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!
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.
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?
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.
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.
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.
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.
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.
