Bi-level image display signal processing apparatus.

摘要

An image signal processing apparatus for converting step-gradation density values (Ixy) of successive picture elements to bi-level values (Pxy) for display by a bi-level display device, in which a bi-level error (Exy) between a bi-level value determined for a picture element and an appropriate density value for the element is apportioned among a set of peripherally adjacent picture elements (A to D) by computing a corresponding set of error apportionment values (GA to GD), and in which a difference between the sum total of these apportionment values and the bi-level error is derived, and error apportionment is modified such as to eliminate the effects of this difference. Improved reproduction is thereby attained of image regions which are of uniformly high density or low density.