The knack of sharpness is the 'unsharp mask' (UM). ALL digital images need a little post processing to improve sharpness. The camera has to take a compromise on it's .jpg images and it's on the soft side.
I use Photoshop Elements 8 for post processing at the moment. The Unsharp Mask option dialog box looks like this.
It has three variables, Amount (A), Radius(R) and Threshold(T).
When you take picture you need to process A COPY!!! as follows.
If you intend to reduce the size of the image for display I have found the following process works quite well.
Set A=75%, R=1 to 1.5 and T=1
Apply to the image.
Resize the image.
Apply UM again, using the same values.
When you save the image there is little point in saving at a quality level greater than '7'. You get a much bigger file for no discernible quality improvement on screen.
Experiment with the ART values to see what suits you.
If you are processing to print the above values do not apply.
A more detailed description is given here http://www.cambridgeincolour.com/tutori ... p-mask.htm