Use Of Fourier Descriptors Research Articles

Digital dual test syphilis/HIV detection based on Fourier Descriptors of Cyclic Voltammetry curves

Background:Effective and timely detection is vital for mitigating the severe impacts of Sexually Transmitted Infections (STI), including syphilis and HIV. Cyclic Voltammetry (CV) sensors have shown promise as diagnostic tools for these STI, offering a pathway towards cost-effective solutions in primary health care settings. Objective:This study aims to pioneer the use of Fourier Descriptors (FDs) in analyzing CV curves as 2D closed contours, targeting the simultaneous detection of syphilis and HIV. Methods:Raw CV signals are filtered, resampled, and transformed into 2D closed contours for FD extraction. Essential shape characteristics are captured through selected coefficients. A complementary geometrical analysis further extracts features like curve areas and principal axes lengths from CV curves. A Mahalanobis Distance Classifier is employed for differentiation between patient and control groups. Results:The evaluation of the proposed method revealed promising results with classification performance metrics such as Accuracy and F1-Score consistently achieving values rounded to 0.95 for syphilis and 0.90 for HIV. These results underscore the potential efficacy of the proposed approach in differentiating between patient and control samples for STI detection. Conclusion:By integrating principles from biosensors, signal processing, image processing, machine learning, and medical diagnostics, this study presents a comprehensive approach to enhance the detection of both syphilis and HIV. This setts the stage for advanced and accessible STI diagnostic solutions.

The Structure of Classifiers of Hand Gestures with the Use of the Active Contour Model and Fourier Descriptors

Abstract In this article, the research results of the usage of selected methods of the analysis of images for the recognition of hand gestures in human-computer interaction was depicted. The usage of this type of interaction is important in case of the so-called wearable computers (computer is integrated with the work clothing of an operator. For the recognition of gestures, the combination of two methods associated with the image processing was suggested and that is the Chan-Vese active contour model enabling to recognize objects on a given image, based on the curve evolution technique, Mumford-Shah functional, level-sets and the methods to create shapes with the use of Fourier descriptors. For the classification criteria as a compatibility measure a scalable Mahalanobis distance was used.

The Use of Fourier Descriptors for the Classification and Analysis of Peripheral Blood Smears Image

The article discusses the use of Fourier descriptors for the analysis and classification of blood cells. A model describing the contour boundaries in the form of two-dimensional numerical sequence Fourier descriptors. The influence of the shape and orientation of the figures on the parameters of the Fourier descriptors. Explore ways to ensure the invariance of the Fourier descriptors with respect to geometric transformations. A model of the graphical representation of the Fourier descriptors of computer graphics tools. A method of forming a space of informative features based on Fourier descriptors for the neural network, classifying the contours of borders image segments.

3D printable geomaterials

One of the many attributes of three-dimensional (3D) printing is the ability to produce particles with independent control of morphology and material properties, parameters that are inexorably entwined in naturally occurring geomaterials. In this paper the 3D printing of surrogate granular materials is described, with examples of the particles produced, and results are presented showing their ability to capture real soil behaviour. Three approaches are demonstrated for the 3D generation of model grains. The first method involves the superimposition of a fractal surface with higher level stochastic features on the face of a closed volume, such as a geodesic spheroid. The second method involves the use of Fourier descriptors or fractal geometry generated from two-dimensional (2D) cross-sections and their interpolation to produce simulated geomaterial particles in three dimensions. The third method involves the generation of complex particles by the aggregation of polyhedral elements such as cubes or octahedra which is suitable for the simulation and fabrication of porous or branching particles. Triaxial tests have been performed on particles produced by the second method, which most readily allows input parameters to be obtained from natural geomaterials. Results of these tests show the ability of the printed particles to reproduce soil behaviour, and demonstrate the effect of particle shape on the material response. Finally, applications of the fabrication of surrogate materials by 3D printing are discussed, for use as standardised, printable geomaterials in future up-scaled geotechnical experiments and other geomechanical research.

Analysis of simulated and experimental backscattered images of turbid media in linearly polarized light: estimation of the anisotropy factor

Optical characterization of biological tissues is of real interest to improve medical diagnosis, in particular in the detection of precancerous tissues. We propose a new, noninvasive method allowing the estimation of the anisotropy factor. This method is based on the image analysis of the Q element of the Stokes vector backscattered from the turbid medium. These Q-element images show specific patterns depending on g. Therefore the use of Fourier descriptors (FDs) on simulated data to discriminate the specific geometrical features of the Q element enabled us to determine a linear relation between the anisotropy factor and six FDs. This method was applied on experimental data obtained with calibrated solutions. The anisotropy factor was estimated with a maximum relative error of 13%.

Vecteurs de Stokes rétrodiffusés par des milieux diffusants : estimation du facteur d’anisotropie et du coefficient de diffusion réduit

Optical characterization of biological tissues is of real interest to improve medical diagnosis and in particular in the detection of precancerous tissues. The reduced scattering coefficient μ′ s and the absorption coefficient μ a are the most commonly retrieved coefficients. Some methods also allow to obtain the anisotropy factor g, but only few of them are noninvasive. We propose a new noninvasive method allowing the estimation of the anisotropy factor and the reduced scattering coefficient with polarized incident light. This method is based on the image analysis of the Q-element of Stokes vector backscattered from the turbid medium. These Q-element images show specific patterns depending on g, and μ′ s is determined by the size of the patterns. Therefore, the use of Fourier descriptors (FD) on simulated and experimental data to discriminate the specific geometrical features of the Q-element enables the determination of the anisotropy factor and the scattering coefficient.

