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Matte Choker (PB only)


    The Matte Choker repeats a sequence of choking and spreading the matte to fill undesired holes (transparent areas) in opaque regions. The repetition is necessary because the entire matte must be choked and spread; the spreading fills the hole, but the edges of the matte must be choked back to preserve the matte shape.

    The sequence of choking and spreading occurs in two stages, each with its own set of identical controls. Typically, stage two does the opposite of stage one. After a specified number of back-and-forth adjustments (which are handled automatically by the Matte Choker), the hole is filled and the matte shape is preserved.

    Undesired transparent and semitransparent pixels (holes) in image (left). Holes filled by Matte Choker, preserving shape of image (right).
    Undesired transparent and semitransparent pixels (holes) in image (left). Holes filled by Matte Choker, preserving shape of image (right).

To close a hole in a matte using the Matte Choker:

  1. Select the layer and choose Effect > Matte Tools > Matte Choker.
  2. Set stage-one controls (the first three sliders) to spread the matte as far as possible without altering its shape, as follows:
    • Geometric Softness specifies (in pixels) the largest spread or choke.
    • Choke sets the amount of choke. Negative values spread the matte; positive values choke it.
    • Gray Level Softness specifies how soft to make the edges of the matte. At 0%, the matte edges contain only fully opaque and fully transparent values. At 100%, the matte edges have a full range of gray values, but may appear blurred.
  3. Set stage-two controls (sliders four, five, and six) to choke the matte by the same amount you spread it in stage one.
  4. Use the Iterations slider to specify how many times After Effects repeats the spread-and-choke sequence. You may need to try a few different settings so that the sequence is repeated as many times as necessary to close any unwanted holes.