ABSTRACT
One of the main problems affecting image quality, leading to unpleasant pictures, comes from improper exposure to light. Beside the sophisticated features incorporated in today’s cameras (i.e., automatic gain control algorithms), failures are not unlikely to occur. Digital
consumer devices make use of ad-hoc strategies and heuristics to derive exposure setting parameters. Typically such techniques are completely blind with respect to the specific content of the scene. Some techniques are completely automatic, such as those based on average / automatic exposure metering or more complex matrix / intelligent exposure metering. Others provide the photographer with a certain control over the selection of the exposure, thus allowing space for personal taste or enabling the user to satisfy particular needs. In spite of the great variety of methods for regulating the exposure and the complexity of some of them, it is not rare for images to be acquired with a nonoptimal or incorrect exposure. This is particularly true for handset devices (e.g., mobile phones) where several factors contribute to badly exposed pictures: poor optics, absence of flash, complex scene lighting conditions, and so forth.
