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Luma Keying Blonde Hair

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Max Jackson
Luma Keying Blonde Hair
on Feb 8, 2011 at 1:41:24 am

Hi CC,

I'm trying to remove light wispy blonde hair from a white cyc background.

I've toyed with Luma Key and Extract but haven't the foggiest on what to do with a luma key this tricky, only solid objects.

Are there rule of thumb techniques for this kind of situation?


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Joey Foreman
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 3:16:45 am

Locked down or moving camera? Hair blowing in the breeze, or just softly undulating?

Joey Foreman
Editor/Compositor/VFX Artist


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Max Jackson
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 3:43:24 am

breeze, the a fan blowing from one side to make her look like she's running really fast.

Once she's still it's not too difficult. I can seem to pull a pretty good matte in the blue channel, but I have no idea how to translate what I see in that channel with the levels pumped into the full RGB.

Is there another option, or is that the idea? (not that there has to be just one)


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Joey Foreman
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 3:47:44 am

How about duplicating the layer, then applying Shift channels to the one above, setting all to Blue. Pump the levels on that and use it as a Luma (or Inverted Luma) track matte for the original layer.

Joey Foreman
Editor/Compositor/VFX Artist


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Max Jackson
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 5:38:12 am

That worked pretty good, but I've still got a large deal of light reflection on her head. That and a small light white line around the matte.



If I push the blue too hard it eats into the reflection on her head. Is that something that commonly has to be rotoscoped? I'd use a choker of some kind that works with this approach?

The simple choker's grabbing the entire comp and not the matte.


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Joey Foreman
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 5:50:17 am

Try tweaking the Levels effect, and maybe smart blurring that layer as well. I think (but I'm not sure) than Minimax may help too.

Joey Foreman
Editor/Compositor/VFX Artist


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Joey Foreman
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 5:56:56 am

Simple Choker can expand the matte as well, maybe to better effect than Minimax.

Joey Foreman
Editor/Compositor/VFX Artist


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Max Jackson
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 6:19:54 am

Yeah, it was more effective in getting the matte reverse to come out using the choke. But I clicked color key on the thick yellow (anti-blue) trace and it turned grey (which I guess makes sense as they cancel each other out).

Minimax looks like a cool effect, but...I feel I've started to hit a dead end using a choke method as I'm using color and not luma values. I might try that smart blur and maybe a linear color key in reverse somehow...maybe?

It feels I'm really close and in some instances might get away with it. I might be trying to do too much in one key again too.

Thanks Joey! :D


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Joey Foreman
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 2:38:17 pm

Sorry, it was late in Georgia too, and when I wrote Smart Blur I meant Fast Blur. You might also try the Matte Choker, as it has some additional softening control.

If you're still hitting a brick wall, you could post a full res grab of an unprocessed frame, and I'm sure someone here would be willing to play around with it and let you know what they come up with.

Joey Foreman
Editor/Compositor/VFX Artist


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Max Jackson
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 7:49:21 pm

Cool, I'll try apply fast blur, and matte choker instead of simple choker.

I'd post the files but they're copyright sensitive and don't want to get in trouble. I'm just using them because it's a great real job scenario demonstration to work with. What's funny is their resolution isn't that great. If you check my blog in the main AE forum you'll see what I mean. :P

Thanks Joey! You've been a great help!


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Angie Taylor
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 8:17:37 am

Hi there,

Have you tried using Keylight? I find that it offers a much higher level of control for this kind of job. The Luma key is pretty basic.

cheers,

Angie

Angie Taylor animation & illustration for television, film, web and devices

http://www.angietaylor.co.uk
Twitter: theangietaylor
Linkedin: theangietaylor
http://www.facebook.com/pages/Angie-Taylor/118378194869002



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Max Jackson
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 8:32:26 am

Hi there,

Yes, I started out using it a bit, but since the blond hair was so much like the white BG it seemed like the wrong way to go for a luma key/matte.

Should I have played more with the bias settings?


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Angie Taylor
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 8:44:31 am

Hi there,

Well, you can try but sounds like you've already given it a go. Have you looked at the individual channels? Quite often the Red channel can be used as a matte for keying if it's strong enough. Try looking at all three channels individually. If the red is strong, duplicate the layer, use Shift Channels to isolate it on one of the layers (take Red, Green and Blue from Red). Add levels effect to boost contrast. If you get good results yo can precompose this and then use the Luma Track Matte option in the Switches column to create alpha info from the Luma info.

Hope this helps! :-)

cheers,

Angie

Angie Taylor animation & illustration for television, film, web and devices

http://www.angietaylor.co.uk
Twitter: theangietaylor
Linkedin: theangietaylor
http://www.facebook.com/pages/Angie-Taylor/118378194869002



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Max Jackson
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 8:53:54 am

Yeah, totally. That's what I started doing using the blue channel. Joey told me how to filter all of them through a color using the Shift Channels.

