Preview

PDF whole_GunawanDa...pdf | Download (22MB) Available under University of Tasmania Standard License. | Preview

Abstract

Visual communications services are now making a significant impact on modern society.
Video conferencing, HDTV and multimedia are just examples where this technology is
being used to good effect. Communicating using video signals does, however, require a
large volume of data to be transmitted, and even with modern high-bandwidth communication
links this can be expensive. This requires the implementation of efficient
video coding and compression schemes. This thesis investigates both image and video
coding compression schemes and aims to develop a scheme with the highest possible
performance.
In image coding there are two main types of compression: statistical and psychovisual.
This thesis concentrates on the latter, since it is shown that psychovisual techniques,
in general, provide greater levels of compression than statistically based methods. The
standardised technique for video coding uses psychovisual compression of the coefficients
of the discrete cosine transform (DCT). Despite being an international standard
for low bit rate video coding the DCT suffers from a number of drawbacks. Firstly,
the psychophysical and psychological models of the human visual system (HVS) are
based on a multiresolution approach whereas the basis functions of the DCT are fixed
in resolution. Secondly the basis functions of the DCT only possess good localisation
properties in the frequency domain and not the spatial domain, a characteristic that
blurs edges and discontinuities in an image. By contrast the wavelet transform is a multiresolution
approach and its basis functions can possess good localisation properties in
both the spatial and frequency domains. Furthermore, due to the excellent localisation
properties of the wavelet function most of the transform coefficients are practically zero
and the use of wavelet transform can be expected to achieve a higher compression ratio
than the DCT. This thesis therefore investigates psychovisual transform coding using
the wavelet transform instead of the DCT.

Item Type:	Thesis - PhD
Authors/Creators:	Gunawan, D
Keywords:	Video compression, Wavelets (Mathematics)
Copyright Holders:	The Author
Copyright Information:	Copyright 1995 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).
Additional Information:	Thesis (Ph.D.)--University of Tasmania, 1995. Includes bibliographical references (p. 187-198)
Item Statistics:	View statistics for this item

Actions (login required)

Item Control Page