The Photoshop Unsharp Mask filter gets its name from a traditional darkroom process used to sharpen an image. The Unsharp Mask filter in Photoshop works by increasing the contrast around the edges in an image, which makes them look crisper and sharper.
How to sharpen photos with the Unsharp Mask filter
01 Crop and resize
Open your start image in Photoshop. Use the Crop tool to crop the image as desired. Choose Image>Image Size, enable the Constrain Proportions and Resample Image check boxes and set your desired resolution and size. We set Resolution to 300 Pixels/Inch and Width to 16 Centimetres. Click OK.
02 Launch the filter
To sharpen the image, choose Filter> Sharpen>Unsharp Mask. Click a portion of the image that contains detail such as the centre of the flower. This then appears in the filter dialog box sized at 100%.
03 Set the Amount
Set the Amount to 150%. The Amount controls how much sharpening is applied to the image. You can readjust this later, but for now, you want to see the results of adjusting the other sliders clearly.
04 Rradius tweaks
The Radius sets the width of the haloes around the image edges. The larger the Radius, the wider the haloes are. For a sharp image, set the Radius to something between 0.5-1.5. We used a setting of 1.0 here.
05 Adjust the threshold
The Threshold setting controls how much difference in brightness there must be between adjacent pixels for them to be considered an edge. A small Threshold value sharpens everything and a large one sharpens nothing. We set the Threshold to 10.
06 Fine-tune the result
Readjust the Amount to fine-tune the result. When sharpening for your monitor, adjust the Amount based on what you see on your screen. When sharpening for print, oversharpen a little because printing softens the image a little. Click OK to apply.
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