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Banding/posterisation problem I cannot fix.

Sep 17, 2012 2:18 PM

Tags: #problem #brushes #painting #gradients #banding #posterization

Hi, I am currently experiencing extremely bad banding in photoshop.

 

I've used photoshop to paint for many years (I'm a production artist for children's television) and never had this kind of thing before. It could be a total coincidence, but it seemed only to get like this since I upgraded to Production premium CS6.

 

I've trauled these forums and others and tried everything people have suggested but nothing works. I have the newest Nvidia drivers, the latest photoshop and production suite updates. I've tried turning off GPU acceleration and I've calibrated my monitors and cintiq several times using the Spyder 3 Elite calibration tools. I've created 8bit, 16bit  and 32bit images and the problem persists no matter what. Other stats:

 

Adobe Photoshop Version: 13.0.1 (13.0.1 20120808.r.519 2012/08/08:21:00:00) x64

Operating System: Windows 7 64-bit

Video Card: NVIDIA GeForce GTX 280M

 

Am I missing something here?

 

This is a 16bit image saved as a jpeg, but still a relatively accurate example of what I see in photoshop. In fact it looks better here. It was created using a low opacity brush with hardness set to zero.

 

banding_problem.jpg

I feel like I've tried everything and I'm pulling my hair out. And help would be gratefully appreciated!

 

Thank you,

 

David

 
Replies 1 2 Previous Next
  • Currently Being Moderated
    Sep 17, 2012 2:27 PM   in reply to Davy-Art

    There was a very similar problem a few weeks ago. I'll go try to find the thread.

     
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  • Noel Carboni
    23,514 posts
    Dec 23, 2006
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    Sep 17, 2012 2:30 PM   in reply to Davy-Art

    I'm not sensing any more posterization in that image than would be expected on a 24 bit display.

     

    I assume you're seeing some multiple level jumps between adjacent colors?

     

    Does the following PNG look anything but smooth to you when shown at 100% full size?

     

    sRGB_Gradient.png

     

    How about this one?

     

    ProPhoto_Gradient.png

     

    Do you normally work in 16 bits/channel or 8?

     

    -Noel

     
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  • Currently Being Moderated
    Sep 17, 2012 2:30 PM   in reply to conroy

    Have a look at the linked thread. That problem was in a mask but I think you may find the thread relevant.

     

    Layer masks posterized

     
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  • Currently Being Moderated
    Sep 18, 2012 7:32 AM   in reply to Davy-Art

    Davy, have you made progress? Did you understand the relevance of the thread which I linked? That person had banding in a mask because they painted the mask in the same way as you created your image - overlapping low-opacity soft brush strokes.

     

    If your display is 8-bit per channel, a 16-bit per channel image will appear to have banding that's similar to an 8-bit per channel image. Banding is highly evident in dark smooth gradients because our eyes are increasingly sensitive to a given step in brightness as the brightness decreases. Dither helps reduce a banded appearance by adding very low-level noise to break up regions of solid colour.

     

    Photoshop will apply dither by default when converting images from 16-bit to 8-bit with Image > Mode > 8 Bits/Channel. But it will simply truncate values to 8-bit and not apply dither when saving a 16-bit image to JPEG which only supports 8 bits per channel.

     

    A 10-bit per channel output graphics card and monitor is required to make banding imperceptible in dark smooth gradients in 16-bit images.

     
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  • Currently Being Moderated
    Sep 18, 2012 7:35 AM   in reply to conroy

    Added info to previous post: 16-bit values are truncated to 8-bit with no dither when saving to JPEG.

     
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  • Currently Being Moderated
    Sep 18, 2012 10:23 AM   in reply to Davy-Art

    What's posterization?

    A reduction of the available number of levels in a given level range.

    Less than 256 in the range of 0 to 255.

    Less than 101 in the range of 10 to 110 of 255.

     

    What's banding?

    The appearance of posterization, either for inherent posterization or

    for an image which contains all levels in a given range.

     

    The next image shows the histogram for a diagonal selection in the

    original image in aRGB = AdobeRGB(1998).

     

    Result: no posterization.

     

     

    banding-aRGB.png

     

    The next image shows the histogram for a similar selection after converting

    the image to sRGB. There are small gaps in the histogram, but that's not

    posterization.

     

    banding-sRGB.png

     

    Whether banding is visible or disturbing (for images without posterization)

    depends not only on the monitor and the graphics card including calibration,

    but also on the viewer.

     

    "Entire Image" means here: image without text layer, but only the selected

    part.

     

    Best regards  --Gernot Hoffmann

     
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  • Currently Being Moderated
    Sep 18, 2012 10:39 AM   in reply to Davy-Art

    I wanted to say that the original image in aRGB is not posterized.

    Assuming that your monitor is near to sRGB (not to aRGB, 10 bpc)

    there will be some losses of levels.

