Images that have been halftoned with a periodic screen may suffer from several kinds of defects, including Moiré patterns which result when the original image contains periodic structures with periods near that of the screen. A random quasiperiodic halftone process is proposed to eliminate these defects. The process can be implemented either as a contact screen or electronically. The statistical mean and covariance of the spectrum of the halftone image are derived. Experimental work confirms the results of the analysis and shows the effectiveness of the random quasiperiodic process in eliminating the defects found in periodically halftoned images.
© 1976 Optical Society of AmericaPDF Article