alternative to unsharp mask

Here is a nice alternative to unsharp mask you may want to try, I am a professional graphic designer who has gotten very good results with this technique:

In Photoshop, duplicate your background layer, and change the mode of the new layer to "overlay."

Go to Filter / Other / High Pass, and experiment with different levels of radius until you get the desired effect.

This seems to work as good as unsharp mask, but without all of the edge artifacts - give it a try!

Another thought on unsharp mask - if you have an image with a lot of definition in one channel (blue for example, underwater, or perhaps black on a shipwreck with lots of hard edges), try applying the unsharp mask filter to that channel only. A lot of the sharpening artifacts that appear are the result of saturation in all three color channels - only sharpening one of them can give you crisp edges without oversharpening non-detail areas of subtleties in other colors - especially delicate reds & yellows when you sharpen the blue channel.