Modulo Camera Rescues Overexposed Images

by Nancy DuVergne Smith on August 20, 2015 · 1 comment

in Media

An overexposed photo, left, compared to information recorded by a modulo camera, center, and the results.

An overexposed photo, left, compared to information recorded by a modulo camera, center, and the results. Courtesy: MIT Camera Culture.

MIT’s Camera Culture research group works on “making the invisible visible.” A new project restores depth and detail to bleached-out skies and other poorly exposed surfaces in digital photos using a specialized modulo camera.

This invention could improve individual photographer’s efforts by eliminating the need for fumbling with aperture size and exposure length and boost the clarity of robot vision. With current cameras, a driver-less car might be blinded by entering a tunnel that mixes a dark environment with super bright exits. With the modulo camera, it could see both tunnel and exits clearly.

A poster explains how the modulo camera works.

Click the image to see details on how the camera works.

As a project in computational photography, the modulo camera relies on high dynamic range (HDR) imaging “a method that allows both very bright and very dim light sources to be pictured in a single image with no loss in quality.” Contemporary HDR cameras rely on multiple images but the modulo camera requires only one shot, so it’s less likely to suffer from motion blurring.

The project, formally called Unbounded High Dynamic Range Photography Using a Modulo Camera, was created in a collaboration between the Media Lab’s Camera Culture group, MIT Lincoln Lab, and Singapore University of Technology and Design.

How does it work? The Camera Culture website describes it this way:

Conventional camera sensors will get full, or saturated, after receiving an excess amount of light. This is because conventional camera sensors have a limited well capacity, or a limited amount of light the sensors can take in before they overflow. The modulo camera solves the saturation problem by resetting the sensor capacitors whenever the well gets full, and it uses an inverse modulo algorithm to calculate how much light the reset sensors took in. This algorithm recovers a much larger dynamic range. For example, if a certain camera sensor can record eight bits of information, then when those eight bits are filled, the capacitor will be reset to zero. The number of resets is recovered by the algorithm, which then calculates the relative brightness of each area of the photo.

Learn more about Camera Culture research.

{ 1 comment… read it below or add one }

Emil M Friedman August 20, 2015 at 10:44 pm

I miss the challenge associated with using an old-fashioned match-needle SLR.

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