1. A method of measuring a vitality of a subject by using an image sensor, comprising: receiving light reflected on the subject through a lens by the image sensor, wherein the image sensor includes a plurality of IR pixels and a plurality of visible pixels; obtaining IR strength of the light which is incident to the IR pixels; obtaining color strengths of the light which is incident to the visible pixels; and measuring a vitality of the subject based on equation of 
 vitality =2 ×IR /( R+IR ) wherein ‘IR’ denotes the IR strength and ‘R’ denotes the color strengths.