9 Replies Latest reply on Mar 22, 2010 12:16 AM by Mentors Channel

    Chroma key while fading in

    Mentors Channel

      Hello,

       

      I've got a blue screen video that is fading in while it starts. I want to use chroma key on it and place a background image. Using the usual chroma keying causes this fade effect to overcome the keying and it doesn't look good. It seems like the chroma key is taking effect step by step until the fade in is being completed. I would like to know if there is a way to solve this. (Please see some images attached) 01.JPG

      02.JPG

      04.JPG

      03.JPG

      Thanks a lot.

        • 1. Re: Chroma key while fading in
          Mylenium Most Valuable Participant

          Do the key in a pre-comp, then fade the pre-comp as a layer in your main comp.

           

          Mylenium

          • 2. Re: Chroma key while fading in
            Clint Porter Level 1

            Is the fade already baked into your source footage? (if not, do what Mylenium said)

             

            If so, since you're only dealing with a handful of frames, you should totally rotoscope this. (Mask it and animate the mask path frame-by-frame)

             

            You may even get away with keyframing the mask on only every 4th or 5th frame if his motion is pretty smooth.

             

            Clint

            1 person found this helpful
            • 3. Re: Chroma key while fading in
              Mentors Channel Level 1

              Hi Clint,

               

              Thanks for the detailed reply.

              Yeah it is in the source file, I guess it will take a while to over the frames of 60 files like this.

               

              Thanks for helping me out.

              • 4. Re: Chroma key while fading in
                Clint Porter Level 1

                60 files - ouch!!

                 

                No doubt you're running to educate the cameraman/prior editor on effects they should never *ever* add to bluescreen footage…


                I was thinking about this after I wrote the other note, and you may be able to streamline this process a bit:

                 

                1. You go to the first frame after the dissolve, enable your Keylight effect, and then use AE's Auto-trace to create the mask for you. Add a keyframe to the Mask Path property.

                 

                2. Turn off Keylight, go back to the first frame (that you can see) and add another keyframe to the mask path. Adjust the mask shape as necessary.

                 

                3. Go to the frame exactly between your two keyframes, and adjust the mask as necessary. Repeat this step as many times as necessary (but no more - you have better things to do!)

                 

                One other thing, you might find the Exposure control in the viewer pane useful for making the picture easier to make out at the beginning of the dissolve.

                1 person found this helpful
                • 5. Re: Chroma key while fading in
                  Mentors Channel Level 1

                  yes, the camera man surely made a mess of this.

                  I appreciate your help Clint. Thanks a lot!

                  I will have to consider whether it is worth to waste so much time on this though.

                  Maybe I'll put a constant image that fades in with the man+background and play the video from the frame when the chroma key takes effect it will surely look less professional but it will save a lot of time, no to mention the awful lightning that I have to deal with at the background...

                  • 6. Re: Chroma key while fading in
                    Rick Gerard Adobe Community Professional & MVP

                    This is a perfect application of time remapping. Take your clip that contains the fade in and apply Time Remapping. Now move to the first frame where the fade in is complete and set a keyframe there.  Now delete the first keyframe at the start of the Time Remapping property.

                     

                    The first frame will hold until the first keyframe, then play normally. All other settings should stay the same.

                     

                    Here's what the TLW should look like. In this example I've assumed that your fade in ends at frame 24 so I've added a new keyframe there. You then select the first keyframe - the one in yellow, and delete it.

                     

                    timeRemap.png

                    I hope this saves you some time

                    • 7. Re: Chroma key while fading in
                      Mentors Channel Level 1

                      Hello Rick,

                       

                      Thank you for your advice. I did what you suggested but the audio was cut as well. The video did hold till the frame where the keying started but without the audio...

                       

                      Thanks again.

                      • 8. Re: Chroma key while fading in
                        Rick Gerard Adobe Community Professional & MVP

                        Just duplicate your layer and take only the audio from the duplicate. Turn off the audio on the layer with time remapping applied. Turn off the visibility of the duplicate you're using for audio.