Sharpen photos with Unsharp Mask
Found via the drop-down Filter>Sharpening>Unsharp Mask, the Unsharp Mask (USM) Dialog Box has three sliding controls called Amount, Radius and Threshold.
The Amount slider sets the overall level of sharpening. Radius dictates how large an area around an edge is sharpened.
Overuse of the Radius control is a common cause of over-sharpening and it is responsible for the introduction of strong outlines and halos.
The Threshold slider is used to specify which edges are sharpened. When a large value is used, the sharpening is only applied to high contrast edges, while a low value means that the sharpening is also applied to low contrast edges and finer details.
Finding the correct values takes experimentation, but start with a low Threshold and move the Amount and Radius sliders up and down until the image looks right.
Required values vary from image to image, but aim to keep the Radius below 3. An Amount of 150-180 is a good starting point.
PAGE 1: Why use Photoshop to sharpen photos
PAGE 2: Sharpen photos with Unsharp Mask
PAGE 3: Sharpening the luminance
PAGE 4: Sharpen photos in Adobe Camera Raw
PAGE 5: Sharpen photos with Smart sharpen
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