Research Of High Dynamic Range Imaging Technology

For human being, most of the information is acquired by human vision, and image is the most important visual information source. The digital imaging technology plays great pole in the modern information fields. Theoretical and experimental researches for the high dynamic range digital imaging system are carried out in this paper.Information theories are imported into the dynamic range research of imaging system for the first time. The relationship between information rate and dynamic range is revealed clearly: with constant exposure, system dynamic range has a negative reciprocal relation with the image entropy, which means the bigger dynamic range leads to bigger image entropy.According to the information theory view, three directions to extend the system dynamic range are concluded: temporal extending, spatial extending and self-adaptive extending. Three new dynamic range extend methods with spatial light modulator (SLM) are proposed: temporal SLM multi-exposure method, spatial light encoding method and self-adaptive PID feedback control method. The influence to the dynamic range of these methods are discussed, the theoretical maximum dynamic range is the product of the SLM dynamic range and image sensor dynamic range. Results of data simulation prove that the system dynamic range can be extended effectively.Designed and successfully realized a high dynamic range imaging system based on LCoS and CCD. Three dynamic range extending experiments are performed with this system: temporal SLM multi-exposure method, spatial light encoding method and self-adaptive PID feedback control method. Experimental results and discussion for each method are provide, the applicable range of each method is also discussed.Optimize method based on information rate calculation for multi-discrete-devices imaging system is proposed for the first time. By this method, the information rate of the whole system is taken as the indicator to seek the optimized matching relation among discrete devices, and also to determine the optimized position of these devices, and thus the influence of Moire fringe in the system can be reduced effectively.A new tune mapping arithmetic based on incomplete beta function is proposed for the first time. This method combined the global method and local method, and has high efficiency and good adaption. High dynamic range can be compressed into normal range to be displayed on general monitor.