An improved algorithm based on randomized circle detection is presented The large amount of useless accumulations yielded by random sampling of randomized circle detection algorithm and the useless square computations resulted from the outlier edge points during the evidence-collecting phase are solved First

the edge pixels with 8-adjacency connectivity are connected

and three edge pixels in the same connected curve which can exactly determine a possible circle with center and radius are randomly picked When a possible circle is found

an evidence-collecting process is implemented to further verify whether the possible circle is a true circle or not

in which only the edge points locate between the circumscribed square and the inscribed square of the possible circle are considered Compare to conventional detecting algorithm

the proposed algorithm consumes less computing resources

has better detection performance when comparing to other methods and can detect circular arc or partly overlapped circles by the experiments