Focal depths expose picture quality

Members of the Graphics Group at MIT in Cambridge, Massachusetts have demonstrated that combining several low-quality exposures with different focal depths can yield a sharper photo than a single, higher-quality exposure.

Working with MIT professors Fredo Durand and William Freeman, and Kiriakos Kutulakos of the University of Toronto, MIT’s Dr Sam Hasinoff 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 said 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, said Hasinoff, and the camera could have a distinct operational setting that invokes the table. The multiple-exposure approach, he added, offers particular advantages in low light, or when the scene covers a large range of distances.