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NOVA scienceNOW: Profile: Hany Farid
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Program Overview
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This segment describes the work of Hany Farid, a professor
of computer science at Dartmouth College, who has done pioneering work the
field of digital forensics by analyzing how people alter digital images and
developing techniques to detect manipulated images.
This NOVA scienceNOW segment:
points
out that photographs have been manipulated since the 1800s, but that the
digital age has given rise to a great increase in the number of altered images.
explains
that digital images contain distinct patterns and that software tools can
detect inconsistencies in these patterns. relates
how Farid's team developed algorithms and software to analyze pixel
patterns in images. notes
that the most common manipulation is the addition or removal of an element in
an image. discusses
cloning—pasting one image or parts of an image over another—and
describes how it leaves a mismatch of pixel values that can be statistically
analyzed and detected. describes
how in a cloned image the lighting of subjects does not match and that the
differences in shadows and light direction can be detected with Farid's
light-direction tool. explains
that Farid modified his light-detection software, which analyzed lighting
differences in two dimensions, to pinpoint a lighting source
three-dimensionally by analyzing the light reflecting off a subject's
eyeballs. offers
many examples of faked images that were presented as authentic.
Taping Rights: Can be used up to one year after the program is taped off the air.
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