Something is either wrong with my eyes or with my monitor. I don't see any banding in either image. I see what looks like some oversaturation in the red shirt if that is what you are referring to. Have you tried adjusting your saturation are playing with the HSL sliders?
I was kind of hoping maybe you would ascertain from my writing that I have a level of technical knowledge that puts me well ahead of a solution of "playing with HSL sliders"...lol
Look at where the blue light hits the upper left corner of the forehead. Or the blue light on the white shirt. It should be a smooth gradient but instead it is banded very heavily. I don't understand how it is possible that you could not see this. It is very blatant and obvious.
I am not referring to any oversaturation. I haven't pushed or pulled HSL at all. Pushing or pulling won't do anything. Heck, if I convert to grayscale it will still look like crap because it's banded...
I am referring to the sections of color that should be smooth gradients but are instead blotchy patches. It is where blue light and red light meet and mix.
You can see it very clearly here:
If you can't see it there something is definitely wrong with your eyes or monitor. Maybe your GFX card has some automatic intelligent dithering to it... I dont know... Looking at this on 3 different displays it looks the same on all of them.
Okay I've done a bit more testing.
I sent the RAW CR2 file to a friends computer. When he opened the CR2 in Adobe Camera Raw it indeed down converted to 8 bit (as it did for me) and was very clearly still very badly banded. Changing the workflow options to 16 bit did nothing. After closing everything and reopening, the "Workflow Options" indeed now say 16 bit by default, but it's obviously still 8 bit.
And to reiterate, I can process my RAW CR2 files in Canon Digital Photo Professional 4 and export as TIFFs and they stay 16 bit (and open as such in PS) and they look great with no banding.
And to reiterate, I have my Workflow Options set to sRGB 16 bit depth, but PS is still clearly down converting my RAW files to 8 bit.
I can do color grading in Canon's software, then export as TIFF, open in PS and do everything else, but I would highly prefer to keep my workflow within PS if possible.
The JPEG previews of the RAW CR2 files show none of the highly visible banding that I've seen across multiple computers in Adobe Camera Raw.
I shoot a Canon 6D. My Adobe PS & Camera RAW versions are up to date.
It seems to do this automatic down converting in Lightroom as well.
Also I considered that possibly Photoshop was just displaying my 16 bit images as 8 bit, and maybe the dithering algorithm was screwed up, but it's not. Saving the RAW CR2 (processed in PS w/ACR) as TIFFs just leaves me with a screwed up 8 bit TIFF, while processing RAW CR2 with Canon's software leaves me with a good looking 16 bit TIFF.