Research on Skewed License Plate Recognition: A Systematic Literature Review

A plate recognition system is an application of computer vision technologies for detecting and recognizing vehicle license plates. Several disturbances cause the system to be inaccurate in detecting and recognizing vehicle license plates. One of several disturbances is perspective distortion due to image taking with an incorrect camera angle. This distortion causes the captured license plate to be bent from its actual shape. In order to overcome perspective distortion, a variety of techniques have been developed to increase the plate recognitions system's ability. However, to the authors' best knowledge, there is no review paper that discusses various studies on handling perspective distortion in plate recognition systems. Here we present a systematic literature review to help researchers in addressing the recognition of skewed license plates. This study compares several studies published between 2015 and 2020 on plate recognition techniques, especially those related to skewed license plate recognition. The search process was conducted on databases of research literatures and resulted in 25 primary studies. This paper also identifies various datasets and methods to obtain a comprehensive understanding as a reference in developing the plate recognition algorithm.