Comparison of real-time DSP-based edge detection techniques for license plate detection

In this paper, edge detection techniques and their performance are compared when applied in license plate detection using an embedded digital signal processor. License plate detection remains to be the crucial part of a vehicle´s license plate recognition process. The edge detection algorithms compared in this work are those reported capable of delivering real-time performance. These are Canny-Deriche-FGL, Haar and Daubechies-4 wavelet transform and the classic Sobel. These particular algorithms are chosen and compared due to their good performance on digital signal processors. The comparison is drawn in terms of speed and detection success of a license plate. The results show Haar wavelet-based edge detector performs better on a DSP with LP detection speed of 7.32 ms and 98.6% success using 45,032 UK images containing license plates at 768×288 resolutions.