3 Replies Latest reply on Jan 19, 2015 11:59 PM by wigasper

    Banding due to automatic downconverting of RAW files to 8 bit


      I'm running into an interesting problem that I can not solve on my own.


      It appears that Photoshop or the Adobe Camera Raw Editor is automatically down converting my 14 bit Canon RAW files to 8 bit depth.


      I took some photos to illustrate my problem and maybe someone can shed some light on the issue.


      Screen Shot 2015-01-19 at 6.36.10 PM.png

      So here you can see some very serious, very bad banding. In my workflow options at the bottom you can see it says "16 bit". You can also see that this is a CR2 RAW file. It says 16 bit but it's plainly obvious from the extreme banding that the photo has been down converted to 8 bit.


      As a comparison I opened up the same photo in Canon's "Digital Photo Professional 4" software. There was no visible banding and I exported the photo to a TIFF. Here is that photo being displayed in PS:

      Screen Shot 2015-01-19 at 6.39.59 PM.png

      So, the exact same RAW file processed through "Digital Photo Professional 4" to a TIFF shows no visible banding. It appears that Adobe Camera Raw is downconverting my RAW files to 8 bit automatically.


      It is clearly not a display (dithering) issue, as you can see it looks fine in the file that was processed with Canon software.


      I have done a lot of searching and have not found a solution but I do not understand what is happening here. I have found threads where people have the same issue but none of the answers provided actually solve the problem.


      If I do not find a solution my only option will be to do RAW processing in the Canon software which is not as intuitive, nor do I like as much, as PS. I would really prefer to do my RAW processing in PS but it will not be an option for my unless I can get this automatic down converting of bit depth figured out.

        • 1. Re: Banding due to automatic downconverting of RAW files to 8 bit
          JimHess Adobe Community Professional & MVP

          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?

          • 2. Re: Banding due to automatic downconverting of RAW files to 8 bit
            wigasper Level 1

            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:

            Screen Shot 2015-01-19 at 11.51.50 PM.pngScreen Shot 2015-01-19 at 11.51.10 PM.png


            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.

            • 3. Re: Banding due to automatic downconverting of RAW files to 8 bit
              wigasper Level 1

              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.