PURPOSE: To acquire the proper image signals even with a subject that has a large difference of luminance between the bright and dark areas.

CONSTITUTION: The video signals acquired from a CCD 14 thorugh the image pickup are amplified by an amplifier 15 and then converted into the digital image data A by an A/D converter 18A, then, the data A is stored in a 1st frame memory 21. Meanwhile the video signals acquired from the CCD 14 are amplified by the amplifiers 15 and 17 and converted into the imge data B by an A/D converter 18B and the data B is stored in a 2nd frame memory 22. The amplification factor of the amplifier 17 is set at such a level that secures the proper brightness for the relatively dark area of a subject. A multiplexer 24 selects the data showing the relatively bright area of the subject out of those image data read out of the memory 22 and the data showing the relatively dark area of the subject out of those image data read out of the memory 22. These selected data are synthesized and the image data showing a bright image as a whole can be ontained.