Color Shading Correction Using Weighted Basis Maps
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Solution Overview
Problem
Conventional color shading correction methods in image systems are costly and inefficient, requiring repetitive calibration for each unit and struggling with accurate illuminant identification, leading to suboptimal image quality due to manufacturing variations and complex calibration processes.
Innovation Solution
A method that uses a set of predetermined bases to calculate coefficients for generating correction maps, allowing for adaptive correction of color shading across different image systems and illuminants, reducing the need for individual calibration and enhancing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional color shading correction methods are used, then color shading can be corrected, but the calibration process is costly and time-consuming requiring repetitive calibration for each unit
Solution Approach 1:
The patent pre-calculates color shading correction maps for multiple illuminant conditions during the manufacturing process and stores them in memory. During actual image capture, the system simply retrieves the pre-computed correction map corresponding to the detected illuminant type, avoiding time-consuming real-time calibration while maintaining correction accuracy across different lighting conditions
Solution Approach 2:
The patent changes the approach from unit-specific calibration to illuminant-based correction by introducing illuminant type as the key parameter. The system detects illuminant type (e.g., daylight, incandescent, fluorescent) and selects appropriate pre-computed correction maps, replacing the need for repetitive individual unit calibration with a more efficient parameter-driven selection process
2Reliability
If conventional color shading correction methods are used, then color shading can be corrected, but the calibration process is complex and requires repetitive procedures for each unit
Solution Approach 1:
The patent creates universal correction maps that work across multiple units by characterizing color shading based on illuminant type rather than individual unit properties. A single set of correction maps can serve multiple image systems, reducing calibration complexity while maintaining effectiveness through the universal categorization of illuminant conditions
Solution Approach 2:
The patent simplifies the calibration process by changing from complex unit-specific procedures to a simpler illuminant-based parameter system. The correction approach shifts from adjusting multiple parameters for each unit to selecting pre-computed maps based on illuminant type, significantly reducing process complexity
3Reliability
If conventional color shading correction methods are used, then color shading can be corrected, but accurate illuminant identification is difficult leading to suboptimal image quality
Solution Approach 1:
The patent changes the detection approach from attempting to identify specific illuminant sources to categorizing illuminants into broad types based on color temperature and spectral characteristics. This parameter simplification makes detection more reliable by focusing on dominant characteristics rather than precise identification, leading to better image quality through appropriate correction map selection
Data Source
AI summary
A method for correcting color shading artifact of an image and associated apparatus is provided. The method comprises: providing a plurality of bases, calculating a plurality of coefficients respectively associated with the bases, generating a correction map by summing the bases respectively weighted by with the coefficients, and providing a corrected image by correcting the image according to the correction map. Each basis is capable of providing a basic correction value for each pixel of an intermediate image which is associated with the image.