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Skin Tone Correction - Unclipping

Last update:  12-31-1969

Submitted by byRo

An important, and often forgotten, first step to skin tone correction. (in PS 7.0, but nothing limited)

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Overall Recommendation

Recommended

Rating
 

8

 

Expertise     8.8
Utility     7.6
Clarity     6.6
Relevance   8.9

Or, how to get from here....                                  to here....

 

  (images from the thread "Maria"  , OK’ed with Danny)

Not a lot of difference, OK. But this is a first step. Without this, you will run into problems pretty quick!

About Clipping

When a photo is over-exposed, or badly manipulated, one or more of the channels will hit the limit value of 255 (for 8 bits). This is what is called clipping .

It is normal for a well-adjusted final image to have some instances of the maximum value, in fact the PS default  “Auto-adjust” will put 0.5% of the pixels at the limit. However, if large patches of the image reach the limit the effects of clipping become   clearly evident.

What we see in this case is often referred to as “blown-out ” or “shiny ” and this will most probably occur on the forehead, nose or cheeks.

When the original image is already clipped we may not even notice, but if parts of the image are already at their limit value, any further manipulation will tend to introduce even more clipping.

A shiny nose, for example, may well be at pure white (255,255,255). If we lower the luminosity, to take out the shine, we just end up with a shade of gray and not a skin tone. This is because we see colors as the ratio between the R,G and B values, and in this case the are all the same, and that means gray. To save our nose (as it were), besides lowering the luminosity we will have to give back some color information.

To avoid introducing clipping the easiest way is to keep each channel well within the limits of 0 - 255. Most people have their own numbers, but for me I like to stay inside the range 25 – 230.

Here’s the image showing where clipping has ocurred.

Unclipping

 

OK, let’s get to work. There is an action posted here, but it would be good to go through it all manually. Well, at least once, OK?

A - Duplicate, to save the original, we are going to need it (ctrl-J);

B - Image>Adjustments>Brightness / Contrast (*1) set Contrast to -20 - to put into working range;

C - Duplicate and set blending to Color;

 

D - Make a new Hue / Saturation adjustment layer and set Saturation to 50 – this makes it easier to visualize what’s going on;

- Go back to layer B, Filter>Other> High Pass with radius 1 – this layer is also just to make the work easier;

- Go to layer C;

(this is where the action ends and the work starts)

 

If everything went OK, you are looking at this:

 

Great, and what is this?

 

We are looking at just the colors in the photo. The reddish / orange color is the basic skin tone, without luminosity information, the gray parts are where we have a problem to solve. Now we can see that the clipped areas that we had seen above (left nose, right hair) are grayed out, but besides these we have found some more things to fix.

Painting the colors back in:

- Select a brush with blending set to Color and low opacity, 20 to 40 should do;

- Turn off the Hue / Saturation layer;

- Use <alt> to sample a nearby color and paint the gray areas.(*2) ;

- Turn the Hue / Saturation layer on again to identify the remaining gray areas;

- Repeat until all grey is gone.

When satisfied, or just curious, turn off the Hue / Saturation layer and change your painted layer blending from Color to Normal.

If something looks a bit wrong, just paint some more (blending color). Remember, you don’t need the High-Pass and Hue/ Saturation layers - they were just to help out, they don’t affect anything.(*3)

Corrected Image... 

 

Final step – as always .

If you’re like me - and a lot of folks are – you’ve probably gone too far.

Leave on just your painted layer and the original (you saved it, remember ). Set the painted layer opacity to 50% and take a look. Pretty good chance you’re going to like it better that way!

(*4)

 

Notes:

*1) Yes, Brightness / Contrast. It´s   a nail. We don’t need a multi-function tool-kit – just a hammer.

*2) If some region stays gray, and just won’t budge, it’s because the original was very clipped and the -20 contrast wasn’t enough. Apply another dose of -20 contrast on the painted layer.

*3) No, I wasn’t wasting your time. You could have gone straight in with the colored brush. You just wouldn’t have any control, and would probably have missed some important parts.

*4) Although it is easier to think of clipping at the white end of the scale, all that was said and done here applies to the “dark side”.