6 Replies Latest reply on Dec 9, 2011 6:35 PM by phillyac

    Correcting Rotobrush w/out re-propogation when unfreezing

    5 O'Clock

      I've successfully refrained from asking a question for over 1 year of Adobe use... so humor me here!


      I've rotobrushed a 3 sec clip, which is separated into 4 spans.  Made lots of changes to original brush-selected edges along the way via additional strokes (by strokes I mean swipes of green/red with rotobrush if that is the correct term).  Hit Freeze.


      Now several days later, and having added a background, I see the need to fix certain edges of roto'd item in approximately 10% of the frames.  The rest of the frames are roto'd as I'd like them to stay.


      When I "unfreeze" it repropagates everything, eliminating all my previous work in refining the lines.


      So what is the best approach to go back and change the rotobrushed edges in select frames, without it automatically changing other frames?


      (Just FYI, refine matte options, etc, are inadequate to fix the edges on the frames I'm discussing, thus changing the edges of roto effect is necessary).



        • 1. Re: Correcting Rotobrush w/out re-propogation when unfreezing
          Mylenium Most Valuable Participant

          Export everything with an Alpha channel, reimport, then refine. Alternatively, use the rendered snippet as a matte on the original and keep refining that.



          1 person found this helpful
          • 2. Re: Correcting Rotobrush w/out re-propogation when unfreezing
            Rick Gerard Adobe Community Professional & MVP

            If I have a complex rotobrush project I almost always end up with more than one layer. Did one the other day that required about 50 frames of hand masking to fix problems rotobrush just couldn't handle.


            The compression and colorspace of your original footage also makes a big difference. GOP footage that is highly compressed doesn't work very well. Apple ProRez444 or other YUV nearly lossless codecs work much better. It even helps to transcode footage from P2 or XDCam before trying the rotobrush.


            Hope these suggestions help.

            1 person found this helpful
            • 3. Re: Correcting Rotobrush w/out re-propogation when unfreezing
              5 O'Clock Level 1

              Ok, as I understand it, if I not only need to cut out more of background, but also need bring back portions of the object that have been cut out by roto, this would be accomplished best by your second method of matte over original.


              With the first method, does it retain the ability to add to the alpha and reintroduce previously cut-out portions of the object?


              I thought of just trying add and subtract mask w/ pen tool as necessary, but didn't think this a very practical solution, and on first try seemed to eliminate rotobrush strokes. 


              I suppose I better just test all these myself before asking further questions.


              Thanks for the good options!

              • 4. Re: Correcting Rotobrush w/out re-propogation when unfreezing
                5 O'Clock Level 1

                So just masking w/ pen tool on another layer does work like it should.  I'll go back and figure out what I did wrong when I tried.


                I'm shooting Canon 5D, using CS5 on PC, so I should transcode to YUV uncompressed then I suppose.  Didn't realize this was relevant in this context, as I thought rotobrush would see color and contrast as "a pixel is a pixel" so to speak.  No need to explain it to me, I'll do as you say, and research later to better grasp the concept.


                Thanks for lending your knowledge!

                • 5. Re: Correcting Rotobrush w/out re-propogation when unfreezing
                  5 O'Clock Level 1

                  Ok, paint brush with paint option "channel" set to "alpha" on the originial roto'd layer accomplished the goal.  It took me a while to get all the details figured out.

                  • 6. Re: Correcting Rotobrush w/out re-propogation when unfreezing

                    OMG THAT'S IT!!!! Thank you so much for posting this solution. I have been trying for several days to fix a few frames here and there with my RotoBrush work. The brush works great, but after I set the comp, I'll notice small imperfections that I wanted to tweak, and didn't know how, on a frame by frame basis. Using the paint brush in Alpha mode is genius! Why doesn't Adobe post this with their RotoBrush tutorials??? It's a quick instant fix without having to correct anything the rotobrush originally set up. THANK YOU!