4 Replies Latest reply on Oct 6, 2015 10:58 PM by Mathias Moehl

    Adding Just videos shadows


      I'm working on replacing a license plate in a video with a still image of another license plate.  I've got the tracking effect working great so it looks like it covers it perfectly, but the issue comes when a shadow of one of the actors passes over the plate.  It causes the still image to briefly look like it's floating oddly since the shadow doesn't effect it.  Any recommendations on how to make the shadow effect it?  So far all I've tried is duplicating the video and attempting to create different layer modes (hue, darken, etc), but none seem right.    

      I feel like this is something I've done before and am just brain farting on it....but stuck is stuck.  Any help would be greatly appreciated.

        • 1. Re: Adding Just videos shadows
          Mylenium Most Valuable Participant

          Extract the shadow by turning it into a b/w version using channel effects, use the license plate as a matte for it and use multiply blending mode.



          • 2. Re: Adding Just videos shadows
            shongu Level 1

            Would you mind explaining that with a little more detail please?  I have the duplicated video in black and white, but when I set the license plate to track matte to link (either Alpha or Luma) with the license plate layer as multiply, the image of the license plate either vanishes entirely or becomes a black license plate shaped spot.  If I set the black and white video layer as multiply, it appears to have no effect what so ever.  Any further details about which step I'm messing up would be a big help.  Thanks in advanced!

            • 3. Re: Adding Just videos shadows
              Rick Gerard Adobe Community Professional & MVP

              It would really help to see the shot with the shadow. Depending on the shot I'd probably add a colored solid above the original footage and then set the blend mode to something like screen or add or multiply so that I could see through the layer. The color of the solid depends on the color of the license plate. Let's say you choose orange. If orange was the color then multiply would probably work pretty well.


              Then I'd set the in point of the colored solid to the place where the license plate just starts to receive the shadow and start a simple roto of the shadow crossing the license plate. As soon as the shadow has passed the plate you can set the out point. Now you have a colored layer that crosses the license plate. Turn on the replacement license plate layer, move the colored layer above the replacement plate, then change the color to dark gray and set the blend mode to multiply. Adjust the opacity until the shadow matches the original shadow. If the shadow has soft edges then feather the replacement layer as needed.


              I think this would be easier than trying to extract the shadow from the original footage because the shadow is going to look different as it passes over the lighter and darker parts of the plate. Here's what I did in a couple of minutes to show you the process.

              Original footage:

              Screen Shot 2015-10-06 at 10.21.15 PM.png

              New Plate:

              Screen Shot 2015-10-06 at 10.21.32 PM.png

              Roto of shadow: (turns out blue showed up the best)

              Screen Shot 2015-10-06 at 10.19.50 PM.png

              Adjusting the color to make the shadow look right:

              Screen Shot 2015-10-06 at 10.22.32 PM.png

              Final Tweak a little mask feather.

              Screen Shot 2015-10-06 at 10.23.10 PM.png

              If there is a lot of camera movement or there is a bunch of other movement in the shot then stabilizing the shot to do the roto or using Mocha to do the roto may save you a bunch of time. It all depends on the shot, but the trick is using a dark solid rotoscoped layer as the replacement shadow and only doing the composite on the frames that absolutely need fixing.

              • 4. Re: Adding Just videos shadows
                Mathias Moehl Adobe Community Professional

                I would create a stabilized precomp for the region around the license plate with MochaImport+ or MaskTracker+ (both part of my Tracking Bundle).


                Inside the stabilized precomp, your license plate is not moving anymore, such that you can easily replace it with another one.

                If you just need to change a few numbers, you can do it with the clone stamp. Then you have only very little regions where you need to fix the shadows.


                Probably, for reconstructing the shadow, you need some manual masks + color correction. But in the stabilized precomp it will be much easier to get those masks right.


                See these tutorials to get started with stabilized precomps:


                MochaImport+ for AE Mini Tutorial 5: Stabilized Precomp | mamoworld



                MaskTracker+ in depth tutorial | mamoworld

                (mostly chapter 6 is relevant here)