Method of minimizing stitching artifacts for overlapping printhead segments

Summary

Wide-format and pagewide inkjet printers cover the full media width by lining up multiple printhead modules side by side. Each head prints its own strip, and the strips have to meet seamlessly. They never do quite seamlessly — every join shows up as a faint streak running down the page, sometimes light, sometimes dark, always visible.

The classic fixes are limited. A “butt join” sets a fixed boundary in the overlap zone and lets one head print everything to its left and the other everything to its right — fine for plain text, but the join becomes a visible vertical line in a photograph. “Feathering” gradually fades printing from one head to the other across the overlap zone — better for photos but vulnerable to misalignment, where overlapping droplets stack unpredictably and create moiré streaks.

This patent borrows an idea from image resizing — seam carving — and turns it into a print-stitching tool. Instead of a straight boundary, the algorithm finds a continuously wandering path through the overlap zone that threads through low-ink, high-luminance pixels and routes around text characters and dark edges. High-density content stays under the control of a single head; the seam wanders through the parts of the image where a stitch can hide. The result is a join that vanishes into normal image content, and a single algorithm that handles photos, text, and mixed-content jobs without per-job tuning.