Not too long ago, I was looking at some of my favorite "People" pictures. Don "Popeye" Zimmer was the subject of one of those pictures. I captured this portrait at Tropicana Field in St. Petersburg back in 2008. Tropicana Field is an indoor venue, so the lighting is artificial. Looking at the picture now, Zimmer's skin tone looks far too yellow. Back in 2008, I didn't have any understanding of the tools at my disposal to analyze and correct skin tones. Since Photoshop provides an objective way of measuring the skin tone, I thought this process would make for an interesting post! Here is the photo is question:
Next, convert the RGB values inside of the Info palette to CMYK percentages by clicking on the little eyedropper on the left side of the readings. The readings should for the selected sample should now appear as CMYK percentage values. For this control point, the cyan reading is 11%, the magenta reading is 48% and the Yellow reading is 74%:
Before proceeding, I refer to a few guidelines for reading an average caucasian's skin tone:
In the above photograph, the yellow value is too high as compared to the magenta reading. So, my instinct is correct--the skin is too yellow! My next step is to make some adjustments to the color curves to correct the skin tones. Before getting started with those adjustments, I create a Curves adjustment layer. I then select the Blue channel within the Curve.
Then, I select the portion of the curve that represents my first control point and drag the curve up (more blue, less yellow) until the yellow reading drops closer to the magenta reading:
Next, I make an adjustment to the same portion of the curve, but this time I open the Red channel and drag it down (less red, more cyan) until the cyan reading reaches about half of the magenta value. At this point, the cyan is just under half of the magenta value. And, the yellow value is 20% (1/5th) higher than the magenta value. Based upon these relationships, we know that Zimmer's color is now typical for a caucasian skin.
The skin color now looks accurate to me--and far better than in the original image. And, the numbers bear that out. If you are not yet satisfied, you can always drop more Color Sampler points on different portions of the skin and use the same method for correcting each area. Also, if you don't like what's happening to the color of the background, feel free to mask it off in the layer.
I've used this method quite often when skin tones need correcting. Once you get the hang of it, you can accomplish the steps quite quickly.