How Selective Color Works
Although this is very useful for retouching, this is not only for skin color adjustment, you can use it for selectively adjust color of anything.
For this example I will use a wallpaper of Jennifer Morrison. You can download the image using the link below:
http://www.psdbox.com/wp-content/uploads/2011/08/2006-04-05-Jennifer.Morrison..jpg
http://www.psdbox.com/wp-content/uploads/2011/08/elisha-cuthbert.jpg
Video Demonstration
Step 1
Open the provided image in Photoshop and add a Selective Color adjustment layer from the menu Layer>New Adjustment Layer>Selective Color or using the adjustment layers quick access located on the bottom of the layers palette.

Step 2
Now start making the adjustments. You have to make tiny slider adjustments because it’s very easy to make the picture worse. There are 2 things you must know. The first one is that this adjustment layer will affect all layer below it even though non-destructively but I will show you how to fix that.
The second thing you must know is which of the color channels will have a greater impact on the part you want to adjust. In our example for example we must focus on the Red and Yellow channels because those are the main colors of the human skin (except if you’re working with a dark skin model). Making changes on the Magenta channel for example, will not have any effect on the skin on this image. It’s important that before doing anything you stop and asses your image for a few moments and then decide what should be done.
In our example, the skin of our model has a slight green cast and it’s too yellow. I want to make it look more natural looking and I will only use the Selective Color adjustment layer.
Select the Yellow channel first and “play with the sliders”. Actually I’m not really playing, you have to know what you’re doing, otherwise it’s very likely you will spoil your image. Make adjustments to the yellow channel as shown below. I will explain how the sliders work later.

You will notice that the skin color already improved by only adjusting the yellow channel. Now select the Red channel and make the following adjustments.

You can now hover the mouse over the image below to see the before and after.

Adjustments explanation
The reason why most people don’t use this adjustment layer and use Hue/Saturation instead is because they don’t know how it works. Sure you can use Hue/Saturation but in many situations it just doesn’t work.
Notice that for all color channels, you have the same sliders: Cyan, Magenta, Yellow and Black. The first three are used to change color value and the Black channel is to change the overall luminosity of the chosen color channel. Negative values on the Black will make the image brighter (you remove black) and positive values make the color darker (you add darks).
The other three sliders work the same but a bit different. Positive values on the Cyan slider will add more cyan to the selected color channel. But what happens when you you have negative values? You reduce Cyan obviously but that will have a secondary effect which is to increase Reds. This is what confuses people. So by reducing Cyan you add Red. Take a look at the illustration below.

On the image above we have the Red channel selected and we reduced 4% of the cyan thus adding 4% red. On the magenta slider, we added 5% magenta and decreased the green by 5%. Same on the yellow, we increased yellow by 9% and at the same time decreased blues by 9%. Once you understand when happens when you move the sliders you can accurately achieve any color you want.
On this particular image it was very easy because we didn’t have many colors. When you add an adjustment layer, by default it comes with a layer mask. You can use that layer mask to hide the effects caused by your adjustments on unwanted areas. For example if I would have another person in the same image and I didn’t want the Selective Color adjustments to affect that person’s skin I could mask that area.
About The Author
Andrei Oprinca
PSD Box creator
Hello, my name is Andrei, I was born in 1988 and I'm a self taught graphic artist (I don't consider myself an artist though, I'll have to check for the definition of that). I write Photoshop tutorials about all the techniques I know and I also provide my brushes and also stock images and other resources. I hope you like my site.
Imposiby
Nice tutorial, thank you!
Video is ok, but i had a feeling that you haven’t prepare for it. I have to be shorter than 12 minutes, it becames really dull in the middle, your actions must be clear.
Andrei
Ok, thanx for the suggestion.
mesco
tks, the illumination make me well understand, but sometimes, I can’t handle the rate to add or reduce.