Monday, March 3, 2008
Turbo'd Image Sensors
At the heart of it all, the tiniest technology makes every picture possible
The Undiscovered Country
The only mainstream photographic sensors that capture color data at every pixel come from Foveon, the company behind the X3 sensors found in Sigma D-SLRs. What makes Foveon's design unique is that each photosite captures each color like photographic film. Silicon absorbs light's different wavelengths at different depths, so the light sensors are embedded one atop the next in the first 10,000th of an inch of the silicon chip. It works much like color film, with three layers of RGB sensitivity across the entire surface. The process also makes for a higher pixel count because each photosite on a Foveon sensor is effectively worth three pixels on a Bayer pattern filtered chip. Since the on-chip real estate is reduced, however, the chips can stay small, and their price per pixel can remain low.
Other technologies may one day revolutionize digital photography again, but for the foreseeable future, it appears that CMOS and CCD will remain the dominant technological forces that shape photography for the next generation. Even without a major revolution in technology, these image-capturing devices could soon be capable of producing ultra-high-ISO photographs with the noise characteristics of low-ISO settings of today. The effects of this could be astounding: flashless photographs in the dimmest of conditions, the ability to stop action in any environment and a complete revolution in how cameras record light—and how photographers use cameras. Even if ISOs don't rocket through the roof, photographers could see advancements that allow post-exposure RAW-type image editing on the pixel level of everything from focus to depth of field.
Even without these amazing sci-fi advances, it's clear that today's CMOS and CCD sensors are already technological marvels. After all, they have carried an entire revolution on their tiny little shoulders, and they're only continuing to improve.
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