banding in my gradients

Discussion in 'Beyond the Basics' started by kkamin, Apr 1, 2010.

  1. kkamin

    kkamin TPF Noob!

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    [​IMG]

    On my monitor, I can see banding in the radial gradient on the background. I created this in Photoshop. Why is this happening? Is there anyway to avoid this?
     
  2. Chris of Arabia

    Chris of Arabia Herding cats since 1988... Supporting Member

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    Gradients are something that Photoshop doesn't really excel at from what I can gather. It might be worth trying putting a 50% grey layer over the top of it, then apply a Gaussian monochrome blur over the top of it with a high'ish radius applied to it. Then just vary the opacity of that layer till you get the effect you're after.
     
  3. Garbz

    Garbz No longer a newbie, moving up!

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    Two reasons usually cause this. Editing in 8bit rather than 16bit mode in photoshop, and colour space conversion errors. How did you go about editing?
     
  4. kkamin

    kkamin TPF Noob!

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    I edited in 8-bit srgb. If I edited in 16-bit, wouldn't this happen when I convert from 16-bit to 8-bit anyways? Thanks, Garbz.
     
  5. Garbz

    Garbz No longer a newbie, moving up!

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    No. All colours in the sRGB gamut can be displayed in 8bits. So the conversion from 16bit to 8bit would not give any noticeable difference.

    If you open an 8bit image you have limited data to work with. So you bump up the contrast and photoshop starts to make educated guesses. The more you work the image the nastier these guesses get. The first places these guesses become obvious is in shadows and gradients.

    If you start with a 12bit RAW from your camera, open it in CameraRAW as a 16bit file, then you have a lot more information to begin with. To put this in perspective: A 12bit file represents 4096 possible values. An 8bit file only 256. So you get a factor 16 increase in data that makes your educated guesses more accurate.
     
  6. kkamin

    kkamin TPF Noob!

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    Sorry I'm a little confused.

    So it would be better to work in 16-bit srgb and then when finished convert to 8-bit for output?
     
  7. Chris of Arabia

    Chris of Arabia Herding cats since 1988... Supporting Member

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    Correct
     
  8. Dwig

    Dwig TPF Noob!

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    Yes, but this will not always eliminate banding.

    If banding persists in the reduced 8-bit output file you may need to add a little noise to the gradient while in 16-bit mode. This will dither the boundary between the two tones, blues in the original example, making it much less noticeable if noticeable at all.
     
  9. Dmitri

    Dmitri No longer a newbie, moving up!

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    Be aware that 16 bit PSD files are quite a bit larger than 8 bit, so unless it's a photo you plan to do something with - save your HD space.

    That said I seem to recall seeing a tutorial once about using curves to get rid of banding. I can't seem to find it but maybe it sparks someone else's memory?
     
  10. KmH

    KmH Helping photographers learn to fish Supporting Member

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    With memory running about $100 per TB, image file size is becoming less and less of a concern.
     
  11. Dominantly

    Dominantly TPF Noob!

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    I think it just has something to do with the gradient you are using/ the way you are creating it.
     
  12. kkamin

    kkamin TPF Noob!

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    thanks
     

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