1. A printing system, comprising: an identification module to identify line regions of an image corresponding to lines based on image data, and to identify non-line regions of the image corresponding to image portions without lines based on the image data; and an image pipeline module including a linear threshold array algorithm and a halftoning algorithm to process the image data, the image pipeline module to apply the linear threshold array algorithm to the line regions and to apply the halftoning algorithm to the non-line regions to form filtered image data, wherein the printing system forms an image of the filtered image data on a substrate.