Qualifer: selecting skin tone versus red background

Hi folks,

I've been grading in Davinci for a few projects and using qualifier mostly for sky and skin tones.

This last project I'm grading was shot with a red bg (inside a theather), I made a qualifier for the skin tone just for increasing the exposure and I had issues with the actor's lips: selecting the full skin tone ended up including a bit of the lips as well, and that edge of the selection keeps changing intermittently from frame to frame, causing the exposure of the lips to noticeably flicker. I could simply select the lips along with the skin tone and change their exposure, but the lips are the same color as the background, so the qualifier selects all of it.



Qualified:


Here is the image with the lips selected (and a lot of bg included against my will)



In short: if I try to exclude the lips completely, the full skin tone can't be selected. If I try to include the lips, I bring the background along. If I try to include just a bit of the lips, the selection keeps changing and causing them to flicker.

So: does anybody know a quick, efficient solution I may be overlooking?

I really appreciate your attention! Thanks

I'm Using Davinci 12.3.2

[Samuel Fortunato]

You could do it a few ways.

Here are two:

To get it all in one correction, do you skin key on one node, then another key for the lips, with simple soft power windows tracked to the mouth.Then combine those keys in a key mixer and use that as a key input for your correction.

The other way would be similar to the above (skin key + lip key with windows) but done in a parallel stack - would let you adjust the lips independently from the skin.

The two approaches mentioned in the previous response would do it. Also, we can use a power window for the lips in an inverted mode to protect them from the qualification.

I think you may find you need two PPW windows drawn more precisely to the actor's head and tracked with a combination of auto tracking and manual tracking when necessary. You may also need an occlusion mask if something passes in front of the actor's face. The manual goes into this stuff pretty well.

Having background images with similar shades to foreground skintones is never ideal, but I get that sometimes we fall into these projects late and have zero control over what was shot.