Determining Optimal Halftone Angles for CMYK Printing

Abstract

CMYK halftone prints are all around us, yet the halftone angles used to generate these prints are traditionally set to specific values without substantial documentation explaining why these angles are optimal. Investigating the optimization of these angles is important for enhancing print quality and minimizing visual artifacts, which can significantly impact the visual appeal and accuracy of printed materials especially in low-resolution printing such as relief and screen printing techniques. This research investigates optimal halftone angles under low-resolution. The algorithm for this system generates low-resolution images from an input image, aiming to cover the full range of permutations of possible angles for each halftone in discrete variations of 15◦. We performed this on a various range of input images and computed a similarity score between each output image and its original input image, to assess a specific angle permutation’s performance. The study led to the formulation and validation of two hypotheses: 1) images with distinct halftone angles for each color channel generally achieve higher similarity scores than those with repeated angles; 2) permutations with the black halftone oriented at 0◦ benefits images with a high prevalence of black pixels. This thesis contributes to understanding halftone angle optimization in CMYK printing, offering practical guidelines for improving print quality and reducing visual artifacts, thus benefiting the printing industry and its diverse applications.