I chose blue because I was dealing with blonde on white and it come out the most contrasty on a channel-to-channel check.

Even though I couldn't quite get past the white fuzz. It sounds like this is a common method for what everybody does. It's late here in California, but I'll practice some more tomorrow and then try a few more tweaks to get it solid.

Thanks Angie! :D


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Dave LaRonde
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 3:38:50 pm

Mind you, all I did was scan this thread, but I saw no mention of this: what kind of camera did you use to shoot this? HDV? XDCam? If you did, it's going to be tough to pull a perfect-looking key, I'm afraid.

The reason: these kinds of cameras record wide pixels to begin with. That wouldn't be a horrible problem all by itself. But the codecs used to record the video have God-awful color sampling (aka color resolution), either 4-1-1 or 4-2-0. The gist is this: for every four pixels of luminance information there is only ONE pixel of color information. It's enough color information to fool the human eye, but computers are more discerning.

So what you need to pull a good color key? You get three guesses, and the first two don't count.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Max Jackson
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 7:56:10 pm

Hi Dave!

I'm pulling a luma key/matte, and yes the footage isn't that great:

http://forums.creativecow.net/readpost/2/994740

It's really noisy footage too. I did a color reverse channel blur on green, but it didn't help too much. So yeah, blonde hair on white with noisy, semi-grade footage has been an interesting challenge.

That might be a reason I'm having a more difficult time. I've gotten close though, just need to try a couple more things. Then I'm going to have to put up a thread looking for more white cyc backgrounds to practice on. :P


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Joey Foreman
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 8:02:17 pm

Actually, Max, all you need to do in the future is avoid white cyc backgrounds all together. Go green screen next time, and most of these issues will vanish. Especially if you take Dave's advice and shoot with a camera that does at least 4:2:2 color sampling.

Joey Foreman
Editor/Compositor/VFX Artist


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Max Jackson
Re: Luma Keying Blonde Hair
on Feb 8, 2011 at 8:26:54 pm

Joey, I'm totally with you, white is harder than green, blonde or not. But ABC shot it this way and we were handed it at the agency to do something with for a rich media campaign. So, I'm taking a real do-or-die boot-camp approach to self-training as I expect I could see something like this again and would hate to lose a future client.

It's possible the footage wasn't given that much focus because they knew the end product was going to be about 600x400 pixels max size...or at least that's my guess.

Just trying to be ready for anything so I can start feeling comfortable saying 'yes' to After Effects jobs.

Thanks Joey,
-maX


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Dave LaRonde
Re: Luma Keying Blonde Hair
on Feb 9, 2011 at 4:43:39 pm

[Max Jackson] "...ABC shot it this way and we were handed it at the agency to do something..."

Is this ABC as in the American Broadcasting Company? I'm willing to bet they shot on a nice chroma key set, and that white background wasn't there in the first place. It's just one heck of a good-looking key; the network doesn't fool around. As a promo guy for an ABC affiliate, I frequently see their stuff.

But if this footage is related to the "water flying around the screen" look they've adopted, you might also have luck using AE's Threshold and Invert effects to build a matte.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Max Jackson
Re: Luma Keying Blonde Hair
on Feb 9, 2011 at 7:32:44 pm

Hi Dave,

Yeah, that's what I was wondering. The footage was actually splintering up, but I learned from Spencer in another thread I posted that it was a compression issue. That when going from DNxHD (I think it's called) the compression sometimes creates artifacts.

Here's the thread:

http://forums.creativecow.net/readpost/2/994740

I believe this footage was shot with a very nice company-owned camera, but the white backdrop was intended in one way or another because they had the actor pushing a green-coated object out of the way. The grip was even using green gloves so they knew what they were doing. It was to make the actor look like he was pushing something out of the way, that something was to be the web page revealing the ABC rich media banner.

Why they had him holding on to a greened out object with a white cyc behind him is beyond me. Maybe they figured that's all we were going to need? Like a car commercial or something? Heh, as things go, it didn't turn out that way...had to luma key.


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Angie Taylor
Re: Luma Keying Blonde Hair
on Feb 9, 2011 at 8:38:10 pm

Hi again,

Also, what may be causing a lot of your noise isues is the fact you're using the blue channel. The blue channel is most often the one that contains the majority of noise. I usually find the red channel is the best to use as it maintains a lot of skintones and is usually fairly noise-free.

cheers,

Angie

Angie Taylor animation & illustration for television, film, web and devices

http://www.angietaylor.co.uk
Twitter: theangietaylor
Linkedin: theangietaylor
http://www.facebook.com/pages/Angie-Taylor/118378194869002



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Max Jackson
Re: Luma Keying Blonde Hair
on Feb 9, 2011 at 8:46:53 pm

Hi Angie,

That's great to know. Yeah, it's REALLY noisy. Like, chunky even.

I'll take another pass at it using red instead of blue. I just used blue to start because it was providing the most contrast right off.

Any bonus with skin tones would be great too.

Thanks!


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