Skin Tone Color-Swap in Curves

[Michael Bonner]

In case anyone's not familiar with the technique I'm referencing, it's a method to correct select areas of bad skintone with a curves later- you sample the RGB values of the problem tone, then the RGB values of the desired tone and plug those values into the input/output field in the different channels within the Curves dialog box. Fill layer mask with black and paint white where necessary.

My question is whether there's a shortcut to plugging in those input/output values rather than doing it manually. In my ideal world, I'd have an input eyedropper and an output eyedropper and they'd fill in the RGB values for me. Am I overlooking something or is this feature really not in there?

[pixelzombie]

there's a plug-in called Coco that works in that manner...

[Michael Bonner]

€195!?! O.o I think I'll just keep typing in those six values! Thanks a lot for the suggestion, though!

[davidpz888]

Hi Michael, I am not too familiar with this technique. If you have the time, I would really appreciate it if you could elaborate a bit more on this technique. Which part of the bad skin are you sampling? I think I've heard something similar where you sample the highlight, midtone, and then shadows. Correct me if I'm wrong.

[Michael Bonner]

Originally Posted by davidpz888

Hi Michael, I am not too familiar with this technique. If you have the time, I would really appreciate it if you could elaborate a bit more on this technique. Which part of the bad skin are you sampling? I think I've heard something similar where you sample the highlight, midtone, and then shadows. Correct me if I'm wrong.

Sure, David! I think I actually found this technique from a link around here somewhere, but here it the process in essence. I'll use a photo I took of a friend as an example:

-In the original file, you can see all the undesirable red tones, predominantly on his nose, but throughout the cheeks as well.

-To correct these, first sample some of the worst-offending skin. I probably took a 3x3 or 5x5 sample from the bridge of the nose.

-Go to Window > Color and make a note of the RGB values.

-Do the same with a patch of good skin tone. This could be a cheek, just above the redness on the nose, etc. The important thing here is to make sure you're picking something that's in the same tonal range, i.e., a midtone with a midtone, otherwise, you're going to get a significant tonal shift in addition to the color shift and your colors may not come out right either.

-Open up a curves adjustment layer and go into each channel separately

-CLICK ANYWHERE IN THE MIDDLE OF THE LINE. If you miss this step, you *will* screw up the process. I do it often enough to annoy myself and I have to go back and fix it right after doing it.

-Enter the R, G, or B values of the two skintones into the appropriate channel's Input and Output boxes. The value for the bad tone goes into Input and the desired tone goes into Output. Do this for every channel and hit okay.

-At this point, your whole photo should have a weird cast to it - this means you did everything right. Depending on the color of blemish you're trying to correct, you'll have a different color cast. Mine was cyan (which makes quite a bit of sense)

-Fill the Curves layer mask with black.

-Select a small white brush, Hardness- 0%, Opacity-100%, Flow- less than 5%. This is where a tablet comes in handy. As a general rule, I set my brush to be just a little bit smaller than the blemish I'm trying to paint away.

-This part takes time...paint over every blemish you want to remove. The slow flow will let you make gradual changes- this keeps you from having to undo and redo forever. The fastest way I've found to do this kind of work is to hit the "D" key to set my fore/background colors to black/white and switch between them using the "X" key to fix anything that I paint too heavily. Toggle the layer on and off periodically to check your status. (NOTE: You may want to do the large flushed areas of the cheeks first with a large brush, flow of about 1 or 2%. Otherwise, you'll be adding more white to the sections you already corrected)

-Toggle the layer on and off when finished to see if there are any problem areas. If the changes introduced an undesired luminosity change, you can fix that by going back into the curves dialog and pull the RGB curve downwards to taste.

I've attached the before and after photos here, along with a copy of my layer mask.

Best of luck!

[TommyO]

Michael,
A nice technique, and very similar to other techniques that have been around a while. We use these to correct everything from rosacea to too much 5-o'clock shadow. For those less adept in PS, we often use Hue/Sat or Channel Mixer AL's with masks in a lighten blending mode. Curves tends to be less intuitive for many users.

I have not seen anything to auto select such areas, however there are many skin correction tools out there. One of my favorites is PhotoTune (old SkinTune) from OnOne, due to it's simplicity but realworld skin tone samples.

Thanks for posting this one.

[davidpz888]

Hi Michael thanks so much for your detailed response!

[Steve Payne]

Hey Michael, one thing I did with this technique which speeds up D&B in general is to map my tablet pen's side button to Keystroke, so instead of two handed switching with your left hand constantly hovering on the x key you can control it all with the pen.

Also rather than taking note of the RGB values by viewing window>colour use the colour sampler (variation of the eye dropper tool) and it will save the values in the info palette.

[Michael Bonner]

Awesome info, Steve! Thanks for sharing- I may have to invest in a pen with more than two buttons now.

[meerkat]

Originally Posted by Michael Bonner

My question is whether there's a shortcut to plugging in those input/output values rather than doing it manually. In my ideal world, I'd have an input eyedropper and an output eyedropper and they'd fill in the RGB values for me. Am I overlooking something or is this feature really not in there?

Not a full reply but half-way there; you can have the curves layer automatically add the Input values for you.

Open up a fresh curves layer, and when the graph shows Shift+Ctrl+Click your colour-to-be-corrected sample on your canvas. The curves graph will be updated with the control points on the Red/Green/Blue channels, ripe for manipulating using Output values.

While we're on the subject, holding down Shift when the Curves dialogue is open brings up the Color Sampler Tool, so you can easily add your Output sample to your Info palette. It will show up as a pair of values, the unadjusted and the adjusted using the Curves layer you're currently editing. A quick glance on your Info palette will thus tell you the values to match to using the Output field.

Hope this helps, it sped up my workflow considerably :]

[Michael Bonner]

Originally Posted by meerkat

Hope this helps, it sped up my workflow considerably :]

Awesome! Thanks so much- I can't wait to get into PS and try this!