I was just reading a photography forum where someone asked about sharpening: if you should do it when you convert the raw file, before your print, or both. To answer, I came up with this metaphor: sharpening is like salt in cooking. You should add some while you are cooking (i.e. editing the raw data) to make the flavors of the ingredients blend well and achieve their potential. You should also add some before serving (i.e. printing the file) to heighten the flavor of the dish as a whole, and to target the taste buds of the diners. Too much at either time and you’ll destroy the flavor. Too little, and the dish won’t achieve its potential.