So it goes without saying that there are a ton of different ways to match skin tones across your subject or between images in Photoshop so it's often just a matter of picking the option that is most convenient or intuitive. Despite the wide array of choices, I seldom see people use the selective color adjustment layer for this task. The beauty of selective color is that it allows us to go off the numbers rather than intuition and achieve an accurate result in little time.
In this video, we'll be using one of the images I shot while filming my Fashion and Beauty Photography/Retouching course and our aim will be to match up the lower part of the models body with the tones in her face. The result of our selective color adjustment can be seen below:
The key to the selective color adjustment layer is to analyze the distribution of CMYK colors at your source and match it at the destination as I demonstrate in the video above. It requires a bit of basic math and ratios, but don't worry, it's nothing too scary. If you've never used the selective color adjustment layer, I highly recommend exploring it a bit as it can be both a powerful correction and color grading tool that allows you to target any of the below by selecting the appropriate color.
For landscapes or environmental portraits, the other color options (Blue, Green, Cyan, etc.) can also be useful for targeting areas like sky, grass, etc. In the video we'll be focusing on either the red or yellow color since skin tones generally fall into those two colors or somewhere in between them. When I train people, they are often confused about which way to move the respective sliders so it's important to remember that if you subtract either Cyan, Magenta or Yellow, you're adding their opposite color. The easiest way to remember those opposite colors is to think RGB vs. CMYK. When we remove Cyan we add Red, if we remove Magenta we add Green and if we reduce Yellow we're increasing the amount of Blue. The Black slider can be thought of as the brightness of that color although I don't recommend making drastic changes there. Keep your adjustments within the -10 to +10 range on the black slider to avoid washing your colors out. If you want to adjust the overall brightness of a certain color, you can use a Black & White adjustment layer, change the blend mode to Luminosity and adjust each color slider accordingly.
Note that if you are trying to match colors from one image to the next, this will only work if the overal lighting is similar across them. You can't match colors properly if the lighting or exposure or even model's skin type are drastically different. I typically use this approach across multiple images when working on an editorial series where the lighting and model have stayed consistent.
For additional color matching techniques, you can use my SACA method/action described here, and also check out my photography/retouching course where I cover color correction and understanding light and color differences in depth.
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