1. A digital image acquisition system having no photographic film, comprising: (a) an apparatus for capturing digital images, including a lens, an image sensor and a processor; (b) a flash unit for providing illumination during image capture; (c) an analysis tool for comparing at least a portion of a captured image and a reference image of nominally the same scene, at least one of said captured and reference images being taken with flash, said analysis tool providing a measure of the difference in illumination between said captured image and said reference image; and (d) a classification tool for comparing said measure with a threshold and for categorizing said scene as outdoor or indoor based on said measure.