Subject: [NEXTEL-1] Theory and Applications of Scale Variant Signal Processing

From: [email-masked]
Date: Wed, 22 Oct 2003 14:10:58 -0400

Theory and Applications of Scale Variant Signal Processing

By Raghu G. Raj

We have recently studied theoretical properties of filtered scale-variant signals
[1]. In
our research project we propose to study applications of scale-variant signal
processing
to visual communications and visual search.

A central problem in wireless video communications is that the bandwidth of
typical
video signals is very large (i.e. video sources have high data rates) which makes
it difficult
to reliably transport video signals through wireless channels which typically are
highly
time varying in nature. Thus it is important to find optimal representations of
image/
video data streams that will minimize the source data rate and yet ensure that the
perceived
image/video quality is not appreciably degraded.

Traditional methods of image/video compression do not take into account the
properties
of the Human Visual System (HVS). By exploiting properties of HVS we can
potentially
remove many redundant features of a video stream which anyway will not be
perceived
by the human eye. A key observation in this regard is that the HVS processes
scalevariant
signals [1]. In particular, the eye densely samples the visual image in the
vicinity
of the point of fixation. The sampling density steeply decreases as a function of
distance
from the point of fixation. This non-uniform sampling of the eye is called
foveation.
In this way the original image is mapped to a foveated image (which is a special
type of
scale-variant image). The HVS uses the resulting scale-variant image for all
subsequent
processing and image understanding. Motivated by this fact researchers in the
Laboratory
for Image and Video Engineering (LIVE) at the University of Texas at Austin have
recently developed novel algorithms for low-bit rate, channel error resilient
wireless
video communications for scale-variant video streams.

As an extension of this we propose to study the Joint Source Channel coding
schemes
for scale varying video streams. It may be noted that due to the delay and
complexity
constraints associated with video communications, the classical Shannon result of
separation of source and channel coding no longer applies. Thus we expect
scale-variant
based Joint Source Channel codes to improve overall visual quantity at the
receiver as
compared to traditional coding schemes.

Another very important application of scale-variant processing which can have
extensive
applications to remote surveillance is visual search. In remote surveillance the
problem
is to automatically find an object in a visual field (which is located at a remote
site) while
continuously streaming the video data back to a central station. Thus the quantity
of
video data to be streamed can be significantly reduced by employing efficient
visual
search algorithms. We believe that exploiting the properties of scale-variant
signals is the key to attacking the above mentioned problems.

--
    "NEXTEL-1 IT'S NOT JUST NEXTEL"
  Note The New address
Subscribe to Nextel-1: http://www.groups.yahoo.com/subscribe/NEXTEL-1

  "NEXTEL2 FOR iDEN SOFTWARE DEVELOPERS"
Subscribe to Nextel2: http://www.groups.yahoo.com/subscribe/NEXTEL2

  "WIRELESS FORUM HOMELAND SECURITY GROUP"
     The Complete Resource for Wireless Homeland Security.
Subscribe to WFHSG:  http://www.groups.yahoo.com/subscribe/WFHSG

------------------------ Yahoo! Groups Sponsor ---------------------~-->
Buy Ink Cartridges or Refill Kits for your HP, Epson, Canon or Lexmark
Printer at MyInks.com. Free s/h on orders $50 or more to the US & Canada.
http://www.c1tracking.com/l.asp?cid=5511
http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/61FxlB/TM
---------------------------------------------------------------------~->

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/