1. A method of adjusting a depth in an input image, the method comprising: extracting a depth value of one or more objects from the input image; extracting spatial depth information of the input image by calculating an average depth value of the one or more objects, wherein the average depth value comprises a single average depth value representing a single object for each of the one or more objects; extracting temporal depth information by calculating a difference between the average depth value of the objects in a current frame and an average depth value of corresponding objects of a previous frame; adjusting a depth map of the input image by using at least one of the extracted spatial depth information and the extracted temporal depth information, wherein in the adjusting of the depth map using the extracted spatial depth information, when the calculated average depth value of the one or more objects is greater than a first predetermined threshold, the depth map is adjusted and wherein in the adjusting of the depth map using the extracted temporal depth information, when the difference between the average depth value of the objects in the current frame and the average depth value of the corresponding objects of the previous frame is greater than a second predetermined threshold, the depth map is adjusted; and outputting the adjusted depth map of the input image.