An imaging system comprises a whole image read out unit for reading out a whole image in a first resolution from an imaging device, a partial image region selecting unit for selecting a region of a partial image in a part of the whole image which is read out, a partial image read out unit for reading out the partial image in the selected region in a second resolution from the imaging device, a characteristic region setting unit for setting a characteristic region, in which a characteristic object exists, within the partial image, a characteristic region image read out unit for reading out an image of the characteristic region, which is set, in a third resolution from the imaging device, and a resolution setting unit for setting such that the first resolution