In a method for forming an image of a subject on a solid-state imaging
device, a first time period for splitting a light beam from a subject
into a plurality of light beams that have different polarization
directions and then combining the plurality of light beams to form a
single subject image on the solid-state imaging device and a second time
period for splitting the light beam from the subject into the plurality
of light beams that have different polarization directions and forming a
plurality of subject images that overlap each other partially on the
solid-state imaging device are switched time-wise. A first image
information on the single subject image is obtained based on pieces of
signal information in the first time period, and a second image
information on one of the plurality of subject images is calculated by
using and computing pieces of signal information in the second time
period. Then, the high-resolution image of the subject is achieved by
using the first image information and the second image information. In
this way, it is possible to obtain an image with a high resolution and a
reduced noise with substantially no loss of the light beam from the
subject.