11 Replies Latest reply on Aug 1, 2008 7:36 PM by (WS_Lam)

    DNG-PE Dual-Illuminant Profile question

    Level 1
      Just want to clarify the correct procedure in building a Dual-Illuminant camera profile.

      So I have shot a colorchecker under 6500k and 2850k (hopelessly gloomy here in Hong Kong now, best I could get is around 5500k)... anyway, i open both shots in PE, and then run the chart wizard.

      Questions:
      1) Does it matter which base profile I choose when I run the Chart wizard?
      2) Once I run the chart wizard once, the Base Profile changes to 'Color Checker'. If I were to proceed to run the other colorchecker, do I need to change the base profile back to the original base profile (e.g. Adobe Std)

      Thanks! ws
        • 1. Re: DNG-PE Dual-Illuminant Profile question
          MadManChan2000 Adobe Employee
          The answer to both questions is "no"
          • 3. Re: DNG-PE Dual-Illuminant Profile question
            Level 1
            Hi again Eric,

            Quick questions:

            1) Is it crucial for me to take the targets at 6500k and 2850k? The sunlight in HK now only gives me 5500k, and tungsten at my home is closer to 2500k.

            2) Does it matter what ISO I choose when I shoot the targets? I was told that the sensor's color response does not really shift at different ISO settings, only that the noise may shift the colors a little? If that assumption is correct, does it mean I can shoot the colorchecker at any ISO and apply it across the full ISO range for a specific camera?

            Really nice work btw, the profile editor is one of the most powerful tools I have seen for a long time!

            ws
            • 4. Re: DNG-PE Dual-Illuminant Profile question
              I shoot the chart with studio flash and umbrellas. Light Color is 4550°K . (I have a thermo colorimeter).
              1) I don't care about the white balance on the camera. Am I right?

              I do a profile with DNG for "6500 K° only".
              I do an other shoot with a 82C filter on the camera as if I had a 6500°K film in my camera. (80D would have been better, but I don't have one) and an other profile for "6500 K° only.

              2) I have 2 different profiles. Is one of them better (more accurate colors on the chart) than the other in any light color situation, or is the one made with the filter better with a 6500°K light, and the other with a 4500°K light ?
              • 5. Re: DNG-PE Dual-Illuminant Profile question
                MadManChan2000 Adobe Employee
                WS,

                1) For daylight it's not that critical. For tungsten it is much more important. Is your indoor bulb really tungsten or is it a compact fluorescent bulb? Many of these CFLs have color temps closer to 2500 K, which is why I ask, and if you are indeed using a CFL you might want to use a separate profile for it (spectrally it's very different from illuminant A).

                2. Please shoot the CC at low ISO. That way the chart wizard is less likely to be confused by noise (it already averages samples, but might as well start with the cleanest data you can). Yes, a profile made from a target shot at one ISO should work well at any ISO.
                • 6. Re: DNG-PE Dual-Illuminant Profile question
                  MadManChan2000 Adobe Employee
                  TDEHESDIN,

                  1. Correct, WB on camera doesn't matter.
                  2. For your case, where you're shooting in a very specific lighting condition (your studio flash in your studio environment) you are better off creating a single profile dedicated to that condition, i.e., follow Tutorial 5 in the PE documentation, where you should select 'Both Color Tables' from the popup in the Chart tab.
                  • 7. Re: DNG-PE Dual-Illuminant Profile question
                    Level 1
                    I'm not speaking about Iso but about colour temp, Kelvin degree. I always work at 100 Iso and I change the shutterspeed (1/125'' with flash, about 4" with ambiance light.)
                    • 8. Re: DNG-PE Dual-Illuminant Profile question
                      Level 1
                      Eric Chan wrote:
                      "2. For your case, where you're shooting in a very specific lighting condition (your studio flash in your studio environment) you are better off creating a single profile dedicated to that condition, i.e., follow Tutorial 5 in the PE documentation, where you should select 'Both Color Tables' from the popup in the Chart tab. "
                      So with a specific and more or less constant lighting, like in studio environment, I shoot one chart in the studio environment and I make only one single profile with the "both color tables".
                      I'm sorry if I make you feel like you're repeating what you just said, but as you can see I'm having quite a hard time understanding.
                      But in this case, when does it worth to do 2 different profiles ? When the light is under 3000° K or upper 6000 ° K ?
                      • 9. Re: DNG-PE Dual-Illuminant Profile question
                        Level 1
                        Thanks Eric! You are absolutely right, I shot the 'Tungsten' under CFL! Hence the 2500k readout! I don't think I have a single lightbulb in my entire house! I have to hunt one down. I will then do a CFL specific profile as you suggested.

                        When I do make a CFL profile, do I generate for both 6500k and 2850k? or do I just generate it via the 2850k option?

                        And thanks for the tip about shooting at the lowest ISO possible. Will do that! You have been of the greatest help! I heard (from LL's LR2 Tutorial, Jeff Schewe) that you are a brilliant guy! I am so glad you are here to directly answer questions!

                        ws
                        • 10. Re: DNG-PE Dual-Illuminant Profile question
                          MadManChan2000 Adobe Employee
                          tdehesdin, it's worth making a dual-illuminant profile if you intend to use that profile in a wide range of illumination conditions. However, your particular situation involves a single illuminant in a fixed environment, which is the perfect situation for following the instructions in Tutorial 5.

                          ws, for CFL I would use Tutorial 5 (both color tables). The reason is that CFLs are spectrally very different from real tungsten / illuminant A, so it is highly unlikely that a profile for CFL would work well for illuminant A (similarly, highly unlikely that a profile for A would work well for CFL). Typically you will get a nasty green or magenta cast with a CFL, even if you set a proper white balance. The chart wizard will fix this.
                          • 11. Re: DNG-PE Dual-Illuminant Profile question
                            Level 1
                            Thanks again Eric!