Hiding Identity Through Mask Shape and Mask Feather

Posted on by Larry

[ This article was first published in the August, 2004, issue of
Larry’s Monthly Final Cut Studio Newsletter. Click here to subscribe. ]

Last month, I showed you how to hide someone’s identity using a traveling matte.

This month, I want to show you a technique suggested by Tom Wolsky, where the mask, shape, and tracking are all contained on one layer, rather than two layers in a traveling matte.

Here’s how it works.

  1. Put a clip which has something you want to hide on V1. (In this technique, audio is irrelevant, so I have deleted it to simplify the screen shots).



  3. Go to the Generators menu and select, “Matte > Color.” This creates a solid frame of 50% gray.



  5. Click the Controls tab and click the small color chip to open the color picker. Change the color to something more appealing, like, um, black.

  7. Edit the color to the Timeline and place it on V2, immediately above the clip on V1. (A fast way to do this is to drag the color from the Viewer to the Canvas and drop it on the Superimpose overlay. FCP automatically places it on top of the V1 clip and trims the color clip to the same length as the clip on V1.)

  9. Select the color clip and apply two filters to it — in this order: Effects > Video Filters > Matte > Mask Shape and Effects > Video Filters > Matte > Mask Feather. Double-click the clip to load it into the Viewer and click the Filters tab.



  11. The Mask Shape should be the top filter. Adjust the shape to meet the needs of your mask.



    For instance, an oval does a great job at hiding a face, in this case, our felon puppy from last month’s article.



  13. Next, adjust the Mask Feather to smooth the edges of your shape to meet the needs of the project; there is no “right setting” for this. In this example, I used a setting of “9.”

  15. Now, go to the Motion tab and set keyframes for the Center position so that the position of the mask blocks whatever you need to hide as it moves during the duration of the V1 clip.

For what it’s worth, after all the effort to create traveling mattes for the show I wrote about last month, the producer decided that even suggesting there was a bare posterior under the effect was far too salacious, so they replaced the shot and killed the effect. Sigh… so much for technique.

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