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Refining Masks

By now you should be feeling more comfortable making layer masks. However, there’s always room for improvement (at least where masks are concerned). Let’s take a look at three ways to refine or adjust a mask.

Using the Masks Panel

Photoshop CS4 offers the new Masks panel just for refining masks. It combines several tools and commands into one location, and makes it much easier than before to adjust a mask (even after applying it). In fact, the Mask Edge and Color Range options are identical to the selection commands you’ve previously explored.

  1. Open the file Ch07_Masks_Panel.psd from the Chapter 7 folder.
  2. Select the Fire Hydrant layer’s mask.
  3. Experiment with the Density and Feather sliders to see their effects.
    • Density: Reduces the overall impact of the mask by essentially lowering the opacity of the layer mask.

    • Feather: Creates a gentle edge to the mask.

  4. Set Density to 100% and Feather to 0 px.
  5. Click the Mask Edge button to open the Refine Mask dialog box. The controls are identical to the Refine Edge dialog box except here they are used to modify the layer mask.
  6. Adjust the Mask Edge properties to remove fringe from around the image.
  7. Click OK to apply the change to the layer mask.

Maximum and Minimum

Photoshop offers two specialty filters for refining masks. Lumped into the amorphous “Other” category, most users miss the Minimum and Maximum filters. Both are useful for modifying a mask because they can expand or contract the mask.

  • Maximum: The Maximum filter applies a choke, which spreads the white areas and chokes the black areas. This filter will expand a Layer Mask outward, which is useful if the matte is hiding too much of the image.

  • Minimum: The Minimum filter applies a spread, which expands the black areas and shrinks the white areas. This filter will reduce a Layer Mask and contract it. This is useful if the matte has a fringe around the outside edge.

  1. Open the file Ch07_Flower.psd from the Chapter 7 folder.

    Notice the thin black border around the flower.

  2. Select the Layer Mask’s thumbnail.
  3. Choose Filter > Other > Minimum to contract the mask. A value of 3–7 pixels should be enough to contract the edge to remove the border.
  4. Click OK when satisfied.

Using Smudge and Blur

Sometimes, a mask is close to being ready to apply but needs a little touch-up. What better way to do this than to paint? By using the Blur and Smudge tools you can polish problem edges.

  • Blur: Choose the Blur tool to soften a hard edge that looks unnatural. Just be sure the mask is selected before blurring.

  • Smudge (Lighten): Choose the Smudge tool and set its mode to Lighten in the Options bar. This is useful for gently expanding the matte. Leave the Strength set to a low value to make gentle changes.

  • Smudge (Darken): Choose the Smudge tool and set its mode to Darken in the Options bar. This is useful for gently contracting the matte. Leave the Strength set to a low value to make gentle changes.

Open the file Ch07_Lion_Mask.tif to experiment with the Smudge and Blur tools.

Adjusting Content Within a Mask

By default, layer masks are linked to their respective layers. Applying a transformation (such as a Free Transform command) will affect a layer and its layer mask. However, there are times when you won’t want this default behavior to occur. Sometimes, it is useful to adjust the contents of a masked layer without repositioning the mask. Let’s give it a try:

  1. Open the file Ch07_Mask_Content.psd from the Chapter 7 folder. Even though the layer mask is accurate, too much of the layer’s content is obscured.
  2. Click the chain icon between the layer thumbnail and layer mask icons for the Newspaper layer. You can now manipulate the layer content or its mask independently.
  3. Select the Newspaper layer’s thumbnail to modify the visible pixels of the layer.
  4. Press Command/Ctrl+T to invoke the Free Transform command. Scale the Newspaper layer smaller and move it slightly to better fit the opening in the newspaper stand. Click the Commit button to apply the transformation.
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