This tutorial shows how to quickly remove multiple skin blemishes using channels and masks in Photoshop with absolutely minimal usage of the Healing Brush or the Clone Stamp.

Here is a picture of a man with a serious acne outbreak. I’m going to use it as an example in this tutorial.

STEP 1

Create a copy of the "Background" layer. Take a look at all of its three RGB channels.

Photoshop Elements users can find information on how to separate an image into color channels here: http://www.webreference.com/graphics/elements3.

The red color channel (shown together with the green and blue channels on the right) is basically acne free.

The green and blue channel show most grunge.

STEP 2

In this step we create a mask that will isolate the grunge.

Copy each color channel to a separate layer in the following order (from top down in the layer stack): red, blue, green and name them accordingly.

In the rest of this tutorial, if the blending mode of a layer is different than Normal, I include it in the name of the layer after a slash.

Switch off the "Red" layer by clicking on the eye icon next to the layer name and switch the blending mode of the "Green" layer to Overlay (I renamed the layer to "Green/Overlay" after this).

The grunge in the "Green/Overlay" and "Blue" layer is now combined and more “contrasty”, as shown on the left.

Turn the "Red" layer back on and change its blending mode to Difference (I renamed the layer to "Red/Difference" after that; see the first image of the tutorial).

In the Difference blending mode , pixels with the same brightness on the compared layers (in our case "Red" layer is compared with the Overlay blend of "Blue" and "Green" layers) show as black, while the rest become gray with various degrees of lightness.

STEP 3

Add a Levels adjustment layer at the top of the stack and group it with the "Red/Difference" layer. This is done by ALT-Left clicking the border between the "Red/Difference" layer and the “Levels” adjustment layer.

Adjust the brightness of the "Red/Difference" layer to make it equal to the brightness of the clear patches of skin of the "Green/Overlay" blend layer beneath. When that happens, those areas become practically black, as seen in the image on the left.

The idea is to create a mask where the acne-affected areas are white and everything else is as dark as possible.

STEP 4

Make a new “copy merged” layer from your current result by pressing CTRL-SHIFT-ALT-E (layer named "Mask before Levels" in the figure on the right). Remember to select the top layer in the stack before pressing CTRL-SHIFT-ALT-E, because the "copy merged" layer is always placed above the currently selected layer.

STEP 5

Create a “face mask” by painting out the rest of the picture with black (using the Paintbrush tool), so only the areas affected by acne remain.

STEP 6

Add a "Levels" adjustment layer to the stack. Use it to increase contrast between the dark and light areas, then create another merged copy layer from your result by pressing CTRL-SHIFT-ALT-E. This produces our finished “face mask” (layer named "Final Mask" in the figure on the right).

STEP 7

Since the acne spots are much darker than the surrounding skin it makes sense to work on the luminosity channel that stores the brightness information of the picture.

To create a "Luminosity" layer first make a 50% gray fill layer:

1. Create a new empty layer
   
2. Go to Edit-->Fill Layer...
   
3. Choose 50% gray with normal blending mode and click OK
   
   
   
   Above the fill layer place in the stack a copy of the "Background" layer and switch its blending mode to Luminosity. The image becomes black and white (as you can see on the left).

Create a merged copy layer of your result CTRL-SHIFT-ALT-E. This is the "Luminosity" layer (see the layer stack on the right).

STEP 8

Above the merged "Luminosity" layer put a copy of the "Red" layer ("Red 2") and add to it a layer mask.

Make a copy of the “face mask” you just produced (layer named "Final Mask" in our example) by:

1. Selecting it in the layer stack
   
2. Pressing CTRL-A, CTRL-C
3. With ALT held down clicking on the layer mask next to the "Red 2" layer
   
4. Finally pasting the “Final Mask” into the layer mask by pressing CTRL-V
   
   The white spots of the mask will let the grunge-free "Red 2" layer show, blocking the view of the unsightly skin underneath.
   
   Make a "copy merged" layer of the current composite image and name (I named it "Luminosity Clean").
   

   
   STEP 9

   
   Use the healing brush on any remaining blemishes (there shouldn't be many) to obtain the perfectly clean "Luminosity Clean" layer shown on the right.

STEP 10

To create a layer representing the color channel ("Color" layer) follow the same steps as with the "Luminosity" layer:

Add a 50% gray fill layer and above it put a copy of the "Background" layer with the blending mode set this time to Color (not Luminosity!).

Create a merged copy of your result by pressing CTRL-SHIFT-ALT-E and name it "Color".

STEP 11

As you can see there are bright red spots on the "Color" layer that need to be smoothed out.

To do that, add a "Hue/Saturation" adjustment layer with the "Final Mask" layer we used before placed in the "Hue/Saturation" layer mask (see the layer stack on the right).

Move the saturation and lightness sliders in the adjustment layer until the spots blend with the rest of the skin.



Tutorial concludes on Page 2.



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