Clustered-Dot Halftoning with Direct Binary Search ∗

Printers employing electrophotographic technology typically use clustered-dot screening to avoid potential arti-facts caused due to unstable dot rendering. Periodic clustered-dot screens are quite smooth, but also suffer from periodic moire ́ artifacts due to interference with other color channels. Stochastic, clustered-dot screens provide an alternative solution. In this paper, we introduce a new approach for stochastic, clustered-dot halftoning and screen design based on direct binary search. The method deviates from conventional DBS in its use of different filters in different phases of the algorithm. We provide an intuitive explanation for the clustering achieved as a re-sult of this modification, and also discuss ways to control the coarseness of clusters. Due to the non-applicability of conventional screen design procedures to the new halftoning method, we propose a new method for screen design also. Results include images of individually designed constant-tone halftones and halftones of screened folded ramps. 1