Contactless Monitoring: software amplifies subtle changes between video frames

The technique makes it possible to see someone's pulse, as the skin reddens and pales with the flow of blood, and it exaggerates tiny motions, making visible the breathing of a newborn baby.
Written by Janet Fang, Contributor on

To highlight changes that are imperceptible to the naked eye, researchers have developed new software that amplifies variations in successive frames of video.

The software makes it possible to actually see someone's pulse, as the skin reddens and pales with the flow of blood, and it can exaggerate tiny motions, making visible the breathing of an infant wrapped up in a neonatal intensive care unit. MIT news announces.

It’s like the equalizer in a stereo sound system (which boosts some frequencies and cuts others), except rather than the frequency of an audio signal, it focuses on color and motion changes in a sequence of video frames.

They call it Eulerian Video Magnification. And you can watch a video here.

The prototype allows the user to specify the frequency range of interest and the degree of amplification. Pictured, 4 frames from the original video on top and the same 4 frames with the subject’s pulse magnified on the bottom.

Although the technique lends itself most naturally to phenomena recurring at regular intervals – such as the beating of a heart or the inflation of the lungs – if the range of frequencies is wide enough, the system can amplify changes that occur only once. So it basically different images of the same scene, allowing the user to easily pick out otherwise unnoticeable changes.

According to project researcher Michael Rubinstein from MIT's Computer Science and Artificial Intelligence Laboratory:

  • The system could be used for ‘contactless monitoring’ of hospital patients' vital signs.
  • Boosting one set of frequencies would allow measurement of pulse rates, via subtle changes in skin coloration.
  • Boosting another set of frequencies would allow monitoring of breathing.
  • The approach could help reduce the number of sensors that must be attached to preemies or other infants requiring early medical attention.
  • Once home, the system could act as baby monitors, so that the respiration of sleeping infants would be clearly visible.

The software works in real time and displays both the original video and the altered version of the video, with changes magnified.

The software [pdf] will be presented at Siggraph, a computer-graphics conference this summer.

[Via MIT news]

Image: Michael Rubinstein

This post was originally published on Smartplanet.com

Editorial standards