Notchless Bi-Level Quantizer for Facsimile and Its Effect on Coding Efficiency

With a facsimile bi-level quantizer, notches often occur along the white and black borders of a document when the output of a photosensor goes up and down around a threshold. The objects of this work are, first, to present a notchless bi-level quantizer, and secondly, to improve coding efficiency by using the quantizer. It is pointed out that quantization is comprised of many important aspects from aesthetic as well as coding efficiency standpoints, and that significant improvement is achieved in coding efficiency through the use of the notchless bi-level quantizer.