Excerpt from The Adobe Photoshop CC Book for Digital Photographers
High Pass sharpening is sometimes called “extreme sharpening,” and that’s really a good description of what it is. Here, I’m going to show you how to apply it and how to control it afterward.
Step One: Open a photo that needs some extreme sharpening, like this photo taken in Prague. Duplicate the Background layer, as seen here, by pressing Command-J (PC: Ctrl-J).
Step Two: Go under the Filter menu, under Other, and choose High Pass. You use this filter to accentuate the edges in the photo, and making those edges stand out can really give the impression of mega-sharpening. I start by dragging the Radius slider all the way to the left (everything turns gray onscreen), then I drag it over to the right. For non-HDR images, I don’t drag it all that far—I just drag until I see the edges of objects in the photos appear clearly, and then I stop. The farther you drag, the more intense the sharpening will be, but if you drag too far, you start to get these huge glows and the effect starts to fall apart, so don’t get carried away. Now, click OK to apply the sharpening.
Step Three: In the Layers panel, change the layer blend mode of this layer from Normal to Hard Light. This removes the gray color from the layer, but leaves the edges accentuated, making the entire photo appear much sharper (as seen here). If the sharpening seems too intense, you can control the amount of the effect by lowering the layer’s Opacity in the Layers panel, or try changing the blend mode to Overlay (which makes the sharpening less intense) or Soft Light (even more so).
Step Four: If you want even more sharpening, duplicate the High Pass layer to double-up the sharpening. If that’s too much, lower the Opacity of the top layer. One problem with High Pass sharpening is that you might get a glow along some edges. The trick to getting rid of that is to: (1) press Command-E (PC: Ctrl-E) to merge the two High Pass layers, (2) click the Add Layer Mask button at the bottom of the panel, (3) get the Brush tool (B), and with a small, soft-edged brush and your Foreground color set to black, (4) paint right along the edge, revealing the original, unsharpened edge with no glow.
Learn more about sharpening in Photoshop in The Adobe Photoshop CC Book for Digital Photographers. Also, be sure to check out all the great online Photoshop courses available at KelbyOne.