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Convergence of Fourier Series01:21

Convergence of Fourier Series

The Fourier series is a powerful mathematical tool for representing periodic signals as an infinite sum of complex exponentials. In practice, this infinite series is truncated to a finite number of terms, yielding a partial sum. This truncation makes the approximation of the signal feasible but introduces certain challenges, particularly near discontinuities, known as the Gibbs phenomenon.
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Spatially variant apodization for image reconstruction from partial Fourier data.

J C Lee1, D R Munson

  • 1Dept. of Electr. and Comput. Eng., Illinois Univ., Urbana, IL 61801, USA. jalee@ieee.org

IEEE Transactions on Image Processing : a Publication of the IEEE Signal Processing Society
|February 12, 2008
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Summary

Spatially variant apodization (SVA) reduces sidelobe artifacts in Fourier data reconstruction without sacrificing resolution. This study demonstrates SVA as a form of minimum-variance spectral estimation (MVSE), offering a robust method for image reconstruction.

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Area of Science:

  • Signal Processing
  • Image Reconstruction
  • Fourier Data Analysis

Background:

  • Sidelobe artifacts are a persistent challenge in image reconstruction from finite Fourier data.
  • Traditional methods like shift-invariant windows mitigate sidelobes but degrade mainlobe resolution.
  • Spatially variant apodization (SVA) was proposed to address this trade-off but lacked theoretical grounding.

Purpose of the Study:

  • To establish a theoretical foundation for Spatially Variant Apodization (SVA).
  • To demonstrate the connection between SVA and Minimum-Variance Spectral Estimation (MVSE).
  • To develop and analyze 2D SVA techniques for partial Fourier data reconstruction.

Main Methods:

  • Theoretical analysis connecting SVA to Minimum-Variance Spectral Estimation (MVSE).
  • Development of four types of two-dimensional SVA algorithms.
  • Simulations using real-valued and complex-valued targets to evaluate performance.

Main Results:

  • SVA is shown to be a specific instance of Minimum-Variance Spectral Estimation (MVSE).
  • The study presents a comprehensive framework for 2D SVA in partial Fourier data reconstruction.
  • Simulation results validate the effectiveness of SVA across various target types, while also identifying limitations.

Conclusions:

  • SVA provides a theoretically sound method for reducing sidelobe artifacts in image reconstruction.
  • The MVSE framework offers a robust basis for understanding and applying SVA.
  • Performance measures confirm SVA's utility, though its limitations require consideration in practical applications.