12 Replies Latest reply: Oct 18, 2008 1:15 PM by Thomas Knoll RSS

    Highlight Tone Priority as Metadata?

    Harald E Brandt Community Member
      In Canons Digital Photo Professional, one can see if the picture was taken with Highlight Tone Priority or not, but in Lightroom one cannot. Is there a way (plugin/hack/...) so that I can get to see this also in Lightroom?
        • 1. Re: Highlight Tone Priority as Metadata?
          Jao vdL CommunityMVP
          No. These tags are proprietary and Canon (nor Nikon for that matter) will tell anybody how they are stored in "their" files.
          • 2. Re: Highlight Tone Priority as Metadata?
            MadManChan2000 Adobe Employee
            No. How would knowing this information improve your workflow?
            • 3. Re: Highlight Tone Priority as Metadata?
              Harald E Brandt Community Member
              > Eric: No. How would knowing this information improve your workflow?

              It has the same effect on the workflow as knowing the shutter speed or aperture, or knowing if the flash was fired or not. One might, on the one hand, argue that once the picture is taken, knowing the shutter speed has no effect on the result. On the other hand, when analyzing the results of sharpness, bokeh, aberrations etc, it is very valuable to know the shutter speed and aperture!

              Likewise, it is very important to know if HTP was enabled or not when analyzing highlight and shadow performance, so one can learn from results. This is because (as I am sure you already know) HTP can have a profound very positive effect on the highlights, especially in combination with Recovery, while (depending on the ISO-setting) it somewhat degrades the noise in the deepest shadows.

              We learn from results, we decide parameters based on historical results. HTP can be as important to control as aperture is. And, if I compare results from different cameras, say 40D and 50D, it becomes meaningless if they use different settings for HTP.

              PS: For those who might not know: HTP affects RAW just as much as JGP.
              • 4. Re: Highlight Tone Priority as Metadata?
                john beardsworth CommunityMVP
                Does it affect the raw, or is it just an instruction for DPP and for the jpeg that's embedded in the raw file?
                • 5. Re: Highlight Tone Priority as Metadata?
                  Harald E Brandt Community Member
                  > Does it affect the raw, or is it just an instruction for DPP and for the jpeg that's embedded in the raw file?

                  It affects RAW data.
                  • 6. Re: Highlight Tone Priority as Metadata?
                    Lee Jay-7OQGJF Community Member
                    As far as I know, it only affects the raw data by under-exposing the image. It's the same as -EC. In other words, it's only a change to metering unless you shoot in JPEG.
                    • 7. Re: Highlight Tone Priority as Metadata?
                      Harald E Brandt Community Member
                      >Lee: As far as I know, it only affects the raw data by under-exposing the image. It's the same as -EC. In other words, it's only a change to metering unless you shoot in JPEG.

                      Curves are involved, but in different ways for HTP and Nikons Active D-lighting.
                      Not the same as -EC (as far as I know). Among other places, check out:
                      http://www.bobatkins.com/photography/digital/canon_eos_40D_review_6.html
                      http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/noise-p3.html
                      (Although the latter does not say so much about the tone curve, since it basically only mentions the *principle*, namely underexposing [in parts of the range of] the image.)
                      • 8. Re: Highlight Tone Priority as Metadata?
                        MadManChan2000 Adobe Employee
                        With HTP you are effectively underexposing by 1 stop at the raw level.

                        If you are shooting raw there's no point.
                        • 9. Re: Highlight Tone Priority as Metadata?
                          Harald E Brandt Community Member
                          > Eric: With HTP you are effectively underexposing by 1 stop at the raw level.

                          Since you work for Adobe, I assume you know exactly what you are talking about. Therefore, I would like to ask the following, to make things perfectly clear:

                          Assuming RAW files:

                          First: Is it "pure" exposure compensation? So it is in every aspect equivalent to -1 stop exposure in the camera and then +1 stop exposure in LR?

                          Second: Nikons Active D-lighting is said to be "similar", but with some differences. Are these two methods exactly the same, or what is the difference?
                          • 10. Re: Highlight Tone Priority as Metadata?
                            Jao vdL CommunityMVP
                            >First: Is it "pure" exposure compensation? So it is in every aspect equivalent to -1 stop exposure in the camera and then +1 stop exposure in LR?

                            The RAW data is really simply underexposed with about a stop. The camera then applies some curves and some exposure compensation to create the jpeg, however nothing happens to the RAW.

                            >Second: Nikons Active D-lighting is said to be "similar", but with some differences. Are these two methods exactly the same, or what is the difference?

                            Nikon's method is more complex. It actually applies a dynamic range reduction technique (called HDR by some folks) in the camera that is similar to applying some shadow fill and some highlight recovery. This cannot be done by simple curves as the shadows are treated differently than the highlights. At the same time, the RAW data is completely unaffected except for the about 2/3 stop underexposure it applies. This only affects the jpeg preview and it affects what Nikon's capture program would do with the data.
                            • 11. Re: Highlight Tone Priority as Metadata?
                              Harald E Brandt Community Member
                              Thanks Jao!
                              I thought I had a pretty good idea what it does -- now I now better! Thus, in raw data, in LR, both HTP and Active D-L amounts to a simple pure underexposure with no other curves applied, 1 stop for Canon (approx(?)) and 2/3 for Nikon!

                              Nice to be enlightened!
                              • 12. Re: Highlight Tone Priority as Metadata?
                                Thomas Knoll Community Member
                                As the raw level, HTP drops the ISO by 1 stop and underexposes by 1 stop.