The source for this week's "Tip of the Week" is a recent thread on Phil Askey's site, Digital Photography Review. Someone asked about using sharpening to enhance image contrast.

(If you have not visited "DPR," I encourage you to stop by. Phil offers very thorough reviews of new digital cameras. His forums are definitely among my personal favorites, too.)

You can indeed apply sharpening in a way that adds to the perceived contrast in an image. I don't take credit for the technique. I learned about it from Michael Reichmann on his site, The Luminous Landscape. Michael credits Thomas Knoll, the father of Photoshop, with the technique.

The technique is simple. Best of all, the technique works!

You use the Photoshop Unsharp Mask (USM) filter with a low setting for Amount and a high setting for Radius. Good starting points are Amount = 10 or 20 and Radius = 30 to 60.

Why low Amount and high Radius? Those settings increase contrast along the edges of small details. As Michael Reichmann notes, when you increase contrast along small adjacent areas, the shadows and highlights appear broader to our eyes.

Still dubious? Here is an image after basic adjustments. I use a two-stage or three-stage sharpening workflow, which you can read about in my sharpening tutorial, "Put a Fine Edge on Your Sharpening Skills." The image already has received a round of capture sharpening.

The image is reasonably sharp. Capture sharpening is light sharpening. Just enough to restore sharpness lost during digital capture.

The next image shows the result of USM settings Amount = 10 and Radius = 20.

The image is visibly sharper. This is most evident in the texture of the log. Contrast also shows a slight improvement. Don't expect the increase in perceived contrast to be readily apparent. The improvement is subtle, but perceptible.

Let's see what happens when USM settings are Amount = 20 and Radius = 50.

There's even more contrast in the fine details. Especially in the lighter striations along the log.

I often apply a round of Local Contrast Enhancement just before I apply output sharpening. When I sharpen for the Web, I can often get by without a final output sharpening layer. Local Contrast Enhancement suffices. Output sharpening needs to be specific for the output device, however, so expect to apply a light round of output sharpening before sending your image to a printer or film recorder.

Please, go take a look at Michael Reichmann's article, "Local Contrast Enhancement." Thanks to Michael and to Thomas Knoll for a technique that's easy to apply to improve our images!

Cheers!