Learn all about using the Subtract and Add blend modes to target the missing colors in skin and fix the color of people’s skin in Photoshop! In this Photoshop tutorial we’ll learn how to sample the colors, what colors to sample, how to find the missing colors, how to add those missing colors to the parts of the model that need them, and finally how to do the final blending to the image to make sure it all looks right.
Create two new layers. Name the first layer “CORRECTION” and name the second layer “CURRENT”
Grab the eyedropper tool and set it to sample 31×31 or something similar. Go with 11×11 if you have more detail packed into a smaller area (i.e. an eyebrow that may affect the darkness of the color sample that is 30px or less from your sample point, etc…)
Shift + click to drop a sample point on an area of good skin tone. Sample should be near an area of soft fall off of any highlight on the skin.
Use the Info panel to see the HSB of the sampled point.
Sample a point in a similarly bright area of skin that has the tone you wish to change.
Use the Info panel to watch the brightness (B) in the HSB data read out. Hold Cmd/Ctrl and click and drag the point until you get to a similarly bright area of the skin.
Sample the first skin color sample point and use the brush tool to dab a circle of this color onto the CORRECTION layer.
Sample the other skin color sample point and dab a circle of this color onto the CURRENT layer so that it partially overlaps the dab of color we just made a moment ago.
Set the CURRENT layer to the blend mode “Subtract.”
Now, sample the color that has appeared in the middle. It will probably look very dark. After sampling the overlapping color, check on the properties of the color in the color picker dialog box and ensure that it is not pure black. There should be a few percentage points of brightness.
Next, create a new layer just above the photograph and name the layer “ADD” and set the layer to the blend mode “Linear Light (Add).”
Paint with this new dark color onto the skin that needs to be corrected to see the change.
Use a curves adjustment layer, set to the Luminosity blend mode to correct the luminosity if the area now appears too bright or dark.
This technique can be useful for copying skin tone from one image to another and it can also be useful for correcting large area of skin blemish, such as severe sunburn.