• Adobe After Effects

  Visible outline on Alpha Channel Mask

  Posted by Will Scott on January 6, 2014 at 1:41 pm

  I am using an alpha channel mask to layer a Tiff over a RAW time lapse sequence, however I cannot get rid of an outline that appears around the mask. Attached is a picture to make things easier.

  Thanks in advance, Will.

  Darby Edelen replied 12 years, 8 months ago 3 Members · 6 Replies
• 6 Replies

• 

  Will Scott

  January 6, 2014 at 4:14 pm

  Just realised how to get the image to show, my bad!

  
• 

  Chris Evans

  January 6, 2014 at 8:38 pm

  Try using the Simple Choker effect.
• 

  Will Scott

  January 6, 2014 at 9:19 pm

  Thanks Chris, I will check that out.
• 

  Darby Edelen

  January 7, 2014 at 4:58 am

  How are you creating the images that you’re laying over the background?

  Darby Edelen
• 

  Will Scott

  January 7, 2014 at 6:53 pm

  Hi Darby,

  I have basically taken 4 frames from the RAW sequence and created TIF files and then keyframed the opacity and movement of these to match the rest of the clip. It was shot with motion control so it is a moving piece. The outline only seems to be on the first one.

  Will.
• 

  Darby Edelen

  January 9, 2014 at 5:06 am

  Possibly a misinterpreted alpha, a rogue effect, or the image was premultiplied with a non-black color (white?). Just guesses. If you can upload the problem image we might be able to diagnose a bit easier.

  Darby Edelen

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