IMAGE ESTIMATING METHOD INCLUDING CALCULATING A TRANSVERSE CUTOFF FREQUENCY, NON-TRANSITORY COMPUTER READABLE MEDIUM, AND IMAGE ESTIMATING APPARATUS

The image estimating method is configured to estimate, using image data generated by capturing an object via an image-pickup optical system at a plurality of positions that are spaced at first intervals in an optical-axis direction of the image-pickup optical system, image data at a position different from the plurality of positions. The image estimating method includes an image acquiring step of acquiring image data, a frequency analyzing step of calculating a transverse cutoff frequency in a direction perpendicular to the optical-axis direction based on the image data acquired in the image acquiring step, and an interval calculating step of calculating the first interval based on the transverse cutoff frequency calculated by the frequency analyzing step.