Techniques for low bit-rate video coding

Pao Yue-kong Library Electronic Theses Database

Techniques for low bit-rate video coding

 

Author: Wong, Kwok-wai
Title: Techniques for low bit-rate video coding
Degree: M.Phil.
Year: 2001
Subject: Digital video
Coding theory
Video compression
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Electronic and Information Engineering
Pages: vi, 111 leaves : ill. ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1557396
URI: http://theses.lib.polyu.edu.hk/handle/200/5301
Abstract: Digital video compression techniques play an important role in the multimedia information era. Hence, the objectives of this research work are to devise and develop efficient methods for video coding. In this thesis, different approaches for video coding such as block-based motion compensation coding scheme, and foreground/background video coding scheme will be described. Furthermore, several successful video coding standards such as H.261/H.263, and H.263+ will be reviewed in this thesis. Due to the nature of block-based coding, blocky artifacts may appear on the compressed video. We will also review some advanced video coding algorithms that solve this type of problems. As for the foreground/background video coding scheme, the first step is to segment out the targeted object in a video sequence. Since the major component for many applications, such as videophone and video conferencing, is the human face, we will also provide an overview of the techniques. In our research, we proposed an efficient algorithm for human face detection and facial feature extraction. The genetic algorithm and the eigenface technique are employed for detecting the face and facial feature regions in our approach. The genetic algorithm is applied to search for possible face regions in an image, while the eigenface technique is used to determine the fitness of the regions. As the genetic algorithm is computationally intensive, the searching space is reduced and limited to the eye regions in order to substantially reduce the computational time. Possible face candidates are then further verified by measuring their symmetries and determining the existence of the different facial features. Furthermore, in order to improve the level of detection reliability in our approach, the lighting effect and orientation of the faces are considered and their related problems solved. A very low bit-rate video coding algorithm by focusing on moving region has also been proposed. Eight patterns are pre-defined to approximate the moving regions in a macroblock. The patterns are then used for motion estimation and compensation to reduce the prediction errors. Furthermore, in order to improve the compression performance, the residual errors of a macroblock are rearranged into a block with no significant increase of high order DCT coefficients. As a result, both the prediction efficiency and the compression efficiency are improved. Finally, a foreground/background video coding system is developed for application of the videophone. We have also incorporated information about the facial features in our moving region based coding algorithm in order to provide a better picture quality perceptually.

Files in this item

Files Size Format
b15573965.pdf 3.859Mb PDF
Copyright Undertaking
As a bona fide Library user, I declare that:
  1. I will abide by the rules and legal ordinances governing copyright regarding the use of the Database.
  2. I will use the Database for the purpose of my research or private study only and not for circulation or further reproduction or any other purpose.
  3. I agree to indemnify and hold the University harmless from and against any loss, damage, cost, liability or expenses arising from copyright infringement or unauthorized usage.
By downloading any item(s) listed above, you acknowledge that you have read and understood the copyright undertaking as stated above, and agree to be bound by all of its terms.

     

Quick Search

Browse

More Information