Studies On The Technologies Of Detection And Restoration Of Blotches In The Degraded Image Sequences

Films are important sources to witness a national development and also invaluable artistic and cultural heritages.However,the image quality of archived films are often degraded gradually through aging,bad storage conditions or improper handling,such as fade,flicker,blotches,warping,scratch,noises etc.It is very important to restore these degraded archived films to obtain better visual effects.With the rapid development of computer and image and video processing technology,digital video restoration becomes the main method of degraded film restoration.Blotches are the common degradation defects in old film archives.Blotches have random sizes,shapes and locations and are usually caused by dirt,loss of film gelatin, improper copy handling.Because that the blotches of films have serious influences to the visual effect of the films and make the viewer feels uncomfortable,this thesis mainly deals with large blotches in the degraded pictures using the approaches of image and video processing such as image smoothing,motion estimation,motion vector repair and image restoration.The detail algorithms of blotches detection and restoration are also given.Blotches in the degraded pictures have the characters of temporal discontinuities and spatial coherence.This thesis designed and realized the algorithms of blotches detection and restoration by making use of these two characters and the model of the blotches detection and restoration proposed in the literature.The blotches detection algorithm is based on the four block-matching motion estimation methods and the SROD blotches detection method.A new post processing method,region labeling and the motion vector repair method based on the blotch mask is proposed.The edges of natural blotches in the sequence of the film are usually blurry.To eliminate the blurry area around the blotch caused by incomplete restoration,the over-restoration method is proposed.The software based on the algorithms proposed in this thesis is designed and developed with MATLAB.Experiments are conducted to test the performance of the proposed algorithm using the digital video data converted from the original films with blotches using a video cassette recorder.Finally,experimental results are given which verified the feasibility and practicality of the algorithm in this article.