Digital image forming apparatus

Abstract

A digital image forming apparatus which detects a center of a book document when reading and writing an image of the document, including a document, a document board on which the document is set, a reading device for reading the document by scanning the document, an A/D converter for converting an analog signal which is read by the reading device to a digital signal, a signal processor for processing the digital signal, including a first detector for detecting the existence of a dark portion in the image of the document and judging the document to be a book document if the document image has the dark portion, based on the signal corresponding to at least two lines on the document in a scanning direction, or in a direction perpendicular to the scanning direction and a second detector for detecting a center portion of the document on the basis of each center dark portion of each signal of the lines if the document is judged to be a book document, and a writing device for writing the digital signal on a photoconductive element in relation to the detected center portion. Edge portions of the document can similarly be detected and used in writing an image of the document so that an unnecessary part of the book document can be erased with simple structure and operation.