An image sensor includes a pixel array in which a plurality of pixels are arranged in a matrix form, each pixel outputting a first pixel datum and a second pixel datum according to a dual conversion gain. The image sensor includes a signal convertor configured to generate first kernel data including first pixel data and second kernel data including second pixel data, which are output from a pixel group including a target pixel and multiple pixels surrounding the target pixel; determine a partial region brightness based on the second pixel data included in the second kernel data; and perform fusion of the first kernel data and the second kernel data based on the partial region brightness.