26 Replies Latest reply on Jun 12, 2010 8:09 PM by Hudechrome

    Prevent double correction of lens distosions in ACR 6.1

    mronen

      Hi,

       

      Some of the newer cameras/lenses have the option of correcting lens distortions automatically, in-camera. This option may usually be enabled/disabled by the user, in the camera menu.

       

      If we set Lens Corrections to be performed automatically (by 'Set New Camera Raw Defaults'), is ACR capable to detect that corrections have already been applied, and thus prevent double correction?  Are there different profiles for such lens/cameras, with or without corrections applied?

       

      Thanks,

      Moshe

        • 1. Re: Prevent double correction of lens distosions in ACR 6.1
          b_gossweiler Level 5

          I've never used one of those cameras/lenses, but are you sure the effect is applied to the RAW image, and not only to the rendered JPG?

           

          Beat Gossweiler

          Switzerland

          • 2. Re: Prevent double correction of lens distortions in ACR 6.1
            mronen Level 1

            I don't know, Beat.  I see no reason why it shouldn't be applied to RAW, especially as you can disable it if you don't want it.

             

            Moshe

            • 3. Re: Prevent double correction of lens distortions in ACR 6.1
              RASouthworth Level 3

              I'll state it more strongly - I don't know of any modern digital camera where raw data is affected by anything other than aperture, shutter speed, and ISO, period.  Some of the early Nikon DSLR's dinked with raw slightly as a function of white balance, but nothing in recent years.

               

              Be aware that manufacturer's software will generally recognize the camera settings and render the default representation of raw data accordingly, but I believe ACR only utilizes the camera white balance tag in their default raw data representation.

               

              Richard Southworth

              • 4. Re: Prevent double correction of lens distosions in ACR 6.1
                Hudechrome Level 2

                Ask Nikon. While Richard is basically correct, I can't imagine why Nikon would not want to apply the lens correction across the board including nef output. The DXO lens correction can be applied without any RAW conversion at all, and comes out as a dng file ready for converting.

                 

                This is a big thorn in the side of Auto lens correction as currently presented, imo. If not now, perhaps in the future, Nikon, Canon and others providing RAW output may correct the lens and why not? Who knows better than they as to what needs to happen to the image making flow to provide the best possible result? I would just as soon have all this done and over with when I import the file. I can envision even that such corrections are generated at the lens itself for individual correction. What a boon that would be and it's not out of the realm of possibility!

                • 5. Re: Prevent double correction of lens distosions in ACR 6.1
                  b_gossweiler Level 5

                  Hudechrome-rzD6dt wrote:

                   

                  Ask Nikon. While Richard is basically correct, I can't imagine why Nikon would not want to apply the lens correction across the board including nef output.  ...

                  ... Because it's then not RAW anymore ....

                   

                  Beat

                  • 6. Re: Prevent double correction of lens distosions in ACR 6.1
                    Hudechrome Level 2

                    Read the rest of my comments with respect to DXO please. It isn't nef but it is RAW, unless someone can inform me of the differences and the consequences.

                     

                    I would really like to know.

                    • 7. Re: Prevent double correction of lens distosions in ACR 6.1
                      b_gossweiler Level 5

                      Hudechrome wrote:

                       

                      ... It isn't nef but it is RAW, unless someone can inform me of the differences and the consequences.

                       

                      I would really like to know.

                      No real "difference" there, RAW is a general term for unrendered sensor data, NEF is the file extension of Nikons flavours of RAW files, as CRW/CR2 is Canons, ORF is Olympus's .....

                       

                      Beat Gossweiler

                      Switzerland

                      • 9. Re: Prevent double correction of lens distosions in ACR 6.1
                        MadManChan2000 Adobe Employee

                        What "raw" means depends on the camera model. Some cameras apply lens corrections to raw sensor data; some do not. Some cameras apply noise reduction to raw sensor data; some do not. Some of these automatic adjustments are user-adjustable (i.e., they can be turned on/off via camera menu settings); some are not.

                         

                        For the questionable cases, for the profiles we've built, we build them with the camera set to disable lens corrections.

                        • 10. Re: Prevent double correction of lens distosions in ACR 6.1
                          Hudechrome Level 2

                          Pretty much what I would expect.There is no physical law of I am aware that says certain adjustments cannot be done before RAW conversion, only rules of the game

                          .

                           

                          Now, Eric, with respect to the use of Lens correction data in PS Photomerge, is the Geometric Correction available by choice strictly data about the lens or is it something else? Why, if no data is available, does a geometric correction happen at all? As I noted in another thread, I ran a stitch using the DXO correction and  another straight nef ; no pass through DXO. Both stitched well, no Lens Correction was available through PS, and unless you switched back and forth, either was acceptable to the eye, meaning maybe neither was optimum.

