1. An image processing apparatus comprising: an obtaining unit configured to obtain image data of a left eye image and a right eye image of a 3D content that has no black border inserted thereto, a black border width according to a parallax amount in a periphery of a right image frame between the left eye image and the right eye image, and a black border width according to a parallax amount in a periphery of a left image frame between the left eye image and the right eye image; and a generating unit configured to generate a border-attached left eye image and a border-attached right eye image by inserting an image having the obtained black border width according to the parallax amount in the periphery of the image frame into at least one of the left eye image and the right eye image and an image having the obtained black border width according to the parallax amount in the periphery of the left image frame into at least the other of the left eye image and the right eye image, wherein at least one of the black border widths includes a width corresponding to the respective parallax amount and an offset separate from the respective parallax amount, and wherein the offset is inserted on the same side of both the left eye image and the right eye image.