On Wed, Mar 17, 2010 at 12:56 PM, Larry Colen <[email protected]> wrote:
> Another post processing question that's been niggling at me. Is there any > reason that a program like lightroom couldn't do binning, and turn 14MP K20 > files into 7MP files with twice the dynamic range? If you're really going from 14 -> 7 MP (binning in one dimension only) you'd improve dynamic range by a factor of sqrt(2), not 2. (That's the reduction in the noise floor from averaging two values.) If you bin 2x2 to improve DR by a factor of 2, you're looking at 3.5 MP, and maybe the thinking is that that's not good enough for much, especially with sophisticated noise reduction software (NeatImage, etc.) available. BTW, cryogenically cooled research CCDs, like you find at astronomical observatories, have intrinsic noise that's almost entirely from read noise (in the amplifier) rather than dark current (which accumulates proportionally to area and exposure time). You can generally bin such detectors on the chip before the amplifier readout occurs, which means you get "one pixel's" worth of read noise per bin, instead of 2-4 pixel's worth of read noise. This is a big win in some cases. (Often, though, the main source of noise is extrinsic--due to sky brightness--and the read noise is insignificant.) -- 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.