                           

                          ...for the profiles we've built, we build them with the camera set to disable lens corrections.

                           

                          Which corrections are disabled, the camera or PS ?

                           

                          Message was edited by: Hudechrome

                          • 11. Re: Prevent double correction of lens distosions in ACR 6.1
                            b_gossweiler Level 5

                            Thanks for the clarification, Eric

                             

                            Beat

                            • 12. Re: Prevent double correction of lens distosions in ACR 6.1
                              dorin_nicolaescu Level 5

                              Some cameras apply lens corrections to raw sensor data; some do not.

                              You mean demosaiced raw like Canon's mRaw/sRaw? Is it possible to apply geometric transformations to bayer pattern data?

                              • 13. Re: Prevent double correction of lens distosions in ACR 6.1
                                MadManChan2000 Adobe Employee

                                Hi Hudechrome, with respect to Photomerge, only optical corrections are considered. Lens profiles are used if available, but it is also possible for the Photomerge to estimate distortion (and vignetting) automatically from the sequence of images provided. It is preferable if lens profiles are available, since it takes out some of the guesswork, but they're not required.

                                 

                                Hi Dorin, lens corrections can be applied to mosaic data, too. In the case of lateral CA and distortion, doing so is less common because it requires a more specialized image resampling method, but it can be done. In the case of vignetting, doing so is straightforward since it's a per-pixel operation.

                                • 14. Re: Prevent double correction of lens distosions in ACR 6.1
                                  dorin_nicolaescu Level 5

                                  In the case of lateral CA and distortion, doing so is less common because it requires a more specialized image resampling method, but it can be done.

                                  But are there any camera today that apply geometric transformation on bayer data?

                                  • 15. Re: Prevent double correction of lens distosions in ACR 6.1
                                    Hudechrome Level 2

                                    Thanks, Eric.

                                     

                                    I assume then, if the lens data is available, Photomerge will apply that data whether the file has corrections or not, especially third party corrections. It would seem that at least, if the corrections have been applied in ACR, Photomerge would know about it.

                                     

                                    I  request therefore, that the operator be given control of whether or not Photomerge actually uses these numbers, as ACR does.

                                     

                                    With respect to Dorin's question and your answer regarding lateral CA and distortion, the whole question about corrections for these matters applied to RAW data in one method like DXO or in camera, then finished in another like ACR needs to be more thoroughly examined. Seamless unity needs work as it did in early color management between platforms. All sources of digital Lens Correction input needs to be considered when setting up ACR and Photomerge to incorporate any data with the operator the final arbiter concerning inclusions or exclusions.

                                     

                                    Finally, you did not address my last question concerning which corrections are disabled. Do camera or Adobe corrections take precedence?

                                    • 16. Re: Prevent double correction of lens distosions in ACR 6.1
                                      MadManChan2000 Adobe Employee

                                      Hi Dorin, at present I am not aware of a camera model that writes an image file containing Bayer mosaic data that has already been distortion corrected.

                                      • 17. Re: Prevent double correction of lens distosions in ACR 6.1
                                        MadManChan2000 Adobe Employee

                                        Adobe builds "raw" lens profiles with the camera settings adjusted so that lens corrections are disabled. (This does not necessarily mean that lens corrections actually are disabled, only that the camera settings are set accordingly. By way of analogy, with some cameras you can set the menus to turn off noise reduction, but the cameras apply NR do the raw data anyways. I say this only to clarify the point regarding how the camera is configured, as opposed to what the camera actually does.)

                                         

                                        Regarding linear DNG files produced by other software like DxO, Capture One, etc. they may or may not have lens corrections baked in. In that sense, they are sort of like TIFF files (but less fully baked). At present, it is up to the user to be aware of what the user has already accomplished in the workflow. If you've used the other tool to apply lens corrections already, you will want to turn off profile-based lens corrections in ACR.

                                         

                                        Adobe is working on and has proposed tags to indicate (for the purposes of interoperability) the status of applied lens corrections to an image (e.g., whether or not distortion correction has already been applied). The goal is to get this into an international public standard. Until that happens, it is partly a manual process if your workflow involves multiple pieces.

                                        • 18. Re: Prevent double correction of lens distosions in ACR 6.1
                                          Hudechrome Level 2

                                          Thanks, Eric.

                                           

                                          The conclusion I come to is that any Nikon lens correction is not the profile that is used in ACR. Probably moot because if I already have useable corrections from the factory, I would not likely go looking for others.

