Unsharp mask for contrast

For Photoshop users ( and possibly others? ) I've found a more sublte way to alter image contrast is to use the Unsharpmask filter.  After-- Filter>Sharpen>Unsharpmask  set the Amount to around 15% ( not critical); Threshold to 0, then use the Radius slider ( pixels) to now adjust the contrast, say 100 Pixels to kick off with, then alter to suit your image.  Seems to be a finer controlled way of altering the Contrast than the usual Contrast adjustment provided.

There's a tutorial here for LCE (Local Contrast Enhancement) ;)

http://www.luminous-landscape.com/tutorials/contrast-enhancement.shtml 

I agree that the unsharp mask can improve apparent contrast, and is particularly useful for enhancing contrast in architectural details, but needs to be used sparingly. I do not have Photoshop, but use Canon Digital Photo Professional, which also has an unsharp mask control. I assume the following comments will apply to any software with an unsharp mask tool.

As I understand it, the threshold slider controls the digital level differences from pixel to pixel at which the mask effect kicks in. Setting the threshold to zero therefore applies the effect at all digital level differences from zero upwards.  

Having looked at a few shots I have taken, I can see that setting the threshold to zero causes unpleasant artefacts on smoother textures such as foliage and skin. Therefore I generally set the threshold to about half way, unless the shot is so poor it needs savage sharpening.