Explore the crucial skill of making selections in Photoshop with our in-depth tutorial, focusing on using alpha channels for precise skin selection and retouching.
This exercise is excerpted from Noble Desktop’s past Photoshop training materials and is compatible with Photoshop updates through 2020. To learn current skills in Photoshop, check out our Photoshop Bootcamp and graphic design classes in NYC and live online.
Topics covered in this Photoshop tutorial:
Making selections using Channels
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Exercise Overview
Selections are one of the most important things you will end up doing as a retoucher. Here we’ll show you how to select skin using an alpha channel.
Selecting the Skin Using an Alpha Channel
From the Photoshop Adv Class folder, open lifestyle.psd.
Save the file back into Photoshop Adv Class as yourname-lifestyle.psd.
Go to the Channels panel. At the bottom, click the Create new channel button
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Double–click anywhere on the new channel (except on the name) to set its options:
- Name it skin.
- Under Color Indicates, select Selected Areas.
- Click the color swatch and choose a bright lime green.
- Set Opacity to 50%.
Click OK.
With the skin channel selected, click the Eye
next to the composite RGB channel to show it.Click the Default colors icon
in the Tools panel so you have black as the foreground color and white as the background color.Select the Brush tool
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In the Options bar at the top of the screen, choose the second brush preset, Hard Round (it may be grouped under General Brushes). This preset ensures that Shape Dynamics are off. If you’re using a Wacom tablet, the size of the brush won’t change based on how hard you press with the stylus.
Change the brush to a more appropriate size (25–30 px is a good start).
- Use the Brush tool to paint over the skin with black (but read these notes first):
- Be sure to take your time when painting this alpha channel because later on you’ll be using it to create a selection for your retouching.
- Paint over all skin: the face, chest, belly button area, and don’t forget the feet!
- Do NOT include the jewelry, cigarette, hair, or anything else that is not skin.
- Your painting will show up as a green overlay on your image. Painting with black lays down color, while painting with white removes the color. (Hit the X key to toggle back and forth between the black and white.) Eventually this channel will be used to create a selection in which places that your channel has color will be selected, empty areas won’t be selected and semi-transparent areas will be partially selected.
Checking the Mask
In the Channels panel, hide the composite RGB so the document will only be displaying the skin channel in black and white.
Look around the channel for empty white spots that you may have missed, or any stray black areas that you don’t want. Fix these areas by painting over them with white or black.
Save the file and just leave it open because you’ll continue to work with it in the next exercise.
