Patent ID: 6553131
Filing Date: 2003-04-22
Classification: G06K

Abstract:
A method for recognizing license plates employing and intelligent camera with a processor and a memory, the method steps comprising:capturing an image including a license plate by the intelligent camera; detecting a region in which the license plate is located by performing a coarse localization of the image; detecting orientation, position, and illumination conditions of the image and accounting for the orientations, position, and illumination conditions of the image to obtain a baseline image of the license plate; performing a find localization of the baseline image to obtain a more accurate depiction of vertical resolution of the baseline image of the license plate; segmenting characters depicted in the baseline image by employing a projection along a horizontal axis of the baseline image to identify positions of the characters; classifying the characters based on statistical classifier to obtain a confidence score for the probability of properly identifying each character; and recursively performing the method steps until each confidence score exceeds a threshold value to recognize the characters, wherein the step of segmenting characters depicted in the baseline image by employing a projection along a horizontal axis of the baseline image to identify positions of the characters includes the steps of: providing a projection profile of pixel intensities across vertical lines of pixels in the baseline image; filtering the projection profile; and identifying locations of characters in the baseline image depicted by area below a threshold value in the filtered projection profile.