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The sky shows banding in Photoshop, but if I press ctrl+shift+A to go into ACR, it's gone.

I assume that no actual pixels are being changed when I enter Adobe Camera Raw, and I'm not touching any buttons/sliders... it's just previewing the image differently on my monitor. The photoshop preview shows banding, the ACR preview doesn't.

However, if I SAVE the image out of photoshop and view it, the banding is there. It's like I can preview a nice band-less sky in ACR, but there's no way to save it.

https://i.imgur.com/0dTd2KD.png

This link sounded exactly like my problem: Why am I seeing banding with Photoshop but not Lightroom? BUT... according to the post, the banding is not really there, it's just a visual artifact due to photoshop take some memory-saving shortcuts.

But, that doesn't sound right to me, because if I save the image and then open it... I still see the banding.

How can I take what I'm seeing in ACR, and save it into my final png/jpg/whatever?

PS: Not sure if it matters but the photo started out life as a 32-bit HDR .psb file, which I then edited and converted to 16-bit.

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  • \$\begingroup\$ What is your monitor's bit depth? To what bit depth are you exporting from PS? \$\endgroup\$
    – Michael C
    Sep 18, 2019 at 20:33
  • \$\begingroup\$ Monitor is just a generic cheap 24-bit, like a standard office monitor. No HDR or huge color gamut or anything. I only tried exporting to an 8-bit JPEG. I didn't think to try, say, a 16-bit TIFF. I could try that for troubleshooting purposes, though it'd be unusable for sharing on the web due to filesize. \$\endgroup\$
    – CreeDorofl
    Sep 19, 2019 at 13:25
  • \$\begingroup\$ Could the preview be a camera-generated JPEG that has been... disbanded or something by the camera firmware? \$\endgroup\$
    – rackandboneman
    Oct 18, 2019 at 22:59
  • \$\begingroup\$ rackandboneman that's an interesting thought, I know RAW files have embedded jpegs... I had the impression though that ACR (and other raw converters) made their own version of an image by de-mosaicing the raw data. Hence ACR's on-screen image is a little different than, say, Capture One or Affinity's. \$\endgroup\$
    – CreeDorofl
    Jan 8, 2020 at 6:04

1 Answer 1

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Banding is due to quantization. If you have a very slow and regular color gradient, and not many available values dues to low bit-depth (8-bit channel), at some point along the gradient adjacent pixels fall together in the next "value slot", so there is a line in your display between the pixels in the previous slot and the pixels in the new slot.. The best way to mitigate it is to add some dithering, in other words, to randomly shake the pixels so that the value change is itself spread over a wider area (because you mix some of the pixels of group X in the pixels of group Y, and vice versa).

I don't know PS but in Gimp this is called "Spread noise":

enter image description here

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  • \$\begingroup\$ yeah I know the cause of banding generally, and how to fix it. What I'm asking specifically is why it's visible in one interface, but not in the other. If I can figure that out, then I don't need to fix it... because it's already "fixed" when viewed in ACR. I want to get that correct-looking ACR version out to the world. \$\endgroup\$
    – CreeDorofl
    Sep 19, 2019 at 13:19

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