Working with Layer Masks


When you work in Photoshop, you rely on masks to perform many of its editing tasks . Masking, as discussed in Chapter 6, is a way to isolate an area of an image. In Chapter 12, you worked with Quick Masks to extend the power of selecting to the painting tools. In the same chapter, you learned how to store selections as alpha channels so that they could be used at any time during the editing process. Selections, alpha channels, and Quick Masks all work to the same ends: to protect an isolated region from the application of a tool or operation. Layer masks are a little different. Instead of protecting an area of the image from the effects of an operation, they reveal or conceal areas of a layer from view.

When you adjust the Opacity controls on the Layers palette, you change the transparency of the entire layer so that the content of layers beneath it in the stack will be visible. But when you apply a layer mask to an image, you can control the transparency of a particular region of the layer. Layer masks use the same visual vocabulary as alpha channels to perform their tasks with a slightly different twist. On an alpha channel, by default, black fully protects an area, white fully exposes an area, and gray partially exposes an area. On a layer mask, black completely conceals an area, white fully reveals an area, and gray partially conceals an area.

Make a layer mask by choosing Layer Add Layer Mask Reveal All or Hide All. If you choose Reveal All, the mask thumbnail appears white and begins by revealing the entire layer. As you paint with black, you conceal areas on the targeted layer. If you choose Hide All, the mask thumbnail appears black and begins by hiding the entire layer. As you paint with white, you reveal portions of the layer. A thumbnail appears in the Layers palette to the right of the targeted layer s thumbnail. When you click the layer mask thumbnail, it displays a double border to indicate that it is ready for editing. By default, the layer mask is targeted after it is created and is indicated in the title bar of the document. By default, the layer mask is also linked to the layer, indicated by the chain icon.

Note  

Not having the correct layer or layer mask targeted is perhaps the most common mistake made by users.

Controlling Layer Masks

After you ve created a layer mask, you can control it in the following ways:

Activating and Deactivating a Layer Mask Press Shift and click the layer mask to turn it on or off, or choose Layer Enable or Disable Layer Mask.

Viewing a Layer Mask Press Option (Macintosh) or Alt (Windows), and click the mask thumbnail to view the layer mask in the image window.

Making a Selection from a Layer Mask Press /Ctrl and click the layer mask to generate a selection outline.

Moving a Layer s Mask and Contents Click between the two thumbnails to reveal or conceal the chain icon. When the two thumbnails are linked and you drag on the image with the Move tool, both the image on the layer and layer mask move as a unit. When the link is not visible, only the content of the targeted thumbnail will move.

Applying a Layer Mask to Another Layer Target the destination layer. Drag the layer mask thumbnail icon from the existing layer to the Add Layer Mask icon at the bottom of the Layers palette.

Removing a Layer Mask Choose Layer Remove Layer Mask Discard or Apply. Discard removes the layer mask and does not apply the effect. Apply removes the layer mask and applies the effect directly to the pixels of the layer. You can also drag the Layer Mask icon (not the Layer icon) to the trash can on the Layers palette.

Making Layer Masks

To understand how layer masks work, you ll use one to conceal part of the contents of a layer. To practice creating a layer mask, follow these steps:

  1. Open the file coffee_time.psd in the h05 folder on the Photoshop CS Savvy CD (see Figure 22.1). The image is composed of two layers: the cup and the pattern layer behind it.

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    Figure 22.1: The coffee_time image and its Layers palette

  2. Open the file uninvited_guest.psd .

  3. Choose the Magic Wand tool . In the Options bar, set the tolerance to the default and select the white area around the beetle . (You might have to click more than once.)

  4. Choose Select Inverse or Shift- /Ctrl-I to select the beetle.

  5. Choose the Move tool . Place your cursor on the beetle, press the mouse button, and drag the selection onto the cup. Place it on top of the coffee. Name the new layer Guest .

  6. Notice that there is a white fringe around the beetle, resulting from the anti-alias of the white background that was selected. To remove it, choose Layer Matting Defringe. In the Defringe dialog box (see Figure 22.2), enter 1 pixel. (To learn more about removing edge pixels, see the section titled Seamless Compositing later in this chapter.) See Figure 22.3.

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    Figure 22.2: Defringe dialog box

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    Figure 22.3: The two images combined

  7. Choose Layer Add Layer Mask Reveal All. A Layer Mask icon appears in the Layers palette that is, by default, targeted for editing.

  8. Choose black as the foreground color and white as the background color . Choose the Brush tool. Choose a 21-pixel Soft brush from the Brushes palette. In the Options bar, set the opacity to 100%. Pass over the topmost portion of the beetle s body. Set the opacity to 50% and make several passes as you work your way down the beetle s body. Reduce the opacity to 35% as you near the middle part of the beetle s body. The result should be a gradual fade on the layer mask, producing the illusion that the beetle is emerging from the depth of the coffee.

  9. Apply the same technique to the legs. You can produce realistic transparency with this technique, as shown in Figure 22.4. Press Option/Alt and click the layer mask thumbnail to view the layer mask, seen in Figure 22.5.

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    Figure 22.4: The transparency effect created by the layer mask

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    Figure 22.5: The layer mask

  10. To enhance the effect, choose the Magic Wand tool. Set the feather radius in the Options bar to 1 pixel. Target the Cup layer and click on the coffee to select it. Choose Filter Distort Zig Zag Pond Ripples; set the Amount to “36 and the Ridges to 5.

    As an alternative technique, apply this filter again. During the second pass, adjust the amount to “42 and ripples to 4 to produce a very interesting reflective effect.

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  11. Double-click the cup icon to display the Layer Styles dialog box. Click on the name Drop Shadow to reveal the Drop Shadow controls. Set the opacity to 35%, the angle to 39 degrees, the distance to 22 pixels, and the size to 7 pixels.

    Note  

    If you make a mistake, choose white as a foreground color and erase it.

  12. As a final touch, paint a shadow of the front leg on the cup in 30% gray; then blur it slightly with the Blur tool. The image should look like Figure 22.6, which can be seen here and in Figure C37 of the color section.

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    Figure 22.6: The completed image




Photoshop CS Savvy
Photoshop CS Savvy
ISBN: 078214280X
EAN: 2147483647
Year: 2004
Pages: 355

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