PHOTOSHOP - image cache level setting can make banding more visible in 16 bit/channel images

  • 2
  • Problem
  • Updated 3 years ago
  • (Edited)
input file is a 16 bit tiff file.
i just made it brighter in different editing tools.

it ́s not a question that even 16 bit files can show banding.
the problem is that photoshop, as the most used image application on earth, has some real issues when using the default settings.

the results are quite devasting for photoshop.
in fact every shareware tool i tested did this better.

i don ́t want to imagine how many images i edited where i thought it ́s a tonal problem and i added (unnesessary) noise to the image to get rid of the banding.

this is GRAVE GRAVE issue!!!

the cache level setting should not influence the appearance of an image!

on the left photoshop .. on the right acdsee.

when i set the cache level in photoshop CC preferences to 1 the result looks much smoother and cleaner:

it doesn ́t matter for the problem if i use "exposure" or a "levels" or "curve" adjustment.

i am using:

win7 64bit sp1
intel i7
24gb ram
nvidia 980 gtx (latest drivers)

photoshop is the latest 64 bit CC version.

i also tested this on my notebook with a nvidia 430 graphics card. the result was the same.

the default cache level of "4" showed massive and ugly banding (i did not test higher cache levels).
reducing the cache level to 1 showed much smoother images. all other image editing tools i tested don ́t show this massive banding issues. only photoshop has this problem.

this issue was always labeld an "user error" in the past by adobe employees (advice was : add more noise to avoid banding").

this example clearly shows that it is NOT an user error.
i can reproduce this behavior on my systems and i asked friends who can also reproduce this with photoshop CC.

more info here:

grettings from germany.
Photo of Tanja Schulte

Tanja Schulte

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Posted 3 years ago

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Photo of Chris Cox

Chris Cox

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Official Response
Yes, that is expected because the upper levels of the image pyramid are 8 bit/channel to improve performance. I think there is already a feature request to change the upper levels to 16 bit/channel for 16 bit/channel images (losing performance, but gaining a little bit in quality depending on the exact image and adjustments used).

Yes, the image cache setting can affect the appearance, because of noisy images or subtle changes applied to the image not being preserved in the downsampled levels of the image pyramid.

The true appearance of the image can only be judged at 100% zoom, for many reasons.

And yes, the solution to 99.9% of banding problems is to add a small amount of noise to break up the smooth edges that make the banding (quantization) visible.