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LightMachine local contrast

Posted: Sat Jan 08, 2005 2:24 am
by madde001

I really like LM. I've been playing with the local contrast enhancement. It has an effect that is subjectively a lot like sharpening. Could you give some insight into how local contrast enhancement might be similar/different from sharpening, and when to use one, or the other, or both?


Posted: Sat Jan 08, 2005 7:53 am
by HaraldHeim
Local Contrast is basically sharpening with a much larger radius. LightMachine's implementation of Local Contrast has a few specialities. The algorithm is similar to that of FocalBlade.

Posted: Tue Feb 22, 2005 5:01 pm
by HaraldHeim
After reviewing this forum I noticed that I didn't answer your question completely, because I wrote it in a hurry when I was about to go on a trip.

Here is what I added to the LightMachine manual about Local Contrast and should answer your question:

"Local Contrast enhancement is basically sharpening with a high radius. Sharpening is usually applied with a low radius of 0.1 to max. 4.0 pixel whereas a radius of 8 to more than 1000 pixel is used for a local contrast adjustment. A local contrast adjustment increases the contrast in an image whereas sharpening makes image edges more recognizable. Local contrast enhancement and sharpening can be used in combination and don't exclude each other. However, I would only use a Local Contrast adjustment if all other contrast adjustments fail like it is the case for extremely brightened up image areas."