It usually happens at the worst time, when you want to shoot the picture of the century: the battery of your digital camera is dead! This era might be over, thanks to researchers of the University of Rochester, who developed two new technologies to extend the lives of our digital cameras. The first one will reduce the power consumption of the chips by a factor of 50 or more while the other will reduce the computational power needed to compress an image when it's captured by a factor of five. These chips should appear in wireless security cameras before being integrated into consumer products such as your camera phone.
The first one needs less transistors than current chips for the analog-to-digital conversion of each captured pixel in a CMOS sensor.
The new designs use as few as three transistors per pixel, reserving nearly half of the pixel area for light collection. First tests on the chip show that at video rates of 30 frames per second it uses just 0.88 nanowatts per pixel--50 times less than the industry's previous best. It also trounces conventional chips in dynamic range, which is the difference between the dimmest and brightest light it can record. Existing CMOS sensors can record light 1,000 times brighter than their dimmest detectable light, a dynamic range of 1:1,000, while the Rochester technology already demonstrates a dynamic range of 1:100,000.
Below is a picture of Mark Bocko and Zeljko Ignjatovic showing their digital pixel sensor (Credit: University of Rochester).
The second technology solves the problem of the computational power needed to compress an image when it's captured with a very elegant mathematical trick.
Ignjatovic and Bocko have laid out the pixels to lie at the peaks of cosine waves resulting in a non-uniformly distributed array, instead of an evenly spaced one. By using this trick, the amount of computation required to compress the image is slashed by nearly five-fold. Since each pixel is positioned exactly where each cosine wave has a peak where the cosine value is "one," multiplying by one is unnecessary. With no multiplication and only a little addition, the processor uses less power.
The press release adds that these two new technologies are patented. But I've only found the first patent, "Sigma-delta analog to digital converter architecture based upon modulator design employing mirrored integrator," which carries the U.S. number 6,707,409.
The two researchers have also founded Signal Sciences, Inc. "to develop and commercialize sensor and signal processing related technologies created in their university research laboratory."
For more information about the technologies described above, please read these pages about the Mirrored Sigma-Delta Analog to Digital Converter Architecture , a CMOS Imager with Built-in Compression and a Digital Pixel CMOS Image Sensor.
So what is the future of these technologies? The researchers plan to build real prototypes and to integrate these chips into wireless security cameras before putting them into consumer cameras and cell phones. So don't expect a camera which will last for years before several years.
Sources: University of Rochester news release, via EurekAlert!, December 7, 2005; and various web sites
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