On Fri, Feb 1, 2008 at 2:51 PM, John Francis <[EMAIL PROTECTED]> wrote:
> > So given, say, a K20D with its 14 Mp, can we somehow > > combine sets of four dots to get a 3.5 Mp image with > > better performance in "available darkness"? Or would > > this also push noise up, perhaps to awfuI levels? > > > > How much would you gain? Four times the pixel area, > > so in theory two stops, but would that happen in > > practice? > > That's not how it works. When you add four pixels, each with > a random noise component, you only improve the signal-to-noise > ratio by a factor of two, not by a factor of four. So theory > says the best you could hope for is one stop of improvement. That's counter-intuitive to me. You've got four times the signal and four times the noise, so I cannot see why S/N ratio should change at all. Can you explain the theory or point to a reference? Anyway, my real question is not how much you theoretically gain, but rather whether current post-processing software lets you do this at all. -- Sandy Harris, Nanjing, China -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
