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Sharpening Images in Adobe Photoshop CS4

Article Description

Photoshop provides a number of sharpening filters, but which are the most useful? Chris Orwig shows you the best way to sharpen your photos.

#93 Using the Smart Sharpen Filter

The Smart Sharpen filter, as its name implies, seems almost as if it is truly smart. It is more powerful than the Unsharp Mask filter (#92) with sharpening controls that Unsharp Mask doesn’t share and can provide better results. So why not always use Smart Sharpen instead of Unsharp Mask? The process of sharpening an image with Smart Sharpen is slightly slower than with Unsharp Mask. But some things, like the high-quality results of Smart Sharpen, are worth the wait.

To use the Smart Sharpen filter:

  1. Select the layer you want to sharpen.
  2. Choose Filter > Sharpen > Smart Sharpen to open the Smart Sharpen dialog box (Figure 93a).
  3. From the Remove menu, choose the mode of sharpening you want:
    • Gaussian Blur sharpens identically to the Unsharp Mask filter.
    • Lens Blur is the best choice in the group because it allows you to sharpen typical optical lens blurring. It provides finer sharpening of detail and does a better job of reducing sharpening halos than the Gaussian Blur setting.
    • Motion Blur works best when you want to remove small amounts of motion blur that resulted from camera movement. Click the wheel to the right of the Angle field to set the direction of the motion that needs to be removed.
  4. Adjust the Amount and Radius controls, which work just like their counterparts in the Unsharp Mask dialog box (see #92), so that the sharpening looks best.
  5. Click OK to apply the sharpening.

Figure 93b shows the result of using the Smart Sharpen filter. Edges are crisper, especially boundaries between contrasting areas.

When you look closely, you will notice the improved details on the building and trees.

Advanced sharpening

If you notice strong, dark, or light sharpening halos after you have doctored your image, you can reduce them for optimal sharpening using the more advanced controls in the Smart Sharpen dialog box. Select the Advanced radio button in the Smart Sharpen dialog box to gain access to the Shadow and Highlight tabs (Figure 93c). On these tabs, you can adjust the following:

  • The Fade Amount slider controls the overall amount of sharpening in the highlights or shadows. Choose a higher value to reduce the overall sharpening in the shadows or highlights.
  • The Tonal Width slider limits the sharpening to specific tonal regions of the image. For example, if you choose a lower Tonal Width in the Shadow or Highlight tabs, the sharpening will be limited to the respective tones. On the Shadow tab, it limits sharpening of the darker tones. On the Highlight tab, it limits sharpening to the brighter tones. A higher value set on either tab expands sharpening to a wider range of tones.
  • The Radius slider works like its equivalent in the Unsharp Mask dialog box and controls the size of the area around each pixel taken into account by the filter. Moving the slider to the left specifies a smaller area, and moving it to the right specifies a larger area.
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