1. An image processing apparatus, comprising: an acquiring unit configured to acquire a first image which is captured by a first image capturing unit having a first angle of view and a second image which is captured by a second image capturing unit having a second angle of view smaller than the first angle of view, the second image including an image of an object same as that in the first image; a transforming unit configured to perform positioning and transformation of the first image and the second image such that images of the same object are superposed; a detecting unit configured to perform processing of edge detection for detecting an edge of each of the images of the object in a region in which the first image and the second image are superposed; a deciding unit configured to decide weights at a time of applying weighted composition to the first image and the second image which are subjected to the positioning and the transformation by the transforming unit; and a composition unit configured to apply the weighted composition to the first image and the second image which are subjected to the positioning and the transformation by the transforming unit, by using the weights decided by the deciding unit, wherein the deciding unit decides the weights such that a weight of the first image with respect to the second image in a partial region including a region, which is detected as the edge by the detecting unit, is smaller than a weight of the first image with respect to the second image in a region other than the partial region.