                                           

                                          I don't think Nikon applies NR to RAW, as I cannot see any difference when turning NR on or off in the camera menu, so I would expect the same behavior in Lens correction, if it is available.

                                           

                                          That last niggling problem with Photomerge needs attention and I'll be a happy camper.I don't look forward to running back and forth between Win and XP just to get stitching I want! Bad enough my scanner has no drivers for win7.

                                           

                                          Hopefully, those standards to which you referred will happen sooner than later. DXO allows and encourages batch processing so multiple pieces are not a problem.

                                           

                                          "Baked in". At first I thought it was a typo but I see it isn't. New technical term, I presume, one which will have a long definition with lots of Latin references!

                                          • 19. Re: Prevent double correction of lens distosions in ACR 6.1
                                            MadManChan2000 Adobe Employee

                                            Hudechrome, when I do Photomerge (e.g., invoked from Bridge or from PS), I apply lens corrections in ACR and disable the Distortion option in Photomerge. That's my recommendation for now.

                                            • 20. Re: Prevent double correction of lens distosions in ACR 6.1
                                              Hudechrome Level 2

                                              Thanks, Eric. I was afraid of that.

                                               

                                              CS4 also uses Geo and Vignette correction and there is no lens reference of which I am aware. There is a definite difference between having Geo checked or not, and since I am not expecting accuracy with respect to the scene, I make use of what shows up best, and aim for smooth, seamless blending. That's first.

                                               

                                              So I cannot understand why added Lens Correction is automatic. Very puzzling!

                                               

                                              So, looks like CS3 remains. I may have to install it on Win7 as well as XP.

                                               

                                              Bummer! Not at all meeting my expectations, such as they are.

                                               

                                              My opinion: Auto Anything has no place in a high end editor without also offering it as a choice.

                                               

                                              Take care and thanks for your patience.

                                              • 21. Re: Prevent double correction of lens distosions in ACR 6.1
                                                Level 4

                                                Hudechrome wrote:

                                                 

                                                …So, looks like CS3 remains…

                                                 

                                                ACR 4.6 in CS3 is light years behind ACR 5.7 in CS4, which in turn lags a bit behind ACR 6.1 in CS5.

                                                 

                                                Anyone willing to sacrifice image quality is of course welcome to revert to CS3—or use the camera manufacturer's software.

                                                • 22. Re: Prevent double correction of lens distosions in ACR 6.1
                                                  Level 4

                                                  Hudechrome wrote:

                                                   

                                                  …My opinion: Auto Anything has no place in a high end editor without also offering it as a choice…

                                                   

                                                   

                                                  That general concept I can agree with.

                                                   

                                                   

                                                  Wo Tai Lao Le

                                                  我太老了

                                                  • 23. Re: Prevent double correction of lens distosions in ACR 6.1
                                                    Hudechrome Level 2

                                                    Not for ACR, TAI, for stitching, particularly Reposition. ACR 6 is undoubtedly way ahead of ACR 4. In fact, I have re run certain files from that period through 6.1.

                                                     

                                                    I'm also re-examining the alternate stitch with Auto Align and Auto Blend.

                                                     

                                                    I know it appears niggling, but I cannot knowingly allow myself to be blindsided by selections others may make for me.

                                                    • 24. Re: Prevent double correction of lens distosions in ACR 6.1
                                                      deejjjaaaa Level 2
                                                      Regarding linear DNG files produced by other software like DxO, Capture One, etc. they may or may not have lens corrections baked in.

                                                       

                                                      DxO outputs linear DNG, C1 does not output linear DNG

                                                      • 25. Re: Prevent double correction of lens distosions in ACR 6.1
                                                        MadManChan2000 Adobe Employee

                                                        To clarify: I disable Distortion correction in the Photomerge options when I run Photomerge.

                                                         

                                                        I apply distortion correction via the controls in CR/LR.

                                                         

                                                        Therefore, there is no hidden/automatic/automagical distortion control going on in the background. It works smoothly for me, without artifacts. If I am doing more complex stitching work (e.g., with PTGui) I do the same thing.

                                                         

                                                        Perhaps you can clarify. I do not understand your concern.

                                                        • 26. Re: Prevent double correction of lens distosions in ACR 6.1
                                                          Hudechrome Level 2

                                                          Ok, maybe I need the title Madman! I cannot replicate what I saw!

                                                           

                                                          So, maybe if you ask the people coding this function if PSCS5 goes out, for whatever reason and condition, and asks for lens correction if one checks the geometry correction box in Photomerge Auto. Maybe it uses fuzzy logic. I know for dam sure it's getting pretty fuzzy for me!