Annotation free license plate recognition method and system

摘要

The invention encompasses methods and systems for automatically recognizing a license, registration or number plate character (ALPR). Synthetic license plate character images are generated for a target jurisdiction (e.g. a particular state). A limited set of license plate images can be captured for a target jurisdiction utilizing an image-capturing unit (e.g. camera). The license plate images are then segmented into license plate character images. The license plate character images collected for the target jurisdiction can be manually labeled. A domain adaptation technique is utilized to reduce the divergence between synthetically-generated and manually-labeled image sets. Additionally, OCR (optical character recognition) classifiers are trained utilizing the images after the domain adaptation method has been applied. Input license plate character images can then be received from the target jurisdiction. Finally, the trained OCR classifier is employed to determine the most likely labeling for the character image and a confidence associated with the label.