1. An image displaying apparatus, comprising: a memory configured to store three-dimensional data associated with a first imaging area including a left breast of a subject to be examined, the three-dimensional data also associated with a second imaging area including a right breast of the subject, the left breast and the right breast being pressed between pressure plates; at least one processing circuit configured to implement a specifying unit configured to specify a nipple position of the left breast on the three-dimensional data based on positional information of the pressure plates, and a generating unit configured to generate at least a left upper half image, a left lower half image, a right upper half image, and a right lower half image, the left upper half image being a projection image corresponding to an entire upper half area of the first imaging area of the three-dimensional data based on the specified nipple position of the left breast, the left lower half image being a projection image corresponding to an entire lower half area of the first imaging area of the three-dimensional data based on the specified nipple position of the left breast, the right upper half image being a projection image corresponding to an entire upper half area of the second imaging area of the three-dimensional data based on a nipple position of the right breast, and the right lower half image being a projection image corresponding to an entire lower half area of the second imaging area of the three-dimensional data based on the nipple position of the right breast; and a display configured to simultaneously display the left upper half image, the left lower half image, the right upper half image, and the right lower half image.