Adaptive Image Reconstruction via Gradient-Based Regularization
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Solution Overview
Problem
Current image reconstruction methods in imaging technologies face challenges in dynamically adjusting the regularization strength based on evolving image gradients, particularly with the Huber regularization term, which limits the adaptability and accuracy of the reconstruction process.
Innovation Solution
A system and method that iteratively updates the regularization parameter based on the gradient of the image estimate, allowing for adaptive switching between linear and quadratic regularization, thereby enhancing the stability and noise reduction in the reconstructed image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed regularization parameter is used in the objective function, then the reconstruction process is stable and simple to implement, but the adaptability to different image regions and gradients is poor
Solution Approach 1:
The patent applies the dynamics principle by making the regularization parameter adaptive rather than fixed. The parameter dynamically adjusts based on the gradient magnitude of the image estimate, allowing different regularization strengths in different image regions. This is achieved through the Huber regularization term which automatically transitions between linear and quadratic regularization based on local gradient characteristics, resolving the contradiction between adaptability and complexity.
Solution Approach 2:
The patent implements parameter changes by modifying the regularization parameter based on image gradient information. The Huber regularization term uses a parameter that changes according to the gradient magnitude, switching between different regularization behaviors (linear for large gradients, quadratic for small gradients). This allows the system to adapt to different image features without requiring complex manual parameter adjustment.
2Shape
If linear regularization is used, then edge preservation is improved, but noise reduction capability deteriorates
Solution Approach 1:
The patent applies the local quality principle by using different regularization types in different image regions based on gradient magnitude. In regions with large gradients (edges), linear regularization is applied to preserve edge sharpness. In regions with small gradients (smooth areas), quadratic regularization is applied to provide stronger noise reduction. This local adaptation resolves the contradiction between edge preservation and noise reduction.
Solution Approach 2:
The patent implements a composite regularization approach by combining linear and quadratic regularization terms through the Huber regularization function. The composite nature of this regularization term allows it to exhibit linear behavior in some regions and quadratic behavior in others, depending on the local gradient characteristics. This composite approach simultaneously achieves edge preservation and noise reduction, resolving the contradiction between these two opposing requirements.
3Object-affected harmful factors
If quadratic regularization is used, then noise reduction is improved, but edge sharpness and spatial resolution deteriorate
Solution Approach 1:
The patent applies the local quality principle by selectively applying quadratic regularization only in regions where it is beneficial (smooth areas with small gradients). In edge regions with large gradients, the regularization automatically transitions to linear behavior, preserving spatial resolution and edge sharpness. This localized application strategy resolves the contradiction between noise reduction and spatial resolution.
Data Source
AI summary
The present disclosure relates to systems and methods for reconstructing an image in an imaging system. The methods may include obtaining scan data representing an intensity distribution of energy detected at a plurality of detector elements and determining an image estimate. The methods may further include determining an objective function based on the scan data and the image estimate. The objective function may include a regularization parameter. The methods may further include iteratively updating the image estimate until the objective function satisfies a termination criterion, and for each update, updating the regularization parameter based on a gradient of an updated image estimate. The methods may further include outputting a final image based on the updated image estimate when the objective function satisfies the termination criterion.


