1. A method for detecting circles in digital images, the method comprising: (a) computationally detecting edge pixels in an image and storing coordinate information of the detected edge pixels in a plurality of edge buffers based on edge angles associated with the pixels; and (b) computationally identifying, successively in each of at least one selected line of the image, centers of circles having radii within a specified range by (i) identifying, for each edge angle, lines of edge pixels whose distance from the selected line is within the specified range of radii, (ii) parsing the identified lines of edge pixels and, based at least in part on the edge angle and the coordinate information of the detected edge pixels, accumulating votes from the edge pixels on the selected line, and (iii) identifying the centers in the selected lines based at least in part on the accumulated votes.