On 17 Jul 2005 at 21:52, Anthony Farr wrote: > I wrote a long explanation of the process, and it was a mess so I deleted > it. > > The simple explanation is that each pixel location on the sensor only gets > light of the colour that is assigned to it. It comes off the sensor as > luminance only, but it is not the same as a greyscale image. Converted to > RGB without interpolation, it would have a luminance value ONLY for its > assigned colour, the remaining colours would have zero luminance at any > pixel. > > A white field from the bayer converted with no interpolation would look > like: 255,0,0 - 0,255,0 - 0,0,255 - 0,255,0 - and so on. > After interpolation it looks like: > 255,255,255 - 255,255,255 -255,255,255 - and so on. > > The luminance data for the unrepresented colour channels is taken from the > neighbouring pixels that represent the missing colours. That data has > spread from its own position to the adjacent pixel.
Thanks for writing this, the often promoted suggestion that the individual colour pixels in a bayer pattern capture provide broadband luminance information is flawed alright, broadband luminance can't be extracted from a bayer capture without interpolation via demosaicing. Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
