5. An image filing apparatus according to claim 2, wherein: said registration controlling means generates, in a case where any title or keyword is inputted from said instruction inputting means, an image file with said title or keyword correlated to said layout features as well as to said read-out image data, and stores the image file in said storing means; and said retrieval controlling means retrieves, in a case where any title or keyword is inputted through said instruction inputting means, any of the stored image files based on comparing said title or keyword in said image files stored in said storing means and said title or keyword as retrieval information, and outputs the image file through said image outputting means.
2. An image filing apparatus comprising: an instruction inputting means for inputting instructions for registering and retrieving an image file; an image reading means for optically reading out image data from a document; an image file storing means for storing therein the image data read out by said image reading means as an image file; a registration controlling means for reading out image data from the document by controlling the image reading means in a case where an instruction for registration of an image file is inputted from said instruction inputting means, generating an image file for said read-out image data to be stored in said storing means; and a retrieval controlling means for retrieving an appropriate image file from the image files stored in said storing means in a case where an instruction for retrieval of an image file is inputted from said instruction inputting means and outputting the retrieved image file through said image outputting means; wherein said image filing apparatus has a feature extracting means for extracting layout features of the document from the image data read out by the image reading means, said layout features indicating geometrical properties of elements within the document; wherein said registration controlling means reads out, in a case where an instruction for registration of an image file is inputted from said instruction inputting means, image data from a first document by controlling the image reading means, extracts layout features of the first document from the read-out image data by controlling said feature extracting means, and generates an image file with the layout features of the document correlated to said read-out image data to be stored in said storing means; and said retrieval controlling means reads out, in a case where an instruction for retrieval of a desired image file is inputted from the instruction inputting means, image data from a second document by controlling said image reading means, extracts layout features in the second document from said read-out image data by controlling said feature extracting means, and retrieves any of the stored image files as the desired image file based on comparing layout features from said image files stored in said storing means and said layout features to be outputted through said image outputting means.