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NOVA scienceNOW: Profile: Hany Farid

Program Overview


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.

Teacher's Guide
NOVA scienceNOW: Profile: Hany Farid
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