measure heart rate in windows phone app using c#

It works off the video taken through the camera. The software monitors the changes in the skin color and transparency caused by the flow of blood in a finger and detect periodic change pattern in these parameters.

The pulses are timed and the pulse rate is inferred from this data. The accuracy of such measurements is a matter of discussion on the Web. Apparently, recognition of such a subtle variation is not an easy task. If you try to count every cycle separately on the fly, you will also have a risk of some false negatives or false positives. Note that for the user, it's hard to guarantee uniform lighting and stable finger position during the measurements, and such parasitic variations could be detected as "extra" pulses or some pulses could be missing.

The software of better accuracy could spend some more time on observing the pattern, and, assuming near-periodic pattern with some tolerance margin, and some expected range of values of heart beat frequencies, to infer the "real" rate, ignoring some parasitic perturbations caused by accidental finger motion and changed in lighting.

I never saw the articles publishing the code for such measurements or disclosing any technical detail. It's possible that the codes are kept in secret, I'm not sure. I would do my own research (I don't mean in the literature, which is obvious, I mean experimental research, to find out how sensitive the methods can be and how stable the results can be; you can always compare your results with the pulse measurements made in the traditional ways).

—SA