Shading Correction Using Local Black and White References
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional shading correction techniques in image processing are prone to location-dependent errors due to variations in light reflection properties, especially when using large area black references, which can affect the accuracy of image quality improvement.
Innovation Solution
An image processing device that includes a sensor and a controller, where the sensor reads both print and non-print regions of a medium, and the controller performs shading correction based on individual location properties of black and white references, using a patch image as the black reference and a non-print region as the white reference, to absorb differences in read results and improve precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a large area black reference patch is used for shading correction, then the sensor can capture sufficient light signal, but location-dependent errors occur due to variations in light reflection properties across different sensor positions
Solution Approach 1:
The patent divides the shading correction process into multiple measurements taken at different sensor positions across the print medium. Instead of using a single large-area reference, the system performs multiple localized readings and combines them to create a comprehensive shading correction map, thereby eliminating location-dependent errors while maintaining sufficient light signal capture.
Solution Approach 2:
The patent applies local quality by performing shading correction measurements at multiple specific locations across the print medium rather than relying on a single uniform reference. Each location's unique light reflection properties are captured and used to create a position-specific correction profile, ensuring accurate compensation for local variations in the printing system.
2Measurement precision
If multiple adjustment patterns at different densities are printed and read, then print quality degradation can be precisely identified, but the process time and complexity increase
Solution Approach 1:
The patent performs preliminary shading correction using black and white reference patches before reading the adjustment patterns. This pre-correction eliminates location-dependent errors in subsequent measurements, allowing accurate print quality assessment to be achieved more efficiently without requiring extensive additional measurements or complex post-processing.
3Loss of information
If the sensor reads both print and non-print regions, then comprehensive shading data can be obtained, but the reading process becomes more complex
Solution Approach 1:
The patent merges the reading of black reference patches, white reference patches, and adjustment patterns into a single integrated process. The sensor systematically reads all regions in sequence, and the controller processes the combined data to perform comprehensive shading correction, thereby obtaining complete shading information while managing process complexity through unified control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise shading correction by accounting for location-dependent variations, leading to improved image quality and reduced errors in print quality degradation identification and correction.
Implementation Method 1
the property of the light reflected on the black reference may vary with a location of a sensor
Data Source
AI summary
An image processing device includes: a sensor that reads a print region and a non-print region of a print medium, an image being printed in the print region, the non-print region being a blank area; and a controller that makes shading correction for an output from the sensor, based on a read result from the sensor. The controller sets a patch image printed in the print region to a black reference, sets the non-print region to a white reference, and makes the shading correction, based on properties of the black reference and the white reference at individual locations.