New system uses video of your face to track health!

Indian-origin researchers are developing a highly accurate video camera-based system that can monitor a person's vital signs by analysing subtle changes in skin colour.
The new system, called DistancePPG, created by Rice University researchers monitors patients' vital signs via video while compensating for skin tone, lighting and movement.
The DistancePPG can measure a patient's pulse and breathing just by analysing the changes in one's skin colour over time.
Where other camera-based systems have been challenged by low-light conditions, dark skin tones and movement, DistancePPG relies on algorithms that correct for those variables.
The team of Rice graduate student Mayank Kumar and professors Ashok Veeraraghavan and Ashutosh Sabharwal created the system that will let doctors diagnose patients from a distance.

Kumar, the project's lead graduate researcher, said DistancePPG will be particularly helpful to monitor premature infants for whom blood pressure cuffs or wired probes can pose a threat. In fact, this was his inspiration.

"This story began in 2013 when we visited Texas Children's Hospital to talk to doctors and get ideas," Kumar said.
"That was when we saw the newborn babies in the neonatal ICU. We saw multiple wires attached to them and asked, 'Why?' The wires monitored the babies' pulses, heart rate and this and that," he said.
"And the wires weren't a problem. The problem was that the babies would roll, or their mothers needed to take care of them, and the wires would be taken off and put back on," said Kumar, adding that it could potentially damage the infants' delicate skin.

Kumar and his colleagues were aware of an emerging technique that used a video camera to detect nearly imperceptible changes in a person's skin colour due to changes in blood volume underneath the skin.
However, there were three challenges. The first was the technique's difficulty in detecting colour change in darker skin tones. Second, the light was not always bright enough. The third and perhaps hardest problem was that patients sometimes move.
The Rice team solved these challenges by adding a method to average skin-colour change signals from different areas of the face and an algorithm to track a subject's nose, eyes, mouth and whole face.

"Our key finding was that the strength of the skin-colour change signal is different in different regions of the face, so we developed a weighted-averaging algorithm," Kumar said.
Kumar said he expects the software to find its way to mobile phones, tablets and computers so people can reliably measure their own vital signs whenever and wherever they choose.
The research is published in the Optical Society journal Biomedical Optics Express.