Abstract: Provided is a method of acquiring image data generated by imaging by the imaging means arranged to have different line-of-sight directions, superimposing the image data while performing alignment in such a way as to eliminate absolute positional shift caused by the different line-of-sight directions in each piece of image data, selecting a transverse line that transverses an overlapping portion of the superimposed image data according to a direction in which ranges of each piece of image data in a superimposed state are shifted, generating epipolar plane image data by arranging each piece of image data of a portion where the selected transverse line and the overlapping portion overlap in an order determined by magnitudes of inclinations of the line-of-sight directions corresponding to each, and detecting a depth of a subject appearing in the image data from a streak pattern appearing in the generated epipolar plane image data.