Two-Dimensional Lens Shading Correction via Sampling
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Solution Overview
Problem
Image capturing systems face challenges in correcting lens shading artifacts due to non-uniform light distribution, which causes light intensity fall-off at image edges, making existing correction methods complex and costly to implement in hardware.
Innovation Solution
A method involving determining a two-dimensional lens shading correction function L(x,y), applying a sampling technique to sample this function at selected points, and storing it for later use in reconstructing missing data points to correct captured images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a two-dimensional lens shading correction function L(x,y) is used to correct lens shading artifacts, then image correction accuracy is improved, but hardware implementation complexity and cost increase
Solution Approach 1:
The patent divides the continuous two-dimensional correction function L(x,y) into discrete sample points stored in a lookup table. This segmentation allows the complex continuous function to be approximated by querying pre-computed values at specific locations, reducing the computational burden during image processing while maintaining correction accuracy.
Solution Approach 2:
The patent pre-computes and stores the lens shading correction function L(x,y) at multiple sample points before actual image processing occurs. This preliminary action transforms the complex real-time computation requirement into a simpler lookup operation during image processing, reducing hardware complexity while preserving correction precision.
2Reliability
If a two-dimensional lens shading correction function L(x,y) is implemented, then lens shading artifacts are corrected, but data storage requirements and processing power increase
Solution Approach 1:
Instead of storing the complete continuous function L(x,y) which would require large amounts of data, the patent segments the function into discrete sample points. This reduces the quantity of data that needs to be stored while still allowing accurate reconstruction of the correction function through interpolation during image processing.
Solution Approach 2:
The patent creates a simplified representation (copy) of the complex correction function by storing only sampled values at discrete points. This sampled version serves as a compact substitute for the full continuous function, reducing storage requirements while maintaining the essential correction information needed for effective lens shading artifact removal.
Data Source
AI summary
In one embodiment of the invention, there is provided a method of correcting a captured image for lens shading artifacts, comprising for a given lens determining a function L(x,y) being a lens shading correction function to be applied to images captured by the lens in order to correct for lens shading artifacts; applying a sampling technique to sample the function L(x,y) at selected points; and storing the sampled function L(x,y) in memory.