PreliminariesBackground Subtraction GregMori CMPT888 Outline - - PowerPoint PPT Presentation

preliminaries background subtraction
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PreliminariesBackground Subtraction GregMori CMPT888 Outline - - PowerPoint PPT Presentation

PreliminariesBackground Subtraction GregMori CMPT888 Outline Alittlebitonbackgroundsubtraction BackgroundSubtraction BasicPipeline Background Mixtureof Background


slide-1
SLIDE 1

Preliminaries
–
Background
 Subtraction


Greg
Mori
 CMPT888


slide-2
SLIDE 2

Outline


  • A
little
bit
on
background
subtraction

slide-3
SLIDE 3

Background
Subtraction


slide-4
SLIDE 4

Basic
Pipeline


Background
 Model
 Mixture
of
 Gaussians
 Background
 Image
 Median
value


  • f
each
pixel

  • ver
time


Absolute
value
of
 difference
with
 background,
thresholded
 EM
fitting
 Likelihood
under
 background
model,
 thresholded
(or
not)


slide-5
SLIDE 5

Many
Pitfalls


  • Background
subtraction
is
not
perfect
in


practice


– Background
changes
 – Foreground
looks
like
background
 – Objects
stop
moving
 – …


  • But
it’s
a
useful
signal,
combine
into
human


detector


slide-6
SLIDE 6

Summary


  • For
more
information:


– Chris
Stauffer
and
W.E.L.
Grimson.
Adaptive
background
 mixture
models
for
real‐time
tracking.
CVPR
1999
 – Kentaro
Toyama,
John
Krumm,
Barry
Brumitt,
and
Brian
 Meyers.
Wallflower:
Principles
and
practice
of
background
 maintenance.
ICCV
1999