An electronic device includes an image sensor including a pixel array, and an image processor electrically connected with the image sensor. The image processor is configured to acquire a first image of a subject generated based on a first group of optical paths and to acquire a second image of the subject generated based on a second group of optical paths, the second group of optical paths having a phase difference with the first group of optical paths from the pixel array, to normalize pixel values included in the first image and pixel values included in the second image in units of a pixel, and to verify a light source of light reflected by the subject or a light source of light produced from the subject, based on a parameter associated with changes in the normalized pixel values.