ECE 449CS 443: COMPUTER VISON LECTURE 4

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ECE 449/CS 443 COMPUTER VISON LECTURE 4

• Camera with lenses
• Sensing
• Radiometry
• Image Formation
• Surface and Image Brightness
• Radiance and Irradiance
• Reading
• Cameras (Chapter 2)
• Radiometry (Chapter 1)

• Homework Exercises 2.4 and 2.5, due next
  Thursday.

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Pinhole Perspective Equation
NOTE z is always negative..
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Affine projection models Weak perspective
projection
is the magnification.
When the scene relief is small compared its
distance from the Camera, m can be taken
constant weak perspective projection.
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Affine projection models Orthographic projection
When the camera is at a (roughly constant)
distance from the scene, take m1.
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Lenses
Snells law n1 sin a1 n2 sin a2
Descartes law
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Paraxial (or first-order) optics
Snells law n1 sin a1 n2 sin a2
Small angles n1 a1 ¼ n2a2
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Thin Lenses
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Photometry

• L is the radiance.
• E is the irradiance.

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Thick Lens
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Spherical Aberration
Distortion
Chromatic Aberration
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Some Lenses
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Vignetting
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Photographs (Niepce, La Table Servie, 1822)
Milestones Daguerreotypes (1839) Photographic
Film (Eastman, 1889) Cinema (Lumière
Brothers, 1895) Color Photography
(Lumière Brothers, 1908) Television (Baird,
Farnsworth, Zworykin, 1920s)
CCD Devices (1970)
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Image Formation Radiometry
The light source(s)
The sensor characteristics
The surface normal
The surface properties
The optics
What determines the brightness of an image pixel?