Ann Dooms is a mathematician who specializes in forensics of a very specific kind — multimedia. The Vrije University researcher uses clever math to analyze digital media — photos and videos — and suss out foul play. “We play our daily episode of ‘CSI: Multimedia,’” she explains in a talk at TEDxBrussels sharing the ways she and her team at the university work on forensics projects.
How does multimedia forensics work? From her talk:
This is a photo of a cat.
Here is what those pixels look like when encoded by color:
These numbers offer Dooms a grand opportunity … for math.
Algorithms can be used to find “patterns, irregularities, additions, and changes,” she says, like …
in these two photos …
which may look the same, but … the numbers say otherwise.
The photos in numbers.
The inconsistencies in those numbers …
reflecting changes that Dooms made to the colors in the photos “barely noticeable to the naked eye” that allow Dooms to do things like hide an entire cat in a scattered image:
Watch her whole talk to learn more: