Image forming apparatus and image forming method employed therefor

摘要

An image forming apparatus for use in an electrophotographic copying process and an image forming method for the apparatus, which are arranged to reproduce an image portion of an original document by a black developing material on a white paper sheet when an area of the image portion of the original document is below a predetermined level, and also, reproducing a background portion of the image by a white developing material on a black paper sheet when the area of the image portion of the original document is above the predetermined level, and thus, the black developing material or white developing material is selectively used according to percentages of image areas on the original document.