16 Replies Latest reply on Nov 3, 2012 5:23 AM by Yammer

    In-camera high ISO noise reduction & ACR

    Mollysnoot Level 3

      I've been involved in a discussion over on DPReview where someone believes that, when shooting with a Nikon dSLR (in this case a D7000, but the model isn't really important) high ISO NR is automatically applied in-camera directly to the raw file, and this will be carried over to any raw conversion software, including third-party software such as ACR/LR.

       

      Now I do agree that even with NR switched off, Nikon do automatically apply some limited NR to high ISO images in-camera, but I'm pretty much 100% certain that this is not something that ACR would interpret, and so it would not actually have any effect on the appearance of the raw file when it's processed. In fact, if the high ISO NR is somehow embedded into the raw file, that would go against my whole concept of how a raw file works in a convertor such as ACR! Surely any "default" high ISO NR is just added to the proprietry part of the EXIF, and is therefore only factored in when using Nikon conversion software (ViewNX, etc)? Otherwise, the file could not truly be considered to be 'raw'.

       

      I think I'm right, but wanted confirmation from some of the experts on here! And of course, I'm also quite happy to be proven wrong!

       

      M

        • 1. Re: In-camera high ISO noise reduction & ACR
          Noel Carboni Level 7

          Do you have such a camera?

           

          Why don't you take a couple of frames with/without the NR enabled under controlled circumstances and see whether there are obvious differences?

           

          -Noel

          • 2. Re: In-camera high ISO noise reduction & ACR
            Mollysnoot Level 3

            Hi Noel.

             

            Yes I do, but the problem is that the NR I'm talking about can't be switched off: it is apparently applied in-camera to high ISO images regardless of whether you have NR switched on or off, so the test you propose isn't possible.

             

            M

            • 3. Re: In-camera high ISO noise reduction & ACR
              Yammer Level 4

              I always understood High ISO NR to be a conversion process, just like Picture Controls, D-Lighting, Lens Corrections, etc. I thought the whole point of Raw was that it was the ... erm ... raw recording of the image, warts 'n' all.

               

              The other type of noise reduction in Nikon (and likely other) cameras is long-exposure. I believe this is done by subtracting an equal exposure from the matrix, taken with the shutter closed. As this is a physical technique to reduce noise, it affects Raw images. Maybe this is what your correspondent means?

              1 person found this helpful
              • 4. Re: In-camera high ISO noise reduction & ACR
                Mollysnoot Level 3

                Yes, that was my exactly understanding too: "warts and all" is a good term to use actually!

                 

                I don't believe that they were talking about long exposure NR, just high ISO (above 1600), where, according to the manual, mild NR is applied by default, regardless of what you set in-camera. I really don't think this is carried across to ACR.

                 

                M

                • 5. Re: In-camera high ISO noise reduction & ACR
                  areohbee Level 6

                  I think you are right Mollysnoot: raw means raw / raw is raw.

                   

                  People get confused because manufacturer software does not have an option to turn baseline noise reduction off in camera, nor in software app, so when using mfr sftwr, for all practical purposes, the NR will be "baked in" (to the RGB image that you see), whether you like it or not.

                   

                  My theory about this is:

                   

                  Manufacturer does not want people to see how many warts are really present in the raw data coming from their hardware.

                   

                  I could be wrong.

                   

                  Another possibility is that the baseline NR is integrated into the raw conversion process, so converting without it isn't an option.

                   

                  Again - dunno 'bout that either.

                   

                  Summary:

                  -----------

                  What could (theoretically) be baked into the raw data:

                  * things that don't necessarily require RGB data - some lens corrections for example (distortion).

                   

                  What can't be baked into the raw data:

                  * things that require RGB data (I don't know enough about noise reduction to know if it's theoretically possible to perform NR on pre-converted raw data, but so far it has NOT been done for any cameras I am familiar with (e.g. Nikon & Canon DSLRs).

                   

                  Dunno 'bout D7000 specifically.

                   

                  Cheers,

                  Rob

                  1 person found this helpful
                  • 6. Re: In-camera high ISO noise reduction & ACR
                    Mollysnoot Level 3

                    Thanks Rob - just the kind of information I was hoping to get. Essentially, you're confirming what I already thought, but I was starting to doubt myself having got into the discussion over on DPR.

                     

                    M

                    • 7. Re: In-camera high ISO noise reduction & ACR
                      Yammer Level 4

                      Noel gave you the best answer. Try it and see.

                      • 8. Re: In-camera high ISO noise reduction & ACR
                        areohbee Level 6

                        You're welcome. It could be things will change in the future. But so far, there has been no value in consuming resources to transform raw sensor data before storage on card, since it would degrade shooting performance without any advantage. I can imagine all kinds of things in the future, but so far they are all "science fiction".

                        • 9. Re: In-camera high ISO noise reduction & ACR
                          Mollysnoot Level 3

                          But as I said Yammer, I can't test this by shooting with NR on and off as Noel suggested because as described by Nikon it is, by default, apparently always on for high ISO shots above 1600... I already know that user selected NR settings have no effect in ACR (as expected).

                           

                          I completely agree that if this were not the case, Noel's advice would have been the best way to go, and I appreciate his input here.

