Curve layer with gradation creates banding in image

[brandonish]

Quite often, I will take a image that is a little dark on one side and add a curve layer that increases brightness by a little bit, fill the mask with black, then use gradation tool dragging it from one side to the other to bring up brightenss on that one side.  in doing so, I see banding in the image on this side.  Is there a way to do this without getting banding?  I've tried 16 and 32 bit, which helps alittle, but I'd rather not have banding in the first place and still getting the same increase brightness results I'm looking for. Everyone online talks about how to remove banding, but how to get the same effect without banding is what I'm looking for.
Newest version of photoshop, mac w latest version OS, 50mp file at 8bit.  canon image.  

thx!

[Stephen_A_Marsh]

Masks are 8 bpc, even in 16 bpc mode docs.

Banding may be a display issue, or could also affect the pixels.

Do you have dither active in the gradient tool when creating the graduated mask?

One can also add minor noise to the mask. Standard application of noise affects highlights and shadows, but with a little creativity, one can avoid this in the mask if desired.

[D Fosse]

Actually, masks are document bit depth. If the document is 16, then the mask is 16.

However, selections are always 8 bit depth, and a mask created from a selection will inherit that 8 bit depth.

Generally, if the data are all 16 bit depth, any banding you see on screen is in your display system, not the file.

There used to be a gotcha in that zoom ratios less than 66.67% displayed everything at 8 bit depth, but that has been fixed with this checkbox:

[Stephen_A_Marsh]

@D Fosse - Thanks, I was saying to myself "are you sure that you remembered that correctly"!

[D Fosse]

@Stephen_A_Marsh  If I had a dollar - or Norwegian kroner in this case - every time I did that... 😉

[brandonish]

both of these boxes are checked on my end.

[brandonish]

Yes, dither was on.

[Stephen_A_Marsh]

Yes, dither was on.

By @brandonish

That is subtle, but usually enough to begin with.

So now you need to determine if the banding is affecting the file data, or if this is just a display issue.

One method is to print. Another is to use the info panel and move the mouse over the areas that display banding and to look at the numbers in the info panel to see if the pixel values are matching with the bands.

Adding minor noise to the gradient mask may be required if the banding is in the file itself.

[c.pfaffenbichler]

Could you please post screenshots taken at View > 100% with the pertinent Panels (Toolbar, Layers, Options Bar, …) visible?