High Pass sharpening is the absolute best way to sharpen photos. If you plan to print or display your images on the web, sharpening is an essential process to make your pictures look their best.
In the days of yore, a printer would sandwich a negative with a slightly blurred positive and make a quick exposure. He would then complete the exposure with the original negative. This would create a print with sharp edges.
As digital came of age and film scanning became the norm, the Unsharp Tool was created in Photoshop to replicate this process. It was a great tool for scanned film, but unfortunately, users continued to use it as the world moved to pure digital capture.
Today, the best tool for sharpening is the High Pass Filter.
How to use High Pass Sharpening in Photoshop
When I was in college, I was very fortunate to have a professor named Joan Wantanabe teach me this technique. Here is her method:
Duplicate the layer that needs to be sharpened:
Ctrl J – Win
Cmd J – Mac
If there are multiple layers from retouching, merge copy onto a new layer:
Ctrl Alt Shift E – Win
Cmd Alt Shift E – Mac
Note: Sharpening should be the last step after all retouching has been completed
Rename new layer to “High Pass Sharpening” and set layer blendmode to “Soft Light”
Note: the blendmode is in the top left corner of the layers palette.
Crtl Shift U – Win
Cmd Shift U – Mac
Zoom into at least 100% to see the most detail. Select the High Pass Filter:
Menu Filter Other High Pass
On the High Pass Filter, move the slider to the left to make everything gray. Then slowly move the slider to the right until the edges are defined.
Examine image for haloing, noise, and artifacts. If necessary, target specific areas for sharpening instead of the whole image:
Place a black mask over the layer and brush in sharpness with a low opacity brush.
Note: If overall sharpness needs to be increased, duplicate the layer. If overall sharpness needs to be decreased, lower the layer opacity.
The High Pass filter is a really cool tool because sharpness can be brushed into the image. Most of the time I set the filter between 1 and 3 and do little else. The important thing is to look for haloing on the edges and noise in the flat areas. If any dubious items appear, just add a mask and brush away the problems.