1. An image processor comprising: dot-area extraction means for extracting a dot area in an image based on image data of a subject image; and moire-removing spatial filter means for performing a process of limiting spatial frequency components of the extracted dot area to an image data portion corresponding to the dot area, wherein the moire-removing spatial filter means has a characteristic of attenuating an entirety of the spatial frequency components to be contained in the image and further attenuating or removing a predetermined spatial frequency component liable to cause moire appearance.