Re Sensitivity to brightness: Human eyes can see single photons (well, one is too few, but ten will definitly do it). Which means that if there is some light - any light at all - we will see it. Not the direction (if we are talking about single photons) but still. Oh, well, there will never be a TV good enough :)
The human eye is very sensitive but can we see a single photon? The answer is that the sensors in the retina can respond to a single photon. However, neural filters only allow a signal to pass to the brain to trigger a conscious response when at least about five to nine arrive within less than 100 ms. </quote> http://math.ucr.edu/home/baez/physics/Quantum/see_a_photon.h...
Definitely. And it's pretty apparent that the responder wanted to actually reference something, rather than just rely on someone saying, "10 photons should be enough for anyone"
