A version of this tutorial first appeared in an issue of Photoshop Fix
Unsharp masking (USM) is considered standard practice for “sharpening” a soft image. It works by exaggerating the edge contrast of details, but this can also exaggerate textures, faults, and other artifacts in your image. Photoshop’s High Pass filter and layer blending modes offer a more controllable alternative.
Some general sharpening tips:
The amount of sharpening is determined by the printing size and the viewing distance. The smaller the final output, and the closer it will be viewed, the less sharpening the image will tolerate. A single image can require several sharpened versions.
Highly textured areas such as foliage need the least sharpening, while faces need the most.
Watch out for “haloing”. These pale outlines that can trace around details are tell-tale evidence of oversharpening.
1 Download mousegirl.jpg, then select File > Save As, choose PSD for the file format and click OK. Duplicate the background layer by dragging it to the Create a new layer icon, and name the new layer Sharpen. Change the blending mode of the Sharpen layer to Overlay. This will temporarily increase the overall contrast of the image.
2 Select Filter > Other > High Pass. Arrange the filter dialog box so you can clearly see it alongside the image window and verify the Preview option is checked. Zero the Radius setting, then slowly drag the Radius slider towards the right. Watch in the image window as the image begins to sharpen. Concentrate on one critical area, such as the face. Use Command/Ctrl-(plus key) and Command/Ctrl-(minus key) to zoom in and out, and hold the spacebar down while dragging inside the image window to navigate. Once you’ve found the optimal radius, in this instance 10 pixels, click OK.
3 Press Command/Ctrl-0 to inspect the entire image. To compare the sharpened and unsharpened versions, toggle the Sharpen layer’s visibility off and on by clicking its eye icon. Here, her face looks appropriately sharpened, but her hat has been oversharpened. Click on the Add layer mask icon to add a layer mask and click on the layer mask thumbnail to select it. Hide the sharpening by painting over the hat and background area with a soft black brush. Restore any accidentally removed sharpness, such as the mouse’s fur, by painting over it with a soft white brush.
4 Her shirt could use a bit more sharpening, so duplicate the Sharpen layer by dragging it down to the Create new layer icon. This makes everything too sharp, so click on the layer mask icon to highlight it and paint over everything but her shirt with a soft black brush. Even now her shirt is still a bit too sharp, so finish off by lowering the layer opacity to 34%. Compare your final version to the unsharpened original by Option/Alt-clicking on the background layer’s eye icon.