Is there a demo link for this application?
So strange that tye dont put up a live demo!
I haven't tried it out, but give this a shot it was linked on the original research paper's site[1]:
Webcam Pulse Detector
71–80 of 85 posts
Re: Webcam Pulse Detector
#72Earlier quoted context omitted.
> ... unperceivably redder But why is he analyzing the green channel then? :)
Look at the absorption spectra at http://omlc.ogi.edu/spectra/hemoglobin/index.html . Green is ~510nm, red is ~650nm, blue is ~475nm. The difference between the absorption of Hb and HbO2 in the red range is the reason why pulse oximeters use red. In this case, we don't care about differentiating oxy- vs. deoxy-hemoglobin, we just care about the total absorption. Since more light is absorbed at green than at red, it w…
> I am not confident in this explanation, and still don't know why green over blue.
I'm not sure either, but I can tell you that if you examine digitized (RGB) 35mm film -- across all 35mm film stocks -- the blue channel is the most noisy.
So my guess is: He might have chosen green over blue due to the blue channel being noisier.
Re: Webcam Pulse Detector
#73Has anyone been able to get it to work? Whenever I try to open the stats display, I get: OpenCV Error: Assertion failed (p.checkVector(2, CV_32S) >= 0) in polylines, file /tmp/buildd/opencv-2.3.1/modules/core/src/drawing.cpp, line 2064
I have the same problem and have opened an issue: https://github.com/thearn/webcam-pulse-detector/issues/1 Maybe somebody that knows more about OpenCV than I do can figure out what's wrong.
I did a git pull this morning, and it's working now.
Re: Webcam Pulse Detector
#74Earlier quoted context omitted.
that's the tragedy of it. something cool is invented and now it'll be fenced off and buried for 25 years in all likelihood, and/or becomes part of a big patent portfolio.
doesn't a patent imply that you must let other people use your idea in exchange of a fair price?
No.
In fact, patents are exactly the opposite.
They only grant the right to exclude others from doing something. So if i own a patent on X, it gives me the right to prevent others from doing X.
Even if i license my patent on X to you, it does not necessarily mean you can do X, because doing X may also require other patents that my patent is an extension of. In other words:
Imagine we have patented processes, each building on the last. Patent A covers doing thing one Patent B covers doing thing one, then thing two Patent C covers doing thing one, then thing two, then thing three.
Granting you only the right to perform patent C does not enable you to perform the process described by patent C, you'd still need licenses for patent B and patent A to do that.
Re: Webcam Pulse Detector
#75Earlier quoted context omitted.
doesn't a patent imply that you must let other people use your idea in exchange of a fair price?
ICBW, but no, I don't think it does, except it perhaps a narrow set of circumstances. Compulsory Licensing[1] is maybe what you're thinking of, but from what I can tell seems to apply mostly to drug patents, or things {the,a} government wants from you. It has a wider applicability in copyrighted forms of IP, I believe. Patents that are part of some organised standard are often required to be placed under 'FRAND[2] (F…
It would be more correct to say that "patents that their owners contribute to some organised standard ..."
If I add a patented process to an important standard, but I don't own the patents, you still don't get those patents just because they are part of some important standard.
Re: Webcam Pulse Detector
#76Cool!
Reminds me of this question on Stack Overflow:
http://stackoverflow.com/questions/12416772/is-there-an-equi...
Re: Webcam Pulse Detector
#77Earlier quoted context omitted.
Look at the absorption spectra at http://omlc.ogi.edu/spectra/hemoglobin/index.html . Green is ~510nm, red is ~650nm, blue is ~475nm. The difference between the absorption of Hb and HbO2 in the red range is the reason why pulse oximeters use red. In this case, we don't care about differentiating oxy- vs. deoxy-hemoglobin, we just care about the total absorption. Since more light is absorbed at green than at red, it w…
> I am not confident in this explanation, and still don't know why green over blue. I'm not sure either, but I can tell you that if you examine digitized (RGB) 35mm film -- across all 35mm film stocks -- the blue channel is the most noisy. So my guess is: He might have chosen green over blue due to the blue channel being noisier.
Is that noise inherent to film? Do webcams have the same noise?
Re: Webcam Pulse Detector
#78Earlier quoted context omitted.
that's the tragedy of it. something cool is invented and now it'll be fenced off and buried for 25 years in all likelihood, and/or becomes part of a big patent portfolio.
doesn't a patent imply that you must let other people use your idea in exchange of a fair price?
Your thinking of a Compulsory license. However that's not the general case, for example the vast majority of drug patents have no such restrictions.
http://en.wikipedia.org/wiki/Compulsory_license
PS: The only real exception in the USA is the US Government get's to ignore patents at it's digression.
Re: Webcam Pulse Detector
#79Earlier quoted context omitted.
> I am not confident in this explanation, and still don't know why green over blue. I'm not sure either, but I can tell you that if you examine digitized (RGB) 35mm film -- across all 35mm film stocks -- the blue channel is the most noisy. So my guess is: He might have chosen green over blue due to the blue channel being noisier.
Is that noise inherent to film? Do webcams have the same noise?
The green channel has the least noise for Bayer-sensor digital cameras (which is almost all of them).
50% of the sensor sites are green (25% each for red and blue), so there is more signal given the same amount of noise.
Re: Webcam Pulse Detector
#80Earlier quoted context omitted.
Look at the absorption spectra at http://omlc.ogi.edu/spectra/hemoglobin/index.html . Green is ~510nm, red is ~650nm, blue is ~475nm. The difference between the absorption of Hb and HbO2 in the red range is the reason why pulse oximeters use red. In this case, we don't care about differentiating oxy- vs. deoxy-hemoglobin, we just care about the total absorption. Since more light is absorbed at green than at red, it w…
> I am not confident in this explanation, and still don't know why green over blue. I'm not sure either, but I can tell you that if you examine digitized (RGB) 35mm film -- across all 35mm film stocks -- the blue channel is the most noisy. So my guess is: He might have chosen green over blue due to the blue channel being noisier.
[deleted]