On Wed, 30 Jun 2004 16:44:56 GMT, "James D"
wrote:
Just one more question, why does Adobe call it "UNsharp" mask when it appears to sharpen the image like the sharpen filter?
It's from darkroom practice. Originally, to sharpen an image you would lay a second neg, slightly misregistered over the top of the original. Hence the mask bit. And because it "unsharpens" the image by making the edges fuzzy, it is an unsharp mask. Incidentally, never, ever, use sharpen to sharpen an image - you'll destroy it. (Sharpen has one or two uses, but sharpening an image really isn't one of them <g>).
USM works by putting a halo around the image - it puts a dark halo around the edges of darker objects and a light halo around lighter ones where the objects meet. So, as a starting point try either using LAB mode and the ,luminosity channel, or sharpening on separate channels. Separate channels is best as then you can avoid sharpening channels where there is a lot of noise.
--
Hecate
veni, vidi, reliqui