Research On The Methods Of Electronic Image Stabilization For Shipborne Mobile Video

Shipbome mobile video technology covers the shortage of Radar and AIS in detecting small targets on sea surface,improving the situational awareness ability.However,the shipbome camera system moving with ship is affected by wind,current and vibration.It causes unstable images and difficulties to recognize targets.This thesis explores the digital image stabilization methods for shipborne mobile video to improve the video stability and support the target detection,motion tracking and target classification.It has been studied and analyzed about the characteristics of shipbome mobile video.Additionally,the inertial data and video data were collected synchronously.The finally yet importantly,it has been explored about two kinds of algorithms for shipbome video stabilization.They are based on feature matching with vibration measurement,and sky-sea line detection with genetic algorithm correspondingly.In the aspect of analyzing characteristic of shipbome mobile video,the inertial sensors were used to measure the vibration characteristics of ship and shipborne cameras,and the internal relations of vibration characteristics of ship and shipbome cameras were analyzed,in addition,the motion mechanism of shipbome mobile video was analyzed based on the camera imaging model,which establishes the foundation of developing digital image stabilization algorithm.In order to acquire the inertial data and video data synchronously,the camera was triggered by synchronizing signal from the inertial sensors,and synchronous acquisition prototype was developed.Basing on the synchronous data,a digital image stabilization method based on feature points matching and vibration measurement was proposed firstly,the strong and stable Harris corners which locate around the targets were selected by adaptive threshold Harris algorithm to improve the motion estimation accuracy,moreover,the motion filtering algorithms based on Fourier series curve fitting and vibration measurement were developed which output the motion compensation value to motion compensation algorithm,the experimental results show that the mean squared error declines 68%.Secondly,a digital image stabilization method based on sky-sea line detection and genetic algorithm was researched,the location of sky-sea line in next frame is estimated by fusing inertial data and Hough transform based on the location and angle of sky-sea line in the current frame,and the search region of sky-sea line declines about 80%-96%,the interference of sea clutter were declined at the same time,and the detection accuracy is 100%.Futuremore,the image motion was estimated by sky-sea line motion according to the sky-sea line motion analysis,and a filtering model for low frequency image waggles,which aims to stabilize the shipborne video and keep the image loss under a certain threshold was proposed,and it was solved by genetic algorithm,the experimental results show that the mean squared error declines 36%-62%.The research findings improve the stability of shipbome mobile video,moreover,the abilities of collision avoidance,anti-piracy,search and rescue were improved.