Inkjet Nozzle Correction for Density and Color Shift
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Solution Overview
Problem
Inkjet printing technologies face challenges in maintaining color accuracy due to variations in ink ejection volumes among nozzles, leading to density unevenness and color shifts when printing with multiple inks, despite the use of head shading techniques.
Innovation Solution
An image processing apparatus and method that selects and applies correction parameters based on the specific printing characteristic ranks of nozzles for each ink combination, adjusting image data to account for variations in ink ejection volumes, thereby reducing color shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If head shading technique is used to correct ink ejection volume variations, then density unevenness is reduced, but color shift occurs when multiple inks are overlapped
Solution Approach 1:
The patent changes the correction parameters based on the combination of ink colors being printed. Different correction values are applied depending on whether a single ink or multiple inks are involved, allowing the system to optimize for either density uniformity or color accuracy based on the specific printing scenario
Solution Approach 2:
The patent applies different correction strategies to different situations: when a single ink is printed, head shading is applied for density uniformity; when multiple inks are overlapped, different correction parameters are used to maintain color accuracy. This localized approach to correction resolves the contradiction by adapting the correction method to the specific printing context
2Manufacturing precision
If correction parameters are applied to adjust ink ejection volume variations, then density uniformity improves, but color reproduction accuracy deteriorates
Solution Approach 1:
The patent dynamically selects correction parameters based on the printing conditions, specifically the combination of inks being used. The correction approach transitions from static head shading to a dynamic system that adapts correction strength and method based on whether multiple inks are involved, thereby maintaining both density uniformity and color accuracy across different scenarios
Data Source
AI summary
Printing heads of combinations of four ink colors and seven printing characteristic ranks are previously used to print an image for measurement, and table parameters corresponding to all of the combinations of nozzle ink colors and printing characteristic ranks are obtained on the basis of a measurement result of this image for measurement and stored in a memory. Then, when printing is actually performed in a printer, a primary color image for measurement is printed for each nozzle of a printing head for each of four ink colors. A printing characteristic rank for each nozzle is obtained for each of four ink colors based on a measurement result of this image for measurement, and a table parameter is selected that corresponds to the same combination as the combination of the obtained printing characteristic rank of each nozzle of four ink colors, by referring to the memory.