Use of the Hough transform to determine the center of digitized X-ray diffraction patterns

Dammer, Christoph; Leleux, P.; Villers, D.; Dosière, M.

doi:10.1016/s0168-583x(97)00440-0

Cited by 9 publications

(2 citation statements)

References 9 publications

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“…Both parts of our algorithm rely on analysis of each image's Fourier transform to recover illumination angles. Fourier domain pupil analysis of intensity images has been used previously to deduce imaging system aberrations [37] and determine the center of diffraction patterns [38,39] for system calibration. We show here that the individual Fourier spectra can be used to determine illumination angle.…”

Section: Methodsmentioning

confidence: 99%

Efficient illumination angle self-calibration in Fourier ptychography

2018

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Fourier ptychography captures intensity images with varying source patterns (illumination angles) in order to computationally reconstruct large space-bandwidth-product images. Accurate knowledge of the illumination angles is necessary for good image quality; hence, calibration methods are crucial, despite often being impractical or slow. Here, we propose a fast, robust, and accurate self-calibration algorithm that uses only experimentally collected data and general knowledge of the illumination setup. First, our algorithm makes a fast direct estimate of the brightfield illumination angles based on image processing. Then, a more computationally intensive spectral correlation method is used inside the iterative solver to further refine the angle estimates of both brightfield and darkfield images. We demonstrate our method for correcting large and small misalignment artifacts in 2D and 3D Fourier ptychography with different source types: an LED array, a galvo-steered laser, and a high-NA quasi-dome LED illuminator.

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Section: Methodsmentioning

confidence: 99%

Efficient illumination angle self-calibration in Fourier ptychography

2018

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“…The transformation is implemented by quantizing the parameter space into finite intervals called the accumulator array. Possible magnitudes of recognized parameters are voted (Dammer et al , 1997) in their corresponding accumulator bin in parameter space. After processing all the edge points in the image, the local maximum in the accumulator array corresponds to the parameter of specified shape.…”

Section: Minor Axis Estimation Using Hough Transformationmentioning

confidence: 99%

Automatic calibration of powder diffraction experiments using two-dimensional detectors

et al. 2007

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Calibration of powder diffraction experiments using area detectors is essential to extract high quality one-dimensional powder diffraction pattern. Precise calibration necessitates a sensible characterization of the Debye-Scherrer rings formed on the detector plane. An algorithm, designed and developed to automate this process, is described in this paper. All the parameters required for an experimental calibration are extracted using robust pattern recognition techniques. Several image preprocessing methods are employed, reducing the computational cost but retaining high signal quality. A modified version of a one-dimensional Hough transformation is used to determine the final parameters of the ellipses. After extraction, the parameters are optimized using nonlinear least squares fit. The presented algorithm is insensitive to image artefacts and was successfully applied to a large number of calibration images. The performance of the algorithm is demonstrated by the comparison of results obtained from the presented automatic calibration method and an existing manual method.

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Center positioning of circular interference fringe patterns for fine measurement

Chen

et al. 2014

Optik

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Use of the Hough transform to determine the center of digitized X-ray diffraction patterns

Cited by 9 publications

References 9 publications

Efficient illumination angle self-calibration in Fourier ptychography

Efficient illumination angle self-calibration in Fourier ptychography

Automatic calibration of powder diffraction experiments using two-dimensional detectors

Center positioning of circular interference fringe patterns for fine measurement

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