Step 4-
Sharpen & Blur A Quickmask

There is more to creating a Quickmask than simply painting an area and converting it to a selection. Remember that Photoshop lets you use all of its tools on the painted mask you've created. This means that you can apply local or global sharpen/blur effects, further modifying the selection you've created. Once you have a basic Quickmask area defined, you can use the following methods to further modify the mask:

• Use the Sharpen/Blur/Smudge Tool
  
• Use the Dodge/Burn tool
  
• Use the Curves controls
  
• Use Edge effects- comprised of Invert /Equalize/Threshold /Posterize
  
• Use Filters to add patterns and distortion
  

Use the Sharpen/Blur/Smudge Tool

The Sharpen/Blur/Smudge tool is an effective way to modify local edge areas
of a selection. For example, if you want to have the edge of a selection fade
out on one side, but be crisp and sharp on the other, you would use the Sharpen
and Blur tools as needed. In the same way, selecting the smudge tool lets
you smear and distort selection edges in varying degrees(Figure 18.5).

Figure 18.5- The effects of the Sharpen, Blur, and Smudge tools on a Quickmask.

The key differentiator between these approaches and selecting feather edges
or a distort filter, for example, is that these commands apply their effects globally to the entire selection, while the Sharpen/Blur/Smudge tools allow you to modify local areas of the mask. Quickmask allows you to use individual tools on specific areas of a selection as needed.

Use the Dodge/Burn tool

The Dodge/Burn tool provides another way to modify a mask by making the mask value darker or lighter. This approach allows you to darken an edge, which sharpens it and eliminates any anti-aliased or feather effects that may be applied there. Conversely, the Dodge tool lets you soften an edge, creating more of a feathered selection. In this respect, the dodge/burn tool modifies a mask in the way as the sharpen/blur tools, but it does go one step further.

The Dodge/Burn tools also let you modify the translucency of a mask, making it more opaque or transparent. You can use the burn tool to darken and solidify a selection area, while the Dodge tool lightens and feathers an area. This lets you move beyond modifying only the edges, letting you modify internal areas of a mask and selection as well(Figure 18.6).

Figure 18.6- The Dodge/Burn tool can create or delete transparent sections of an existing Quickmask.

Use the Curves controls

Once you've started a translucent mask, either with a gradient, or any of the tool listed above, you can modify the relative translucency with curves.
Its as simple as selecting Image>Adjust>Curves while in Quickmask mode, and moving the curve up or down to lighten or darken the current mask. You can make similar modifications with the Brightness /Contrast controls, or the Levels controls.

Use Edge effects-
Invert /Equalize /Threshold /Posterize

It is also possible to modify a mask using the four edge effects controls found at the bottom of the Adjust Submenu in the Image menu. These controls can deliver quick shortcuts to various mask editing requirements.

• Invert will turn the current mask inside-out, switching the selected and deselected areas.
  
• Equalize will sharpen the mask globally, while adding a slight degree of feather, depending on whether it was present in the original selection.
  
• Threshold eliminates all feather, defining an absolute edge between the selected and deselected areas. You can control where this break occurs by moving the threshold slider in the dialog box that appears when you select this command(Figure 18.7).
  
• Posterize will divide the mask into distinct levels of opacity, which in turn will create distinct levels of translucent selections. Simply select the posterize command and enter the number of levels desired in your mask, and Photoshop will divide the mask into distinct sections. Be sure the Preview box is checked so that you can preview the effect from the dialog box.

Figure 18.7- The Threshold slider controls the edge and area covered by the Quickmask.