My first reaction upon hearing about Nokia’s 41-megapixel 808 Pureview was that it was an absurdity, a perfect example of the very worst of consumer electronics, and a total miss. But the more I read, the better I understood that this phone isn’t just some freak of nature with a ridiculously high number attached to it. It’s just the slightly awkward first steps of a serious move by Nokia to differentiate itself. If you’ve only skimmed the news, there are some things you should probably know about this strange beast of a camera.
First, the 41 megapixel figure is really misrepresentative, not to say untrue. It doesn’t take 41-megapixel photos in any way, shape, or form. Even in the special high-res creative mode, it “only” produces 38 megapixels. Mostly it will be taking normal-size shots, between 3 and 8 megapixels. So what the hell does this 41 megapixel figure even mean?
It means Nokia is being smart about the way cameras at this size actually work. I wrote a while back about how HD does not always mean high definition, and cameraphones were an excellent example of this. Their tiny sensors and bad lenses meant that while they may produce pictures of a certain size, the quality was sorely lacking. This was because they insisted on wringing every possible pixel out of an incredibly small sensor. The 808′s sensor (supposedly manufactured by Toshiba) is not small. At 1/1.2″, it’s four or five times the size of most cameraphone sensors, including the one in the iPhone 4S. Bigger in fact than the sensors in most point-and-shoots. Now, when you make your sensor bigger, you can either keep the same resolution but have bigger wells or photosites (which detect light and make up pixels), which usually improves sensitivity. Or you can keep the same photosite size and just put more of them on the sensor, which improves resolution. In this case Nokia has done the second thing.
But they’ve done it almost to an absurd amount, and they know that their lens, good as it is (and fairly fast – F/2.4 is solid, though there’s lots of distortion right now), can’t really resolve detail well enough that 41 megapixels would be necessary. Even on full-frame cameras that many pixels is questionable.
So instead of just bumping this one spec and expecting it to sell itself, they built a whole photo system around the idea. The 808 camera doesn’t take 41-megapixel photos; it collects 41 megapixels of data and uses all that data to create a very nice photo of a much smaller size. Imagine a photo around 8000?�5000 pixels that isn’t particularly sharp; now shrink it down to something significantly smaller – maybe around 3000?�2500 pixels (~8MP), just as an estimate. You do it intelligently, sharpening and de-aliasing and doing noise removal.