Disclosed is an image sensor comprising: an image sensing unit array, for sensing an object and comprising a plurality of image sensing units arranged in a sensing matrix with M rows and N columns; an image data reading circuit, for reading and outputting image data caught by at least part of the image sensing units; and a control unit, for controlling numbers and locations of the image sensing units for each row or each column, from which the image data reading circuit reads the image data; for computing a read region that is in the image sensing unit array and corresponds to the object; and for controlling the image data reading circuit to read at least part of the image data of the column or the row. The part of the column or the row, which is read, comprises the read region.