9 Replies Latest reply on Feb 16, 2009 12:57 PM by craulmedia

    Partial quicktime gamma shift solution...?


      We've been experimenting a bit with the quicktime gamma problem mainly connected to h264.

      A clip rendered from AE (or premiere for that matter) to h264 gets extremely washed out. However if you render the clip to Quicktime Motion JPEGB and then use Quicktime Pro (7.5) to export to h264, the gamma difference is a lot less.

      The weird thing is that if you render to, say a lossless format, like Quicktime with no compression, and then use Quicktime Pro to export to h264 you get the same result as when rendering directly from AE to h264. So as far as we know, this only works with QTMJPGB.

      Lastly we also discovered that the gamma shift disappears if you import the washed out h264 into AE again. This probably means that some Quicktime containers (as AE is based on QT) does not load the gamma altering function or something like that. This could mean that if you compensate the gamma shift before render, or with some filter, the results could get disastrous if say some flash container doesn't load the gamma altering function.

      Any thoughts on this?


      / Olle
        • 1. Re: Partial quicktime gamma shift solution...?
          Level 1
          Open up your project settings and check the Preserve Legacy Gamma option. This should solve your problem.
          • 2. Re: Partial quicktime gamma shift solution...?
            Todd_Kopriva Level 8
            The Match Legacy After Effects QuickTime Gamma Adjustments project setting that Rick mentions is described in the "Gamma and tone response" section of After Effects Help.
            • 3. Re: Partial quicktime gamma shift solution...?
              Level 1
              Im sorry but this didn't solve my problem.

              Maybe I just don't get this, but this is a general problem amongst filmproducers all over the world.

              I have uploaded an image for you to look at, where I have tested and compared different settings in AE. Of course my wish is to get the representation of the video in Quicktime as close to the representation in After Effects, as possible (so that the video image in Quicktime matches color- and general image adjustments in After Effects ...obviously). I have numbered the images in the order I thought was natural to compare the images in. As you can see, match legacy gamma does nothing. The best result is when using HDTV-16-235 with compensate for scene-referred profiles unchecked, and then EXPORTED to h264 from AE. You can see this as the closest image match is between image 10 and 11. Everything is in 8bpc.

              The image is located here:



              / Olle
              • 4. Re: Partial quicktime gamma shift solution...?
                mr. ichybob Level 1
                Have you seen this article at Provideocoalition.com?

                http://provideocoalition.com/index.php/cmg_blogs/story/brightness_issues_with_h264_quickti me_movies/

                It has a couple of work arounds. I personally suspect this same (or similar) issue may affect DVC PRO HD.
                • 5. Re: Partial quicktime gamma shift solution...?
                  edit4all Level 1
                  Mine is fluctuating. Mine worked without having the Match Legacy Gamma Adjustment on and then off then on. I did something which seemed to overwrite a setting and reset something. Not sure.

                  Try this.
                  In project settings, Turn on the Blend Colors Using 1.0 Gamma.
                  Render something in the render que. My video suddenly got darker and the results were darker than normal.
                  I went back, checked it off, re-rendered it, and it worked out perfectly.
                  • 6. Re: Partial quicktime gamma shift solution...?
                    Level 1
                    mr. ichybob

                    Thanks for your answer. But I have indeed seen that article before, as well as Andrew Kramers solution.


                    And it doesn't work.

                    Firstly provideo coalitions article adresses a slightly different problem where gamma shifts when rendered with QT Pro and appears on Mac and in Safari but not on Windows.

                    I believe that this is the same problem in the core but that the problem has changed since updates. The problem now appears in Windows and not only when "re-exported" as they say in the article...I have tried the gammastripper from FUELVFX and it can neither find or remove the gamma "tag". (I believe that maybe it did at some point but not anymore).

                    Regarding x264 I'm very sceptical. Not using the industry standard h264 seems like a dangerous idea. Can our customers use it without complications without themselves having to install a new codec?

                    (It's like shipping a professionally crafted powerpoint presentation without the fonts that were used in it...or worse).

                    Even more importantly, can we use it as we always have? Can we rely on the codec-development not to be abandoned? Maybe I'm paranoid but with all technical problems we have to fight with in this business, you can't be too careful. (The reason I haven't really tried it is that I don't want to install unnecessary codecs on my computer that can alter otherwise completely functional stuff.)

                    And the other solutions mentioned in the article...the bad...are exactly that.

                    But maybe someone can convince me with some facts that the x264 codec is ultimate?

                    / Olle
                    • 7. Re: Partial quicktime gamma shift solution...?
                      Level 1
                      Robert Scott.

                      Thanks for the answer. But did not work for me.

                      / Olle
                      • 8. Re: Partial quicktime gamma shift solution...?
                        mr. ichybob Level 1
                        Olle, I share your frustration, and have not found a solution. I have resorted to a adjustment layer called ".9 gamma adjust", not a solution but a work-around.

                        regards, Bob
                        • 9. Re: Partial quicktime gamma shift solution...?
                          craulmedia Level 1
                          as far as you work with quicktime, especially with H264 encoding, you'never find an end to this problem. Apple behaves so stupid whenever it comes to these kinda questions because they don't give a damn about pro apps users. anytime they bring out another quicktime release, something else is fixed, and different things are messed up.
                          By the way, quicktime player is a bad thing for referencing you work.
                          if you drop a H264 file into firefox browser, the gamma should be then ok.

                          if you want to have a peace of mind try working with image sequences as PNG, TIFF, TGA or try a much more reliable codec like Sheer Video Codec from Bitjazz.com