Inkjet Image Processing Reducing Band Seam Streaks
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Solution Overview
Problem
Conventional inkjet printing devices often produce dark streaks along the seams between adjacent bands printed in different main scans due to ink penetration and spreading, which existing techniques struggle to fully mitigate.
Innovation Solution
An image processing device adjusts pixel values in the image data before the halftone process to reduce ink density at the edges of printing areas, specifically by determining index values and adjusting gradation values for CMY colors while keeping pigment ink values unchanged, thereby reducing ink usage and minimizing streaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ink is ejected with normal density at edge portions of unit printing areas, then the printed image maintains original color and density quality, but dark streaks are produced along the seams between adjacent bands
Solution Approach 1:
The patent applies different processing to different regions of the image data. Specifically, edge portions of unit printing areas are identified and processed differently from central portions. The adjustment section reduces ink density only at edge portions while maintaining normal density in central portions, thereby eliminating streaks without affecting overall print quality.
Solution Approach 2:
The patent performs preliminary adjustment of pixel values before the halftone process. The adjustment section modifies the density of edge portions in advance, reducing ink quantity in these regions before printing occurs. This preliminary action prevents the formation of dark streaks at band seams by ensuring that adjacent bands have reduced ink density at their meeting edges.
2Object-generated harmful factors
If the density of edge portions is reduced to prevent streaks, then streaks are mitigated, but the total quantity of ink used increases
Solution Approach 1:
The patent selectively adjusts only the edge portions of unit printing areas while leaving the central portions unchanged. This localized approach ensures that ink density is reduced only where necessary (at edges prone to streaking) rather than uniformly across the entire image, thereby minimizing the total ink quantity consumed while still achieving streak mitigation.
3Object-generated harmful factors
If pixel values are adjusted before halftone process, then ink density at edges is reduced and streaks are prevented, but the image processing complexity increases
Solution Approach 1:
The patent integrates the adjustment section to perform preliminary modification of pixel values before the halftone process. By identifying edge portions and adjusting their density in advance, the system prevents streak formation without requiring complex post-processing or additional hardware components, thus managing processing complexity efficiently.
4Object-generated harmful factors
If ink density is uniformly reduced across the entire image, then streaks are prevented, but the overall print quality and color accuracy deteriorate
Solution Approach 1:
The patent selectively processes only the edge portions of unit printing areas while maintaining normal ink density in the central portions. This localized adjustment ensures that streaks are prevented at band seams without compromising the overall print quality and color accuracy of the main image areas.
Data Source
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AI summary
An image processing device for processing image data indicative of an image to be printed by a print execution section, the print execution section having a print head that is reciprocated in a main scanning direction and that is capable of printing a partial image in a unit printing area for each main scan. The image processing device includes: a process section; a generation section; and a supply section. The process section is configured to execute an image process on image data so as to generate processed image data. The generation section is configured to execute a halftone process on the processed image data so as to generate print data. The supply section is configured to supply the print data to the print execution section. The process section includes: an index value determination section; and an adjustment section. The index value determination section is configured to determine an index value for each of a plurality of target pixels included in edge image data, the index value for each target pixel being related to density of the target pixel, wherein the edge image data corresponds to an edge portion of a unit printing area and is part of partial image data within the image data, and the partial image data corresponds to the unit printing area. The adjustment section is configured not to adjust a pixel value of the target pixel in a first case where the density of the target pixel is determined to be relatively low based on the index value of the target pixel, and configured to adjust the pixel value of the target pixel so as to reduce the density of the target pixel in a second case where the density of the target pixel is determined to be relatively high based on the index value of the target pixel.