Multi-Channel Digital Printer Alignment via Pixel Pattern Matching
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Solution Overview
Problem
Digital printing systems face challenges in aligning image data across multiple channels due to dimensional changes in the receiver medium and variations in printing modules, leading to misregistration issues.
Innovation Solution
A method that involves scanning test patterns, analyzing their locations, and adjusting spatial parameters to modify image data for non-reference printheads, ensuring improved alignment by inserting or deleting pixels based on predefined patterns to match reference printheads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple printing modules are used to print different channels, then printing capability and color density are improved, but alignment precision deteriorates due to dimensional changes in the receiver medium
Solution Approach 1:
The system performs preliminary actions by printing test patterns before the actual multi-channel image, measuring their positions, and calculating spatial adjustment parameters in advance. This allows the system to pre-determine the dimensional changes and misalignment characteristics of the receiver medium, then apply corrective transformations to the image data before printing, thereby compensating for the precision loss caused by using multiple printing modules.
Solution Approach 2:
The system implements feedback by measuring the actual positions of printed test patterns and using this information to calculate spatial adjustment parameters. The measured misalignment data feeds back into the image processing pipeline, allowing the system to adaptively adjust the image data for each printing module based on actual performance, thereby maintaining alignment precision despite variations in receiver medium behavior.
2Manufacturing precision
If spatial adjustment parameters are applied to correct misalignment, then alignment precision is improved, but device complexity increases due to additional processing steps
Solution Approach 1:
The system extracts the alignment correction function from the physical printing process and implements it as a separate image data transformation step. By taking out the spatial adjustment parameters and applying them to the digital image data before printing, the system avoids the need for complex mechanical adjustments or recalibrations of the printing modules themselves, thereby reducing device complexity while maintaining alignment precision.
Solution Approach 2:
The system creates a corrected copy of the image data with spatial transformations applied, rather than modifying the physical printing process. The original image data is copied and transformed with the calculated spatial adjustment parameters, producing a corrected version that compensates for misalignment. This approach simplifies the overall system by keeping the printing hardware unchanged while achieving precision through data manipulation.
3Manufacturing precision
If test patterns are printed and measured to determine spatial parameters, then alignment accuracy is improved, but printing time increases
Solution Approach 1:
The system applies partial action by printing test patterns with only the essential features needed for measurement, rather than complete test images. The test patterns contain minimal necessary information (such as simple geometric shapes or markers) that can be quickly printed and measured, allowing the system to obtain the required spatial parameters with reduced printing time while still achieving the needed alignment accuracy.
Data Source
AI summary
A method for aligning multi-channel digital image data for a digital printer having a plurality of printheads is described. A test pattern including test pattern indicia printed using individual printheads is scanned and analyzed to detect locations of the printed test pattern indicia. One of the printheads is designated to be a reference printhead, and one or more of the other printheads are designated to be non-reference printheads. Spatial adjustment parameters are determined for each of the non-reference printheads responsive to the detected test pattern indicia locations. Digital image data for the non-reference printheads is modified by designating an input pixel neighborhood within which an image pixel should be inserted or deleted, comparing the image pixels in the input pixel neighborhood to a plurality of predefined pixel patterns to identify a matching pixel pattern; and determining a modified pixel neighborhood responsive to the matching pixel pattern.