Mask details no bigger than a hair
13. Create the Gradient channel.
To create the final mask, you need to blend the two channels you’ve created (First Levels Adjustment and Second Levels Adjustment). The best way to do this is to create a new alpha channel with a gradient that marks the point where the two Levels Adjustment channels diverge.
Tip: Use a ruler guide to mark the point at which you want to join your two Levels Adjustment channels. When you create the Gradient channel, you’ll want to line your gradient up with this transition area.
The Gradient channel I created is shown above. To create this gradient, I set the Gradient tool to Color Burn mode and 100% opacity. The black area indicates where the First channel is good; the white area is best expressed in the Second channel. We can blend the two channels using Calculations.
14. Choose the Calculations command.
Choose Image > Calculations to display the Calculations dialog box. Then set the options as follows:
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Set the Channel option for Source 1 to Second Levels Adjustment.
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Set the Channel option for Source 2 to First Levels Adjustment.
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Turn off both Invert check boxes.
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Set Blending to Normal.
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Turn on the Mask check box and then change the final Channel setting to Gradient.
Click the OK button to create the new alpha channel.
15. Name the new alpha channel.
Double-click the newest Alpha item in the Channels palette to highlight the channel’s name. Then call it “Gradient Mask Combo” to indicate that alpha channels were combined using a gradient mask.
Now all that’s left is to clean up the alpha channel by painting inside the image window. But instead of using the brush tool, we’ll be lightening and darkening pixels with the dodge tool.
16. Select the Dodge tool in the toolbox.
For convenience’s sake, we’ll use this one tool to do both the dodging and burning.
17. Change the Range setting in the options bar to Highlights.
You can do this from the keyboard by pressing Shift+Alt+H (Shift+Option+H on the Mac). This restricts the dodging to only the lightest colors in the mask. Also, increase the Exposure to 50 percent and enlarge the brush diameter to somewhere between 150 and 200 pixels. For the smoothest results, keep the brush soft (Hardness: 0 percent).
18. Drag over the areas that should be white.
The white areas represent your mask. Chances are, there are some things you want included in the mask that are currently gray. You can paint over these areas with Dodge tool to lighten them and make them part of the masked area.
I used the Dodge tool to paint over the light grays in the shoulders and the outer edge of the hair. (Don’t worry about the central stuff such as the face; we’ll delete that wholesale in a moment.)
Drag as many times as you need to, but be careful not to lighten too much. Used in excess, the dodge tool can expand the selection too far from the natural edges of the hair.
19. Change the Range to Shadows.
You can do this by pressing Shift+Alt+S (or Shift+Option+S). This will restrict the changes to the darkest colors.
20. Alt-drag over the areas that should be black.
(If you’re working on a Mac, press the Option key and drag.) Pressing Alt or Option when dragging with the Dodge tool burns the image. This permits us to continue to use the same brush size and Exposure settings that we established in previous steps.
As ever, beware of overdoing it. Overdarkening can choke the selection and result in transitions that are too sharp. You can rarely go wrong by leaving too many gray pixels, especially around the edges of hairs.
21. Lasso the central portion of the image.
Now to round up all that extraneous junk in the center of the image. Press the L key to get the lasso tool. Then drag around the interior details.
22. Fill the selection with white.
Press D for the default colors, which are foreground white and background black when working in a mask. Then press Alt+Backspace (Option+Delete on the Mac) to clear the middle of the mask. As shown below, I made the face, neck, dress, and straps go away.
23. Save your alpha channels.
Choose File > Save to save the changes made to your image, including all of your new alpha channels.
At this point, I’d say you owe yourself a pat on the back. Whether you know it or not, you just finished making one of the Most Closely Held Secrets of the Photoshop Masters, a professional-level mask.
