7 Replies Latest reply on Jul 6, 2009 11:42 PM by Yammer

    ACR - almost perfect, but what about auto CA correction?

    Yammer Level 4

      As the title. I love ACR to bits, but one of the most time-consuming parts of my adjustment procedure is getting the lateral chromatic aberration correction "just right".

       

      I've heard before that Nikon does this in Expeed/CaptureNX with lens data tables, but can anyone confirm this? My guess is that, if I can do it by seeing how much red/cyan and yellow/blue there is in the photo, a computer can do it too (and much quicker) without any lens data.

       

      I bought a so-called "professional" lens recently, and noticed that even an expensive lens still needs significant CA correction in most shots, so I can't just spend my way out of the problem. Does anyone know if Adobe are looking into auto CA correction as a possibility?

       

      Thanks for reading.

        • 1. Re: ACR - almost perfect, but what about auto CA correction?
          Jeff Schewe Level 5

          Yammer P wrote:

           

          Does anyone know if Adobe are looking into auto CA correction as a possibility?

           

          Yes, there are people who would know whether or not Adobe is looking into what you are asking about. But their ability to talk about it is of course very limited...Top Secret–tell nobody!

           

          On the other hand, people who have used ACR 5.4 for Panasonic cameras find that the CA and a few other lens things are being automatically corrected without user intervention.

           

          So, does that answer your question?

          • 2. Re: ACR - almost perfect, but what about auto CA correction?
            Singh, Shangara Level 1

            ACR does have auto CA correction but in 100% of the cases, I have to apply manual CA correction.

             

            Years ago, I used Fuji software and it corrected CA without recourse to a lens database.

             

            An auto CA correction that worked on all images would save an incredible amount of time over the course of a year.

            • 3. Re: ACR - almost perfect, but what about auto CA correction?
              Yammer Level 4

              Thanks Jeff, it does answer my question, but not necessarily with the answer I wanted! ;-)

               

              I'm intrigued by your comments about Panasonic corrections. This is something I've missed. Are they including correction data in their raw files?

               

              Also, Mr/Ms Walrus, I'm astonished to read your "ACR does have auto CA correction" comment. That is also something I've missed.

               

              See, stop following a forum for a few months, and look what happens.

               

              Message was edited by: Yammer P (typo)

              • 4. Re: ACR - almost perfect, but what about auto CA correction?
                Singh, Shangara Level 1

                Well, auto defringe to be precise, now that I think about it. Under Lens Correction: choose Defringe > All Edges, or Highlight Edges, or Off.

                 

                Maybe someone can enlighten us about the differences between CA and Defringe settings?

                 

                It does live under the Chromatic Aberration heading, so easy to assume it's for correcting CA automatically, but maybe not.

                • 5. Re: ACR - almost perfect, but what about auto CA correction?
                  MadManChan2000 Adobe Employee

                  They are designed to address different phenomena, with different underlying

                  physical sources.

                   

                  The CA controls are designed to correct relatively mild and simple cases of

                  lateral (i.e., transverse) chromatic aberration, which often manifests

                  itself as red/green fringing or yellow/blue/purple fringing towards the

                  edges of the frame, regardless of how far one stops down the lens. Color

                  fringing towards the center of the frame is typically negligible. The

                  effects are more noticeable on larger sensors, since they capture more of

                  the projected image circle from the lens ... And lens performance typically

                  degrades noticeably towards the edges of the image circle.

                   

                  The Defringe controls are designed to minimize relatively mild cases of

                  purple fringing artifacts, often occuring near highlight areas, or edges of

                  significant contrast. Such artifacts can occur anywhere in the frame,

                  including the center. It can also be used to reduce residual effects of

                  chromatic aberration, though less effectively.

                   

                  Eric

                   

                   

                  Well, auto defringe to be precise, now that I think about it. Under Lens

                  Correction: choose Defringe > All Edges, or Highlight Edges, or Off.

                   

                  Maybe someone can enlighten us about the differences between CA and Defringe

                  settings?

                   

                  It does live under the Chromatic Aberration heading, so easy to assume it's

                  for correcting CA automatically, but maybe not.

                   

                  1 person found this helpful
                  • 6. Re: ACR - almost perfect, but what about auto CA correction?
                    Bill_Janes Level 2

                    Yammer P wrote:

                     

                    As the title. I love ACR to bits, but one of the most time-consuming parts of my adjustment procedure is getting the lateral chromatic aberration correction "just right".

                     

                    I've heard before that Nikon does this in Expeed/CaptureNX with lens data tables, but can anyone confirm this? My guess is that, if I can do it by seeing how much red/cyan and yellow/blue there is in the photo, a computer can do it too (and much quicker) without any lens data.

                     

                    Some Nikon cameras do perform automatic correction of lateral chromatic aberration, but do so without a lens correction table. This is done with JPEGs by the Expeed engine. With raw, the needed correction information is included in metadata and can be applied by Capture NX. The process works for 3rd party lenses as well. See this review of the D3 for more details:

                     

                    http://www.imaging-resource.com/PRODS/D3/D3A4.HTM

                     

                    Automatic correction of light falloff at the corners of the image would also be nice, but I think this would require a lens data table. Such a correction can be applied automatically by Capture NX, but only with Nikon lenses.

                    1 person found this helpful
                    • 7. Re: ACR - almost perfect, but what about auto CA correction?
                      Yammer Level 4

                      Thanks, Bill.

                       

                      I don't know if you could tell from my tone, but I was doubtful that lens data was used, as that would require a lot of extra data in the firmware. So, it seems that it's not an impossible dream. This is really what computers were made for — automating tedious jobs.