Apparatus for reducing exposing time of an image processing system is disclosed herein. The image processing system including a shift register coupled to a photo-sensing means, the photo-sensing device is used to convert an optical image from a lens to a plurality groups of charge to form an electrical signal. The apparatus includes control device (counter) and a reset gate. The control device generates the first reset signal and the second reset signal depending on whether the image processing system is in a first resolution mode or a second resolution mode. A first number of cells of the photo-sensing device are exposed to the light of the optical image during the first resolution mode, and a second number of cells of the photo-sensing device being exposed to the optical image during the second resolution mode. The first number of cells is greater than the second number of cells. The reset device is used to eliminate the residual charges in the shift register responding to the first reset signal and the second reset signal. The reset device is coupled to the shift register, and throwaway charges generated by the cells of the photo-sensing device, which are not exposed to the light of the optical image.