How to protect/lock/isolate skin tone in Lumetri?

[Eko Wardoyo]

Hi all, usually, when doing color corection and grading, changing the shadow, midtone, changing color background and so on will make skin tone changes too. So how to protect skin tone from being changed? thanks.

[Richard van den Boogaard]

You typically approach this the other way around.

With color correction, you do a base grade so that the image generally matches the desired look and feel that you're after. That typically is your primary pass.

Then, with additional secondary passes you can target specific areas of color so you can adjust them as well.

Please check out this video: https://www.youtube.com/watch?v=1QyI3txuHvk

Hope this helps.

[Eko Wardoyo]

thanks @Richard van den Boogaard , this tutorial using HSL secondary to select skin then adjust it.

what about if i ad another lumetri color for another grading? changing midtone and shadow for example, of course the skin is affected.

For now, my color grading layer is like this :

I give adjustment lyer and some lumetri color effect below.

- Lumetri color (for color corection)

- Lumetri color (for change shadow and midtone)

- Lumetri color (for another and another)

- Lumetri color (for skin tone)

Skin tone is always the last thing i do. I think, it is really not eficien method. Is there another trick to lock the skintone first?

thanks

[Richard van den Boogaard]

Adding additional Lumetri Color Effects to a single clip will work much like an Adjustment Layer. The last in line (that is bottom in the stack order of the Effects) will always affect an entire image, unless you are only using secondaries in which specific areas and/or colors are affected only. As such, there is no way to "lock" skintones in that additional passes of CG will not affect them any longer.

Again, the best way to work with color correction/grading is to first do a general pass bringing the image to 90-95% of where you like it to be, disregarding the skintone corrections, which are best done with a secondary pass on top of the general pass (although visually the top is the bottom inside the Effects order).

In the end, you can add another layer to boost saturation or contrast. For the latter, you may use a contrast slider, but adding an S-curve preserves the color latitude rather than crushing it. If, after applying that final touch, the skintones still come out wrong, you may need to go back to that Effect and do more adjustments.

Hope this helps.

[R Neil Haugen]

Eko,

I'm a contributing author on color correction in Premiere Pro over on MixingLight.com, a pro colorist's instruction site. So I deal with this sort of stuff daily.

Richard's right, there's no way to lock in skin then change everything else ... it doesn't even make sense that there would be.

Color is typically taught as doing the more  'gross' adjustments first, small area adjustments last.

So getting color space, input transforms/LUTs, that sort of thing is the start. Then apply the "bulk" fixes to batches of clips, say if all your Red clips get one tech-color adjustment (from chip-chart testing the cameras) and your BlackMagic B cams get another, the drone shots a third.

Then do the main pass of 'neutralizing', matching the shots to a general 'neutral' image no matter what you'll do later in "Look" work, as this makes shotmatching so much easier. Neutral being no color casts, no crushed blacks or clipped whites, general tonal distribution leaves everything with detail. This is your first full 'pass' down the sequence, and this is ALL you do this pass!

Then go down the line again ... a separate pass! ... shotmatching shot to shot. Now you should have visual continuity from shot-to-shot down the line, and you can turn to fixing things that need it, and then finally to the "look" of the show.

So after shotmatching, you would do the 'secondary' work, that only affects part of an image. Some by keying in the HSL panel, some by setting a mask on a Lumetri effect instance to only affect one physical area of the image, some ... both combined.

There is another techinique for getting a "key" from the original image data, which is handy when setting things like skin tones after doing all the other work. It uses the Track Matte effect.

Alt-drag the clip up a track from V1 to V2, let go ... go into the ECP panel, and remove all effects on this clip on V2. Then click/Alt-drag that up one more. Now you have the original with corrections on V1, two copies without corrections on V2 and V3.

On the clip on V3, using Lumetri's HSL panel, set a key for what you want to control. In this case, skin tones. Set it wide enough to get most skin tones, then add some blur and denoise. Set the mask to Black/Color and LEAVE THE MASK ACTIVE!

Now go to the clip on V2, drag/drop the Track Matte effect on it. Set the input option to V3, set the type of mask to Luminance.

Now in Lumetri on the V2 clip, do what changes you want to skin tones ... usinng any tool in Lumetri, you're not bound to using the HSL panel because the key is already set in the clip on V3. So you can use the marvelous HSL curves tools to shape the skin tones here.

Working with a track-matte stack, the data for the key on V3 is original data, no matter what you've done or will do to the clip on V1. So the pixels used for the key won't change no matter what.

And the result is applied on the original clip on V1, no matter what else you've done to the clip. Plus ... if you drag/drop another couple instances of the clip on V4 and V5, you can do another paired Track Matte effect on something else in the image, taken again from the original, applied to the original.

Yea, there's times I've had up to six sets of track matte pairs on one clip. Doing this, you can do a lot of things that people will tell you Premiere can't do ...

Neil

[Eko Wardoyo]

Thanks so much @R Neil Haugen 

[chrisw44157881]

Neil's method goes about as far as Premiere allows, at least until they refine its interface. I'd also like to bring up another method of thought. When you are color correcting, after a general neutralization(most likely unless your DOP shot in a night club) you can use hue v hue to move skin onto the skin tone line. Obviously, even with a skinny refine curve, this will move other reds as well, and that may be perfectly ok, and actually look more natural. After all, a red brick house may, indeed share red with skin!

The benefit of hue vs hue over HSL qualifiers is that you don't have to re-key as precisely (expecially if the subject moves in the shot and luma may shift around needing keyframes) and the most important benefit may be simply that its less likely to look un-natural.

I've seen many qualifiers go so heavy handed that the skin is so different in the scene, that the brain doesn't see a 'motivation' for why it's so perfect and everything else is washed in a heavy tint or white balance is offset for a creative look.

Also consider, an inverted loose garbage matte. If the subject isn't crossing a red object in frame, you can use a quick garbage matte to work on skin tones with hue vs hue and hue vs lum because it only cares about how much is inside the garbage matte and maybe a lot faster than trying to refine a HSL key. Or try a global hue adjustment and rotate the whole image hue around till it hits skin tone, sometimes the simplest ways work the best.

But again, if the background and foreground are lit with different lights or temperatures. HSL may be still be the better option. It's all about the right tool for the right job.

p.s. with the track matte effect. you can use it to do some weird concepts like luma vs hue (changing hue over gamma curve) or compressing color modes.

[R Neil Haugen]

The HSL curves in the Curves tab are some of the most powerful tools in Lumetri. And yes, by far the best for something like adjusting skin tones, especially when used with the Vectorscope YUV so you can check your hue.

If you've got color chip-charts of multiple cameras in a job, all shot under the same lighting ... that can be a tool to make presets built around the Hue v Hue and Hue v Sat curves to more closely match the different cameras. Applied to all clips of the specific cameras in the bins, that can come a long ways to making the shotmatching easier.

Neil