1. An image display apparatus comprising: a specifying unit configured to specify an area in a first image; an extraction unit configured to extract image data included in the area specified by said specifying unit; a display controlling unit configured to control to cause a second image based on the image data extracted by said extraction unit to be displayed on a display unit; a detection unit configured to detect an amount of characteristics of image data included in the area and image data in a neighboring area of the area; a determination unit configured to determine, on the basis of the amount of characteristics detected by said detection unit, whether or not a notification display indicating that the area specified by said specifying unit is likely not to be a target area needs to be presented; an image generation unit configured to generate a notification image enabling the area to be identified with respect to the first image, in a case that said determining unit determines that notification display needs to be presented; and a synthesizing unit configured to combine the notification image generated by said image generation unit with the second image to generate a composite image and displaying the composite image on the display unit; wherein if the area specified by said specifying unit is likely to be the target area, the second image is displayed over the full screen of the display unit.