I don't know that there is any 'rule of thumb', and radius depends on the image resolution. I would start here:
http://www.ledet.com/margulis/Sharpen.pdf and continue on to here: <<http://members.ozemail.com.au/~binaryfx/PSTV_links.html#S>> Maris Mike Johnston wrote: >> are there some recommended starting >> values for the unsharp mask for amount, radius and threshold? > > > Darned if I know. I think there are actually plug-ins that help > calculate this for you. Being an incorrigible empiricist, I just try > different things and then look at the results. <g> > > --Mike
