Researchers sharpen photographs by capturing multiple low-quality images (Oct. 2, 2009) — The MIT Graphics Group is showing that combing several low-quality exposures with different focal depths can yield a sharper photo than a single, higher-quality exposure.

stayfocusedrHasinoff, MIT professors Fredo Durand and William Freeman, and Kiriakos Kutulakos of the University of Toronto devised a mathematical model that determines how many exposures will yield the sharpest image given a time limit, a focal distance, and a light-meter reading.

Hasinoff says that experiments in the lab, where the number and duration of digital-camera exposures were controlled by laptop, bore out the model’s predictions.

A digital camera could easily store a table that specifies the ideal number of exposures for any set of circumstances, Hasinoff says, and the camera could have a distinct operational setting that invokes the table.

The multiple-exposure approach, he says, offers particular advantages in low light or when the scene covers a large range of distances.

Today’s fastest consumer cameras can capture about 60 images in a second, Hasinoff says. If the MIT researchers’ model determined that, under certain conditions, the ideal number of exposures in a tenth of a second would be eight, the fastest cameras could manage only six. “But there’s still a big gain to be had,” Hasinoff says.

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