An image sensor includes a pixel array of pixels arranged in one or more rows and one or more columns, the pixel array configured to generate an image based on light being incident on one or more pixels of the pixel array. The image sensor includes pixel load circuitry connected to one column of pixels and including transistors serially connected to each other. The image sensor includes switches connected in parallel to separate, respective nodes between adjacent transistors. The image sensor includes image sensor processing circuitry configured to receive, from image processor circuitry, gain information indicating an intensity of light concurrently with an image being generated by the image sensor, and control at least one switch of the plurality of switches to be turned on/off to change an electrical path of a current that passes through the pixel load circuitry, based on the gain information.