1. A method for controlling exposure in a film scanner for scanning a developed still photographic film relative to a line sensor at a generally constant speed, said film having a first reserved area provided before a first frame and a second reserved area provided following a last frame; said method comprising the steps of: measuring R, G and B output voltages outputted from an amplifier while capturing at least one of a first negative base area before said first reserved area, a second negative base area following said first reserved area, a third negative base area before said second reserved area, and a fourth negative base area following said second reserved area; setting a gain level associated with an amplifier such that, at the gain level, maximum R, G and B output voltages correspond to a predetermined reference voltage where the maximum R, G, and B output voltages are established with reference to an observed reference negative base area observed to be subjected to less exposure than an image area.