Unifying Approach for Fast License Plate Localization and Super-Resolution

This paper addresses the localization and super resolution of license plate in a unifying approach. Higher quality license plate can be obtained using super resolution on successive lower resolution plate images. All existing methods assume that plate zones are correctly extracted from every frame. However, the accurate localization needs a sufficient quality of the image, which is not always true in real video. Super-resolution on all pixels is a possible but much time consuming alternative. We propose a framework which interlaces successfully these two modules. First, coarse candidates are found by an weak but fast license plate detection based on edge map sub-sampling. Then, an improved fast MAP-based super-resolution, using local phase accurate registration and edge preserving prior, applied on these regions of interest. Finally, our robust ICHT-based localizer rejects false-alarms and localizes the high resolution license plate more accurately. Experiments which were conducted on synthetic and real data, proved the robustness of our approach with real-time possibility.