Learn to adjust your images to perfection in Photoshop with this detailed tutorial that covers using curves for testing selections, editing channels, and other useful techniques.
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:
Using Curves to Test Selections, Editing Channels
Exercise Preview
Exercise Overview
A good way to test your selections is to temporarily boost the contrast of your image so you can see what you did and did not select. You can then refine your selection so it is as close to perfect as you can get. In the image above, notice the white “halos” that show the edges that were missed.
Testing Selections to Make Sure They’re Good
If you don’t still have it open, re-open yourname-lifestyle.psd.
In the Channels panel, make sure the composite RGB channel is selected.
Hide the skin channel.
Cmd–click (Mac) or CTRL–click (Windows) the skin channel to load it as a selection.
With the selection loaded go to the Layers panel, then click the Create new fill or adjustment layer button
and choose Curves.In the Properties panel, crank the settings to make the photo either really dark or really light. While doing this, look at the edges to see if there are any parts where the selection went too far outside the skin, or for any skin you missed.
With the Curves layer selected (so that you’re editing its mask), use the Brush tool
(set to white to add to the selection or set to black to remove from the selection). Refine the selection until all the edges look good.
Updating the Skin Channel
The mask has been updated, but the channel used for the original selection also needs the same corrections. To do this, in the Layers panel, Cmd–click (Mac) or CTRL–click (Windows) the Curves mask to load it as a selection.
Go to Select > Save Selection.
In the Channel menu, select skin.
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Under Operation, make sure Replace Channel is selected, then click OK.
Now you have a perfect selection channel.
Hit Cmd–D (Mac) or CTRL–D (Windows) to deselect.
You can delete the curves layer. We were only using it to test the selection.
IMPORTANT! Be sure to save the file when you are done. You will be using this file again!
Updating a Channel the Fast Way: Using Keystrokes
You just learned one way to update a channel based on the work you did on a layer mask. While not hard, there’s another way that can be faster if you like to use keystrokes.
In the Layers panel, click the Curves Layer Mask to select it.
Hit Cmd–A (Mac) or CTRL–A (Windows) (Select > All).
Hit Cmd–C (Mac) or CTRL–C (Windows) (Edit > Copy).
In the Channels panel, select the channel you want to update.
Hit Cmd–V (Mac) or CTRL–V (Windows) (Edit > Paste).
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Hit Cmd–I (Mac) or CTRL–I (Windows) (Image > Adjustments > Invert).
NOTE: We have to invert the channel because of the way we’ve set up our channels to display. If your setup is different, you might not need to do this step.
