Most halftone screens are designed to get nicely distributed dots in highlights and shadows. The place where growing dots touch each other however is often not controlled. Depending on parameters such as tile size, screen angle and ruling, the dot centers will be positioned differently on the discrete image matrix. This makes that in some regions of the tile, dots will already touch while in other regions they are still separated. Also depending on the spot size of the imaging device used, this will result in slightly lighter and darker regions in one tile, which becomes visible when the tile is replicated. This paper describes a method that uses morphological filters and operators to find the regions around the connection points. The thresholds in those regions are rearranged so dot connections become nicely distributed over the tile for all levels.
Rudi Bartels, "Redistributing Dot Connections to Avoid Visible Tile Replication in AM Halftone Screens" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP15), 1999, pp 354 - 357, https://doi.org/10.2352/ISSN.2169-4451.1999.15.1.art00092_1