First color film - 1902
• Captured by Edward Raymond Turner
• Predates Prokudin-Gorskii collection
• Like Prokudin-Gorskii, it was an additive 3-color system.
• Never successfully commercialized
Recap of Friday
Sampling and Reconstruction
Aliasing and how to prevent it (blur / low pass filters)
Linear filtering and convolution
Linear Filtering (See Szeliski 3.2)
Slides from Alexei Efros, Fei Fei
Li, Steve Marschner, and others
CS 129: Computational Photography
James Hays, Brown, Spring 2011
Slide credit Fei Fei Li
Slide credit Fei Fei Li
Slide credit Fei Fei Li
Slide credit Fei Fei Li
1.66
-0.33
10.66
-2.6
A gallery of filters
• Box filter
– Simple and cheap
• Tent filter
– Linear interpolation
• Gaussian filter
– Very smooth antialiasing filter
• B-spline cubic
– Very smooth
© 2006 Steve Marschner • 40
Box filter
© 2006 Steve Marschner • 41
© 2006 Steve Marschner • 42
© 2006 Steve Marschner • 43
© 2006 Steve Marschner • 44
Yucky details
• What about near the edge?
– the filter window falls off the edge of the image
– need to extrapolate
– methods:
•
•
•
•
•
clip filter (black)
wrap around
copy edge
reflect across edge
vary filter near edge
© 2006 Steve Marschner • 48
Median filters
• A Median Filter operates over a window by selecting the
median intensity in the window.
• What advantage does a median filter have over a mean
filter?
• Is a median filter a kind of convolution?
by Steve
Steve Seitz
©Slide
2006
Marschner • 49
Comparison: salt and pepper noise
by Steve
Steve Seitz
©Slide
2006
Marschner • 50