Downsampling reduces noise?

Started Jun 11, 2012 | Discussions thread
Draek
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Re: Downsampling reduces noise?
In reply to mike_2008, Jun 11, 2012

mike_2008 wrote:

No, you're both wrong actually. In the simplest case of a monichromatic ccd SNR increases as the square root of the downsampling ratio. 4 pixels downsampled into one doubles the SNR of the final pixel compares with the 4 averaged pixels.

If it's not too complicated, would you mind explaining how that works? because intuitively, all four pixels are samples of different data and thus SNR shouldn't be affected by it.

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