Luma Keying Blonde Hair

[Joey Foreman]

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

Joey Foreman
Editor/Compositor/VFX Artist

[Max Jackson]

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)

[Joey Foreman]

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

[Max Jackson]

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.

[Joey Foreman]

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

[Joey Foreman]

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

Joey Foreman
Editor/Compositor/VFX Artist

[Max Jackson]

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! 😀

[Angie Taylor]

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

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

[Max Jackson]

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?

[Angie Taylor]

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

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