     

    If an image causes the appearance of unintentional posterization

    (banding) for some observers, maybe not for all observers, then

    - in my humble opinion - the design should be modified, until

    observers with average monitors have a pleasant appearance.

     

    Best regards --Gernot Hoffmann

     
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  • Noel Carboni
    23,514 posts
    Dec 23, 2006
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    Sep 18, 2012 10:39 AM   in reply to Davy-Art

    It occurs to me that we are struggling with terminology to such an extent that Davy-Art is not able to communicate what he's really seeing to those who aren't sitting there with him.

     

    The image he provided is clearly painted with overlapping brush strokes in such a way that there are (fuzzy) areas of similar color.

     

    We haven't even established that he's seeing posterization yet.

     

    I've prepared another image, using your colors, but with an absolutely smooth gradient (as smooth as can be with 8 bits/channel data).

     

    Do you see posterization in this?

     

    GreenGradient.png

     

    -Noel

     
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  • Currently Being Moderated
    Sep 18, 2012 10:58 AM   in reply to Davy-Art

    Davy-Art wrote:

     

    Hi conroy, I did read that thread but I'm not seeing much of a difference at all.

     

     

    I tried to explain that banding will be apparent with an 8-bit per channel output graphics card and monitor when viewing a 16-bit file without dithering the image values to 8-bit. It will look as banded as a noise-free 8-bit image.

     

     

    And it wouldn't be feasible to keep converting back and forth for all my brushstrokes anyway.

     

    The idea is not that you "keep converting back and forth for all my brushstrokes". You can work in 16-bit then finally dither to 8-bit to export an 8-bit image.

     

    There are some old filters in Photoshop that only work in 8-bit, but image adjustments and painting are better done in 16-bit. 16-bit adjustments are far less likely than 8-bit to introduce posterization. Do you use Mixer Brush? In 8-bit mode there can be terrible colour shifts which are avoided in 16-bit mode.

     
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  • Currently Being Moderated
    Sep 18, 2012 11:27 AM   in reply to Noel Carboni

    Davy described seeing even worse banding/posterization while working on the 16-bit image than in the distinctly banded JPEG (8-bits, of course) he posted.

     

    Here's the JPEG with boosted exposure to make the banding extremely obvious.

     

    Screen-shot-2012-09-18-at-19.16.09.png

     
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  • Noel Carboni
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    Sep 18, 2012 12:02 PM   in reply to conroy

    That's nothing more than the normal, typical limits of using 8 bits/channel color as far as I can see.  On a well-calibrated high quality display system 256 luminance levels of a given color is *just* noticeable, but isn't at all distracting.

     

    That Davy has said something has changed, and has also stated the following, however, lead me to wonder whether something more subtle is happening here, making me want to ask more questions:

    Looking at the two images you provided I am seeing a very very slight banding yes, but nothing like the one I created.

     

    I'm wondering maybe whether his display profile is faulty somehow and Photoshop's GPU-resident color-management logic is making bad-looking results because of it.  Note that we have already seen where ProPhoto RGB documents can be shown to have colored bands with Photoshop CS5 and CS6.

     

    Davy, if you go into Photoshop and visit your Edit - Preferences - Performance dialog, press the [Advanced Settings] button, and choose Basic mode.  OK out, then close and restart Photoshop.  Do you still see the same issues?  I ask you to try this because in Basic mode Photoshop does its display color management in a whole different way (i.e., in the CPU) than in Normal or Advanced modes.

     

    -Noel

     
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  • Currently Being Moderated
    Sep 18, 2012 12:42 PM   in reply to Noel Carboni

    Noel Carboni wrote:

     

    That's nothing more than the normal, typical limits of using 8 bits/channel color as far as I can see.  On a well-calibrated high quality display system 256 luminance levels of a given color is *just* noticeable, but isn't at all distracting.

     

    Not only is Davy's image using only about 100 luminance levels, these levels are low, right where our vision is very sensitive to quantization steps.

     
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  • Currently Being Moderated
    Sep 18, 2012 2:31 PM   in reply to Davy-Art

    I can make out rings in Noel's image, too, but your vision may be exceptionally sensitive to the steps in low-level brightness. Nevertheless, I think a software problem is likely to be largely responsible for your finding the rings to be very obvious.

     

    Have you compared displaying your particular problem document at home and at work?

     

    If you feel that the problem appeared only at home after installing CS6, then there's a strong probability that there's a profiles problem in your home setup.

     

    You've posted a JPEG saved from Photoshop, but it might provide a clue if you also post a screenshot of the original document being displayed in Photoshop. I think it would greatly help if you additionally provide (e.g. in Dropbox) the PSD file or one created as an example of the problem.

