Banding problems… why?

S
Posted By
Smurfy
Mar 13, 2009
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367
Replies
4
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Closed
A file I’m working on has heavy banding when greys fade to black. Even applying a blur on this banding will not fix it (oddly enough, it seems to make it worse).

It’s a straight up, high-res, 8-bit per channel RGB file. Nothing unusual about the gradient. Not sure what circumstances are causing the banding here, but it’s there, in this file. And the more we turn up the brightness, the more obvious it becomes.

Anyone have any clue what I can do about this? I gotta send this off to a printer, for a 10’x10′ booth display, and I’m afraid the banding will come through.

Using CS4.

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J
jaSPAMc
Mar 13, 2009
"Adam" found these unused words:

A file I’m working on has heavy banding when greys fade to black. Even applying a blur on this banding will not fix it (oddly enough, it seems to make it worse).

It’s a straight up, high-res, 8-bit per channel RGB file. Nothing unusual about the gradient. Not sure what circumstances are causing the banding here, but it’s there, in this file. And the more we turn up the brightness, the more obvious it becomes.

Anyone have any clue what I can do about this? I gotta send this off to a printer, for a 10’x10′ booth display, and I’m afraid the banding will come through.

Using CS4.
Might try a low setting of grain. If it’s ‘pure grey’ then there’s nothing to break up the perception of the step. Nature isn’t ‘pure’ so we get smoother ‘steps’ in 8 bit.
G
gowanoh
Mar 13, 2009
Without having any idea what you are seeing:
Some processing steps/filters add banding that is more prominent in some images than others.
If the image originated as a jpeg and has banding I don’t what can be done about it.
A freshly opened raw image should not have banding, barring some major camera problem, so the banding has to have been added somewhere in your processing steps.
GJ
Geoff J
Mar 14, 2009
"Adam" wrote in message…
A file I’m working on has heavy banding when greys fade to black. Even applying a blur on this banding will not fix it (oddly enough, it seems to make it worse).

It’s a straight up, high-res, 8-bit per channel RGB file. Nothing unusual about the gradient. Not sure what circumstances are causing the banding here, but it’s there, in this file. And the more we turn up the brightness, the more obvious it becomes.

Anyone have any clue what I can do about this? I gotta send this off to a printer, for a 10’x10′ booth display, and I’m afraid the banding will come through.

Using CS4.

Are you sure it is not your monitor that is wrong? The reason I ask is that a few weeks ago I was advising someone who reported a similar problem that turned out to be caused by his display somehow getting changed from 32 bit to 16 bit. Try looking at others images on your screen or your file on another computer, if only to rule out the problem being with your display.


Geoff J.
MR
Mike Russell
Mar 14, 2009
On Fri, 13 Mar 2009 08:53:51 -0400, Adam wrote:
Good advice from others. I would add a couple of points by way of clarification.

A file I’m working on has heavy banding when greys fade to black. Even applying a blur on this banding will not fix it (oddly enough, it seems to make it worse).

Yes – banding is a low frequency phenomenon and is not easily removed by blurring.

It’s a straight up, high-res, 8-bit per channel RGB file. Nothing unusual about the gradient. Not sure what circumstances are causing the banding here, but it’s there, in this file. And the more we turn up the brightness, the more obvious it becomes.

Is it a photograph or an artificially generated image? Can you see the banding in one channel, or is it in all the channels? Making the image artificially brighter is not necessarily an indication of what will happen in print.

Anyone have any clue what I can do about this? I gotta send this off to a printer, for a 10’x10′ booth display, and I’m afraid the banding will come through.

As a general rule, remove banding by adding noise to the channel that has the problem, perhaps using a mask to restrict the noise to the shadows, though this is not generally necessary because the noise will affect mainly the shadows. After that, it may be appropriate to blur. —
Mike Russell – http://www.curvemeister.com

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