Photoshop color Banding help

There's one pretty simple way to find out: Find a good, fine-grained photograph shot at low ISO (not a jpeg!), one that also has some of these smooth gradients.

If there's banding there too, something's wrong. But there most likely won't be, because there's just enough noise. Yes, the common advice is to add noise, and then people stall because they imagine tons of it is needed. But it takes very little, so little that you don't see it. All you see is the banding goes away.

You don't say which LG monitor, but if this bothers you, get a 10 bit capable monitor, one that also lets you hardware calibrate directly to the internal high-bit LUT. You also need a 10-bit capable video card to go with it, and you absolutely need a calibrator to make sure your monitor profiles are good.

One last thing to add, this is the selection I showed because it is the selection that I worked on. Any blues that do not represent the banding occurring is because I did not blend any other colors there, so no, it's also not an extreme. This is a selection yes, but a selection of where I worked. If it's extreme, then it should show the severity of this issue.

If you're certain this changed after the Windows Update, the explanation has to be that you got a bad display profile as part of that update. That's a fairly common problem.

In a 16 bit file, any banding you see on screen is in your display system. That's the whole path from display profile to GPU to the panel itself. Don't forget, your display pipeline is consistently 8 bit, even with a 16 bit file.

There are only two possible exceptions to this:

• One is that you're viewing at less than 66.67% zoom. At these ratios all Photoshop previews are 8 bit. This is just legacy code for performance reasons.
• The other is that you have used a selection as basis for an extreme tonal adjustment. While masks follow the bit depth of the document, selections are always 8 bit.

I don't see any banding beyond the expected in your examples. You have this gradient in the face tones - that's only 15 or so discrete display values:

Now, as for a bad display profile, the fix for that is to use a calibrator to make a new one. If you don't have one, use sRGB IEC61966-2.1 until you do. It won't be entirely accurate, but better than a profile that is broken. Change the profile in the Windows Color Management > Devices tab. Relaunch Photoshop when done, it needs to load the profile at application startup:

One more thing:

I have an LG IPS monitor that reflects color as accurately to printed material as possible

That's a pretty meaningless statement unless you specifically calibrate the monitor to do so. No monitor ever made does that out of the box - it simply can't. You need to set the parameters for white point and black point so that it corresponds to the paper and ink. If you happen to get a good match to your own desktop printer, that's purely by accident, and you can probably get a better match.

It should be said that in some cases calibrating the monitor can introduce banding on its own. This happens if the adjustments are done in the video card, again in 8-bit depth. In high-end monitors these adjustments are done directly to the monitor's internal LUT, in high bit depth, and that avoids this particular problem. But it can still be minimized with video card calibration tables, by doing as much as possible in the monitor's OSD controls prior to running the calibration.

And to be clear - the monitor profile is not the same as calibration. The profile is a description of the monitor's response in its calibrated state, used only by color managed software. The profile has a much higher precision level than the calibration.

And finally: To break up banding in synthetic gradients, add a tiny bit of noise. It doesn't take much. A photograph usually has just enough so you don't see banding.