The Art of Sharpening
Nearly all digital photos must be artificially sharpened due to the effects of the anti-aliasing filter used in most DSLRs (as explained in What are the Advantages of RAW Format?).
Skillful sharpening is an art form of its own and requires a lot of experience to be performed successfully. Interpreting the results of sharpening is also very subjective. This is why the many sharpening tools and techniques available are constantly being improved.
Sharpening is slightly self-contradictory, as it simultaneously improves the overall look of an image while destroying some fine detail. Allow for the distance your finished image will be viewed from when sharpening – the greater the distance, the more you can sharpen, as fine detail ...