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Search Results: 1 - 10 of 2862 matches for " elliptic fourier descriptors. "
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Determination of host-associated variability in the shape of the mandible of white rice stem borer Scirpophaga innotata (Lepidoptera: Pyralidae)
Alma L. I. Alegre,Mark A. J. Torres,Cesar G. Demayo
Advances in Environmental Sciences , 2011,
Abstract: Host-plant modifications are known to promote high taxonomic diversity andecomorphological disparity among its insect-herbivores. Studies on mouthpart morphology specificallythe mandible are central to understanding these adaptive modifications as they are used as majorfeeding apparatus. In this study, mandible shape of a monophagous white rice stem borer, Scirpophagainnotata Walker (Lepidoptera: Pyralidae) which were obtained from different host-plant rice cultivarswere assessed using image analysis and Elliptic Fourier techniques. Contours of the mandibles wereextracted via chain-coding and principal component analyses were performed to determine patterns ofshape differences. Observed variation ranges from the arrangement and length of its teeth, from thebasal and external margins and the contour of the side of attachment from the body. The greatestvariations accounted by the first two principal components (PC’s) are on the arrangement, length andnumber of its teeth which is attributable to continuous wear of the individual mandible in effect of thebiochemical properties of the plant. Intra-population variation is associated with the influence of riceplant morphological characteristics associated with resistance or susceptibility to white stem borer.
Inferring possible population divergence in Espeletia pycnophylla (Asteraceae) through morphometric and paleogeographic approaches
Benavides,Felipe; Burbano,Jorge; Burbano,Diana; Prieto,Rodrigo; Torres,Carlos;
Revista de Biología Tropical , 2010,
Abstract: the phenotypic structure within and between plant populations is generally influenced by their distribution patterns in space and time; therefore, the study of their divergence is a central issue for the understanding of their microevolutive processes. we boarded the hypothesis that three populations of espeletia pycnophylla show phenotypic divergence as one of the possible implications of their geographic isolation in the southern colombian andes. we used the elliptic fourier descriptors (leaf shape) and traditional leaf morphometry (leaf size) of 347 leaves to measure inter and intra-population variation and a comparison between a paleogeographic reconstruction with an actual estimate of the distribution areas of e. pycnophylla in order to identify their main changes during the last 14 000 years. the three populations showed significant differences in leaf morphometry and a positive correlation between the matrices of morphometric and geographic dissimilarities, indicating that the inter-population divergence increases between further populations, so that the morphometric structure reflects their spatial distribution. the geographical and paleogeographical estimates evidenced a conspicuous process of reduction and fragmentation of the distribution area of e. pycnophylla since the late-glacial until the holocene. we suggest that these results support possible scenarios of vicariance events, which allow us to approach the divergence of these populations in terms of their historic biogeographic relations. however, genetic analyses are still needed to support these results. rev. biol. trop. 58 (4): 1261-1270. epub 2010 december 01.
Inferring possible population divergence in Espeletia pycnophylla (Asteraceae) through morphometric and paleogeographic approaches
Felipe Benavides,Jorge Burbano,Diana Burbano,Rodrigo Prieto
Revista de Biología Tropical , 2010,
Abstract: The phenotypic structure within and between plant populations is generally influenced by their distribution patterns in space and time; therefore, the study of their divergence is a central issue for the understanding of their microevolutive processes. We boarded the hypothesis that three populations of Espeletia pycnophylla show phenotypic divergence as one of the possible implications of their geographic isolation in the Southern Colombian Andes. We used the Elliptic Fourier Descriptors (leaf shape) and traditional leaf morphometry (leaf size) of 347 leaves to measure inter and intra-population variation and a comparison between a paleogeographic reconstruction with an actual estimate of the distribution areas of E. pycnophylla in order to identify their main changes during the last 14 000 years. The three populations showed significant differences in leaf morphometry and a positive correlation between the matrices of morphometric and geographic dissimilarities, indicating that the inter-population divergence increases between further populations, so that the morphometric structure reflects their spatial distribution. The geographical and paleogeographical estimates evidenced a conspicuous process of reduction and fragmentation of the distribution area of E. pycnophylla since the Late-Glacial until the Holocene. We suggest that these results support possible