Last night I was working on an image that had a lot of small imperfections in flat areas that had been emphasized by Helicon stacking. In Photoshop CC, I created a duplicate layer, and applied the dust and scratches filter.
Oops. Contouring.
I scratched my head and tried a median filter. Same damn thing.
Thinking it could be the display subsystem, I wrote out the file and looked at in in Lightroom. Still there.
Is it possible that the Noise filters are only 8-bits? Indeed it is.
The most recent document I can find on the Adobe web site says the following:
The following filters support 16-bit/channel and 32-bit/channel documents:
- All Blur filters (except for Lens Blur and Smart Blur)
- All Distort filters
- The Noise > Add Noise filter
- All Pixelate filters
- All Render filters (except for Lighting Effects)
- All Sharpen filters (except for Sharpen Edges)
- The following filters under Filter > Stylize:
- Diffuse
- Emboss
- Trace Contour
- All Video filters
- All filters under Filter > Other
I’ll have to use less-effective 16-bit filters from now on. That’s too bad. I’m also concerned that I may have missed banding in files that I have previously edited. I’ll have to do some looking.
I wonder when Adobe is going to make all the filters 16-bit?
I have known that some of the filters in PS were 8 bit but I thought that they were all ghosted in Photoshop’s dropdown menus when using a 16 bit file. What I find confusing is that in my up-to-date PS 19.1.5, some filters Adobe identifies as 16 bit are ghosted (but un-ghost when changing to 8 bit mode) and some of the supposedly 8 bit filters identified on Adobe’s list are not ghosted.
The cynic in me thinks it might be Adobe-confusing but not Adobe-surprising.
Bruce
The filters themselves use 16bits, but the image under 50% zoom is 8bit.
I’m seeing contouring at 100%.
If the Adobe NR filters are only 8 bit and induce banding in the image, it might be worthwhile to try some of the third party filters such as Topaz Denoise or Nik Define? Are these 16 bit?