This paper presents a newly developed automatic exposure (AE) system f
or digital still cameras (DSC). The through the lens (TTL) system whic
h has been employed mainly by conventional camcorders has been applied
as an exposure control system for DSCs. However, the TTL system requi
res a longer time to obtain an appropriate exposure value, and it is t
herefore not a suitable control method for DSCs which demand immediate
imaging after the shutter button is pushed. The authors have develope
d a high-precision AE capable of controlling the exposure quickly by c
onverting the brightness of an object directly using the obtained valu
e of an integrated image without using the photometric sensors other t
han a charge coupled device (CCD). They have also confirmed that the n
ew system enables excellent exposure control without any problem.