In addition to the transparency mask that accompanies every layer (except the background), you can add a mask to a layer to make certain pixels in the layer transparent. Now, you might ask, "Won't simply erasing portions of a layer make those portions transparent?" The answer, of course, is yes. And I hasten to add, that was a keen insight on your part. But when you erase, you delete pixels permanently. By creating a layer mask, you instead make pixels temporarily transparent. You can return several months later and bring those pixels back to life again simply by adjusting the mask. So layer masks add yet another level of flexibility to a program that's already a veritable image-editing contortionist.
To create a layer mask, select the layer you want to mask and choose Layer ^ Add Layer Mask ^ Reveal All. Or more simply, click the layer mask icon at the bottom of the Layers palette, as labeled in Figure 12-34. A second thumbnail preview appears to the left of the layer name, also labeled in the figure. A second outline around the preview shows the layer mask is active.
Tip If the second outline is hard to see, keep your eye on the icon directly to the left of the layer name. If the icon is a paintbrush, the layer and not the mask is active. If * the icon is a little dotted circle, the mask is active.
Indicates layer mask is active
Layer mask thumbnail
Layer mask thumbnail
To edit the mask, simply paint in the image window. Paint with black to make pixels transparent. Because black represents deselected pixels in an image, it makes these pixels transparent in a layer. Paint with white to make pixels opaque.
Thankfully, Photoshop is smart enough to make the default foreground color in a layer mask white and the default background color black. This ensures that painting with the paintbrush or airbrush makes pixels opaque, whereas painting with the eraser makes them transparent, just as you would expect.
In Figure 12-34, I created a feathered oval, inversed it, and filled it with black by pressing Ctrl+Backspace. This results in a soft vignette around the layer. If I decide
I eliminated too much of the hair, not to worry. I merely paint with white to bring it back again.
Photoshop goes nuts in the layer mask department, adding lots of bells and whistles to make the function both convenient and powerful. Here's everything you need to know:
4 Reveal Selection: If you select some portion of your layer, Photoshop automatically converts the selection to a layer mask when you click the layer mask icon at the bottom of the palette. The area outside the selection becomes transparent. (The corresponding command is Layer ^ Add Layer Mask Reveal Selection.)
Tip Hide Selection: You can also choose to reverse the prospective mask, making the area inside the selection transparent and the area outside opaque. To do this, choose Layers Add Layer Mask Hide Selection. Or better yet, Alt click the layer mask icon in the Layers palette.
4 Hide everything: To begin with a black mask that hides everything, choose Layer ^ Add Layer Mask ^ Hide All. Or press Ctrl+D to deselect everything and then Alt click the layer mask icon.
Tip View the mask: Photoshop regards a layer mask as a layer specific channel.
You can actually see it listed in italics in the Channels palette. To view the mask on its own — as a black and white image — Alt click the layer mask thumbnail in the Layers palette. Alt-click again to view the image instead.
4 Layer mask rubylith: To view the mask as a red overlay, Shift+Alt-click the layer mask icon. Or simply press the backslash key, \, which is above the Enter key.
Tip After you have both layer and mask visible at once, you can hide the mask by pressing \, or you can hide the layer and view only the mask by pressing the tilde key (~). So many alternatives!
4 Change the overlay color: Double-click the layer mask thumbnail to access the Layer Mask Display Options dialog box, which enables you to change the color and opacity of the rubylith.
4 Turn off the mask: You can temporarily disable the mask by Shift-clicking on the mask thumbnail. A red X covers the thumbnail when it's disabled, and all masked pixels in the layer appear opaque. Shift-click again to put the mask back in working order.
4 Switch between layer and mask: As you become more familiar with layer masks, you'll switch back and forth between layer and mask quite frequently, editing the layer one minute and editing the mask the next. You can switch between layer and mask by clicking on their respective thumbnails. As I mentioned, look to the icon to the left of the layer name to see whether the layer or the mask is active.
Tip You can also switch between layer and mask from the keyboard. Press
Ctrl+tilde (~) to make the layer active. Press Ctrl+\ to switch to the mask.
♦ Link layer and mask: A little link icon appears between the layer and mask thumbnails in the Layers palette. When the link icon is visible, you can move or transform the mask and layer as one. If you click the link icon to turn it off, the layer and mask move independently. (You can always move a selected region of the mask or layer independently of the other.)
♦ Convert mask to selection: As with all masks, you can convert a layer mask to a selection. To do so, Ctrl-click the layer mask icon. Throw in the Shift and Alt keys if you want to add or subtract the layer mask with an existing selection outline.
Ij-1 ♦ In Photoshop 6, you can apply a mask to a set of layers. Just select the set and click the layer mask icon. The mask affects all layers in the set. If a layer in the set contains its own mask, no worries; Photoshop's smart enough to figure out how to mix them together. For another method of masking multiple layers, see the section "Masking groups of layers," coming up soon.
When and if you finish using the mask — you can leave it in force as long as you like — you can choose Layer S Remove Layer Mask. Or just drag the layer mask thumbnail to the trash can icon. Either way, an alert box asks whether you want to discard the mask or permanently apply it to the layer. Click the button that corresponds to your innermost desires.
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Adobe Photoshop can be a complex tool only because you can do so much with it, however for in this video series, we're going to keep it as simple as possible. In fact, in this video you'll see an overview of the few tools and Adobe Photoshop features we will use. When you see this video, you'll see how you can do so much with so few features, but you'll learn how to use them in depth in the future videos.