Composite
If on, Maya renders objects so that they are not anti-aliased against the background. For example, a pixel on the edge of an object is not mixed with the background color. (In TIFF terms, Maya generates unassociated alpha.) If off, Maya anti-aliases objects against the background. Composite is off by default.
Tip
If you are rendering images for film or video, turn Composite off. If you are rendering images for a video game, turn Composite on.
Composite Threshold
Controls the amount of edge anti-aliasing in a matte if Composite is on. If you are rendering images for use in a video game, and you are using 8 or 16 bit color, set Composite Threshold to 1 for smooth matte edges, with no jagged edges. The default value is 0.