first color film - 1902 - brown university · • predates prokudin-gorskii collection • like...
TRANSCRIPT
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
Slides from Alexei Efros, Fei Fei
Li, Steve Marschner, and others
Linear Filtering (See Szeliski 3.2)
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
-2.6 -0.33
1.66 10.66
© 2006 Steve Marschner • 40
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 • 41
Box filter
© 2006 Steve Marschner • 42
© 2006 Steve Marschner • 43
© 2006 Steve Marschner • 44
© 2006 Steve Marschner • 48
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 • 49
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?
Slide by Steve Seitz
© 2006 Steve Marschner • 50
Comparison: salt and pepper noise
Slide by Steve Seitz