Using Painting Tools and Filters

Because selection masks are composed of grayscale images, you can use only black and white paint, or shades of the two, to modify a mask. When you activate an alpha channel containing a selection that you wish to modify, the foreground and background colors are automatically set to white and black, respectively. However, when you enter Quick Mask mode (Q), the foreground and background colors are set to black and white, respectively.

Painting with black in the alpha channel expands the masked areas and contracts the selected areas; painting with white has the opposite effect: masked areas contract and selected areas expand. If you paint with a shade of gray, areas become partially masked or partially selected, depending on the intensity of the gray. You can paint with a shade of gray by varying the opacity for the Brush tool from the options bar, or by using the numeric keyboard: Tap 1 to 10 to alter in 10% increments, for example; tap 2 to change the opacity to 20%; or tap a figure between 1 and 100.

There is one other way to paint with shades of gray without having to change the foreground color. If you have a pen and tablet, you can open the Brushes palette and enable Pen Pressure in the options for Other Dynamics. Now when you paint, you can control the shades by simply applying more or less pressure.

When it comes to modifying active selections, the Quick Mask mode is particularly good for running filters on the selection. When the mode has been invoked, you can use filters to contract, expand, soften, harden, or transform selection edges. For example, you can use the blur filters to soften edges (as noted previously), the Maximum and Minimum (Filter ^ Other) to expand and contract selected areas, respectively, and the distort or artistic filters to create fanciful selections. Try the various filters to see which ones work and which don't (Figure 9-9). Not all filters can be applied in Quick Mask mode.

Here's another use for Quick Mask mode and filter combo. It's almost impossible to create smooth selections with the Lasso tool. If you need to smooth the jagged edges before you can use a selection, you have two options. One, choose Select ^ Modify ^ Smooth and enter a numeric value in the Smooth dialog box or, two, enter Quick Mask mode and apply Filter ^ Noise ^ Median. Both will produce similar results, but with the latter method, you will have visual feedback.

Figure 9-9: A frame created by (1) applying a border to a selection, (2) entering Quick Mask mode, (3) applying the Fresco filter, (4) creating a new layer and filling with a color, and (5) applying a layer style.

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