Sharpening without an Aura

[Ed_L]

Patrick,

I have two questions (and that's before I tried the technique) .
You suggest changing from 8 bit to 16 bit mode so as not to lose histogram quality. I've always been under the impression that changing from 8 bit to 16 bit mode does nothing for the quality of the image. But you didn't say it did. You said it has to do with quality of the histogram. I'd like to hear your thoughts on this because I wouldn't be interested in what the histogram looks like if it doesn't affect the image. The other question is that you recommend using 1/200 X resolution as a starting point for the high pass setting. Your example shows a 1.5 pixel radius. Isn't that 1/100 of the (150) resolution, and wouldn't 1/200 be .75 pixel radius?

Thanks,
Ed

View here

[CJ Swartz]

Well, I tried it, and it certainly works. I tried it against the technique of using Unsharp Mask in Lab mode on the Lightness channel, and think the Lab method might allow for more sharpness -- but it's handy having another technique for the tool chest. At first, I was bothered by not being able to see the amount of sharpness gained by Patrick's method until the procedure was finished, but then I just set the blending mode between the background layer and copy to Hard Light before I started and I could better gauge the level of sharpness as I was working.

[john_opitz]

What I do for sharpening is to look at your channels. I don't use historgrams because I want good looking images,not good looking historgrams.To see what you want sharpened. For faces(headshots) I only sharpen the red channel(RGB mode) or the cyan and black(CMYK) and always fading the effect to luminosity. You can hammer the sharpening effect when doing it with the red(RGB),cyan and black(CMYK) channel only, without halos showing. For 8/16 bit images. I don't find a difference working in either. On the historgrams., it shows a difference. But the final product(image,print) it doesn't.

Here's some links to Dan's(The Man) Margulis articles on this subject.


sharpening



8 bit vs. 16 bit

[john_opitz]

Sounds like I'm only a Dan Margulis fan. Katrin Eismann is also good. She has an action for sharpening as well, for P.S. people who don't want to get heavy into the sharpening thing.

Katrin Eismann site

It's where she has her images for her book. smart_sharpen.atn.

The book even shows you how to make(script) the action(Chapter 8,p.191). She uses the blue channel. You can even make one for the green if you want. I don't use the blue channel for sharpening. Too(most of the time) much noise and detail, you don't want to cause unwanted halos in faces. Nevertheless it works because it's not sharpening noise,anything unwanted. It's more of a find edges filter. It finds the edges only, finds noise and blurs it. There's times I use it...Depends on the image.... when I get lazy...Or when I have a hot date... I mean, to get images out fast. It works like the lifestyle I live. Fast cars,fast food,fast women...I mean images..images.

[Doug Nelson]

Sounds like as good a time as any to chime in with Bruce Fraser's two-part article on sharpening here and here.