Spatially Adaptive Photographic Flash

Abstract

Using photographic flash for candid shots often results in an unevenly lit scene, in which objects in the back appear dark. We describe a spatially adaptive photographic flash system, in which the intensity of illumination varies depending on the depth and reflectivity of features in the scene. We adapt to changes in depth using a single-shot method, and to changes in reflectivity using a multi-shot method. The single-shot method requires only a depth image, whereas the multi-shot method requires at least one color image in addition to the depth data. To reduce noise in our depth images, we present a novel filter that takes into account the amplitude-dependent noise distribution of observed depth values. To demonstrate our ideas, we have built a prototype consisting of a depth camera, a flash light, an LCD and a lens. By attenuating the flash using the LCD, a variety of illumination effects can be achieved.