1. An image processing apparatus for converting a 2D image into a 3D image composed of an image for a left eye and an image for a right eye, the image processing apparatus comprising: a calculation unit that calculates a sharpness of a 2D image for each region thereof; an image processing unit that performs image processing, in a region with a sharpness calculated by the calculation unit being higher than a first predetermined value, to increase that sharpness, and performing image processing, in a region with a sharpness calculated by the calculation unit being lower than a second predetermined value which is equal to or lower than the first predetermined value, to reduce that sharpness; and a generation unit that generates, from the 2D image processed by the image processing unit, an image for a left eye and an image for a right eye by shifting the 2D image in a horizontal direction.