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Ok, here we're getting into confusion about terminology here. To clarify: In the Bayer filtered Canon CCD each individual photosensor is covered in a colored
by jonah 16y ago
Ok, here we're getting into confusion about terminology here.
To clarify:
In the Bayer filtered Canon CCD each individual photosensor is covered in a colored filter [1] in a pattern such as:
B G
G R
So when capturing an image 1/4 of the sensors are capturing blue light, 1/4 capturing red, and 2/4 capturing green.
In contrast the CCD in the rover's cameras do not have filters in front of individual photosensors. Instead, there is a set of filters on a disc which are mechanically positioned in front of the sensor. Using this method three images are taken. On each with a red, green, and blue filter covering 4/4 of those same sensor elements giving you 2x-4x the number of elements capturing each color and thus much higher image quality at a given resolution.
B B
B B
then
G G
G G
then
R R
R R
Similar multi-shot technology was used in the early days of terrestrial digital photography to provide better color, exposure latitude and resolution. [2] for a bit of discussion on multishot vs. single shot medium format digital camera backs.
[1] http://en.wikipedia.org/wiki/Bayer_filter http://en.wikipedia.org/wiki/Bayer_filter
[2] http://www.luminous-landscape.com/reviews/cameras/h3d50ii.shtml http://www.luminous-landscape.com/reviews/cameras/h3d50ii.sh...
- Tamerlin 16y agoThe part that threw me off was where you said that the Canon sensor contains 3 photosites per pixel -- which based on this pots leads me to believe that you meant that it uses 3 photo sites to record each pixel, which is still not entirely accurate; the Rover's capture every color at every photosite, so they use all of their sensor's resolution. Canon (and everyone else but Foveon, for that matter) making a single-shot sensor can't do that, they instead sacrifice the real resolution of the sensor due to the Bayer filter, and use interpolation to make up the difference.