1. An image processing apparatus, comprising: a generation unit configured to generate a new two dimensional tomographic image based on a first plurality of two-dimensional tomographic images of an object, the first plurality of two dimensional tomographic images acquired before acquisition of a second plurality of two-dimensional tomographic images of the object, wherein a three-dimensional image of the object is generated based on the second plurality of two-dimensional tomographic images, and wherein the first plurality of two-dimensional tomographic images is acquired while adjusting a position in a depth direction of the object; and a display control unit configured to display at least one of the new two-dimensional tomographic image and the three-dimensional image on a display unit.