1. An operation method of an image sensor comprising: determining a distance between the image sensor and an object; activating at least one of a color pixel, a depth pixel and a thermal pixel included in a pixel array of the image sensor based on the determined distance and a reference distance, wherein the activating includes activating the thermal pixel if the determined distance is shorter than the reference distance and activating the color pixel and the depth pixel if the determined distance is longer than the reference distance.