A computation apparatus that calculates subject information by using subject data, includes a calculation unit that calculates spatial distributions of a first-order phase value and a first-order measurement target value by using the subject data, a calculation unit that calculates an error correction function including the first-order phase value as a variable by using information of the spatial distribution of the first-order measurement target value and the spatial distribution of the first-order phase value, and a calculation unit that calculates information of a spatial distribution of a second-order measurement target value corresponding to a spatial distribution obtained by correcting the spatial distribution of the first-order measurement target value by using the error correction function, the information of the spatial distribution of the first-order phase value, and the information of the spatial distribution of the first-order measurement target value.
COMPUTATION APPARATUS, PROGRAM, AND IMAGE PICKUP SYSTEM