     
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  • Currently Being Moderated
    Sep 19, 2012 6:25 AM   in reply to Davy-Art

    Davy-Art wrote:

     

    It's sounding to me like maybe it's normal that there is banding in images created in photoshop, however not normal for me to be able to see it to the extent that I am.

     

     

    Yes, that sounds correct to me.

     

    Your PSD is only 8-bit, but I see nothing unusual in that file, so if that one looks very obviously banded to you then I expect there is a problem with your system setup.

     

    There is something to be aware of when working in 16-bit mode. If "Cache Levels" in Preferences > Performance is geater than 1 (default is 4, I believe), when the document window zoom is less than about 64%, the calculation of the displayed image is performed with less precision and that can introduce displayed banding which is not really in the document.

     

    I want to show you a distinct benefit of working in 16-bit mode. The following screenshots show 10 applications of a 50% opaque soft brush.

     

    First, done in 8-bit - the banding is horrendous. Second image done in 16-bit (but an 8-bit screenshot, of course) - no obvious banding. Third image is the 16-bit converted to 8-bit by Image > Mode - still looks smooth.

     

    8-bit.png

     

    16-bit.png

     

    16-bit-to-8-bit.png

     
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  • Noel Carboni
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    Sep 19, 2012 4:52 PM   in reply to Davy-Art

    Davy-Art wrote:

     


    Also, I've tried switching to basic mode and I've even tried turning the graphics processor funtion off all together and it still appear to be the same.

     

    Doesn't sound like a Photoshop issue then...

     

    Are you seeing it in other apps - e.g., a color-managed browser such as Firefox or Safari?

     

    What happens if you temporarily associate the sRGB IEC61966-2.1 color profile with your monitor?

     

    -Noel

     
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  • Currently Being Moderated
    Sep 19, 2012 5:13 PM   in reply to Davy-Art

    This will sound too obvious, but one very basic thing to check is that, in Displays Preferences, your monitor is set to show Millions of colors, not Thousands and not 256.

     

    Picture 37.png

     
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  • Noel Carboni
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    Sep 20, 2012 10:13 AM   in reply to Davy-Art

    Davy-Art wrote:

     


    So it sounds like there is no way to solve this thing then. I'm very close to nukeing the computer (again) and starting from stratch just to see if that helps, since nothing else does.

     

    Are you ignoring my questions and suggestions on purpose?

     

    -Noel

     
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  • Noel Carboni
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    Sep 20, 2012 12:36 PM   in reply to Davy-Art

    At this point I'm starting to wonder whether you have a hardware problem with your video card itself.  I admit to having lost track of the specifics:

     

    • Are you seeing it on all monitors?
    • If not, what hardware is common to all the places you see it?

     

    -Noel

     
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  • Currently Being Moderated
    Sep 20, 2012 1:15 PM   in reply to Davy-Art

    Hi, Davy_Art,

     

    I just looked at the psd and I see very slight variations in tonality which could be construed as banding but given they are brush strokes, I would not conclude here and now on my screen it is banding of the type caused by jumps in digital levels.

     

    I have experienced these jumps myself, especially when digitizing a negative which contained a sky reflection with very subtle changes in values. The banding was obvious and uncontrollable which makes the analog print unique as I cannot print the digital without the banding!

     

    I am seeing this using Win7 64, CS6 on a Dell u2412, ATi 7750 video card.

     
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  • Noel Carboni
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    Sep 20, 2012 7:40 PM   in reply to Davy-Art

    Is the laptop under warranty?

     

    Without being able to see precisely what you're seeing it's impossible to tell whether you're seeing egregious banding or just the normal amount, but happen to be particularly sensitive to it in these colors.  The very first gradient I posted up above should look really, really smooth.  I can spot the level changes, but only *just barely* and only if I'm looking for them.

     

    I have a gamma calibration check chart...  If you view the first chart at 100% full size (click on it), does it look like the small one below to you?

     

    2.20 Gamma Calibration.png

     

    WhatItShouldLookLike.png

     

    -Noel

     
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  • Noel Carboni
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    Sep 21, 2012 5:15 PM   in reply to Davy-Art

    Assuming you looked at the first image at 100% original size, then it not looking like the bottom one says your monitor is egregiously out of calibration.

     

    Here's a photo of how it looks on a well-calibrated monitor:

     

    Calibrated.jpg

     

    -Noel

     
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  • Noel Carboni
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    Sep 22, 2012 6:32 AM   in reply to Davy-Art

    Could be a totally bogus calibration, where your calibrator hardware has somehow failed?  That test chart really does need to look right (as displayed through a color-managed application), or you're just not properly calibrated and profiled.

     

    -Noel

     
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  • Currently Being Moderated
    Mar 13, 2013 11:38 PM   in reply to Davy-Art

    did a new computer fix it for you?
    getting a new computer didnt budge the problem for me :/

     
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