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Jonathan Lipkin
Inspiring
April 26, 2018
Question

Gradient Banding in CC 2018

  • April 26, 2018
  • 2 replies
  • 1952 views

I've been experience banding problems in CC 2018, which I have not experienced before in earlier versions of PS. This happens both on my computer in my studio (2013 Mac Pro, NEC 90 series monitor, calibrated with Spectra View) and at the labs where I teach (iMac 16,2).

If i put a gradient into the mask for an adjustment layer, there is noticeable banding/posterization. I tried simply making a selection with the oval marquee, then feathering it - same issue. I also tried a large brush with a soft edge. Same issue.

Images are 16 bit in either Adobe RGB 1998 or Pro Photo

I can see at 100% view, and when I move from one 'line' of the banding to another, I can see the rgb values move from 128 128 128 to 129 129 129, for instance. But it looks TERRIBLE at other magnifications, and quite distracting to the point where I can't evaluate the image

I haven't tried printing yet.

Any thoughts on what is causing this? Is it just a software glitch? Display problem? It is noticeably worse than in earlier versions of PS

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    2 replies

    D Fosse
    Community Expert
    D FosseCommunity Expert
    Community Expert
    April 26, 2018

    A "real" cause for banding is what c.p. mentioned about selections being 8 bit. If such a selection is used for extreme adjustments, you get banding, and this is real banding in the image data. To avoid this, the mask should be made natively and not converted from a selection.

    But from here on in, any banding you see in a 16 bit file is in your display system.

    What you describe as 128 to 129 and so on, is of course the normal banding you will see with an 8 bit display pipeline. There's no way around that except a 10 bit display system. But it should be regular, each value step equally spaced.

    But "other than 100%" - is that above or below? There's a threshold at 66.67%, below which all previews are 8 bit even with a 16 bit file. This is just legacy Photoshop code for performance reasons. Add to that an 8 bit display path with different values after the monitor profile conversion, and you start to get irregular banding. But this is still screen only.

    And then you have one very common problem: calibration tables in the video card. This is again 8 bit, coming on top of everything mentioned above. A true hardware calibrated monitor adjusted in the unit's internal LUT avoids this.

    Finally, the display panel itself, or a bad monitor profile (although monitor profiles have high bit precision). And let's not forget the GPU - with Photoshop in "Normal" or "Advanced" modes, all display color management is executed by OpenGL code in the GPU. A buggy video driver can cause problems here. In "Basic" mode it's handled in the CPU.

    J
    jonathan.lipkin
    Known Participant
    April 27, 2018

    Thanks, CP and DF.  I think you are correct

    I did some looking, and here's what I found: I don't have access to cc 17 at the moment, so can't tell if this is something that existed before, but perhaps it did, and my adjustment layers weren't making such extreme adjustments and it was not noticable.

    It is certainly more noticeable when I create a gradient in layer masks gradients in pixel layers - I didn't know that masks were only 8 bit, so this makes sense.

    When I said other than 100% I was primarily talking about less than that. I work with large images, so to see them on the screen, they are often at less than 33%.

    I don't think it's a monitor issue - I have an NEC 90 series monitor that is said to be 12 bit, and I've calibrated it using spectraview hardware, and PS does support my GPU

    PS, I'd like to mark the answers above as correct, but the forum won't allow me

    c.pfaffenbichler
    Community Expert
    c.pfaffenbichlerCommunity Expert
    Community Expert
    April 26, 2018

    Is Dither checked for the Gradient?

    Does the Brush have Noise?

    Selections are 8bit so when editing Selections themselves instead of Channels (Layer Mask, Alpha Channel, …) 16bit one »throws away« data.

    J
    Jonathan LipkinAuthor
    Inspiring
    April 26, 2018

    Thanks for the reply

    Yes, gradient is checked - I tried unchecking it and it appears to have no effect. Where would I check to see if the brush has noise? I just went into another lab, and tried on a different machine running cc 2017. The banding is very noticeable at magnifications other than 100%,

    I also tried in 8 bit and 32 bit, but the issue is the same

    I'm going to go back to my studio tonight and do some more testing to try to isolate the problem

    It is HUGELY distracting when trying to edit images. Maybe I have to turn off those adjustment layers until the end of the editing process...

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