1. An image processor comprising: a detection unit that detects a plurality of specified images each having a shape from an image read out by an image reading apparatus; a first determination unit that determines presence or absence of other specific image other than a specified image out of the plurality of specified images detected by the detection unit, in a position determined in advance for the specified image; and a second determination unit that determines whether or not the specified image is to be subjected to a processing on the basis of a result of the determination of the presence or absence of the other specified image by the first determination unit.