1. A method comprising, in combination: (a) using a light source to emit light in a temporal sequence of frequencies, such that (i) the light illuminates a scene, (ii) reflected light from the scene reaches a light sensor, and (iii) a first frequency is emitted during a first period of time in the sequence and not during other periods of time during the sequence, a second frequency is emitted during a second period of time in the sequence and not during other periods of time during the sequence, and a third frequency is emitted during a third period of time in the sequence and not during other periods of time during the sequence; (b) using a light sensor to capture multiple frames for each respective frequency in the sequence; and (c) using one or more processors (i) to analyze data in the frames and (ii) to calculate a set of complex numbers for each respective pixel in the light sensor, such that the set of complex numbers includes a complex number for each respective frequency in the sequence for each respective path length in a set of path lengths, wherein the set of path lengths consists of path lengths of paths of light that end at the respective pixel.