System and method for processing documents with four-line CCD sensor

摘要

An image forming apparatus includes a four line CCD which produces RGB data and K data that are read out selectably, and a selector which selects whether to output the RGB data that is provided from the four line CCD. The image forming apparatus also includes a storage part which stores a plurality of patterns, and a judgment part that produces a judgment signal based on a comparison of the RGB data and the plurality of patterns stored in the storage part.