1. A method for detecting at least one target rectangle in an image, the method comprising: receiving, in an image memory, an image from an image source; transforming the received image into a grayscale edge detection image; transforming the grayscale edge detection image into a binary image using a threshold value; determining horizontal and vertical sub-exlons for each picture element in the binary image; generating horizontal and vertical sub-exlon arrays from the determined horizontal and vertical sub-exlons; scanning the sub-exlon arrays to identify exlons for each of four corner types; and identifying the at least one target rectangle using the identified exlons by confirming that one of each of four corner types are properly oriented and connected by correctly oriented horizontal and vertical lines.