1. An image processor capable of generating a reduced-size image from a digital image signal of an original image having pixels of a plurality of colors arranged in a color array with a periodicity, and of displaying the reduced-size image, the image processor comprising: a reduction resizing processor configured to reduce an original image from a single-sensor color imaging device and obtain a reduced-size image of a size conforming to a display size of a display monitor; and a rearranged color array data generation processor configured to generate, based on the reduced-size image obtained by the reduction resizing processor, one or more types of display reduced-size images by rearranging color information of the original image relative to a reference pixel position.