Help with radius scales for sharpening in LR, PSP

paddler4

I do my editing in Lightroom 2 and Paint Shop Pro X2. I am confused by the sharpening settings in the two. Both have a radius setting, which runs from 0.5 to 3.0 in increments of 0.1 in LR2 and from 0 to 100 in increments of 1 in PSP (if you use the slider, although it will allow typing in non-integer values). Most of what is on the web refers to both of these scales as the number of pixels affected on either side of the sharpened edge. However, it does not make a lot of sense for one program to have 33 times the range, and I can't understand how the software can sharpen by changing 1/10 of a pixel, since pixels (or at least the colored subpixels) are the basic unit of the display.

Can anyone explain what these scale really are, and if they are really pixels, how one can change a tenth of a pixel?

Thanks very much.

arodney

The settings in the two have no relationship. The sharpening settings in LR are for capture sharpening. They are based on editing in a linear encoded color space which LR uses for all processing. Its not anything like Photoshop or other products even though they may share sliders with similar names. Now with a Radius slider, one usually is defining pixels. But the other sliders like threshold are applying different degrees of effect due to the different engines. The real trick is to use the Option key to turn on and off the masking while altering the sliders. That's way cool and useful in this visually based sharpening (only capture sharpening)*

*http://www.creativepro.com/story/feature/20357.html

This should help:

http://lightroom-news.com/2007/08/02/lightroom-tutorial-podcast-36-adobe-raw-sharpening-controls/