Multi-tuple interpolation using Fourier descriptors

This paper presents a new object interpolation method called multi-tuple interpolation. Its principal feature is the use of Fourier descriptors to represent a contour and to obtain its four attributes, namely, shape, scale, orientation and position. Each attribute is interpolated in the frequency domain under the control of its individual parameter. A suitable combination of these parameters, which can be regarded as a kind of prior knowledge, can generate a result adaptable to the real 3D object. Several experiments are performed on both synthetic and real medical images to demonstrate this new approach. It is shown that the proposed method can be applied to other similar domains, e.g. shape blending.

The Use of Fourier Descriptors for the Spectrophotometric Identification of Substances: Identification of Some Benzenoid Compounds.

Fourier descriptor (FD) values computed from spectrophotometric measurements were used to compute a purity index. The Fourier Descriptors calculated for a set of absorbencies are independent of concentration and is sensitive to the presence of interferents. Such condition was proven by calculating the FD for pure and degraded benyzylpenicillin. Absorbance data were measured and recorded for twelve different benzenoid compounds. The calculated FD values for these compounds showed significant discrimination between them. Also the reproducibility of FDs was tested by measurement over several successive days and the relative standard deviation obtained was less than 2 %.

Recognition of 2D object contours using the wavelet transform zero-crossing representation

A new algorithm to recognize a two-dimensional object of arbitrary shape is presented. The object boundary is first represented by a one-dimensional signal. This signal is then used to build the wavelet transform zero-crossing representation of the object. The algorithm is invariant to translation, rotation and scaling. Experimental results show that, compared with the use of Fourier descriptors, our algorithm gives more stable and accurate results.

The use of Fourier descriptors in the classification of particle shape

ABSTRACTA new quantitative method for characterizing quartz grain shape is presented. The method employs a harmonic analysis based upon Fourier descriptors which is a distinct variation of the traditional and widely used Fourier series. Quartz grain images from a scanning electron microscope were ‘frame grabbed’and converted to a digitized grey‐level image. The image processing techniques of enhancement, segmentation and boundary tracking were applied to remove all features except the image boundary. This boundary was sampled at uniform intervals of are length and represented mathematically on the complex plane. In this way problems associated with the location of particle centroid and re‐entrant values were avoided. The resulting data was standardized relative to scale, rotation and starting position. Hence the discrete Fourier transform was applied using modern fast Fourier transform techniques and the modulus of the resulting harmonic amplitude used to characterize the grain shape. The technique was applied to a sample of 0–5‐m quartz grains from three distinct populations: desert quartz, beach grains (Fire Island, New York) and Brazilian crushed quartz. Whilst plots of average amplitude vs. harmonic number for each population appeared similar, discriminant analysis applied to each grain sample distinguished characteristic grain shape with an excellent degree of success. The problems of location of the centroid and re‐entrant values were eliminated. This allowed the technique to be applied to a much wider group of irregularly shaped sedimentary particles such as loess.

Some physiologically meaningful features obtained from the vectorcardiography

The nature of the information provided by the vectorcardiograph (VCG) is described, and the use of Fourier descriptors in VCG classification is discussed. The Fourier transform relation of the VCG loop, cardiac axis determination from Fourier descriptors, and PVC screening using Fourier descriptors are considered. To demonstrate the usefulness of the features discussed as a feature set for the classification process, two different data sets from the MIT/BIH database are serially analysed. The use of Fourier descriptors in 2-D template matching is also discussed.

Use of Fourier descriptors for the estimation of general motion in image sequences

Motion estimation in image coding using block matching and pel-recursive algorithms is almost always restricted to pure translation. A new technique using Fourier descriptors (FDs), which estimates general 2-D motion, including translation, rotation, and scaling is reported.

A Fourier descriptor model of hysteresis loop phenomena

In this paper the task of modeling the B/H plane behavior of ferromagnetic materials is treated as a shape identification problem solvable with the use of Fourier descriptors. This representation is found to be parsimonious in terms of data storage requirements and allows direct calculation of hysteresis losses.

Global And Partial Shape Discrimination For Computer Vision

The use of Fourier descriptors for rapid recognition of complete shapes is discussed. A Fourier-Mellin correlation procedure for recognition of partial shapes is also presented. Some example recognition experiments, including industrial parts inspection and aircraft recognition, are shown.

A PARAMETRIC APPROACH TO EDDY CURRENT NDT SIGNAL PROCESSING

Abstract An application involving the use of Fourier descriptors for characterizing eddy current impedance plane trajectories is described. The amplitude coefficients in the Fourier descriptors are incorporated into a feature vector along with the ‘phase angle” of the trajectory. Defect classification is obtained by clustering the feature vectors in the multidimensional feature space using the K-Means algorithm. Advantages of the method include the insensitivity of the method to drift in the gain and zero settings of the measuring eddy current instrument and also fluctuations in the probe speed. In addition the curve can be reconstructed using the descriptors. Experimental evidence showing that the method can be successfully used for identifying defect signatures is presented.

Shape interpolation using Fourier descriptors with application to animation graphics

We propose a way to generate a sequence of closed curves leading from an initial curve to a final one, making use of Fourier descriptors. In order to ensure a good closure of intermediary shapes, we have to pay attention to the definition of these descriptors. The change between successive shapes can be fully controlled through the frequency content of these shapes; many parameters are at the disposal of the user providing a great flexibility in the use of this method. We illustrate the variety of possibilities with three examples of interpolation algorithms.