A plurality of photography operations are performed with respect to a single subject with different photography conditions, to obtain a plurality of image data sets. The obtained image data are processed to obtain a single dynamic range expanded image data set. A photography method is selected from among: a first method, in which photography is performed at least twice at different exposures; a second method, in which photography is performed with an underexposure at a step number based on a set dynamic range; and a third method, in which photography is performed at least twice with different underexposures at step numbers based on a set dynamic range, based on whether photography operations are possible at exposure ratios corresponding to the expansion ratio of the dynamic range and whether flash is emitted. Photography is performed according to the selected method, thereby preventing limitations of dynamic range due to hardware specifications.