An image processing apparatus comprising: an imaging unit (12, 122) that divides an image of a subject into a plurality of pixels; a measuring unit (15, 151) that measures, for each pixel, a distance to a point on the subject corresponding to the pixel from a reference position and inclination of the point based on three-dimensional shape data of the subject, the reference position being a position of lens included in the imaging unit; a first calculating unit (15, 152) that calculates, for each pixel, a weight according to the distance and the inclination according to the following equations Wi = Z i n i ⋅ e z wi = W i ∑ i = 1 N W i where N refers to the total number of pixels, Z i refers to a height of a point on the subject that corresponds to the i-th pixel, n i refers to a unit normal vector at a point on the subject that corresponds to the i-th pixel, e z refers to a unit normal vector in a Z-axis direction, W i refers to a value that is determined by a height and inclination of a point on the subject that corresponds to the i-th pixel, w i refers to a weight according to a height and inclination on the subject that corresponds to the i-th pixel, and is a value obtained by normalizing W i; a correcting unit (15, 153) that corrects, for each pixel, a size information relating to a size of the subject that is projected in the pixel based on the weight calculated by the first calculating unit (15, 152) according to the following equation X G = ∑ i = 1 N w i x i where X G is the corrected coordinate, N refers to the total number of pixels, x i refers to coordinates of the i-th pixel, w i refers to a weight according to a height and inclination on the subject that corresponds to the i-th pixel and is a value determined by the previous equation; and a second calculating unit (15, 153) that calculates a statistical amount of the subject based on each size information corrected for each block by the correcting unit. an imaging unit (12, 122) that divides an image of a subject into a plurality of pixels; a measuring unit (15, 151) that measures, for each pixel, a distance to a point on the subject corresponding to the pixel from a reference position and inclination of the point based on three-dimensional shape data of the subject, the reference position being a position of lens included in the imaging unit; a first calculating unit (15, 152) that calculates, for each pixel, a weight according to the distance and the inclination according to the following equations Wi = Z i n i ⋅ e z wi = W i ∑ i = 1 N W i where N refers to the total number of pixels, Z i refers to a height of a point on the subject that corresponds to the i-th pixel, n i refers to a unit normal vector at a point on the subject that corresponds to the i-th pixel, e z refers to a unit normal vector in a Z-axis direction, W i refers to a value that is determined by a height and inclination of a point on the subject that corresponds to the i-th pixel, w i refers to a weight according to a height and inclination on the subject that corresponds to the i-th pixel, and is a value obtained by normalizing W i; a correcting unit (15, 153) that corrects, for each pixel, a size information relating to a size of the subject that is projected in the pixel based on the weight calculated by the first calculating unit (15, 152) according to the following equation X G = ∑ i = 1 N w i x i where X G is the corrected coordinate, N refers to the total number of pixels, x i refers to coordinates of the i-th pixel, w i refers to a weight according to a height and inclination on the subject that corresponds to the i-th pixel and is a value determined by the previous equation; and a second calculating unit (15, 153) that calculates a statistical amount of the subject based on each size information corrected for each block by the correcting unit.