1. An image processing device, comprising: a first composition setting unit configured to set a first composition for a two-dimensional input image by a first technique based on at least a size of a first subject in an input image; and a second composition setting unit configured to set a second composition for a three-dimensional input image by a second technique based on depth information associated with the input image and the size of the first subject in the input image, wherein the second technique is different from the first technique.