Along with progress of digital technology and enhancement of life quality, digital electronic products have gone deeply into every aspect of life. Because digital still cameras (DSCs) have the advantages of small volume, convenient use, powerful function, real-time preview, and unneeded development of negatives as compared with conventional cameras, they have been widely used by people, and have become indispensable digital electronic products in life and travel.
Generally speaking, a DSC will provide a preview mode and an auto-exposure mode. In the auto-exposure mode, the DSC will automatically adjust exposure parameters like exposure time and gain value according to the environmental brightness so that a user can easily take high-quality digital pictures. In the preview mode, a user can preview the photographed pictures in real time. When a conventional DSC operates in the auto-exposure mode, a central processing unit (CPU) thereof needs to calculate exact exposure time and gain value momentarily according to the environmental brightness, hence consuming more power and shortening the usable time of battery of the DSC. It is thus necessary for the user to bring more spare batteries or charge the battery of the DSC momentarily, resulting in much trouble and inconvenience in use.
Accordingly, the present invention aims to propose an auto-exposure power-saving device of a DSC to resolve the above problem.