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bayer filter pattern array questions
what device dependent RGB does the bayer pattern use?
I know they double the green cells because the eye has more G rods or cones than RB does bayer assume rec709 video? bayer doesn't assume sRGB or ProPhotoRGB since those came much later why not have a sensor filtration that is CIEXYZ compatible? that way the camera can be easier to use in device independent color like http://www.color.org the preference of G cells in the bayer pattern I think can cause noise in places like hair, etc -- Dale |
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bayer filter pattern array questions
On 13/02/2014 15:55, Dale wrote:
what device dependent RGB does the bayer pattern use? It doesn't have to use RGB at all! Another variant more commonly used for video sensors uses CMYG or CMYW and yet another Sony CCD used RGBE (E = emerald green/cyan). Kodak has also patented RGBW patterns. See http://en.wikipedia.org/wiki/Bayer_mask They are severely limited by the properties of light stable dye filters and the need to be able to physically manufacture the filter mask. I know they double the green cells because the eye has more G rods or cones than RB does bayer assume rec709 video? bayer doesn't assume sRGB or ProPhotoRGB since those came much later why not have a sensor filtration that is CIEXYZ compatible? that way the camera can be easier to use in device independent color like http://www.color.org Bayer specifies the pattern and a means to demosaic it back to YCbCb or RGB taking advantage of the predominance of G in the Y channel and limitations of the human eyes colour resolution capability. You are stuck with what the chemical dyes for red, blue and green can actually deliver in practice. Red is very good (but not always light stable), green is so-so and blue may have a small long wavelength red leak. Wratten filters being one set that is used in scientific work graphs: http://www.edmundoptics.com/optics/o...n-filters/1326 Whilst insanely priced bandpass filters are possible they do not help perceived image quality in conventional colour imaging and would be all but impossible to manufacture on the scale needed for consumer CCDs. The demosaic into RGB or YCC can be done back to whichever colour space you want to choose and then embed the appropriate colour profile. the preference of G cells in the bayer pattern I think can cause noise in places like hair, etc It limits the resolution you can hope for when imaging in monochromatic red hydrogen alpha light or blue hydrogen beta, but apart from that it really isn't a big problem. You can design bespoke testcards that Bayer struggles with and Foveon fans spend all their time obsessing about it. In fact a bug in most JPEG decoders is much more of a hindrance for using monochromatic blue or red light for imaging with a Bayer mask. -- Regards, Martin Brown |
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bayer filter pattern array questions
On 2014.02.13, 10:55 , Dale wrote:
what device dependent RGB does the bayer pattern use? I know they double the green cells because the eye has more G rods or cones than RB does bayer assume rec709 video? bayer doesn't assume sRGB or ProPhotoRGB since those came much later why not have a sensor filtration that is CIEXYZ compatible? that way the camera can be easier to use in device independent color like http://www.color.org the preference of G cells in the bayer pattern I think can cause noise in places like hair, etc Download dcraw.c and you'll get all sorts of data about bayer patterns in various cameras as well as color space application. -- Those who have reduced our privacy, whether they are state or commercial actors, prefer that we do not reduce theirs. - Jaron Lanier, Scientific American, 2013.11. |
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