In Situ conservation of maize in Mexico: Genetic diversity and Maize seed management in a traditional community

Abstract

Image segmentation plays an important role in image processing and computer vision. It is often used to classify an image into separate regions, which ideally correspond to different real-world objects. Several segmentation methods have been proposed in the literature, being thresholding techniques the most popular. In such techniques, it is selected a set of proper threshold values that optimize a determined functional criterion, so that each pixel is assigned to a determined class according to its corresponding threshold points. One interesting functional criterion is the Tsallis entropy, which gives excellent results in bi-level thresholding. However, when it is applied to multilevel thresholding, its evaluation becomes computationally expensive, since each threshold point adds restrictions, multimodality and complexity to its functional formulation. Therefore, in the process of finding the appropriate threshold values, it is desired to limit the number of evaluations of the objective function (Tsallis entropy). Under such circumstances, most of the optimization algorithms do not seem to be suited to face such problems as they usually require many evaluations before delivering an acceptable result. On the other hand, the Electromagnetism-Like algorithm is an evolutionary optimization approach which emulates the attraction-repulsion mechanism among charges for evolving the individuals of a population. This technique exhibits interesting search capabilities whereas maintains a low number of function evaluations. In this paper, a new algorithm for multilevel segmentation based on the Electromagnetism-Like algorithm is proposed. In the approach, the optimization algorithm based on the electromagnetism theory is used to find the optimal threshold values by maximizing the Tsallis entropy. Experimental results over several images demonstrate that the proposed approach is able to improve the convergence velocity, compared with similar methods such as Cuckoo search, and Particle Swarm Optimization. " 2015 Elsevier Ltd.",,,,,,"10.1016/j.eswa.2015.03.028",,,"http://hdl.handle.net/20.500.12104/42126","http://www.scopus.com/inward/record.url?eid=2-s2.0-84928024901&partnerID=40&md5=c0375db274bb01564fb4567ed4450db1",,,,,,,,"Expert Systems with Applications",,,,,,"Scopus",,,,,,"Electro-magnetism optimization; Evolutionary algorithms; Image processing; Segmentation; Tsallis entropy",,,,,,"Improving segmentation velocity using an evolutionary method",,"Article in Press" "43912","123456789/35008",,"Louette, D., Instituto Manantlán de Ecología y Conservación de la Biodiversidad IMECBIO, Universidad de Guadalajara, 151 Av. Independencia Nacional, AutlánJalisco, 48900, Mexico; Charrier, A., Chaire de Phytotechnie, Ecole Nationale Supérieure Agronomique de Montpellier ENSAM, 9 Place Viala, Montpellier cedex, 34060, France; Berthaud, J., Unité de Recherche Diversité Génétique, et Amélioration des Plantes, Institut Francais de la Recherche Scientifique pour le Developpement en Cooperation ORSTOM, 911 Av. Agropolis, Montpellier cedex, 34032, France",,"Louette, D.

Charrier, A.

Berthaud, J.",,"1997",,"Results from a study of maize varieties and seed sources in a traditional community in Jalisco, Mexico, raise questions about the relationship between genetic erosion and the introduction of varieties. The relevance of models for in situ conservation of crop genetic resources based on geographical isolation of a community is discussed. The morphophenological diversity of local materials is shown to be enhanced by introductions of both improved cultivars and landraces from farmers in other communities. On the other hand, the geographical point of reference for defining "local" landrace is shown to be larger than the community itself. Farmers will classify seed obtained from other farmers in and outside the community as that of a local landrace if it resembles their own according to the phenotypic characteristics they use to distinguish varieties. Maize diversity in this community is then the result of a certain level of introduction of genetic material and not of geographical isolation. " 1997 The New York Botanical Garden, Bronx, NY 10458 U.S.A.