Fringe-orientation estimation by use of a Gaussian gradient filter and neighboring-direction averaging

Zhou, Xiang; Baird, J. P.; Arnold, J.F.

doi:10.1364/ao.38.000795

Cited by 38 publications

(25 citation statements)

References 9 publications

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“…␤ k ͑͒ , however, is a direct measurement but because of the sign flips of the irradiance gradient is defined only modulo . 4 However, as was shown in Ref. 5, it is possible to recover ␤ k ͑2͒ by unwrapping W͕2␤ k ͑͒ ͖, where W͕ ͖ denotes the wrapping operator.…”

Section: A Phase Demodulation With a Quadrature Operator And The Relmentioning

confidence: 92%

Fast algorithm for estimation of the orientation term of a general quadrature transform with application to demodulation of an n-dimensional fringe pattern

2004

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The spatial orientation of fringes has been demonstrated to be a key point in reliable phase demodulation from a single n-dimensional fringe pattern, regardless of the frequency spectrum of the signal. Recent publications have shown a general method for determination of the orientation factor by use of a regularized phase-tracking ͑RPT͒ algorithm. We propose a generalization of a RPT algorithm for estimation of the spatial orientation in a general n-dimensional case. The proposed algorithm makes use of a simplified cost function that remains one dimensional regardless of the dimension of the problem. This makes the calculation faster than with a standard RPT algorithm, with which it is necessary to minimize an n ϩ 1-dimensional cost function for each point of the sample space. We have applied the method to the three-dimensional demodulation of a time-evolving fringe pattern, with good results.

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Section: A Phase Demodulation With a Quadrature Operator And The Relmentioning

confidence: 92%

Fast algorithm for estimation of the orientation term of a general quadrature transform with application to demodulation of an n-dimensional fringe pattern

2004

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“…This shows an ultra smooth result and this for a very short execution time (<0.5s). Note that other approaches such as the Gradient Method with averaging [41] gives equivalently smooth results. While this technique worked perfectly for all images, a problem did show up which was not mentioned in the original articles.…”

Section: D2 Fringe Direction Determinationmentioning

confidence: 99%

Analyzing closed-fringe images using two-dimensional Fan wavelets

2015

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In this paper, it will be shown how the use of two 2D Fan wavelets to analyse closed-fringe images can lead to a relatively fast and exceptionally noise-resistant algorithm capable of extracting not only local phase but also local frequency information. Our algorithm is up to 10 times faster than the current state-of-the-art in Wavelet processing techniques and even up to 30 times faster than 'Windowed Fourier' Transform programs which achieve similar noise-resiliency figures. This improvement is mainly achieved by the use of Fan wavelets instead of Morlet wavelets, but a more efficient scale-space discretisation strategy is also described and three different alternatives are suggested capable of solving the phase sign ambiguity problem in a quick and efficient manner. Finally, the application of the algorithm to real and numerically generated images shows that a precision of 1/30th of a fringe is achievable for noise levels going up to 1/5th of the input contrast.

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“…(7) will not have the correct magnitude and will not point in the correct direction. 7 This is usually the case in experimental techniques as holographic interferometry, photoelasticity, and shadow moiré. In this case the use of a normalization technique (background suppression and modulation equalization) is recommended.…”

Section: N-dimensional Orientation Term Computationmentioning

confidence: 99%

“…6,7 The cosines of the angles defined by Eqs. (9) and (10) are If the modulation and the background are smooth functions, the irradiance gradient can be approximated by ٌI Ϸ Ϫm sin ٌ, and therefore these cosines are related by…”

Section: N-dimensional Orientation Term Computationmentioning

confidence: 99%

Estimation of the orientation term of the general quadrature transform from a single n-dimensional fringe pattern

et al. 2005

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The spatial orientation of the fringe has been demonstrated to be a key point in the reliable phase demodulation from a single n-dimensional fringe pattern regardless of the frequency spectrum of the signal. The recently introduced general n-dimensional quadrature transform (GQT) makes explicit the importance of the fringe orientation in the demodulation process. The GQT is a quadrature operator that transforms cos into Ϫsin -where is the modulating phase-and it is composed of two terms: an orientation factor directly related to the fringe's spatial orientation and an isotropic n-dimensional generalization of the one-dimensional Hilbert transform. We present a method for the determination of the orientation factor in a general n-dimensional case and its application to the demodulation of a single fringe pattern by the GQT. We have tested the algorithm with simulated as well as real photoelastic fringe patterns with good results.

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Fringe-orientation estimation by use of a Gaussian gradient filter and neighboring-direction averaging

Cited by 38 publications

References 9 publications

Fast algorithm for estimation of the orientation term of a general quadrature transform with application to demodulation of an n-dimensional fringe pattern

Fast algorithm for estimation of the orientation term of a general quadrature transform with application to demodulation of an n-dimensional fringe pattern

Analyzing closed-fringe images using two-dimensional Fan wavelets

Estimation of the orientation term of the general quadrature transform from a single n-dimensional fringe pattern

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