Cheap Naked Chips Snap a Perfect Picture
New Scientist (10/07/09) Marks, Paul

Swiss Federal Polytechnic Institute (EPFL) engineer Edoardo Charbon and his team are developing a gigavision sensor, based on an ordinary memory chip, which they say can operate well with both bright and dim light.

In the past, light has been the bane of the memory chip–it “simply destroys the information,” says EPFL researcher Martin Vetterli. But Charbon and colleagues learned to aim the light hitting a memory chip so that each cell that is corrupted by the light changes depending on how much light is hitting it.The light effectively creates an image that the chip preserves.

The researchers say the new sensor could enable cell phones and other devices to take richer, better pictures. Moreover, the process is far more efficient than sensors based on charge-coupled devices (CCDs) or complementary metal oxide semiconductors (CMOS).

Both technologies use similar methods to store images. Each pixel holds a charge whose strength corresponds with the amount of light that hits it. Charges in a CCD are passed from one pixel to another, so that the image forms in a wave of light starting at one edge of the chip and finally reaching the other.

An analog-to-digital converter (ADC) labels the pixels according to an 8-bit grayscale from zero to 255. CMOS uses the same scale, although it transforms charges into voltages before doing so. However, Vetterli says that because a memory chip creates an image immediately, its cells will always be 100 times smaller than those belonging to CMOS sensors.

This means that it can pack 100 pixels in the space of just one digital camera sensor–a gigapixel camera. Memory chip sensors can only store zeros or ones–light or dark–and cannot yet record shades of gray. EPFL’s Feng Yang is working on an algorithm that can assign shades of gray to 100 pixels of information. Dubbed spatial oversampling, the technique is more accurate than ADC. Vetterli hopes to have a functional gigavision memory chip by early 2011.

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I admit it:  I posted this primarily because the title made me look twice. 🙂