نتایج جستجو برای: pass fourier filtering

تعداد نتایج: 166691  

Journal: :Applied optics 1995
T Szoplik J Garcia C Ferreira

In all-optical processors, enhancement of image details is the result of high-pass filtering. We describe an optoelectronic processor in which detail enhancement results from the digitally calculated difference between an original input image and its low-pass filtered version. The low-pass filtering is realized through the rank-order median and the morphological opening and closing operations c...

1997
Helmer Strik

effect of low-pass filtering exactly is. This was the first Voice source parameters are often obtained by are not optimally suited for this task (see e.g. [6]). Finding parametrizing glottal flow signals. However, before an appropriate evaluation method was the second goal of parametrization these glottal flow signals are usually lowour research. The evaluation method should make it pass filter...

Journal: :Optics express 2014
Chris Edwards Basanta Bhaduri Tan Nguyen Benjamin G Griffin Hoa Pham Taewoo Kim Gabriel Popescu Lynford L Goddard

Quantitative phase imaging systems using white light illumination can exhibit lower noise figures than laser-based systems. However, they can also suffer from object-dependent artifacts, such as halos, which prevent accurate reconstruction of the surface topography. In this work, we show that white light diffraction phase microscopy using a standard halogen lamp can produce accurate height maps...

2004
Vutipong Areekul Ukrit Watchareeruetai Sawasd Tantaratana

Since two-dimensional Gabor filter can be separated into onedimensional Gaussian low pass filter and one-dimensional Gaussian band pass filter to the perpendicular, a new set of separable Gabor filters are implemented for fingerprint enhancement. This separable Gabor filtering consumes approximately 2.6 time faster than the conventional Gabor filtering with comparable enhancement results. This ...

1994
Walid K. M. Ahmed Peter J. McLane

In Mobilesat communications, offsets in frequency are important to estimate before further processing and decoding of the received signal. In this work, we devise a straightforward technique for coarse frequency acquisition through FFT computation of a set of special preamble schemes suitable for any Nyquist pulse. We have considered the noise samples model when such samples are assumed to be u...

Journal: :Psychophysiology 2015
Darren Tanner Kara Morgan-Short Steven J Luck

Although it is widely known that high-pass filters can reduce the amplitude of slow ERP components, these filters can also introduce artifactual peaks that lead to incorrect conclusions. To demonstrate this and provide evidence about optimal filter settings, we recorded ERPs in a typical language processing paradigm involving syntactic and semantic violations. Unfiltered results showed standard...

Journal: :Signal Processing 2006
Prasanta Kumar Ghosh Thippur V. Sreenivas

We show that a stationary signal concept such as the Fourier transform (FT) can be linked to a time-varying (TV) concept such as linear TV filtering. In particular, we give a continuous-time and discrete-time linear TV filter interpretation to continuous-time FT and discrete Fourier transform (DFT), respectively. As a consequence, important variants such as warped DFT, DCT, DST also can be view...

Journal: :IEEE Trans. Speech and Audio Processing 2003
Ing Yann Soon Soo Ngee Koh

This paper presents an innovative way of using the two-dimensional (2-D) Fourier transform for speech enhancement. The blocking and windowing of the speech data for the 2-D Fourier transform are explained in detail. Several techniques of filtering in the 2-D Fourier transform domain are also proposed. They include magnitude spectral subtraction, 2-D Wiener filtering as well as a hybrid filter w...

Journal: :Comput. Graph. Forum 2016
Josiah Manson Peter-Pike J. Sloan

Game and movie studios are switching to physically based rendering en masse, but physically accurate filter convolution is difficult to do quickly enough to update reflection probes in real-time. Cubemap filtering has also become a bottleneck in the content processing pipeline. We have developed a two-pass filtering algorithm that is specialized for isotropic reflection kernels, is several time...

Journal: :SIAM J. Imaging Sciences 2016
Greg Ongie Mathews Jacob

We introduce a method to recover a continuous domain representation of a piecewise constant twodimensional image from few low-pass Fourier samples. Assuming the edge set of the image is localized to the zero set of a trigonometric polynomial, we show the Fourier coefficients of the partial derivatives of the image satisfy a linear annihilation relation. We present necessary and sufficient condi...

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