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Stan Patz
Currently Being Moderated

Real streaks or screen artifacts?

Jun 22, 2013 11:37 AM

Tags: #layers #cs6 #gradient_feather #streaks #screen_artifacts

I am using CS6, but this applies to all past versions.

 

When I use a feathered Brush (or Gradient tool, or Eraser, etc.) on a toned background, upon close inspection I see streaks or posterization. The flaws in the gradient appear to persist at any screen magnification. The question is, are these marks real or screen artifacts?

 

Even though this is a good theoretical question, I am working on a full page ad for magazine reproduction. The art director asked for a full bleed so about 60% of the page will be something I am creating. Will the subtle marks I now see on this background appear in print - magazine repro, probably 133/line screen?

 

(And, no, I do not want to add noise to the background because it will not match the grainlessness of my digital image.)

 

Stan Patz

 
Replies
  • Currently Being Moderated
    Jun 22, 2013 12:31 PM   in reply to Stan Patz

    Can you attach, or link to the Image, so that others can see what you are seeing?

     

    Good luck,

     

    Hunt

     
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  • Trevor Dennis
    5,905 posts
    May 24, 2010
    Currently Being Moderated
    Jun 22, 2013 4:48 PM   in reply to Stan Patz

    Stan, I have looked and looked and can see no problems.  Sounds like your setup - video driver perhaps?

     

    [EDIT]  What bit depth are you working in?  That's a pretty fine gradient and could well tend towards some posturization at 8 bit.  It's nice work, and I'd say you know what you are doing, and would know a wee bit of noise can hide those sort of artefacts. 

     
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  • Currently Being Moderated
    Jun 22, 2013 5:54 PM   in reply to Stan Patz

    Stan,

     

    Sorry, but I can see the streaks on my monitor in two of your sample pictures.

     

    In the close-up pic, I see shades of dark gray and purple streaks running top to bottom. I don't see anything In the photo next to it. In your third picture, I see shades of white and grays running left to right. Is that what you see???

     

    I did not download the pic's and look at them in Photoshop or Lightroom. I browsed them using a Google Chrome Browser. My screen resolution is 1920x1080. Oh, I don't see streaks on my photos when using a gradient tool.

     

    Phil

     
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  • Trevor Dennis
    5,905 posts
    May 24, 2010
    Currently Being Moderated
    Jun 22, 2013 10:19 PM   in reply to Stan Patz

    Stan the banding is very evident on my screen in your post #4.  Running the eye droper down it, I am seeing definitely stepping, and very subtle colour shifts.  Note I can only see those by the numbers, and not on the screen.  If I apply Gaussian blur at strength 50, I get a very smooth and even change of the numbers, with zero colour shift.  I'm using a Dell 2709W with Huey Pro.  The banding looks worse on my second monitor - A Philips 19inch 4:3 (also controlled by the Huey Pro)

     

    I always say that the numbers don't lie, regardless of what you think you can see.

     
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