IMAGE COLLATING APPARATUS AND IMAGE COLLATING METHOD

An image collating apparatus and an image collating method, in which a document larger than an image reader can be collated using a preregistered image even in the case where the document is read by the image reader, are disclosed. The image of the document read by the image reader is collated sequentially with the document images of different sizes preregistered in a data base. The document size is determined from the document image input from the image reader. In the case where the document size is smaller than the preregistered image size, the preregistered image is retrieved in accordance with the document size, so that the document features are extracted and matched between the read document image and the registered image set in size to each other, thereby collating the read image with the preregistered image.