An image sensor includes a pixel unit configured to output a bayer pattern by converting an optical signal of a subject into an electrical signal; and a vertical interpolation unit configured to generate a vertical binning image by adding or averaging values of vertical pixels of the bayer pattern based on weight information set for each row region of the bayer pattern. Further, the image sensor includes a horizontal interpolation unit configured to generate a horizontal binning image by adding or averaging values of horizontal pixels of the bayer pattern based on weight information set for each column region of the bayer pattern; and an image composition unit configured to generate a weight-based binning image by composing the vertical and horizontal binning images.