A system and method for altering the characteristics of a display based on environmental data is disclosed. Exemplary embodiments provide a light sensor, an environmental processing unit which is adapted to receive electrical signals from the light sensor and generate an environmentally-reactive control signal (Sa), an image signal processor which accepts Sa and an encoded image signal (Se) and generates a pre-decoding image signal (Sp), and an image signal decoder which accepts Sp and generates a decoded image signal for the display. The environmentally-reactive control signal (Sa) may contain the instantaneous value of the desired display black level Sb. Alternatively or additionally, the environmentally-reactive control signal (Sa) may contain a signal linearity modification value.