Sharpening Photos and Using Unsharp Mask
Scanning 101 - Sharpening Images
Improve the clarity of scanned images without increasing resolution using unsharp masking. Includes a good overview of the Unsharp Mask paramaters found in Photoshop and other software.
Sharpen Your Photos For Display
From Photoxels: "Most of us upload our pictures or print them the way they were captured by our digital cameras. We read and hear of a post-processing technique called "Sharpening" using "USM" (or "UnSharp Mask") and decide it is just too difficult for us. If you are comfortable using a computer and can load an image into an image editing software... then be prepared for a pleasant surprise!"
"Probably the one area for which lots has been written but little understood is the topic of sharpening. This article attempts to clear up some of the confusion, and offer a few useful options."
Tips for sharpening with the Unsharp Mask filter in Photoshop, Paint Shop Pro, and Fireworks.
"Photographers as a group are pretty hung-up on sharpness. I'm no exception. Unfortunately for some seeking the holy grail of ultimate image sharpness becomes a substitute for creating interesting and worthwhile photographs. Since the concept of sharpness is a means, not an end it itself, I thought it worthwhile to look at what is meant by the word sharpness as used in photography."
Understanding the Digital Unsharp Mask
"The USM dialogue has three sliders -- Amount, Radius, Threshold. They all have an effect, but finding an optimal setting seemed a hit and miss process because one never knew quite what the sliders were actually doing." This article attempts to unravel the mystery.
Unsharp Mask - Scantips.com
A detailed explanation of the Unsharp Mask (USM) filter included in most photo editing and scanning software. Plus tips for using it.