Two-Dimensional Fast Fourier Transforms in Image Processing

1984 ◽  
Author(s):  
Donald E. Lewis
Keyword(s):  
Image Processing ◽  
Fourier Transforms ◽  
Fast Fourier Transforms ◽  
Two Dimensional

Data Acquisition and Processing of Weak Low-Frequency Magnetic Signals

2011 ◽  
Vol 65 ◽  
pp. 299-302 ◽  
Author(s):  
Shou Qiang Men ◽  
Christian Resagk
Keyword(s):  
Magnetic Field ◽  
Data Acquisition ◽  
Fourier Transforms ◽  
Low Frequency ◽  
Fast Fourier Transforms ◽  
Two Dimensional ◽  
Calibration System ◽  
Magnetic Field Sensors ◽  
Data Acquisition And Processing

A simple calibration system for magnetic field sensors was designed, and experiments were carried out to calibrate two-dimensional fluxgate sensors and a sensor ring composed of eight fluxgate sensors. Fast Fourier Transforms and trapezoidal numerical integrals were applied to deal with the raw signals. It is found that it is not suitable to apply fast Fourier Transforms only to deal with signals with several peaks close to each other, but trapezoidal numerical integrals should also be used in combination with the FFT method.

Parallelisation of a 2-D Fast Fourier Transform Algorithm

1991 ◽  
Vol 02 (01) ◽  
pp. 363-366 ◽  
Author(s):  
ANDREW HAMMERSLEY
Keyword(s):  
Fourier Transform ◽  
Data Analysis ◽  
Fast Fourier Transform ◽  
Fourier Transforms ◽  
Computational Physics ◽  
Fast Fourier Transforms ◽  
Two Dimensional ◽  
Fast Fourier Transform Algorithm ◽  
Higher Dimension ◽  
Parallel Network

The calculation of two and higher-dimension Fast Fourier Transforms (FFT’s) are of great importance in many areas of data analysis and computational physics. The two-dimensional FFT is implemented for a parallel network using a master-slave approach. In-place performance is good, but the use of this technique as an “accelerator” is limited by the communications time between the host and the network. The total time is reduced by performing the host-master communications in parallel with the master-slave communications. Results for the calculation of the two-dimensional FFT of real-valued datasets are presented.

scholarly journals INTERPOLATION IN THE SPATIAL DOMAIN OF TWO-DIMENSIONAL DISCRETE SIGNALS USING FAST FOURIER TRANSFORMS

2019 ◽  
Vol 17 (1) ◽  
pp. 88
Author(s):  
O V Ponomareva ◽  
A V Ponomarev
Keyword(s):  
Fourier Transforms ◽  
Spatial Domain ◽  
Fast Fourier Transforms ◽  
Two Dimensional ◽  
Discrete Signals

Показано, что обобщение одномерных методов цифровой обработки дискретных сигналов на двумерный случай является не только нетривиальной задачей, но часто решение такой проблемы просто невозможно. Предложено решение задачи интерполяции в пространственной области двумерных дискретных сигналов с помощью быстрых преобразований Фурье. Показано различие задач интерполяции и аппроксимации двумерных дискретных сигналов. Дано определение дискретного двумерного сигнала на прямоугольной пространственной опорной плоскости в виде матрицы. Приведен математический аппарат матричного и алгебраического дискретного двумерного преобразования Фурье двумерных дискретных сигналов в пространственной области. Рассмотрен математический аппарат матричного и алгебраического дискретного двумерного преобразования Фурье двумерных дискретных сигналов в пространственно-частотной области. Разработан метод и алгоритм интерполяции действительных и комплексных дискретных двумерных сигналов в пространственной области. Проиллюстрирована обоснованность и достоверность предложенного метода интерполяции. Приведены результаты экспериментальных исследований предложенного алгоритма интерполяции на модельных двумерных дискретных комплексных сигналах. Выдвинута рабочая гипотеза повышения эффективности предложенного алгоритма интерполяции путем обобщения базиса дискретного двумерного преобразования Фурье (системы двумерных дискретных экспоненциальных функций), с целью учета специфики предложенного метода интерполяции.

Analysis of the 9th November 1990 flare

2000 ◽  
Vol 179 ◽  
pp. 229-232
Author(s):  
Anita Joshi ◽  
Wahab Uddin
Keyword(s):  
Image Processing ◽  
Two Dimensional ◽  
Temporal Behaviour ◽  
Contour Maps ◽  
Dimensional Measurements ◽  
Processing Software ◽  
Image Processing Software

AbstractIn this paper we present complete two-dimensional measurements of the observed brightness of the 9th November 1990Hαflare, using a PDS microdensitometer scanner and image processing software MIDAS. The resulting isophotal contour maps, were used to describe morphological-cum-temporal behaviour of the flare and also the kernels of the flare. Correlation of theHαflare with SXR and MW radiations were also studied.

Specific Labeling of Protein Domains with Antibody Fragments

1981 ◽  
Vol 39 ◽  
pp. 416-417
Author(s):  
U. Aebi ◽  
L.E. Buhle ◽  
W.E. Fowler
Keyword(s):  
Image Processing ◽  
Specific Protein ◽  
Antibody Fragments ◽  
Supramolecular Organization ◽  
Two Dimensional ◽  
Ordered Structures ◽  
Virus Capsids ◽  
Processing Techniques

Many important supramolecular structures such as filaments, microtubules, virus capsids and certain membrane proteins and bacterial cell walls exist as ordered polymers or two-dimensional crystalline arrays in vivo. In several instances it has been possible to induce soluble proteins to form ordered polymers or two-dimensional crystalline arrays in vitro. In both cases a combination of electron microscopy of negatively stained specimens with analog or digital image processing techniques has proven extremely useful for elucidating the molecular and supramolecular organization of the constituent proteins. However from the reconstructed stain exclusion patterns it is often difficult to identify distinct stain excluding regions with specific protein subunits. To this end it has been demonstrated that in some cases this ambiguity can be resolved by a combination of stoichiometric labeling of the ordered structures with subunit-specific antibody fragments (e.g. Fab) and image processing of the electron micrographs recorded from labeled and unlabeled structures.

Shifting perspectives: method, media and the complex image

1998 ◽  
Vol 10 (1-3) ◽  
pp. 100-108 ◽  
Author(s):  
Alicia Colson ◽  
Ross Parry
Keyword(s):  
Image Processing ◽  
Three Dimensional ◽  
Geographical Location ◽  
Spatial Relationship ◽  
Two Dimensional ◽  
Dimensional Approach ◽  
Complex Image ◽  
Cultural Resonance

This article argues that the analysis of a threedimensional image demanded a three-dimensional approach. The authors realise that discussions of images and image processing inveterately conceptualise representation as being flat, static, and finite. The authors recognise the need for a fresh acuteness to three-dimensionality as a meaningful – although problematic – element of visual sources. Two dramatically different examples are used to expose the shortcomings of an ingrained two-dimensional approach and to facilitate a demonstration of how modern (digital) techniques could sanction new historical/anthropological perspectives on subjects that have become all too familiar. Each example could not be more different in their temporal and geographical location, their cultural resonance, and their historiography. However, in both these visual spectacles meaning is polysemic. It is dependent upon the viewer's spatial relationship to the artifice as well as the spirito-intellectual viewer within the community. The authors postulate that the multi- faceted and multi-layered arrangement of meaning in a complex image could be assessed by working beyond the limitations of the two-dimensional methodological paradigm and by using methods and media that accommodated this type of interconnectivity and representation.

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