We introduce a class of non-stationary processes, or signals, that are close to stationary and call them locally stationary. They arise in many applications in seismology, in speech analysis and elsewhere. We show that their local spectral characteristics can be obtained eeciently using an adaptive windowed Fourier transform. We illustrate with some examples from seismology the use of our metho...

A white-light spectral interferometric technique is used to retrieve a relative spectral phase and group delay of a multilayer mirror from the spectral interferograms recorded in a dispersive Michelson interferometer. The phase retrieval is based on the use of a windowed Fourier transform in the wavelength domain, and characterization of the multilayer mirror is completed by a three-step measur...

We consider brightness/contrast-invariant and rotation-discriminating template matching that searches an image to analyze A for a query image Q. We propose to use the complex coefficients of the discrete Fourier transform of the radial projections to compute new rotation-invariant local features. These coefficients can be efficiently obtained via FFT. We classify templates in “stable” and “unst...

In chirped pulse experiments, magnitude Fourier transform is used to generate frequency domain spectra. The application of window function as a tool for lineshape correction and signal-to-noise ratio (SnR) enhancement rarely discussed in spectroscopy, with the only exception using Kaiser-Bessel trivial rectangular window. We present specific function, called "Voigt-1D" window, designed spectros...

This paper describes an estimation and representation method for object structure in 3D image data. A windowed Fourier transform is used to estimate the parameters of 3D local structures (lines, planes and spheres) across a number of window sizes or scales. We present the estimation method and describe a decision process which aims to find the simplest object description. Results of the method ...

We introduce quaternionic Gabor filters for the classification of local image structure. These filters are constructed as windowed basis functions of the quaternionic Fourier transform. We show that – in contrast to the 2D complex Gabor filters – the quaternionic Gabor filters are intrinsically 2D filters. A generalized phase concept is introduced and compared to the classical one. It is shown ...

Blinking and eye movement are one of the most important abilities that most people have, even people with spinal cord problem. By using this ability these people could handle some of their activities such as moving their wheelchair without the help of others. One of the most important fields in Human-Robot Interaction is the development of artificial limbs working with brain signals. The purpos...

Image computation is a fundamental tool for performance assessment of astronomical instrumentation, usually implemented by Fourier transform techniques. We review the numerical implementation, evaluating a direct implementation of the discrete Fourier transform (DFT) algorithm, compared with fast Fourier transform (FFT) tools. Simulations show that the precision is quite comparable, but in the ...

Shape reconstruction using coded structured light (SL) is considered one of the most reliable techniques to recover object surfaces. Among SL techniques, the achievement of dense acquisition for moving scenarios constitutes an active field of research. A common solution is to project a single one-shot fringe pattern, extracting depth from the phase deviation of the imaged pattern. However, the ...

A new feature called multi-directional local feature (MDLF) is proposed and applied in automatic speaker recognition. In order to extract the MDLF, a windowed speech signal is processed by fast Fourier transform and passed through 24 mel-scaled Filter Bank, followed by log compression. A three-point linear regression is then applied in four different directions, which are horizontal (time axis)...