scenarios of vicariance events, which allow us to approach the divergence of these populations in terms of their historic biogeographic relations. However, genetic analyses are still needed to support these results. Rev. Biol. Trop. 58 (4): 1261-1270. Epub 2010 December 01. La estructuración fenotípica entre y dentro de poblaciones vegetales responde generalmente a sus patrones de distribución espacio-temporales, por lo tanto, el estudio de su divergencia es un tema central dentro de sus procesos microevolutivos. En esta investigación abordamos la hipótesis que tres poblaciones de Espeletia pycnophylla presentan divergencia fenotípica como uno de los posibles efectos de su aislamiento geográfico en los Paramos del suroeste de Colombia. Utilizamos los Descriptores Elípticos de Fourier (forma foliar) de 117 hojas y algunas medidas morfológicas tradicionales (tama o foliar) como indicadores de la variación intra e inter-poblacional, además de una comparación entre una reconstrucción paleogeográfica con una estimación del área de distribución actual de la especie para identificar sus principales cambios durante los últimos 14 000 a os. Todas las poblaciones mostraron diferencias significativas y ademá
Extracting and smoothing contours in mammograms using Fourier descriptors  [PDF]
Cyrille K. Feudjio, Alain Tiedeu, Marie-Laure Noubeg, Mihaela Gordan, Aurel Vlaicu, Samuel Domngang
Journal of Biomedical Science and Engineering (JBiSE) , 2014, DOI: 10.4236/jbise.2014.73017
Abstract:

Contour is an important pattern descriptor in image processing and particularly in region description, registration and length estimation. In many applications where contour is used, a good segmentation and an efficient smoothing method are needed. In X-ray images, such as mammograms, where object edge is not clearly discernible, estimating the object’s contour may yield substantial shift along the boundary due to noise or segmentation drawbacks. An appropriate smoothing is therefore required to reduce these effects. In this paper, an approach based on local adaptive threshold segmentation to extract contour and a new smoothing approach founded on Fourier descriptors are introduced. The experimental results of extraction obtained from a set of mammograms and compared with the breast regions delineated by radiologists yielded a percent overlap area of 98.7% ± 0.9% with false positive and negative rates of 0.36 ± 0.74 and 0.93 ± 0.44 respectively. The proposed method was tested on a set of images and improved the accuracy, leading to an average error of less than one pixel.

Facial Expression Recognition Based on Local Fourier Coefficients and Facial Fourier Descriptors  [PDF]
Gibran Benitez-Garcia, Tomoaki Nakamura, Masahide Kaneko
Journal of Signal and Information Processing (JSIP) , 2017, DOI: 10.4236/jsip.2017.83009
Abstract: The recent boom of mass media communication (such as social media and mobiles) has boosted more applications of automatic facial expression recognition (FER). Thus, human facial expressions have to be encoded and recognized through digital devices. However, this process has to be done under recurrent problems of image illumination changes and partial occlusions. Therefore, in this paper, we propose a fully automated FER system based on Local Fourier Coefficients and Facial Fourier Descriptors. The combined power of appearance and geometric features is used for describing the specific facial regions of eyes-eyebrows, nose and mouth. All based on the attributes of the Fourier Transform and Support Vector Machines. Hence, our proposal overcomes FER problems such as illumination changes, partial occlusion, image rotation, redundancy and dimensionality reduction. Several tests were performed in order to demonstrate the efficiency of our proposal, which were evaluated using three standard databases: CK+, MUG and TFEID. In addition, evaluation results showed that the average recognition rate of each database reaches higher performance than most of the state-of-the-art techniques surveyed in this paper.
Categorization of the main descriptors of different ampicillin crystal habits
Flórez-Acosta, Oscar;Tobón-Zapata, Gloria;Valencia-Velasquez, Jaime;
Brazilian Journal of Pharmaceutical Sciences , 2010, DOI: 10.1590/S1984-82502010000400009
Abstract: with the purpose of enabling the analysis by digital methods of particles of multisource pharmaceutical raw materials, this study analyzed different crystal habits of ampicillin particles, by grouping the external shapes obtained from 3 different solvents (acetonitrile, ethanol, and methanol), thereby reducing the number of descriptors necessary to adequately represent each shape. for this purpose, a selection of morphological descriptors was used including: circularity, roughness, roundness, compactness, aspect ratio, effective diameter, solidity, convexity, fractal dimension, and 10 complex fourier descriptors. these measures cover highly diverse morphological properties and define the crystal habit of a particle. principal component analysis (pca) and the cluster analysis (ca) were the grouping techniques used, which demonstrated the possibility of using between 2 and 4 descriptors instead of the 18 proposed initially.
