With five megapixels and up, today’s digital cameras have more than enough resolution to take photos that can be enlarged to poster size. Yet, to meet demand from customers, manufacturers are racing to cram more and more megapixels onto cameras’ image sensors. But they’re also beginning to consider other ways to distinguish their products.
Now Dalsa, an image sensor maker based in Eindhoven, Netherlands, has developed technology that uses excess pixels to take pictures that look clear and bright – even when there’s just one-quarter as much natural light. Ordinarily, increasing a camera sensor’s light sensitivity introduces more “noise” into an image, in the form of random specks of color. But Dalsa’s technology, described at this week’s meeting of the Institute of Electrical and Electronics Engineers in Washington, DC, increases sensitivity without adding noise.
Dalsa’s sensor, which is designed for professional photographers, has a capacity of 28 megapixels – or more than five times that of a typical consumer digital camera. But this impressive figure isn’t noteworthy in itself. This fall, Kodak announced 31- and 39-megapixel sensors, for example, and Dalsa has made its own 66-megapixel sensor, although not for mass production.
“At this point everybody knows how to put many pixels on a piece of silicon,” says Albert Theuwissen, Dalsa’s chief technology officer. “Differentiation comes through features.”
What’s new is what photographers can do with Dalsa’s technology. For one thing, they can record from each pixel separately, creating a gargantuan image with enough information to produce sharp, wall-sized ads. Or they can combine signals from clusters of neighboring pixels, in effect amplifying the signal while averaging out the random noise.
This latter technique, called “charge binning,” because the electronic charge from multiple pixels accumulated as if in bins, has been used in the past for black and white photography. But adjacent cells in a color sensor alternate between green, red, and blue, in a checkerboard pattern, so that simply adding up the light readings from these neighboring cells would blur the colors together. Dalsa’s innovation is a system that combines signals only from the same-colored pixels, keeping the colors distinct. Theuwissen claims that Dalsa is the first to have accomplished this.