On Fri, Feb 01, 2008 at 02:40:12PM +0800, Sandy Harris wrote: > There are lots of photos that do not need to have high resolution. > The new high-definition TVs are just under 2 megapixels, as is a > 4" by 5" print at 300 dpi. PC screens range from about .5 to > about three Mp. For most web display anything over one Mp > or so is wasted. > > 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. -- 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.
