A conventional image sensor has a narrow dynamic range, so that the conventional image sensor has the limitation of not representing very dark portions or very bright portions depending on the exposure time when representing an image having such dark and bright portions. The present invention provides an image sensor including at least two storage units for respectively storing at least two image signals; a first switch unit for performing switching applied image signals to be respectively stored in the at least two storage units; and a second switch unit respectively connected to the at least two storage units and for equalizing the image signals stored in the at least two storage units.