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Using the Unsharp Mask Filter
The Unsharp Mask filter creates a visually sharper image by locating pixels that differ in value from surrounding pixels. When the filter is applied to the image, the bordering pixels specified by the threshold option get lighter and the darker pixels get darker. It's important to understand that the Unsharp Mask does not actually sharpen the image; it only attempts to create the illusion of sharpness. Be careful, an over application of this filter creates harsh images with ragged edges and shadows. Also, the effects of the Unsharp Mask filter appear more severe on a monitor with its low resolution, then when the document is output to a printer.
Use the Unsharp Mask Filter
Select the Layers palette.
Select the layer you want to sharpen.
Click the Filter menu, point to Sharpen , and then click Unsharp Mask .
Select from the following options:
Preview.
Select the option to view changes to the image directly in the active document window.
Amount.
Drag the slider or enter a value to determine how much to increase the contrast of pixels.
Radius.
Drag the slider or enter a value to determine the number of pixels surrounding the edge pixels that affect the sharpening.
Threshold.
Drag the slider or enter a value to determine how different the sharpened pixels must be from the surrounding area before they are considered edge pixels and sharpened by the filter.
Click OK .
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