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Change shape on mask for image on top of clip, frame by frame

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Anders Östman
Change shape on mask for image on top of clip, frame by frame
on Feb 12, 2015 at 9:40:53 am

Hi,
First post here so please be gentle! ;)

I'm struggling to learn Premiere Pro and After Effects the past weeks and now I've got a problem I need to solve. In one video clip I need to hide a small part (a company logo) and what I'd like to do is to cover the part with an image. So far I'm ok and I've also done motion tracking to the underlaying video so the image now smoothly follows the video below.

The problem is that a few times in the video clip there's an object moving and I need to mask the image so that the object in the clip is visible when it's partly over the logo I need to hide.

I understand that I need to do this mask changing on every frame since the mask will need to change shape on each frame. What's the easiest way to accomplish this?
I tried to change the square mask to a more exact form using the pencil but it felt awkward and not that smooth. What I'd like to do is to have a square mask and then use the eraser pen so erase the part of the mask, but I don't seem to get this to work.

Any ideas and hints for me here are highly appreciated!
Cheers!


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John Cuevas
Re: Change shape on mask for image on top of clip, frame by frame
on Feb 12, 2015 at 2:10:55 pm

Use the Rotobrush tool. It's not exactly intuitive, so check out these tutorials.

Rotobrush Tutorial

Isolating a Subject with Roto Brush

Johnny Cuevas, Editor
Thinkck.com

"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.


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Anders Östman
Re: Change shape on mask for image on top of clip, frame by frame
on Feb 12, 2015 at 7:54:01 pm

Thanks for your answer.
I'm not sure it will solve my problem though. I've read about it the past days but I'm not sure...

My problem is that I want to mask out the top layer with the still image, on the frames where the underlaying interacts with that zone.

The still image is a logo that I want to put over a logo in the clip below when one's persons arm is over the logo in the video. So it's not the video clip I want to mask, it is the layer on top with the still image.

Or, do you still believe the Rotobrush will do the trick for me?!

Thx! :)


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John Cuevas
Re: Change shape on mask for image on top of clip, frame by frame
on Feb 12, 2015 at 8:49:02 pm

If I'm reading it right, occasionally something in the video, moves over the logo and you don't want that obscured by your still image. Yes, use rotobrush.

Take your video layer, duplicate and place it at the top of the layer stack. Now roto the things that move over the logo, that were obscured by the still image. It may be easier to make multiple duplicates of your video layer for each instance you need to roto.

Johnny Cuevas, Editor
Thinkck.com

"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.


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Anders Östman
Re: Change shape on mask for image on top of clip, frame by frame
on Feb 12, 2015 at 9:52:09 pm

Thanks, the missing idea in my head was to duplicate movie, place it over the image and use Rotobrush on the top movie. That did the trick! Thanks a lot! :)


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