Pushing Pixels

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Also, by increasing the number of pixels, it becomes more challenging to access the information once it has been detected. "Fifty million pixels is a lot of data," says DeLuca, and a photographer needs to be able to read it off the sensor in a reasonable amount of time.

Until now, Kodak has used a process that involved dumping the information from one row of pixels onto the next and shifting the information along the row, reading it off at the edge, one pixel at a time. This is a relatively slow process, normally carried out two rows at a time. So to cope with the additional amount of data, the new sensor comes with four output channels so that four times the amount of data can be read at once. This enables the sensor to increase the rate at which images can be captured from 0.9 to 1.0 frames a second, even though more information is being captured. And yet this also allows the clock cycle at which the data is read off to be reduced for each output, which further improves the signal-to-noise ratio.

Power savings are achieved by the way that the sensor is reset before each picture is taken. This is carried out just before a shot is taken to ensure that there is no residual charge or electrical noise in the pixels that could reduce the quality of the new image. In previous sensors, Kodak has simply read out each of the pixels row by row, as if collecting the data for a picture, but then it dumped the information instead of storing it. "What we've included now is a new structure in the pixel which allows all the pixels in the array to be cleared out in a single clock pulse," says DeLuca. So instead of having to flush the entire sensor row by row, you flush the entire array in one go, he says.

This dramatically improves the "click to capture" time--the delay between pressing the shutter down and the sensor capturing the image. "Instead of being milliseconds, it takes microseconds," says DeLuca. And in addition to saving time, it also reduces the power that is required to perform a reset.

This technology doesn't come cheap. The sensor alone will cost at least $3,500. But that doesn't appear to have put off one camera manufacturer. Hasselblad has announced plans to launch a new camera featuring the sensor in the coming months. Nor is 50 megapixels going to remain on the cutting edge for long. Just this week, a few days after Kodak's announcement, another digital-imaging firm, DALSA, based in Waterloo, Canada, announced that it has developed a 60-megapixel sensor.