At the recent IEEE International Conference on Acoustics, Speech, and Signal Processing, members of the MIT Media Lab's Camera Culture Group presented a fundamentally different approach to image separation. Their system fires light into a scene and gauges the differences between the arrival times of light reflected by nearby objects — such as panes of glass — and more distant objects. If two light signals — one reflected from a nearby object such as a window and one from a more distant object — arrive at a light sensor at slightly different times, their Fourier decompositions will have different phases. So measuring phase provides a de facto method for measuring the signals' time of arrival. The algorithms adapt a technique from X-ray crystallography known as phase retrieval, which earned its inventors the Nobel Prize in chemistry in 1985. MIT’s proposed  image separation system fires light into a scene and gauges the differences between the arrival times of light reflected by near...