8 Replies Latest reply on Apr 27, 2010 1:01 PM by FelixAE

    Question: Linear Workflow in AE CS4

    FelixAE

      Hey everyone, I've been reading up on LWF and I've got a question about it.

       

      When I set my AE project to 32bpc and "linearize working space", all footage I import (and interpret correctly) looks, blends and renders perfectly fine. As soon as I create something in AE though, say a simple black-white ramp, this will render too bright. If I apply inverse gamma on this ramp though (gamma 0.4545) it will render fine again. I find it hard to believe that this is the correct workflow, so does anybody know what I'm doing wrong here?

       

      Also, when working in a linearized working space, the color picker will show different (lower) RGB values in my composition than it will in the final render of my project. I suppose this is because AE measures the values before applying the project's color space LUT on the view. Again though, when I create something from scratch in AE, the RGB values will be fine in the view, yet too bright when exported from AE. I feel that my problem lies here somewhere.

       

      I would really appreciate if someone could point me into the right direction with this issue!

       

      Cheers,
      Felix

        • 1. Re: Question: Linear Workflow in AE CS4
          yenaphe Level 4

          In what workspace are you working ?

           

          When I work in 32bit, workspace sRGB-IEC61966-2.1, and check the linear workspace, all my colors are right.

           

          Have you got a special profile for your screen, and also, be sure that you are not previewing in another workspace in output simulation.

           

          Hope that helps

          • 2. Re: Question: Linear Workflow in AE CS4
            Mylenium Most Valuable Participant

            I agree with Seb. Sounds like you are using a specific monitor color profile which AE correctly figures in, but you may be applying it twice in the process. Assuming your screen is claibrated correctly, it might not even be required to use the profile. under the assumption that everything is perfectly linear, the monitor profile applied on the system level should sufficiently give a correct representation of all colors.

             

            Mylenium

            • 3. Re: Question: Linear Workflow in AE CS4
              FelixAE Level 1

              Thanks for the replies. I'm working in sRGB on a calibrated monitor, with sRGB as output profile as well. When I have "Display Color Management" disabled, everything looks too dark. If it's enabled, everything looks fine, yet color picker values will still be the "dark" values.

               

              An example: When I import a solid, 50% gray image (8bit, sRGB) into AE and enable "Dispaly Color Management", it looks good, even though my AE color picker will say it's only around 0.2 gray. When I render this image to sRGB then, the gray will be 50% again. When I add a solid inside AE to this image though, setting the solid RGB values to 0.5 and render the composition, the AE solid will be too bright.

               

              Maybe I'm just understanding the workflow the wrong way. Do I maybe have to use a Color Profile Converter effect on my footage or something?

              • 4. Re: Question: Linear Workflow in AE CS4
                yenaphe Level 4

                Hum...

                 

                are you using the system color picker by any chance ? Try switching it to Adobe one to see if you notice any difference. You can change it in the prefs.

                 

                When you say gray is around .2 do you mean it's nearly white, or nearly black ?

                • 5. Re: Question: Linear Workflow in AE CS4
                  FelixAE Level 1

                  I'm already using Adobe's color picker. By 0.2 I mean a 32-bit RGB value, i.e. almost black.

                  • 6. Re: Question: Linear Workflow in AE CS4
                    yenaphe Level 4

                    Well, I'm not a guru in LWF, and the pros will correct me if I'm wrong,

                    but it's normal that a 50% looking gray turns out to be around 0.2 in

                    32bit Linearized.

                     

                    Our eyes and brain apply a gamma curve to make us see clearer than the

                    things actually are. And what we see as a 50% gray is in fact in the

                    real world a value 18% gray (more or less, but it's around that value).

                     

                    What doesn't look logical in your problem is that your imported footage

                    isn't corrected accrodingly. Have you checked the option to do that in

                    the project pref settings ?

                     

                    FelixAE a écrit :

                     

                    Seb

                    I'm already using Adobe's color picker. By 0.2 I mean a 32-bit RGB value, i.e. almost black.

                    >

                    1 person found this helpful
                    • 7. Re: Question: Linear Workflow in AE CS4
                      Daniel Bach Level 1

                      Hi,

                       

                      what you are seeing is actually the expected behaviour. When you work in a linear workspace, 0.5 is no longer perceptual middle gray. Instead, it is merely one stop below full (1.0) brightness, which we perceive as light grey. Numbers in a linear workspace behave like light does in the physical reality. If you take a look at photography, what they use to measure middle grey is called an 18% grey card. If you work in linear light 0.18 is your middle grey value.

                       

                      To make a black to white gradient or really any color value you enter directly in After Effects work as you would expect (=as you are used from your gamma encoded normal workflow), apply a color profile conversion effect directly after the ramp and convert from your non-linearized working space to the linearized working space. For imported footage, this conversion is automatically done for you, but for values created inside AE there is no way of knowing if you want to enter these as values in a linearized space or in a gamma encoded space.

                       

                      You view window displays the image after the display profile has been applied and after the values have been correspondingly gamma encoded again (otherwise your screen would look very dark as soon as you work in linearized space). But yes, the readouts give you the "real" pixel values, not the ones after the view display profile conversion. Again, this really makes a lot of sense, it just takes a while to get used to it.

                       

                      Stu Maschwitz at www.prolost.com has a lot of good articles on compositing in linear light. Keep in mind that it is simply another tool, not necessarily "better" for a given job. Colors behave more like physical light behaves when using a linearized working space, but sometimes it makes a lot more sense to work in a perceptually uniform (gamma encoded) colour space.

                       

                      hth,

                      Daniel

                      1 person found this helpful
                      • 8. Re: Question: Linear Workflow in AE CS4
                        FelixAE Level 1

                        I was already expecting something like this. It all makes sense now! Thanks for clearing this up for me!