotive Motion Graphics Spots
Example: Customer Facing Explainer Video
Example: Infotainment & Package editorial

[Duke Sweden]

Yes, Alex that’s entirely possible that I added a preset, most likely brightness/contrast before tweaking which caused the background to partially reappear.