                           

                          M

                          • 10. Re: In-camera high ISO noise reduction & ACR
                            Noel Carboni Level 7

                            Cameras DO process raw data sometimes in surprising ways.  Some Canon models actually add some sharpening to the raw data.  Cross my heart.

                             

                            Camera makers don't gain anything by being open about how they do their image acquisition.  They may figure giving away their secrets to the competition is a bad idea.

                             

                            Whether Nikon does noise reduction of some sort on the raw data is anyone's guess.  It's possible but there may be no way to know if you can't test for it directly.

                             

                            One possibility for testing does still remain...  If you see image detail grow soft as ISO is increased then there's a good chance it's being done.

                             

                            Perhaps I'll go retrieve some test shots from imaging-resource or dpreview taken of the same subject but at different ISOs and have a look-see.

                             

                            -Noel

                            • 11. Re: In-camera high ISO noise reduction & ACR
                              Noel Carboni Level 7

                              First trial with D7000 images was inconclusive...  I thought maybe I was seeing softening between the ISO 100 and 800 images, but then the ISO 12800 image looks sharper, so I'm chalking this one up to variance in the shooting conditions (e.g., the ISO 800 image was OOF or motion-blurred).

                               

                              ThreeISOsD7000_1.jpg

                               

                              By the way, the reference I found for D7000 shows that the High ISO NR can be disabled.  See this page:  http://www.imaging-resource.com/PRODS/D7000/D7000A7.HTM

                               

                              What camera do YOU have, Molly?

                               

                              -Noel

                              • 12. Re: In-camera high ISO noise reduction & ACR
                                Noel Carboni Level 7

                                This D7000 ISO 100/800/12800 sequence seems to imply that a good bit of detail is lost at ISO 12800, but none at ISO 800.  But again it could be shooting inconsistencies.

                                 

                                ThreeISOsD7000_2.jpg

                                 

                                Off to look for more examples.

                                 

                                -Noel

                                • 13. Re: In-camera high ISO noise reduction & ACR
                                  Noel Carboni Level 7

                                  Here's another set of three D7000 shots, ISO 100/800/12800, supposedly taken under very carefully controlled conditions.

                                   

                                  ThreeISOsD7000_3.jpg

                                   

                                  I honestly don't see evidence that there has been loss of detail at the higher ISO settings.  Some of the detail is hidden by noise, but it doesn't have the feeling of having been blurred.  Maybe others will reach a different conclusion.

                                   

                                  -Noel

                                  • 14. Re: In-camera high ISO noise reduction & ACR
                                    Mollysnoot Level 3

                                    Noel Carboni wrote:

                                     

                                    By the way, the reference I found for D7000 shows that the High ISO NR can be disabled.  See this page:  http://www.imaging-resource.com/PRODS/D7000/D7000A7.HTM

                                     

                                    What camera do YOU have, Molly?

                                     

                                    -Noel

                                     

                                    Hi Noel,

                                     

                                    Wow, I'm impressed with your efforts here!   Your point about blurring being a potential sign of whether or not NR has been applied to the high ISO raw files is a good one, and I agree that, based on that thinking, the examples you've found don't really seem to show much evidence of that, particularly the shots of the focus/resolution target.

                                     

                                    I do have a D7000; I replied as such back in post three ("yes I do" in response to your question "do you have such a camera?"), but I can see how that may not have been as clear as it should have been! I'm going to try some test shots myself to see if I can pick out any evidence of softening/blurring that may indicate NR being applied during the processing of the raw data. However, unfortunately my PC is currently being fixed as I've been having some hardware issues, so that testing won't be happening until I get it back (hoping within a week, missing it already).

                                     

                                    Regarding your reference that indicates that high ISO NR can be switched off, yes it can, but apparently only up to a point - here's what it states in the Nikon manual (and what has in turn sparked off this discussion over on DPR):

                                     

                                    "High ISO NR - option: off - Noise reduction is only performed at ISO sensitivities of ISO 1600 and higher. The amount of noise reduction is less than the amount performed when low is selected for High ISO NR" (as the article indicates, there are three options apart from off: high, normal, and low).

                                     

                                    As I've said previously, my understanding was that all of that had zero bearing on the raw file once it was loaded into ACR: regardless of any NR settings applied in-camera, either by the user or by Nikon bypassing the user, they were all thrown away by the Adobe raw processing algorithms, as are things like picture controls, sharpening, contrast, etc. But following my recent discussion, I started to wonder if my understanding of the raw capture process was incorrect, hence this thread.

                                     

                                    Thanks again for your work here. Above and beyond the call of duty!

                                     

                                    M

                                    • 15. Re: In-camera high ISO noise reduction & ACR
                                      Noel Carboni Level 7

                                      No worries, I'm always interested in learning more about how things work. 

                                       

                                      It occurred to me I didn't notice whether the shooters of the above images made it clear what Noise Reduction settings they had chosen, and they may have made the assumption that Noise Reduction wouldn't affect the raw file.  So there are some unknowns there regarding which settings were active.

                                       

                                      -Noel

                                      • 16. Re: In-camera high ISO noise reduction & ACR
                                        Yammer Level 4

                                        I take your point. I see what you're saying now. Still, it might be worth some sort of test -- sometimes things become more obvious with experiment.

                                         

                                        Meanwhile, this reviewer says you're right - although I don't know where he gets his facts.

                                         

                                        http://www.imaging-resource.com/PRODS/D7000/D7000A5.HTM