computational vision n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Computational Vision PowerPoint Presentation
Download Presentation
Computational Vision

Loading in 2 Seconds...

play fullscreen
1 / 23

Computational Vision - PowerPoint PPT Presentation


  • 114 Views
  • Uploaded on

Computational Vision. Lecture 1: Overview + Biological Vision Jeremy Wyatt. What you should be able to do. Make informed choices about which sort of algorithms to apply to solve specific problems. Use standard vision libraries or software to construct working vision systems.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Computational Vision' - maitland


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
computational vision

Computational Vision

Lecture 1: Overview + Biological Vision

Jeremy Wyatt

what you should be able to do
What you should be able to do
  • Make informed choices about which sort of algorithms to apply to solve specific problems.
  • Use standard vision libraries or software to construct working vision systems.
  • Apply algorithms to simplified problems by hand.
  • Discuss the advantages and drawbacks of different methods, explaining their working.
schedule
Schedule
  • 1 lecture a week, Mondays @ 2pm, Muirhead
  • 1 lab/lecture a week, Thursdays @ 12pm (Robot Lab or Chem Eng)
  • I am currently away on Monday Oct 3 and Monday Nov 14, so there will be no lectures on those days
syllabus
Lectures

Biological Vision

Edge detection

Hough transforms

Motion/Depth

Recognising objects

Recognising events

Recognising faces

Visual attention

Labs

Matlab tutorials

Edge detection

Hough transforms

Face recognition

Object recognition

Syllabus
assessment
Assessment
  • 70% 1.5 hour unseen exam in May/June
  • 30% 3 page experimental write-up of one of your labs (in pairs)

(due Dec 7 12 noon)

biological vision
Biological Vision
  • Light and image formation
  • Retinal Processing
  • Colour
  • Visual Pathway
  • Striate Cortex
visible spectrum
Visible spectrum
  • Humans perceive electromagnetic radiation with wavelengths 380-760nm (1 nm = 10-9 m)

0.1nm 10nm 1000nm

image formation
Image Formation

Light rays

Lens

Image plane

  • f is the focal length (in metres)
  • is the power of the lens (in dioptres)
  • Human eye has power ~59 dioptres

f

image formation1
Image Formation
  • Most of the refractive power of the human eye comes from the air-cornea boundary(49 of 59 dioptres)
  • As an object moves closer the power of the lens must increase to accommodate
  • So if the object is infinitely far away
  • But if it is 1m away the lens must

change shape to produce a sharp image

u

v

image formation2
Image Formation
  • As an object moves in world how does it move across the image plane?
  • If the image plane is curved then as q gets larger this becomes a worse and worse approximation

h

v

q

i

u

retinal processing
Retinal Processing
  • 120m rods, 6m cones
retinal processing1
Retinal Processing
  • Amacrine and horizontal cells integrate receptor outputs
  • More rods connect to each ganglion cells: less acuity, but greater sensitivity
  • Ganglions have receptive fields
types of ganglion cell
Types of Ganglion cell

OFF Cell

ON Cell

  • Centre surround cells

Light

OFF area

ON area

ON area

OFF area

Time

Light spot

colour
Colour
  • Two theories/systems
  • Trichromatic (Young-Helmholtz)
  • Explains
    • How we discriminate wavelengths 2nm in difference
    • How we can match a mixture of wavelengths to a single colour
    • Some types of colour blindness
colour1
Colour
  • Trichromatic theory can’t explain colour blending

Bluey green

Orange

?

Greeny red?

?

Yellowy blue?

opponent colour theory
Opponent Colour Theory
  • Ganglion ON cells sensitive to outputs of cones

OFF

ON

opponent colour theory1
Opponent colour theory

Red on

Green off

Yellow on

Excitatory

Inhibitory

the striate cortex
The striate cortex
  • Composed of hyper-columns
  • Within each are columns of cells tuned to features of a particular orientation
summary
Summary
  • Image formation
  • Very early visual processing
  • Filling in and perceptual effects
  • Colour perception
  • Eye-cortex mapping
reading
Reading
  • Vicki Bruce, Visual Perception, pp1-60
  • Neil Carlson, Physiology of Behavior, pp142-157