Nonuniformly Illuminated Image Enhancement Based on Range-gated Underwater Imaging System
会议名称：《2008 International Conference on Optical Instruments and Technology》
会议日期：2008年
学科分类：08[工学] 080203[工学-机械设计及理论] 0802[工学-机械工程]
基 金：supported in part by the National 863 Program under Contract 2006AA09Z207 in part by the National Defense Pre-research Fund under Contract 51405020405BQ01
关 键 词：Nonuniformly illuminated image range gated underwater imaging
摘 要：Range-gated underwater laser imaging technique can eliminate most of the backscattering and absorption noise *** has a range of from 4 to 6 times that of a conventional camera with floodlights in the strongly scattering waters,which becomes a useful technique in oceanic research,deep-sea exploration,underwater remote control and robotic *** because of the laser pulse stretching,the image obtained through range gated underwater imaging system has obvious nonuniformly illuminated character,such as brighter center and darker *** contrast and grayish white of the image also bring great difficulty for *** order to adjust the lightness of the nonuniformly illuminated image of range-gated underwater imaging system,the water degradation is assumed as illumination variation and retinal-cortex theory based on color constancy is *** integral algorithm has to be applied first to eliminate system noise for the reason that we adopt the system based on intensified gate imaging *** gray stretch ensures that we can attain appropriate *** retinal-cortex models,McCann model and McCann-Frankle model have obvious *** we choose the two models for comparison and improve the second one considering the exponential characteristics of eyes for *** order to evaluate the methods objectively,strength uniformity of signals is *** experimental results demonstrate that the approaches we adopted are all effective and can enhance the image *** the improved McCann-Frankle model gets more satisfying visual effect.