Sigma/Foveon Questions
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From: David J Taylor on 25 Apr 2010 11:16 "nospam" <nospam(a)nospam.invalid> wrote in message news:250420100514133247%nospam(a)nospam.invalid... > In article <hr15k0$b8n$1(a)news.eternal-september.org>, David J Taylor > <david-taylor(a)blueyonder.co.uk.invalid> wrote: > >> >> Furthermore, a 640x480 sensor with a Bayer CFA is four interleaved >> >> arrays of 320x240 red, green, blue and green pixels. The output is >> >> three >> >> overlayed arrays of red green and blue pixels. Going from 320x240 >> >> to >> >> 640x480 *IS* upsizing! >> > >> > except that's not how bayer works >> >> How does it work, then? > > as i said a few posts back, each pixel calculates the missing > components and pixels get reused. there are a number of papers online > about various algorithms. here's one: > <http://www.ece.gatech.edu/research/labs/MCCL/pubs/dwnlds/bahadir05.pdf> ... where you find the basic spatial interpolation described, along with enhancements. David
From: Chris Malcolm on 25 Apr 2010 13:38 nospam <nospam(a)nospam.invalid> wrote: > In article <hqvhdi$doo$1(a)news.eternal-september.org>, David J Taylor > <david-taylor(a)blueyonder.co.uk.invalid> wrote: >> > They were explaining that because the light sensitive area would be >> > reduced by the live view circuitry, noise levels would rise. You might >> > want to google for these threads in the ng. >> > >> > In any case, unless you are somebody who is designing these sensors, you >> > are not in a position to make qualified statements about what is >> > possible and what is not. >> If what you say is correct, Alfred, what they were saying is also correct, >> and in accordance with the physics of the situation. Less sensitive area >> captures fewer photons, which means more noise. Today, improved >> micro-lenses and higher QE may well have offset the reduced sensing area. > people did say that live view would impact the noise levels, but the > missing piece is that sensor technology advanced which offsets any > loss. The new back illuminated sensors put the wiring on the backside of the chip where it no longer encroaches on photosensor space. -- Chris Malcolm
From: Alfred Molon on 25 Apr 2010 14:10 In article <AuLf5SD67A1LFwc3(a)kennedym.demon.co.uk>, Kennedy McEwen says... > as someone who > does make imaging sensors Interesting. What sensors do you make? -- Alfred Molon ------------------------------ Olympus E-series DSLRs and micro 4/3 forum at http://tech.groups.yahoo.com/group/MyOlympus/ http://myolympus.org/ photo sharing site
From: Ray Fischer on 25 Apr 2010 14:15 Alfred Molon <alfred_molon(a)yahoo.com> wrote: > nospam says... > >> > 2/3 of the needed colour information is missing in a Bayer sensor, and >> > that has an impact on the effective resolution. >> >> a small impact. > >2/3 of the data are missing, 2/3 of WHAT data? Do you even know? If you're referring to visible light then you clearly don't know much because a 15MP Bayer sensor collects MORE data than does a 4.6MP Foveon sensor. -- Ray Fischer rfischer(a)sonic.net
From: Ray Fischer on 25 Apr 2010 14:16
David J Taylor <david-taylor(a)blueyonder.co.uk> wrote: >"Ray Fischer" <rfischer(a)sonic.net> wrote in message >news:4bd3ec93$0$1610$742ec2ed(a)news.sonic.net... >> David J Taylor <david-taylor(a)blueyonder.co.uk> wrote: >>>> however, the total number doesn't change. there are 12 million on the >>>> sensor and 12 million in the image, or however many the sensor has. >>> >>>There are 12 million monochrome pixels on the sensor, >> >> No, there are 4.6 million pixels. Any other claim is a lie. >> >>> interpolated to 12 >>>million colour pixels. The sensor only has 3 million red pixels, but >> >> Learn what "pixel" means. > >Ray, > >This part of the thread had evolved to being about Bayer in a hypothetical >12MP DSLR, and whether or not spatial interpolation was involved. A piel is a picture element. You cannot split up the color componenets of a pixel in some arbitrary way and then claim that a single pixel is really three, four, or a thousand pixels. -- Ray Fischer rfischer(a)sonic.net |