On 16 Mar, 13:37, Tom Anderson wrote:
I assume you mean that by downsampling, you average neighbouring pixels,
and so reduce the amount of noise.

The idea is that by downsampling you're no longer seeing the raw
noise, and the end result is more pleasing, even if technically the
image is numerically no less noisy.

That would be true if it weren't for
the fact that CCD signal to noise ratio scales proportionally to the size
of the pixel (or its square root?); smaller pixels will suffer more noise
in the first place.

I doubt there's such a simple mathematical formula in terms of
production sensors, because there are other factors beside pixel size
that influence noise levels (pre-amp and signal path design,
especially). It really depends whether this a theoretical or a
practical discussion.

U

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