8 Replies Latest reply on Mar 15, 2016 5:20 PM by deejjjaaaa

    DNG Profile Editor question.

    Joe_Caldwell Level 1

      Hi, everyone.

       

      I hope this is the right forum to ask this question. I've looked for a DNG Profile Editor forum but couldn't find one.

       

      I have started to use the DNG Profile Editor to create a profile for my camera + light combination. All the tutorials I've read and/or watched so far aren't clear about this aspect of the calibration or profiling process. I have used the ColorChecker Classic and ColorChecker Passport (both have the same 24 color patches).

       

      Here is the problem I am having: After I create the profile using DMG profile editor and a photo of one of the targets above, I try to read the value of the color patches but the measurements are very different from those of the patches. I thought and expected that after the profiling process the measurements I took on screen using the color samplers in ACR would display the same values as those on the color charts. For instance, the White patch has a RGB value of R-243, G-243, B-242 on the ColorChecker Classic target but when I measure my image of it on screen the values are R-246, G-245, B-244. Not a big difference here. However, the Black patch has a value of R-52, G-52, B-52 on the ColorChecker Classic target but the measurements on the screen are R-72, G-73, B-74. Just to illustrate my point:

       

      Red on target: R-175, G-54, B-60

      Red on screen: R-225, G-68, B-76

       

      Green on target: R-70, G-148, B-73

      Green on screen: R-151, G-219, B-119

       

      Blue on target: R-56, G-61, B-150

      Blue on screen: R-62, G-86, B-207

       

      Shouldn't the measurements on screen duplicate those on the target now that the camera has been profiled ? In this case what am I doing wrong and how can I improve my calibration process so my measurements on screen are accurate and reflect real life measurements ?

       

      Thank you in advance for your help.

        • 1. Re: DNG Profile Editor question.
          ssprengel Adobe Community Professional & MVP

          Calibrating with the Color Checker is for color-hue accuracy not absolute luminance-brightness/darkness which changes with the toning sliders.

          • 2. Re: DNG Profile Editor question.
            Joe_Caldwell Level 1

            ssprengel,

             

            I have found the manual work with the sliders to be both unpredictable and very time-consuming. In addition, I have never been able to successful adjust them so my targets have the same values on screen as they have in real life.

             

            Is there a simpler method I can use to accomplish this ? I have also used the software available from X-Rite that accompanies their ColorChecker Passport but it produces the same results (in other words, the image of the target on screen has values that don't match the real values of the target patches).

             

            Any help you can provide me will be greatly appreciated.

             

            Thank you for your help and reply.

            • 3. Re: DNG Profile Editor question.
              ssprengel Adobe Community Professional & MVP

              Here is a way to optimize your color profile with a script or two:

               

              Use the DNG Profile Editor to create a DNG Profile for the lighting of your studio setting.

               

              Use Tindeman's script to optimize the Red/Green/Blue-Hue/Sat sliders on the calibration tab after the script optimizes the White-Valance and Exposure values in Process Version 2010.

              Simon Tindemans | ACR calibrator L

               

              You'll end up with something like this, which tells you how to set the Red/Green/Blue-Hue/Sat sliders when using the selected profile:

              After the calibration is complete and you have set the Hue/Sat slider values, you can use the Rags-Gardner read_colors_CC24 script to show a corrected-colors version and produce a detailed error chart:

              ACR Camera Calibration and Validation

               

              It is important that when you use either the slider-calibration script or the read-colors script you should open your CCPP image in ACR, crop the exactly the patch area, set PV2010, set ProPhoto RGB, and select the profile you want to optimize the sliders for:

               

              Then open in PS and draw a U-shaped pen path by clicking the Pen tool then on Brown, White, Black, Cyan patches:

               

              After that you can use File / Scripts / Browse to select the script to run and set the scripts options and review any prompts that come up.  Although the scripts are written for CS5 and earlier, I have tested with PS-CS6/ACR 9.1.1 and they work as long as you set the Process Version to 2010 not 2012 because the scripts are manipulating PV2010 values:

               

              The script will use the file-path of the current image tab to repeatedly open it in ACR and try different combinations of the Hue/Sat calibration sliders until it finds the result with the least error.

               

              Using a $300 program called Imatest Studio it is possible to create color error plots that show how far off the colors of a CC24 target are.

               

              Here is a PBase gallery of Imatest color-error plots for various profiles.  You will notice that the ones that use the Tindemans script after the profile are the closest:

              Adobe Calibration Results Photo Gallery by Steve Sprengel at pbase.com

              • 4. Re: DNG Profile Editor question.
                deejjjaaaa Level 2

                > Using a $300 program called Imatest Studio it is possible to create color error plots that show how far off the colors of a CC24 target are

                 

                BabelColor Patchtool is way cheaper...

                • 5. Re: DNG Profile Editor question.
                  ssprengel Adobe Community Professional & MVP

                  When I bought Imatest Studio quite a few years back, it was $99.  Now it's $300.  Imatest is for testing optical subsystems with charts.  The ColorChecker function is just one aspect of the testing it does, where others are sharpness and resolution, etc.

                   

                  The $125 PatchTool product seems more useful in a more limited area of colors which is more interesting to me, although I'm not seeing the same sort of error plot, but maybe I haven't looked at every screenshot in detail, yet.

                   

                  This is an example of an Imatest's, error plot where you can easily see this DNG Profile Editor-created profile has the most error in oversaturating reds:

                  • 7. Re: DNG Profile Editor question.
                    ssprengel Adobe Community Professional & MVP

                    I had clicked Next through all of those and didn’t see a comprehensive visual plot of the color error for all patches simultaneously.  I see lists of numbers in tables, split patch comparisons, but the closest thing seems to only show data for one patch at a time.  Maybe I missed something off the bottom of one of the pages.

                    • 8. Re: DNG Profile Editor question.
                      deejjjaaaa Level 2

                      it does not have exactly this type of visual plot if it is the question...