Bitmap Tracer Dialog Box - Final Color Tolerance
Color tolerance is how great a color change is required before the tracer considers two areas to be a different color.
This setting is used for the final pass. It is similar to merging the edges of color transitions to simulate shading.
As a trace proceeds, the color tolerance is reduced from the initial value to the final value, so the initial value must be the larger.
For a trace using only a single pass only this value is used - Initial Color Tolerance is ignored.