Patent US 4,470,072

In a band compression method using an adaptive prediction system preferably applicable to facsimile transmission, a method of selecting picture elements to be referred (hereinafter defined as reference picture elements) for predicting an information value of a picture element wherein the reference picture elements are not selected uniformly and continuously from the neighborhood of the predicted picture element, but a group of picture elements (the first order picture elements) adjacent to the predicted picture element and further a group of picture elements of equal or higher order than the third order are selected as reference picture elements by excluding those shaded picture elements which lie on lines connecting the predicted picture element and the first order picture elements.