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DPChallenge Forums >> Photography Discussion >> What causes this and how do I prevent it?
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09/29/2011 05:33:52 PM · #1
Hey all,
Thanks in advance for those who can help me.

What causes the "waves" in my PS'd vignettes?
Like in the upper left of See in ripples up there? They really bother me, yet every vignette I add has them. I would like for them to be smooth. I even tried running that layer through NI as a last ditch effort, which didn't work...

Oh, might help if I tell you how I make the vignette, since that is where the problem probably lies...

Basically, new layer, "multiply" blending, then filter>disort>lens correction. Or I'll use the "action" through PS, more control over the shape but it gives worse rippling.

Thanks again...

09/29/2011 05:48:29 PM · #2
That is called colour banding. There are loads of why's and how to fix this problem on the internet...here are a couple.

Say goodbye to gradient banding

How to correct banding
09/29/2011 05:49:30 PM · #3
It looks like a compression banding created by shifting color spaces or saving too often or saving on too low a quality. I have the same issues from time to time when I edit on someone else's computer. One cheat way to get rid of them is to apply them as a selective layer and gaussian blur the snot out of it.

Message edited by author 2011-09-29 17:49:57.
09/29/2011 05:53:15 PM · #4
Banding... Ah ha! thanks! "waves in my vignette" didn't produce much in google ;-)
09/29/2011 06:28:03 PM · #5
It's due to the limited color gamut of the JPG file format, combined with some other limitations of color physics and technology. Instead of the smooth gradation you should get, you get definite steps in the color and see that banding. Sometimes efforts to fix it only make it more pronounced. I have had some success with minimizing it using Topaz Denoise. In particular, the "clean color" adjustment is useful in reducing the effect.

Unlike Brennan, my experience has been that gaussian blur tends to make it more pronounced.

Message edited by author 2011-09-29 18:28:49.
09/29/2011 06:30:25 PM · #6
I get them in RAW (or NEF) though...

I tried Judi's links and it looks better, still some ripples though...
09/29/2011 09:11:09 PM · #7
Looks like something you see from Nikon cameras. Doesn't seem to happen with Canons. ;-)

Topaz has a tendency to bring that out, if you goose it too much.
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