2. The digital image forming apparatus of claim 1, wherein said signal processing means comprises means for adjusting the timing for writing so that a center of a sheet of paper on which the image of the document is to be written conforms to a center of the book document.
2. The digital image forming apparatus of claim 1, wherein said signal processing means comprises means for adjusting the timing for writing so that a center of a sheet of paper on which the image of the document is to be written conforms to a center of the book document. 3. The digital image forming apparatus of claim 2, wherein said signal processing means comprises means for erasing the center dark portion from the digital signal when writing the document image.