Image Processing Device Defect Correction Quantization
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Solution Overview
Problem
Inkjet recording devices face issues with streak-like unevenness and reduced granularity due to nozzle discharge failures, leading to artifacts and decreased image quality, particularly when multiple nozzles are defective or non-discharging.
Innovation Solution
An image processing method that includes defect information acquisition, mask processing to render defective nozzles unusable, image concentration correction, and differential quantization methods for regions with and without defective nozzles, suppressing low-frequency components in the quantization pattern to prevent artifacts and maintain granularity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If concentration correction is applied to mask defective nozzles, then streak visibility is reduced, but artifacts and reduced granularity occur in the corrected regions
Solution Approach 1:
The patent applies different quantization patterns to different regions of the image based on nozzle defect information. Specifically, regions affected by defective nozzles use a first quantization pattern designed to suppress streak artifacts, while unaffected regions use a second quantization pattern optimized for general image quality. This local differentiation resolves the contradiction by allowing streak suppression where needed without compromising overall image quality.
Solution Approach 2:
The image is segmented into multiple regions based on nozzle defect maps. The patent divides the image data into regions corresponding to defective nozzles and regions corresponding to normal nozzles, then applies different processing strategies to each segment. This segmentation allows the system to address streak issues in affected regions while maintaining optimal quality in unaffected regions.
2Object-generated harmful factors
If multiple defective nozzles are masked, then streak artifacts are reduced, but image granularity deteriorates in the masked regions
Solution Approach 1:
The patent changes the quantization pattern parameters based on the presence and location of defective nozzles. When multiple nozzles are defective, the system switches to a first quantization pattern with modified characteristics that suppress streak artifacts. When nozzles are normal, the system uses a second quantization pattern that maintains fine granularity. This dynamic parameter adjustment resolves the contradiction between streak suppression and granularity preservation.
3Device complexity
If uniform quantization is applied across the entire image, then processing is simplified, but artifacts occur in regions with defective nozzles
Solution Approach 1:
The patent introduces dynamic selection of quantization patterns based on real-time nozzle defect information. The system automatically switches between a first quantization pattern (for defective regions) and a second quantization pattern (for normal regions) based on the detected nozzle status. This dynamic adaptation allows the system to maintain high image quality without significantly increasing processing complexity, as the pattern selection is driven by pre-acquired nozzle defect data.
Data Source
AI summary
An image processing method corrects the image concentration of pixel rows adjacent to a pixel row corresponding to a masked defective recording element. Different quantization methods are performed for a first image region including the pixel row corresponding to the masked defective recording element and the pixel rows adjacent to the pixel row and a second image region other than the first image region. For at least some gradations, a first quantization pattern which is obtained by the first quantization method applied to the first image region has a pattern characteristic in which a spatial frequency component in a first direction parallel to the moving direction of a recording medium relative to the recording head is suppressed with respect to all spatial frequency components in a second direction perpendicular to the first direction, as compared to a second quantization pattern applied to the second image region.