Study On Key Techniques Of Video Preprocessing

In order to obtain high video quality and high compression, video preprocessing plays more important roles in video processing and communications. In this dissertation, the processes that are performed between the video sensor and the output of the capture device are studied in depth. We pay more attention on the automatic white balance and flicker reduction.Automatic white balance is one of the most important functions in video preprocessing which is introduced to compensate the color difference of video caused by various light sources. A new algorithm is put forward in this paper which is based on the analysis of the property of gray color points under different color temperature sources. The results show that the proposed algorithm can provide a good perceive effect and has the advantages of fast convergence and strong robustness.Flicker is introduced because of the asynchronization between the frequency of the lighting system and the captured frame rate which degrades the video quality extremely. In this paper, a flicker reduction algorithm is proposed which can directly extract the flicker information from a flicker-existing video. Reference blocks are used to trace the variation of the flicker. If the content of these reference blocks changes, the flicker can be predicted according to the periodicity of the flicker. The experiments show that the proposed algorithm can reduce the flicker efficiently and improve image quality significantly.