Using phase to represent radius in the coherent circle Hough transform

Edge orientation is used to reduce the parameter space from three to two dimensions, and lines pointing away from edge points are plotted rather than circles. Intersections of these `spokes´ accumulate edge magnitude, or `energy´, near the centres of circles in the conventional energy CHT. The authors use a complex accumulator space and allow each spoke to vary in phase along its length. They present results for a circle with added noise for both the conventional energy CHT and the new coherent CHT. The results demonstrate that the technique reduces the mean and variance of the background level in the accumulator array, and the peak width