After my recent 'issues' with curves on my 'Dancing Pinkie' post, I have been really watching the effect of any adjustments on highlights. I was just doing another pinkie image, had highlights completely under control, resized the picture for the web, and did one final small USM step. I checked highlights one last time before saving the image, and was surprised to see a significant number of blown highlights!
The processing was all done in NX2. Does this behavior occur whenever you do a USM mask? Is this particular to NX2 or does it occur in PS also?
Randy, this is a common problem with unsharp mask, especially when the settings (for that particular image) become more extreme. What first happens before total saturation is loss of color. One way to mitigate the effects is to reduce radius and amount to minimize the problem. A little more effective in my opinion is to change the image to LAB and work only on the luminance channel. When done you can switch back to RGB. Unsharp mask on the luminance channel minimizes loss of color in the highlights, and thus reduces the apparent saturation.
Last edited by Roger Clark; 03-08-2009 at 09:03 PM.