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by Samuel Buchmann
In a patent, Apple describes a photo sensor that can map 20 exposure levels. This would make any other current sensor obsolete.
So far, it's just a patent. It may never become a market-ready product. But if it does, it would represent a huge leap in the quality of digital photos and videos.
According to the patent description, the new sensors can map a dynamic range of 120 dB. According to C.Y.Magazine, which first discovered the entry, 120 dB is equivalent to about 20 stops of exposure. The best full-frame and medium-format cameras achieve around 15 stops. The sensor apparently achieves the dynamic range regardless of the sensor size, as this is not specified anywhere. This makes the invention particularly interesting for smartphones.
With 20 exposure levels, the sensor also reaches the range that the human eye can capture. Until now, digital photography and videography has had the problem that the dynamic range is inferior to the human eye. If the light contrasts are very high - for example in backlit shots - a conventional photo sensor cannot simultaneously depict the bright and dark parts of the image as we humans see them. This should be possible with a dynamic range of 20 exposure levels.
In order to achieve this dynamic range, additional electronics are installed on the sensor. In addition to a photodiode, each pixel has a circuit called a lateral overflow integration capacitor (LOFIC) circuit» in the patent «. I can't explain exactly how it works, but the sensor is able to store fine nuances in the dark and extremely strong light at pixel level at the same time.
The sensor is not supposed to be able to capture the light in the dark.
The sensor should not only significantly increase the dynamic range, but also reduce image noise. There is also a separate circuit per pixel for this purpose.
Despite its advantages, it is by no means certain that the patent will be realised in a sensor. Production costs are likely to play an important role. Like many other smartphone manufacturers, Apple has been using photo sensors from Sony for a long time. As these sensors are produced in huge quantities, they are relatively cheap. Although Apple going it alone could give it an innovative edge, it would also make production more expensive. Whether this is worthwhile is questionable, especially as smartphones can already compensate for the lack of dynamics quite well with software tricks.
My interest in IT and writing landed me in tech journalism early on (2000). I want to know how we can use technology without being used. Outside of the office, I’m a keen musician who makes up for lacking talent with excessive enthusiasm.