1. An image sensor configured to operate in a plurality of operation modes, the image sensor comprising: a pixel array including unit pixels configured to generate an analog image signal from incident light; a readout circuit configured to output a digital image signal by converting the analog image signal; and a control module configured to generate control signals for controlling operations of the pixel array and the readout circuit according to an operation mode of the image sensor, wherein a first power voltage for driving the image sensor when the operation mode of the image sensor is an image recognition mode for recognizing a body of a user of the image sensor, is lower than a second power voltage for driving the image sensor when the operation mode of the image sensor is an image capture mode for capturing images by the user.