A New Sampling Algorithm Could Eliminate Sensor Saturation (scitechdaily.com)

Baron_Yam shared an article from Science Daily: Researchers from MIT and the Technical University of Munich have developed a new technique that could lead to cameras that can handle light of any intensity, and audio that doesn't skip or pop. Virtually any modern information-capture device -- such as a camera, audio recorder, or telephone -- has an analog-to-digital converter in it, a circuit that converts the fluctuating voltages of analog signals into strings of ones and zeroes. Almost all commercial analog-to-digital converters (ADCs), however, have voltage limits. If an incoming signal exceeds that limit, the ADC either cuts it off or flatlines at the maximum voltage. This phenomenon is familiar as the pops and skips of a "clipped" audio signal or as "saturation" in digital images -- when, for instance, a sky that looks blue to the naked eye shows up on-camera as a sheet of white.

Last week, at the International Conference on Sampling Theory and Applications, researchers from MIT and the Technical University of Munich presented a technique that they call unlimited sampling, which can accurately digitize signals whose voltage peaks are far beyond an ADC's voltage limit. The consequence could be cameras that capture all the gradations of color visible to the human eye, audio that doesn't skip, and medical and environmental sensors that can handle both long periods of low activity and the sudden signal spikes that are often the events of interest.
One of the paper's author's explains that "The idea is very simple. If you have a number that is too big to store in your computer memory, you can take the modulo of the number."

Comments

No, this does not solve the problem.

[dgatwood]

This is an interesting approach, and it would work pretty well for things like audio. It might help with the dynamic range of cameras when used at higher ISO settings, but it will not solve the problem by any means. The problem, though, is that in modern cameras, the sensor's pixels also have a maximum capacity, called the full well capacity. The sensor can't physically accumulate more of a charge than its full well capacity, and the DAC is designed so that its clipping point matches the full well capacity of the sensor at its base ISO. So you would still get clipping when the brightness exceeds what would otherwise by the sensor's clipping point at its base ISO, and if it is already at its base ISO, this wouldn't make any difference at all.

IMO, a better approach (which I proposed several years ago) is to sample the sensor and physically cancel out (subtract) the measured charge in the sensor itself, doing this multiple times per exposure to ensure that you don't hit the full well capacity. That approach also has the advantage of letting you do really cool time-based manipulation of the resulting photo. For example, you could do vector-based motion compensation of the individual subframes to dramatically reduce motion blur, compensate for some amount of camera shake, etc.

Even better, if you represent subsequent subframes relative to the previous subframe (e.g. -12 here, +2 there), you'll also usually get a high percentage of zeroes, which means you should be able to losslessly compress the additional subframes to be pretty small on average, potentially giving you the ability to adjust the image motion compensation after the fact to get an image in which motion is blurred more or less, according to taste.

In theory, you could even do bizarre, per-region motion compensation, such as making a baseball appear to be motionless while the bat is swinging at a high speed or vice versa. :-D But I digress.

Re:already had circuit elements that could do this

[RhettLivingston]

I think you meant to be funny, but it is possible to come full circle on this one.

NASA's Vacuum Tube Transistor