Graphics Programs Reference
In-Depth Information
2 Now press and hold the Ctrl key (Windows) or the Command key (Mac OS) and click the front panel
path thumbnail in the Paths panel. This turns the path into an active selection. You will now apply the
Unsharp mask filter.
Applying Unsharp mask to the selection
Unsharp masking is a traditional film compositing technique used to sharpen edges in an image. The Un-
sharp Mask filter corrects blurring in the image, and it compensates for blurring that occurs during the
resampling and printing process. We highly recommend applying the Unsharp Mask filter whether your
final destination is in print or online.
The Unsharp Mask filter assesses the brightness levels of adjacent pixels and increases their relative con-
trast: it lightens the light pixels that are located next to darker pixels as it darkens those darker pixels.
You set the extent and range of lightening and darkening that occurs using the sliders in the Unsharp
Mask dialog box. When sharpening an image, you should understand that the effects of the Unsharp
Mask filter are far more pronounced on the screen than in high-resolution output, such as a printed piece.
1 Choose Filter > Sharpen > Unsharp Mask. Unsharp mask is an interesting term, because it is actually a
technique used to sharpen the details in an image.
The Unsharp Mask dialog box appears.
2 In the Amount text field, enter 200 . The Amount value determines how much the contrast of pixels is
increased. Typically, an amount of 150 percent or more is applied, but this amount is reliant on the
subject matter. Overdoing Unsharp Mask on a person's face can be rather harsh, so that value can be
set lower (150 percent) compared to an image of a piece of equipment, where fine detail is important
(300 percent+).
3 Click and hold the preview to turn off the Unsharp mask filter preview. Release to see the Unsharp
Mask filter applied.
4 Leave the Radius set to 1.0. This radius determines the number of pixels surrounding the edge pixels
that are affected by the sharpening. For high-resolution images, a radius between 1 and 2 is recom-
mended. If you are creating oversized posters and billboards, you might try experimenting with larger
values.
5 Type 10 in the Threshold text field. The Threshold determines how different the brightness values
between two pixels must be before they are considered edge pixels and are thus sharpened by the fil-
ter. To avoid introducing unwanted noise into your image, a minimum Threshold setting of 10 is re-
commended.
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