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Comment by fferen | Hacker News Reader

I like how this kind of turns the "main idea" of computer vision on its head. Namely, instead of trying to emulate and catch up to human abilities, it augments them the way only a computer can; it plays to computers' strengths instead of their weaknesses.

Also, who would have thought you can determine someone's pulse just by looking at the color change of the face due to blood rushing in and out? If asked beforehand, I wouldn't have even said it was theoretically (physically) possible.

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Yes, it's hard to believe, but it's really possible to sense the small color changes due to blood flow in the face using cameras. My earlier work described how you just need a simple webcam :)(http://web.mit.edu/newsoffice/2010/pulse-camera-1004.html). As a result, I'm working on Cardiio (http://cardiio.com) to bring this technology to both the web and mobile very soon. If you're interested in computer vision based biosensing, please sign up!

That’s awesome!

Hmm, when I tried to sign up I got a message that I was already on the waiting list.

EDIT: It looks like the page is making a request to cardiio.com, specifically, and if you’re at www.cardiio.com (the one you linked to) the response gets blocked by Same Origin Policy, and the page treats it the same as a you’re-already-on-the-list response. You might want to avoid hardcoding the hostname in the JS, and/or force everyone over to the www or non-www domain.

thanks for catching that!

That sounds awesome.

But from a scientific point of view, you don't really need spatial resolution for the heartbeat example, though, do you? If you just spent the same amount of money on getting high temporal and spectral resolution, surely one could do very cool things with 'just one pixel', so to speak. Especially if you had say 16 different wavelengths, instead of just 3.

For increased temporal resolution you can just the rolling shutter with off-the-shelf hardware I guess.

If the face of a "patient" was tied to his bed, and light wasn't changing, and there was no movement around (i.e. in ideal conditions), then yeah.

But in the real world scenarios you want to take a look at more than one pixel, and use the rest of the picture for noise reduction & calibration.

That is for heartbeat. But yes, with better spectral resolution you might get some other cool data.

Congratulations for, what seems to me, opening up the door [1] to a new world of CV applications! And of course for having the courage to commercialize it while your academic career is taking off.

[1] famous illustration from the enlightenment: http://www.lehrer.uni-karlsruhe.de/~za874/homepage/aufklaeru...

Do you think it would be possible to see shifts in photosynthetic activity in plants due to low/high nutrients/humidity? Especially when IR-filter removed?

To measure the pulse of a person, you need to consider an interval of a few seconds, so it's safe to assume that the only thing that the position and strength of the light are almost constant. The time that takes the plants to reduce the amount of nutrients or water is much bigger, so I think that it would be much more difficult to compensate the changes in the ambient light.

Yes. My father does research in this area. Specifically, inferring the health of vegetation (among other attributes of land cover) from statistical analysis of satellite imagery.

From what I recall, you can measure the level of photosynthetic activity in an area given the reflectivity of the land (and, I would think, some basic model of what type of vegetation is present in the area)

One example from his research: the fall of the Soviet Union had a statistically significant impact on weather patterns in Kazakhstan (the breadbasket of the USSR) because the land usage changed so much with agricultural policies before and after the fall.

Quick link to the research overview page: http://globalmonitoring.sdstate.edu/research.php

Just curious have you tried on people with darker skin colour/tan. I am trying to imagine, what adjustments you'll need to make to detect on them?

There was a sample in the video, right after the white guy. The effect was more subtle, but it was there.

that's right. what you're looking for is the transient changes (AC) in color due to increase blood perfusion whereas a person's baseline skin color can be considered the DC component.

What do you think of the many apps already on the market, possibly derived from your earlier work?

https://play.google.com/store/apps/details?id=com.macropinch...

I also found it very surprising that cameras could pick these things up, there's actually an iPhone app from Philips that claims to be able to be able to read heart-rate, I assumed it was snake-oil at first :

http://itunes.apple.com/us/app/vital-signs-camera-philips/id...

I was skeptical too, but when I tried this app a few months ago, I compared it to my Garmin heart rate monitor at rest and after exercise - they were usually within 1bpm of each other. I was very impressed.

There is so much faint and indirect information in the world it's dumbfounding. We're crossing a threshold where computation can make this visible. It's really exciting.

Pulse oximeters work by looking at the fingernails, and they're the usual way to measure a pulse. There's a lot of blood flow in the face - try bumping into something sharp - so this isn't too surprising.

A Pulse oximeter doesn't measure the spontaneous signal.

There's a red/infrared led on one side of the finger, a detector on the other side, and it measures the amount of light absorbed by the blood.

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