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#1
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Noise levels as a function of pixel size
Is there some formula or scientific basis to estimate noise levels as a
function of pixel size? At the moment I'm assuming that noise levels decrease with the square root of the size increase, i.e. doubling the pixel area should lower noise levels by the square root of 2. Is this correct? I'm only referring to "pixel" noise, i.e. not read noise, A/D conversion noise and other external noise sources. -- Alfred Molon ------------------------------ Olympus 50X0, 7070, 8080, E300, E500 forum at http://groups.yahoo.com/group/MyOlympus/ Olympus E500 resource - http://myolympus.org/E500/ |
#2
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Noise levels as a function of pixel size
Alfred Molon wrote:
Is there some formula or scientific basis to estimate noise levels as a function of pixel size? At the moment I'm assuming that noise levels decrease with the square root of the size increase, i.e. doubling the pixel area should lower noise levels by the square root of 2. Is this correct? I'm only referring to "pixel" noise, i.e. not read noise, A/D conversion noise and other external noise sources. The photon-limited noise is proportional to the square root of the number of photons collected. So, if everything else is equal, a pixel which is double the linear size will connect four times the number of photons, and the noise will be twice as much. Therefore the signal to noise ratio will be doubled. Doubling the area will increase the signal-to-noise ratio by a factor of square root (2), with the signal being doubled and the noise being root 2 higher. David |
#3
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Noise levels as a function of pixel size
On Tue, 13 Dec 2005 16:53:06 +0100, Alfred Molon wrote:
Is there some formula or scientific basis to estimate noise levels as a function of pixel size? At the moment I'm assuming that noise levels decrease with the square root of the size increase, i.e. doubling the pixel area should lower noise levels by the square root of 2. Is this correct? I'm only referring to "pixel" noise, i.e. not read noise, A/D conversion noise and other external noise sources. Photon counting is a Poisson statistics problem, so the noise goes like the square root of the signal. The signal/noise ratio thus goes like 1/sqrt(signal). Doubling the linear size of a pixel increases the area (and hence the signal) by a factor of four. The noise only doubles, so s/n doubles. More generally, the s/n ratio scales with the linear size of the pixel. -dms |
#4
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Noise levels as a function of pixel size
In article ,
Alfred Molon wrote: Is there some formula or scientific basis to estimate noise levels as a function of pixel size? No. Try a Kodak 14n and a Canon 5D both at iso 1600, and you'll see. Lourens |
#5
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Noise levels as a function of pixel size
Lourens Smak wrote: In article , Alfred Molon wrote: Is there some formula or scientific basis to estimate noise levels as a function of pixel size? No. Try a Kodak 14n and a Canon 5D both at iso 1600, and you'll see. Lourens There are limits to noise performance base on pixel size. Not every camera comes close to these limits, but no camera passes them. Scott |
#6
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Noise levels as a function of pixel size
I don't see why this would be any different than low noise amplifier
design, so double the area and the SNR improves by 3db (linear square root of two). I don't know if cameras do this, but you could sample the sensor with the shutter closed, then sample with the shutter opened. A certain amount of noise will be cancelled. [Double correlated sampling.] Alfred Molon wrote: Is there some formula or scientific basis to estimate noise levels as a function of pixel size? At the moment I'm assuming that noise levels decrease with the square root of the size increase, i.e. doubling the pixel area should lower noise levels by the square root of 2. Is this correct? I'm only referring to "pixel" noise, i.e. not read noise, A/D conversion noise and other external noise sources. -- Alfred Molon ------------------------------ Olympus 50X0, 7070, 8080, E300, E500 forum at http://groups.yahoo.com/group/MyOlympus/ Olympus E500 resource - http://myolympus.org/E500/ |
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Noise levels as a function of pixel size
"Lourens Smak" wrote in message ... In article , Alfred Molon wrote: Is there some formula or scientific basis to estimate noise levels as a function of pixel size? No. Try a Kodak 14n and a Canon 5D both at iso 1600, and you'll see. Lourens Yes, there is scientific basis to estimate noise levels as a function of pixel size. The intrinsic noise from the CCD or CMOS pixel is mainly a function of thermal energy, and independent of pixel size. The signal is a result of light hitting the pixel surface, which is a function of pixel size because a larger pixel collects more light. Therefore a larger pixel will have a higher signal to noise level. So if you get the same signal output, a larger pixel will have less noise than a smaller pixel. Wannabe ======= |
#8
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Noise levels as a function of pixel size
Lourens Smak wrote:
In article , Alfred Molon wrote: Is there some formula or scientific basis to estimate noise levels as a function of pixel size? No. Try a Kodak 14n and a Canon 5D both at iso 1600, and you'll see. And the 'full frame' 6 MP Contax N Digital has noise levels that are even worse than the Kodak! Far worse, in fact, even at low ISO. ;-) |
#9
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Noise levels as a function of pixel size
Alfred Molon wrote:
Is there some formula or scientific basis to estimate noise levels as a function of pixel size? At the moment I'm assuming that noise levels decrease with the square root of the size increase, i.e. doubling the pixel area should lower noise levels by the square root of 2. Is this correct? I'm only referring to "pixel" noise, i.e. not read noise, A/D conversion noise and other external noise sources. See "http://clarkvision.com/imagedetail/does.pixel.size.matter/" |
#10
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Noise levels as a function of pixel size
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