Processing and Formatting Effects > Flame FX > Matte Edge > Edges Settings >
Basic Settings

Width field
  Displays the value that affects how the basic edge-detection algorithm determines whether each pixel forms part of the edge.
Minimum Input field
  Displays the lower limit of the luminance values. Pixels with lower values are mapped to black.
Maximum Input field
  Displays the upper limit of the luminance values. Pixels with higher values are mapped to white.