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I've noticed when I am in very low light (light that isn't in the same room I'm sitting in), when my eyes adapt to the dark that I see colored particles. Do these colored particles resemble noise in the photography world?
Something like high ISO noise, but the particles are less colored. Also I noticed that this happens when you apply pressure on your eyes, or when you stare at something at dark I can feel the grain; it's not smooth as it looks under light.
The sensor systems are different enough that direct comparison is hard. There are some similarities, but the sensor post processing is exceptionally well tailored to remove undesired artefacts and the maker has not provided a means to turn noise reduction off.
Also, the image is developed by a custom algorithm and the system does not allow access to the RAW data.
Pressing the sensor is cheating and does induce artefacts as signal can be generated which is sensibly indistinguishable from photon stimulation within the criteria established by the wetware. Pressing the sensor, either through the flexible housing or directly may cause degradation or destruction and is not within the standard operating conditions or guaranteed worst case specs and so is not covered by warranty.
There are two sensor systems whose outputs are combined (something like Fuji's dual site size sensor but totally different).
You'll read things like:
To make rubbish of that statement, you'll also read that
Whatever ...
As light levels drop the cones start to stop working. For my eyes - which seem reasonably standard in thsi respect (and not others) at 20 lux colour is not too bad. At about 10 lux you can still see colour but notice it starting to suffer. From there it fades away and by 1 lux it's essentially monochrome. Bright moonlight is a few tenths of a lux. Stumbling around a room that is so dark that you can sort of see doorways so as to get through then level is somewhere under 0.1 lux so by 0.01 vision per se is largely gone.
BUT and the reason why the above is worth saying at all (maybe) is that the dark adapted eye can detect a single photon. If you are in total darkness you will not see every single photon as there is substantial dead area between the sensors, but if a photon strikes a sensor it will fire and you will see a spot of light. What that spot of light registers as is uncertain. If it fires a rod you'd expect monochrome. Whether it's able to fire a cone may depend on energy level - so if so you'd expect blue flashes to be more common.
Finally, long shot: and this is a maybe, you MAY be able to see secondary emissions from Gamma rays !. Gamma ray "telescopes" work by looking for secondary emissions caused by high energy gamma rays striking atoms in the atmosphere and causing a visible photon emission at lower energy. Vanishingly few of the high energy gamma rays make it to earth surface (to contribute to the background count you hear on a Geiger counter) but perhaps a dark adapted eye gets the benefit of a few of these knocking secondary particles off other parts of your eyes! Maybe.
Added.
Relevant (maybe :-) )
http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html
http://en.wikipedia.org/wiki/Rod_cell
http://en.wikipedia.org/wiki/Cone_cell
Good: http://www.cis.rit.edu/people/faculty/montag/vandplite/pages/chap_9/ch9p1.html
Goodish: http://www.vetmed.vt.edu/education/Curriculum/vm8054/eye/RODCONE.HTM
Eye: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/V/Vision.html
First remember that color is only an illusion born into your brain: most of mamals will have a colorspace reduced to red and blue, birds have extended colorspace seeing also in UV bees see yellow blue and UV. Show a picture of a flower to a bird or a bee it will not recognize the color (as our device do not record the UV). The color is build using a combination of the light intensity (from the rod) and the color signal (from the cone)
For human eyes perception details (and a nice picture of the cone on the retina) have a look to http://www.beercolor.com/color_basics1.htm
A very important point is to understand that the perception of the outer world through the eyes is NOT the processing of a simple image: The eye has a good resolution only at the center (where it also see color) therefore when you look at something your eyes will scan the scene geting bits of information and your brain is caching the data, extrapolating some part of your field of view and reconstructing an image. Furthermore ther is a remanance of the image on your retina (used to make you belive that there is some movement in a movie)
You can be aware of parts this process by thinking that when you look at a scene everything is in focus, you eyes are not so good: this is a composit. Think also that your eye has a blind spot that you never notice (the image is extrapolated) there sre some experiment which allow you to evidence it (see the test on http://en.wikipedia.org/wiki/Blind_spot_%28vision%29) RImage reconstruction can also be tricked: this is optical illusion
The color that you see when you press on your eyes are due to mecanical constraint on the retina (the normal behavior of cone is that the pigment they contain will elongate when reacting to light causing a pressur which originate the nervous signal, one may also experience such color patch in some headheach or when hurt in the back of the head. In this case the signal originate directly into the visual cortex.
In low light it is not clear if the noise you see originate in the device (your eyes) or in the processing (your brain)...
You are referring to Phosphene. This doesn't have anything to do with photographic noise.
Your description sounds a lot like the condition known as visual snow, which some people liken to snowy interference on an old analog television. The linked Wikipedia page says:
The cause is unclear. The underlying mechanism is believed to involve excessive excitability of neurons within the cortex of the brain.
If true, then perhaps what you're talking about is related to the high-ISO noise recorded by a digital camera in the sense that it's more or less random data added to the image, but the place where the noise is added is different. In a digital camera, the noise comes from the sensor; with visual snow, it's apparently added in the brain, so later in the imaging process.
It seems that not much is known about visual snow, and there's not even clear agreement in the medical community about whether it's a real problem. The Guardian had an interesting article about the condition, which you can read here: The mysterious eye condition of 'visual snow'.
