| We consider the problem of imaging a scene with a given
depth of field at a given exposure level in the shortest amount of time
possible. We show that by (1) collecting a sequence of photos and (2)
controlling the aperture, focus and exposure time of each photo individually,
we can span the given depth of field in less total time than it takes to
expose a single narrower-aperture photo. Using this as a starting point, we
obtain two key results. First, for lenses with continuously-variable
apertures, we derive a closed-form solution for the globally optimal
capture sequence, i.e., that collects light from the specified depth of field
in the most efficient way possible. Second, for lenses with discrete
apertures, we derive an integer programming problem whose solution is the
optimal sequence. Our results are applicable to off-the-shelf cameras and
typical photography conditions, and advocate the use of dense, wide-aperture
photo sequences as a light-efficient alternative to single-shot,
narrow-aperture photography. |
