I sharpen most of my images at some point and normally use the “Smart Sharpen” filter in Photoshop or, more usually these days, the sharpening offered by Lightroom. Sometimes, however, I want a very dramatic sharpening effect without the haloing you tend to get with the basic sharpening filters. In these cases, here’s a technique I find rather helpful. This involves the Photoshop “High Pass” filter. Here’s the basic process for it.

1. Open your photo in Photoshop and duplicate the background layer.
2. With the duplicate layer selected, chose “Filter/Other/High Pass…”
3. Tweak the “Radius” slider until the preview shows a good representation of the edges of the image. If you move the slider too far right, you will pick up a wider area than you likely want but you will probably want to experiment a bit to determine a suitable setting.
4. Press “OK” to apply the filter. Your duplicate layer should now show a grey representation of the image with darker lines corresponding to all the sharp edges in the image.
5. Change the duplicate layer blend mode to “Overlay” and adjust the layer opacity to give the effect you want.

You can also use “Soft Light”, “Hard Light”, “Vivid Light” or “Linear Light” blend modes. Each has a similar effect but the depth of the effect varies with each mode.

For another variation on this, try replacing “Filter/Other/High Pass..” with “Filter/Stylize/Find Edges” and use blend modes “Darken” or “Multiply”. This is a less tunable effect and rather dramatic but it can be put to good use in some cases.

I used the High Pass method on these images to give them a bit more punch: