A comparison of one and two-dimensional S-Transform in fringe pattern demodulation

Speckles are inherent to SAR. They hide and undermine several relevant information contained in the SAR images. In this paper, a despeckling algorithm using the shrinkage of two-dimensional discrete orthonormal S-transform (2D-DOST) coefficients in the transform domain along with shock filter is proposed. Also, an attempt has been made as a post-processing step to preserve the edges and other details while removing the speckle. The proposed strategy involves decomposing the SAR image into low and high-frequency components and processing them separately. A shock filter is used to smooth out the small variations in low-frequency components, and the high-frequency components are treated with a shrinkage of 2D-DOST coefficients. The edges, for enhancement, are detected using a ratio-based edge detection algorithm. The proposed method is tested, verified, and compared with some well-known models on C-band and X-band SAR images. A detailed experimental analysis is illustrated.

Download Full-text

Fringe Pattern Denoising Using Two-Dimensional Variational Mode Decomposition (2D-VMD) Method for Inspection of Flatness of Reduced Surfaces

Experimental Techniques ◽

10.1007/s40799-021-00459-z ◽

2021 ◽

Author(s):

M. Messagier ◽

S. Meguellati ◽

H. Mahgoun

Keyword(s):

Fringe Pattern ◽

Two Dimensional ◽

Variational Mode Decomposition ◽

Mode Decomposition

Download Full-text

Two-dimensional multiscale windowed Fourier transform based on two-dimensional wavelet transform for fringe pattern demodulation

Optics & Laser Technology ◽

10.1016/j.optlastec.2010.05.007 ◽

2011 ◽

Vol 43 (1) ◽

pp. 72-81 ◽

Cited By ~ 7

Author(s):

Hai Li ◽

Chuping Yang

Keyword(s):

Fourier Transform ◽

Wavelet Transform ◽

Fringe Pattern ◽

Two Dimensional ◽

Windowed Fourier Transform

Download Full-text

Fast 3D Shape Measurement of Complex Objects Combining S-transform Profilometry and Sub-Pixel Refinement

10.21203/rs.3.rs-38856/v1 ◽

2020 ◽

Author(s):

Feng Lu ◽

Jikun Yang

Keyword(s):

Fringe Pattern ◽

Vision System ◽

Phase Unwrapping ◽

Shape Measurement ◽

Complex Objects ◽

3D Shape ◽

3D Shape Measurement ◽

Phase Slope ◽

S Transform ◽

Hybrid Function

Abstract In the fast 3D shape measurement of complex objects, the process of phase unwrapping affects the measurement accuracy and measurement speed. To omit phase unwrapping, a fast 3D shape measurement method is proposed based on S-transform profilometry and sub-pixel refinement. In this work, Deformed fringe pattern is analyzed based on S-transform to get wrapped phase. To reduce the effect of phase unwrapping, a stereo vision system is employed. Firstly, a deformed fringe pattern is directly used and a hybrid function is proposed to get an initial parallax. Secondly, a phase slope algorithm is proposed to confirm edge point. At last, sub-pixel parallax is refined fromIcoordinate. Experiments are carried out to verify the feasibility and advantage of the proposed method. Results verify that the proposed method can provide fast and accurate 3D shape measurement of complex objects, especially for discontinuous objects and shiny objects.

Download Full-text

Spatial carrier fringe pattern demodulation by use of a two-dimensional continuous wavelet transform

Applied Optics ◽

10.1364/ao.45.008722 ◽

2006 ◽

Vol 45 (34) ◽

pp. 8722 ◽

Cited By ~ 109

Author(s):

Munther A. Gdeisat ◽

David R. Burton ◽

Michael J. Lalor

Keyword(s):

Wavelet Transform ◽

Continuous Wavelet Transform ◽

Fringe Pattern ◽

Continuous Wavelet ◽

Two Dimensional

Download Full-text

A fast oversampling orthogonal method for the discrete two dimensional S-transform computing

2009 Asia-Pacific Conference on Computational Intelligence and Industrial Applications (PACIIA) ◽

10.1109/paciia.2009.5406570 ◽

2009 ◽

Author(s):

Guodong Zhang ◽

Changchun Chen ◽

Donghong Sun

Keyword(s):

Two Dimensional ◽

Orthogonal Method ◽

S Transform

Download Full-text

Multichannel Fourier Transform Spectroscopy Using Two-Dimensional Detection of the Interferogram and its Application to Raman Spectroscopy

Applied Spectroscopy ◽

10.1366/0003702934415309 ◽

1993 ◽

Vol 47 (7) ◽

pp. 863-868 ◽

Cited By ~ 15

Author(s):

Satoshi Takahashi ◽

Jeung Sun Ahn ◽

Shuji Asaka ◽

Teizo Kitagawa

Keyword(s):

Fourier Transform ◽

Fringe Pattern ◽

Principal Axis ◽

Monochromatic Light ◽

Fourier Transform Spectroscopy ◽

Present System ◽

The Novel ◽

Two Dimensional ◽

One Dimensional ◽

Ccd Detector

A system for multichannel Fourier transform spectroscopy was constructed by using a CCD detector and an interferometer consisting of Savart plate held between two polarizers, and practical problems associated with its application to Raman experiments were investigated. The novel idea of the present system lies in avoiding the aliasing distortion, seen in the spectrum measured with a one-dimensional multichannel detector, by arranging the principal axis of the sensitized plane of the CCD detector so that it is not coincident with the direction of the fringe pattern of the interferogram. The observed interferogram suffered geometrical distortion due to incompleteness of the Savart plate. In order to circumvent this problem, an algorithm for correcting this distortion by referring to the interferogram of appropriate monochromatic light was successfully developed. The resolution of a Raman spectrum obtained for indene was ∼40 cm−1, in agreement with the theoretical value expected for this system.

Download Full-text