Digital Light & Color

Would anybody know a more graceful method of drawing an outline of a circle other than creating two circular masks with slightly different diameter, centering them, and Compositing solid colors until the circle is left?

The only other thing I can think of also has to do with masks: make a circular mask, feather it in slightly in step/round mode, and then XOR the two and use it in Composite with solid colours...

The Oval Gradient transformation can draw open circles if you feed it a color line with the right transitions.
There is also the Edge transformation, but subtracting two disks will make smoother lines.