Lens Shading Correction via 2D to 1D Function Segmentation
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Solution Overview
Problem
Image capturing systems suffer from lens shading artifacts due to non-uniform light distribution, causing light intensity to fall off towards the edges of captured images, which existing methods find difficult to correct efficiently, especially in hardware implementation.
Innovation Solution
A method and system that determine a two-dimensional lens shading correction function L(x, y) to correct captured images, involving cropping and scaling based on focal length, and using image processor logic to implement this correction, reducing data storage needs by discarding most data points while reconstructing missing data through interpolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a two-dimensional lens shading correction function L(x, y) is used to correct lens shading artifacts, then image quality is improved, but hardware implementation becomes complex and expensive
Solution Approach 1:
The patent divides the correction function into two separate one-dimensional functions: L(x, y) = lx(x) × ly(y). This segmentation transforms a complex 2D correction problem into two simpler 1D problems, reducing hardware implementation complexity while maintaining correction effectiveness
Solution Approach 2:
The patent extracts the correction function determination process as a separate preprocessing step. The correction functions lx(x) and ly(y) are determined in advance and stored, separating the complex 2D function computation from the real-time image correction process, thereby reducing hardware complexity during actual operation
2Measurement precision
If the lens shading correction function is determined for each focal length, then correction accuracy is improved, but data storage requirements increase
Solution Approach 1:
The patent creates a universal correction approach where a single set of correction functions can be applied across multiple focal lengths. By determining the correction function at one focal length and applying it universally (with appropriate coordinate transformations), the system reduces data storage requirements while maintaining adequate correction accuracy across different focal lengths
Solution Approach 2:
The patent transforms the correction function parameters based on focal length relationships. Instead of storing separate correction functions for each focal length, the system uses parameter transformations (scaling and coordinate mapping) to adapt a base correction function to different focal lengths, significantly reducing storage requirements
Data Source
AI summary
In one embodiment of the invention, there is provided a method of correcting a captured image for lens shading artifacts, the captured image being captured by an image capture system, the method comprising: determining a function L(x, y) being a lens shading correction function to be applied to images captured by a lens of the image capture system in order to correct for lens shading artifacts; if a focal length associated with the captured image is less than a focal length associated with, the function L(x, y) then cropping the function L(x, y) based on the focal length associated with the captured image; and scaling the cropped function L(x, y) to a size of the tin-cropped Junction L(x, y).