Local analysis of iterative reconstruction from discrete generalized Radon transform data in the plane
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arXiv
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| Format: | Preprint |
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2024
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| _version_ | 1866918070147088384 |
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| author | Katsevich, Alexander |
| author_facet | Katsevich, Alexander |
| contents | Local reconstruction analysis (LRA) is a powerful and flexible technique to study images reconstructed from discrete generalized Radon transform (GRT) data, $g=\mathcal R f$. The main idea of LRA is to obtain a simple formula to accurately approximate an image, $f_ε(x)$, reconstructed from discrete data $g(y_j)$ in an $ε$-neighborhood of a point, $x_0$. The points $y_j$ lie on a grid with step size of order $ε$ in each direction. In this paper we study an iterative reconstruction algorithm, which consists of minimizing a quadratic cost functional. The cost functional is the sum of a data fidelity term and a Tikhonov regularization term. The function $f$ to be reconstructed has a jump discontinuity across a smooth surface $\mathcal S$. Fix a point $x_0\in\mathcal S$ and any $A>0$. The main result of the paper is the computation of the limit $ΔF_0(\check x;x_0):=\lim_{ε\to0}(f_ε(x_0+ε\check x)-f_ε(x_0))$, where $f_ε$ is the solution to the minimization problem and $|\check x|\le A$. A numerical experiment with a circular GRT demonstrates that $ΔF_0(\check x;x_0)$ accurately approximates the actual reconstruction obtained by the cost functional minimization. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2412_15910 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Local analysis of iterative reconstruction from discrete generalized Radon transform data in the plane Katsevich, Alexander Numerical Analysis Local reconstruction analysis (LRA) is a powerful and flexible technique to study images reconstructed from discrete generalized Radon transform (GRT) data, $g=\mathcal R f$. The main idea of LRA is to obtain a simple formula to accurately approximate an image, $f_ε(x)$, reconstructed from discrete data $g(y_j)$ in an $ε$-neighborhood of a point, $x_0$. The points $y_j$ lie on a grid with step size of order $ε$ in each direction. In this paper we study an iterative reconstruction algorithm, which consists of minimizing a quadratic cost functional. The cost functional is the sum of a data fidelity term and a Tikhonov regularization term. The function $f$ to be reconstructed has a jump discontinuity across a smooth surface $\mathcal S$. Fix a point $x_0\in\mathcal S$ and any $A>0$. The main result of the paper is the computation of the limit $ΔF_0(\check x;x_0):=\lim_{ε\to0}(f_ε(x_0+ε\check x)-f_ε(x_0))$, where $f_ε$ is the solution to the minimization problem and $|\check x|\le A$. A numerical experiment with a circular GRT demonstrates that $ΔF_0(\check x;x_0)$ accurately approximates the actual reconstruction obtained by the cost functional minimization. |
| title | Local analysis of iterative reconstruction from discrete generalized Radon transform data in the plane |
| topic | Numerical Analysis |
| url | https://arxiv.org/abs/2412.15910 |