Abstract

An analytic expression has been developed that can be used for computing the Fourier spectrum of any halftone image as a function of the original continuous-tone image and the halftone process. This result takes into account the nonlinear effects of the threshold step in the halftone process. Although the result is general and can be applied to any original image, in some cases of periodic images the Fourier components of the halftone image are particularly easy to compute. We show important differences between spectra of halftone images and scanned or sampled images. In halftone images, significant image detail is maintained at spatial frequencies greater than half of the screen frequency and aliasing or moiré patterns depend upon object contrast and upon the halftone function differently from similar patterns which occur in scanned or sampled imagery.

© 1975 Optical Society of America

Analysis of halftone dot profile and aliasing in the discrete binary representation of images*

J. P. Allebach and B. Liu
J. Opt. Soc. Am. 67(9) 1147-1154 (1977)

Random quasiperiodic halftone process

J. P. Allebach and B. Liu
J. Opt. Soc. Am. 66(9) 909-917 (1976)

Fourier spectra of digital halftone images containing dot-position errors

Paul W. Melnychuck and Rodney Shaw
J. Opt. Soc. Am. A 5(8) 1328-1338 (1988)

Halftone method with edge enhancement and Moiré suppression

Paul G. Roetling
J. Opt. Soc. Am. 66(10) 985-989 (1976)

Design of a printed spectrum using modified Neugebauer halftone equations

Milton Pearson, Irving Pobboravsky, and John A. C. Yule
J. Opt. Soc. Am. 65(3) 323-326 (1975)