This one is pretty amazing: a team of MIT researchers have created a technique to amplify small changes in a video clip that enables us to see minute changes that otherwise would've been unnoticeable (see 3:20 where they made a person's arterial pulse visible). They called it Eulerian Video Magnification:
Our goal is to reveal temporal variations in videos that are difficult or impossible to see with the naked eye and display them in an indicative manner. Our method, which we call Eulerian Video Magnification, takes a standard video sequence as input, and applies spatial decomposition, followed by temporal filtering to the frames. The resulting signal is then amplified to reveal hidden information. Using our method, we are able to visualize the flow of blood as it fills the face and also to amplify and reveal small motions. Our technique can run in real time to show phenomena occurring at temporal frequencies selected by the user.
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