Eyeglasses Lens Contour Extraction from Facial Images Using an Efficient Shape Description
Diana Borza,Adrian Sergiu Darabant,Radu Danescu
Sensors , 2013, DOI: 10.3390/s131013638
Abstract: This paper presents a system that automatically extracts the position of the eyeglasses and the accurate shape and size of the frame lenses in facial images. The novelty brought by this paper consists in three key contributions. The first one is an original model for representing the shape of the eyeglasses lens, using Fourier descriptors. The second one is a method for generating the search space starting from a finite, relatively small number of representative lens shapes based on Fourier morphing. Finally, we propose an accurate lens contour extraction algorithm using a multi-stage Monte Carlo sampling technique. Multiple experiments demonstrate the effectiveness of our approach.
The Use of Fourier Descriptors for the Classification and Analysis of Peripheral Blood Smears Image  [PDF]
Rimma Tomakova, Vitaliy Komkov, Evgeniy Emelianov, Maksim Tomakov
Applied Mathematics (AM) , 2017, DOI: 10.4236/am.2017.811114
Abstract:
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.
Morphometry and morphology of Crocidura Wagler 1832 (Mammalia, Soricidae) in Italy, Sardinia and Sicily, with Fourier descriptors approach: first results / Morfometria e morfologia di Crocidura Wagler 1832 (Mammalia, Soricidae) in Italia, Sardegna e Sicilia, con il metodo dei descrittori di Fourier: primi dati
Longino Contoli,Barbara Benincasa-Stagni,Anna Rosa Marenzi
Hystrix : the Italian Journal of Mammalogy , 1989, DOI: 10.4404/hystrix-1.1-3892
Abstract: A shape analysis through Fourier descriptors was performed on left mandibles of Crocidura obtained by Barn Owl pellets from peninsular Italy (Emilia and Liguria districts), Sardinia and Sicily. Thanks to some classical analysis (morphometrical mono- and bidimensional diagrams, morphological analysis) and to biogeographical and genetical evidences, the samples of Sardinia, the smaller specimens of Liguria and Emilia and the bigger ones of Emilia were respectively classified, as a working hypothesis, as C. russula, C. suaveolens and C. leucodon. The "misclassification rate" essay was very low, confirming the reliability of the discrimination rule employed. The sicilian samples, showing an unimodal pattern with respect to all the classical morphometrical characters examined, were then tested against the descriptors of C. russula, C. suaveolens and C. leucodon. The specimens were assigned to all the above species, with a quite even distribution. On the other hand, the hypothesis of equality of two mean vectors for sicilian samples with C. russula or C. suaveolens or C. leucodon, tested by Hotelling's T2 test, was rejected at 1% significance level. Owing to the fact that the above results seemed quite unexpected in the light of overall bio- geographical knowledges on Crocidura, the "shape analysis" procedure was repeated, by adding a new "species" for the sicilian samples. The "misclassification rate" essay was very encouraging in the sense of the presence, in Sicily, of a morphological "species", differing from C. russula, C. suaveolens and C. leucodon, possibly to be referred to C. sicula Miller 1901. The euristic value of such up to now first results is discussed. Riassunto L'analisi della forma e l'analisi morfometrica di esemplari di Crocidura sp. pl. conducono a considerare probabile la presenza, in Sicilia, di una forma differente da C. russula, C. suaveolens, C. leucodon, la cui possibile coincidenza con C. sicula Miller 1901, è comunque ancora da discutere. Circa la Liguria occidentale è stata confermata la presenza di C. suaveolens. In Sardegna, si conferma la presenza di una specie, da riferire a C. russula. In Emilia, viene avallata l'ipotesi della presenza di due specie: C. leucodon e C. suaveolens.
Vision-Based Hand Gesture Spotting and Recognition Using CRF and SVM  [PDF]
Fayed F. M. Ghaleb, Ebrahim A. Youness, Mahmoud Elmezain, Fatma Sh. Dewdar
Journal of Software Engineering and Applications (JSEA) , 2015, DOI: 10.4236/jsea.2015.87032
Abstract: In this paper, a novel gesture spotting and recognition technique is proposed to handle hand gesture from continuous hand motion based on Conditional Random Fields in conjunction with Support Vector Machine. Firstly, YCbCr color space and 3D depth map are used to detect and segment the hand. The depth map is to neutralize complex background sense. Secondly, 3D spatio-temporal features for hand volume of dynamic affine-invariants like elliptic Fourier and Zernike moments are extracted, in addition to three orientations motion features. Finally, the hand gesture is spotted and recognized by using the discriminative Conditional Random Fields Model. Accordingly, a Support Vector Machine verifies the hand shape at the start and the end point of meaningful gesture, which enforces vigorous view invariant task. Experiments demonstrate that the proposed method can successfully spot and recognize hand gesture from continuous hand motion data with 92.50% recognition rate.
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