10 Replies Latest reply on Nov 10, 2009 2:35 PM by ssprengel

    Nasty noise in shadows in ACR

    chabashvili

      Hi guys,

       

      Here's the problem I have.

       

      Until a week ago for RAW conversions i was using Digital Photo Professional from Canon (the software that comes with camera). I have Canon 5D. It was reading RAW perfectly, giving clear noiseless picture.

       

      Recently I adopted all-Adobe workflow, so I use Bridge for viewing, ACR for conversion and PS for editing. But the problem is following. In Bridge and after in ACR on perfectly lit pictures where I have a dark-midtones and shadows (not underexposed ones, just plain correct dark-midtones and shadows) in ACR and in Bridge preview I see nasty colored noise, something you would see when artificially increase brightness in shadows. This is with the default setting, without changing anything in ACR (or Bridge) At a glance this is not noticeable, but it is very noticeable when you compare side-by-side with Canon Digital Photo Professional preview and ACR or Bridge preview. And its also noticeable when you view shot in 100% size. Of course whatever I see in ACR is transfered to Photoshop. Well most of the time I can get rid of this noise in PS, but it is still bothering since I have not experienced anything like with with Digital Photo Professional.

       

      Could you guys please help me understand where this noise is coming from and how to get rid of it. Thank you in advance.

       

      My monitor is HP 2445, calibrated. Software Photoshop and Bridge CS4.

        • 1. Re: Nasty noise in shadows in ACR
          Panoholic Level 2

          What about uploading

           

          1. a sample raw file,

           

          2. a 100% crop of the JPEG showing the problem,

           

          3. the adjustment parameters used when converting the image

           

          (use yousendit.com if you don't have web space).

           

          Gabor

          • 2. Re: Nasty noise in shadows in ACR
            chabashvili Level 1

            Hi,

             

            Heres the links:

             

            1. This is a screenshot of 100% crop from Bridge: http://luxfabrica.com/Bridge.png

             

            2. This is a screenshot of 100% crop from ACR 5.5: http://luxfabrica.com/ACR.png

             

            3. This one is actual RAW file: http://luxfabrica.com/IMG_0163.CR2

             

            4. And this one a 100% crop from Canon Digital Photo Professional: http://luxfabrica.com/dpp.png

             

             

            Thank you in advance.

            • 3. Re: Nasty noise in shadows in ACR
              Panoholic Level 2

              Pls give it a try with much less blacks. The shot is very clean, it works even with blacks=0, but try it with 1 or 2. The default in ACR, 5, is brainless.

               

              Because of that change, you should adjust contrast and brightness to your liking.

               

              Another issue: the shot could have been exposed 1 2/3 EV higher without clipping (but it was not underexposed in the sense that it would have caused excessive noise). I am mentioning this only, because you may not know, that ACR adds 0.25 EV "exposure" adjustment to the 5D shots without displaying that on the slider, thereby creating the impression, that the shot was higher exposed as it is in reality. (The adjustment is -0.75 EV with ISO 50, but you should never use that with raw data, as that is simply ISO 100 overexposed.)

               

              Gabor

              • 4. Re: Nasty noise in shadows in ACR
                ssprengel Adobe Community Professional & MVP

                LR3/CS5/ACR6 will have improved color NR and pixel-level detail if the current LR3 beta is any indication.

                 

                Attached is a side-by-side showing LR2/ACR5 vs LR3/ACR6 color-NR, where I've maxed out the brightness, contrast, and saturation. along with an increase in exposure to make the residual noise more obvious.

                 

                Judging from what was posted as a DPP.PNG, DPP leaves green and purple color-noise in the clothing, it is just finer-grained so harder to see in relation to the texture.

                • 5. Re: Nasty noise in shadows in ACR
                  ssprengel Adobe Community Professional & MVP

                  ...see above

                  • 6. Re: Nasty noise in shadows in ACR
                    chabashvili Level 1

                    Gabor Thank you. Your suggestion did it

                     

                    Now regarding the automatic exposure adjustment. Does that mean that I should shot with little bit more exposure on Canon 5D? Or should I adjust it in ACR? Thank you in advance.

                    • 7. Re: Nasty noise in shadows in ACR
                      Panoholic Level 2
                      Does that mean that I should shot with little bit more exposure on Canon 5D? Or should I adjust it in ACR?

                       

                      The camera's metering does not care for ACR's pecular behaviour; if the metering reflects the total scenery's illumination accurately, then follow the suggested exposure. Note, that this adjustment - just like your explicite adjustments - does not change the shot's exposure (it is unfortunate, that Adobe named that slider "exposure"). It does not depend on the raw conversion if the shot is exposed ideally.

                       

                      On the other hand, the clandestine intensity adjustment changes the appearance of the image. This 0.25 EV is not much (some cameras' shots get adjusted by +2 EV with certain ISO settings), but still. You can establish -0.25 EV as default (by saving such a setting). It is not good with ISO 50, but again, you should never use ISO 50 with this camera (or with any other Canon DSLR).

                       

                      On the third hand, what you see in the raw conversion is always far from the raw data. The displayed histograms and clipping are not based on the raw data but on the result of conversion; this is true regarding the in-camera display as well, which is based on the JPEG embedded in the raw file. In case you need to utilize the camera's capability fully, i.e. expose as high as possible without clipping of the raw data, then you have to turn to more "nasty" methods. This is not a subject for this forum, but it has been discussed many times, for example here: http://photography-on-the.net/forum/showthread.php?t=758160

                       

                      Gabor

                      • 8. Re: Nasty noise in shadows in ACR
                        ssprengel Adobe Community Professional & MVP

                        The slider being named "Exposure" makes sense to me, although technically it is more of a digital (simulated) ISO adjustment.

                         

                        What is the source/documentation for the idea that ACR's conversion is 1/4 EV higher than it should be for a 5D?  Is this from your own personal experiments comparing where a mid-tone spike shows up on the camera and an ACR histogram or someone else's experiments of the same or something more complicated?

                        • 9. Re: Nasty noise in shadows in ACR
                          Panoholic Level 2
                          What is the source/documentation for the idea that ACR's conversion is 1/4 EV higher than it should be for a 5D?

                           

                          If you convert a native raw file in DNG with Adobe's DNG converter and look at the BaselineExposure tag in the first IFD, you see the clandestine adjustment, like

                           

                          50730 BaselineExposure SRATIONAL 25/100

                           

                          (other programs may display it in different format)

                           

                          Gabor

                          • 10. Re: Nasty noise in shadows in ACR
                            ssprengel Adobe Community Professional & MVP

                            Ok, I see it using EXIFTool.

                             

                            I also notice the Preview Application Version using LR 3 beta to create the DNG Preview is 2.6, not 3.0, so I wonder if the Process 2 enhancements will be part of LR 2.6 and ACR 5.6, if it just means that the DNG Preview is created using Process 1 and the ACR Engine for Process 1 was already up to ACR 2.6 at Adobe when LR 3 beta was built and released.