[cantagi]

I once tried to reproduce a webcam PPG paper, but not using Eulerian video magnification.

The pipeline started with face detection, then found the mean colour value of a rectangle of forehead. It then did some DSP and returned the pulse frequency.

It worked, but only when the person held extremely still very close to the camera, with auto exposure turned off.

Disappointed with how badly mine worked, I took a look at some open source webcam PPG projects to find out how they were working. It turns out they were pretty similar, except most of them were aggressively filtering the pulse signal to be in the correct range, without really checking there was already a signal there. Of course by taking white noise signal and filtering it to a certain frequency range, you'll get a signal in that frequency range.

I now believe that to make video PPG work, you need some of (1) a very good camera, i.e. not just a low end webcam (2) quite a long recording, i.e. 10s-1m (3) a controlled environment