Research On Algorithms Of Video Compression And Image Stabilization

As the use of video becomes increasingly popular and wide spread in the areas ofbroadcast services, internet, entertainment and security-related applications, providingmeans for fast, automated, and effective techniques to represent video based on itscontent, such as objects and meanings, is important topic of research. In manyapplications, removing the hand shaking effect and making video images stable andclear or decomposing (and then transmitting) the video content into a collection ofmeaningful objects is a necessity. Therefore automatic techniques for video stabilization,extraction of objects from video data as well as transmitting their shapes, motion andtexture at very low bit rates over error networks, are desired.In this thesis the design of a new low bit rate codec is presented. Furthermore amethod for video stabilization is introduced. The main technical contributions resultedfrom this work are as follows.Firstly, an adaptive change detection algorithm identifies the objects from thebackground using a three-stage method. In the first stage, the luminance differencebetween framers is modelled in order to separate noise and illumination variations frommeaningful moving objects. In the second stage the segmentation tool based on imageblocks, histograms and clustering algorithms segments the difference image into areascorresponding to objects. In the third stage morphological edge detection, contouranalysis, and object labelling are the main tasks of the proposed segmentationalgorithm.Secondly, a new low bit rate codec is designed and analysed based on the proposedsegmentation tool. The estimated motion vectors inside the change detection mask, thecorner points of the shapes as well as the residual information inside the motion failureregions are transmitted to the decoder using different coding techniques, thus achievingefficient compression.Thirdly, a novel approach of estimating and removing unwanted video motion,which does not require accelerators or gyros, is presented. The algorithm estimates thecamera motion from the incoming video stream and compensates for unwantedtranslation and rotation.A synchronization unit supervises and generates the stabilized video sequence. Thereliability of all the proposed algorithms is demonstrated by extensive experimentationon various video test sequences.