Introduction
The arithmetic capability of digital signal processors (DSPs), the multiple peripheral interfaces and the high frequency execution of the ARM processors make them an attractive choice for real time embedded systems. DSPs are already widely used for applications such as audio and speech processing, image and video processing, and wireless signal processing. Practical applications include surveillance, video encoding and decoding, and object tracking and detection in images and video. On the other hand, rapid development of Field Programmable Gate Arrays (FPGAs) offers alternative way to provide a low cost acceleration for computationally intensive tasks such as digital signal processing. Most of these applications use ARM, DSPs and FPGAs due to the processing power offered, in order to provide portability and real-time capability, and create custom embedded architectures for different application requirements. The main goal of this work is to design and implement efficient and novel architectures for automatic number plate recognition (ANPR) system using ARM-DSP System-on-Chip platform, which operates in high definition (HD) and in real time. In addition, a separate ANPR algorithm is developed and optimised, by taking advantage of technical features of FPGAs which accelerate digital image processing algorithms. The investigation of the algorithm and its optimisation focused on real time image and video processing for license plate (LP) or number plate localisation (NPL), LP character segmentation (NPS) and optical character recognition (OCR) in particular, which are the three key stages of the ANPR process [1]. ANPR often forms part of an intelligent transportation systems. Its applications include identifying vehicles by their number plates for policing, control access and toll collection.