On Wed, Oct 9, 2013 at 12:53 PM, Godfrey DiGiorgi <[email protected]> wrote:
> Aliasing occurs regardless of how close together the cells are because the > cells are discrete. This kind of aliasing is a function of discrete > mathematics. I think you're dismissing Larry's point too easily. When we first learn about aliasing, it's usually in the context of the Nyquist sampling theorem, which (in the time domain) assumes instantaneous sampling. In a pixel array, "instantaneous sampling" would correspond infinitely small (point-sized) pixels (separated by a certain pitch). Enlarging the sensitive area of the pixels (relative to their pitch) does provide some anti-aliasing effect. The Wikipedia article on AA filters says exactly what Larry is suggesting: http://en.wikipedia.org/wiki/Anti-aliasing_filter "In a monochrome or three-CCD or Foveon X3 camera, the microlens array alone, if near 100% effective, can provide a significant anti-aliasing effect,[2] while in color filter array (CFA, e.g. Bayer filter) cameras, an additional filter is generally needed to reduce aliasing to an acceptable level." The citation [2] is: http://adsabs.harvard.edu/abs/1974eosd.conf....1C which unfortunately is not provided in fulltext. See also this text at Google Books, which agrees that a high fill factor (pixel size relative to pitch) reduces aliasing: http://tinyurl.com/oz44nye > > G > > On Oct 9, 2013, at 9:08 AM, Larry Colen <[email protected]> wrote: > >> It seems to me that if you had a rear illuminated sensor, with no space >> between the pixels, and it had no bayer filter, then aliasing/moire would >> not happen, because the light value would be averaged over the whole sample. >> >> It's the discontinuous aspect of what is effectively three overlayed photos >> that is causing the aliasing. >> >> Is this correct? > > > -- > 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. -- 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.
