Sharpening

One of the most frequently-used yet most commonly misunderstood post-processing operations has to be "sharpening" -- technically "unsharp masking" or USM for short. The confusion is due to a lack of understanding of the difference between resolution and accutance, and what the parameters (amount, radius, threshold) actually mean. This has led to a proliferation of dumbed-down sharpening tools that get better results than just some random application of USM, but rarely as good as doing the job yourself with some understanding of the process. This is also why non-SLR digicams apply much too much sharpening in-camera.

This lesson will explain these concepts, how unsharp masking affects them (or not), and describe two different purposes for which unsharp masking can be used. After mastering these, you will be able to turn down sharpening to the lowest level in your camera and apply it yourself later, which will make your pictures visibly better and more "professionally finished".