Person: Chevalier Del Río, Margarita
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First Name
Margarita
Last Name
Chevalier Del Río
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Medicina
Department
Radiología, Rehabilitación y Fisioterapia
Area
Radiología y Medicina Física
Identifiers
7 results
Search Results
Now showing 1 - 7 of 7
Item Theoretical approach to hyperacuity tests based on resolution criteria for two-line images(Proceedings of Holography, Interferometry, and Optical Pattern Recognition in Biomedicine, 1991) Mondal, Pronab Kumar; Calvo Padilla, María Luisa; Lakshminarayanan, Vasudevan; Chevalier Del Río, MargaritaResolution criteria for resolving two line images under coherent and incoherent illumination are presented. This technique has been used to interpret psychophysical data obtained from hyperacuity paradigms.Item Edge image processing: An analysis of modified heaviside functions as degraded edge generators(17th Congress of the International Commission for Optics: Optics For Science And New Technology, Pts 1 And 2, 1996) Manzanares Ituarte, Ana; Calvo Padilla, María Luisa; Chevalier Del Río, Margarita; Lakshminarayanan, VasudevanItem Line spread function formulation proposed by W. H. Steel: A revision(Applied Optics, 1997) Manzanares Ituarte, Ana; Calvo Padilla, María Luisa; Chevalier Del Río, Margarita; Lakshminarayanan, VasudevanA revised formulation of the image Light distribution of an incoherent line source proposed by Steel [Rev. Opt. 31, 334-340 (1952)] is presented. Analytical and numerical results based on this new representation are given. We explicitly show that a major error in Steel's final expression generates singularities, thereby preventing convenient numerical computation.Item Sampled hard edge reconstruction: Definition of frequency modulation function for a sampling-reconstructing system (not quantized)(17th Congress of the International Commission for Optics: Optics for Science and New Technology, Pts 1 and 2, 1996) Sanz, Inmaculada; Calvo Padilla, María Luisa; Chevalier Del Río, MargaritaItem Edge image quality assessment: a new formulation for degraded edge imaging(Image and Vision omputing, 1998) Manzanares Ituarte, Ana; Calvo Padilla, María Luisa; Chevalier Del Río, Margarita; Lakshminarayanan, VasudevanWe discuss a formalism to characterize degraded edge images formed in a diffraction limited system (with circular pupil of unit radius) under conditions of incoherent illumination. We introduce a novel definition of degraded edges and consider this approach to model a basic optical mechanism involved in the perception of visual depth and edge detection. We introduce a degradation parameter to quantize the degree of edge blur. We present a generalization of such a procedure by assuming the Heaviside function to be a systematic generator of degraded edges. We reproduce experimentally the predictions made by the formalism proposed herein.Item Resolution criterion and contrast factor for resolving two-line images under coherent and incoherent illumination(Optics in Complex Systems, 1990) Mondal, Pronab Kumar; Chevalier Del Río, Margarita; Calvo Padilla, María LuisaWe define a resolution criterion for the case of two narrow line images. For doing so, we have considered the two lines as superposition of gradients of two Heaviside step-functions.Item Digitally generated soft edges with predetermined luminance: An analysis of its influence on image degradation.(Sixth International Workshop on Digital Image Processing and Computer Graphics: Applications in Humanities and Natural Sciences, 1998) Sanz, Inmaculada; Calvo Padilla, María Luisa; Chevalier Del Río, MargaritaThe presence of degraded or soft edges on a scene or digital image may cause ambiguities in depth perception(1,2). This kind of edges has been analyzed by introducing a mathematical model to digitally implement a large category of degraded edges. This model has accounted the origin of degradation, the performance of psychophysical test for measuring the degradation perception, and image characteristics currently used in artificial vision as momenta, number of gray scale level per pixels, etc. It is the subject of current researches to be applied to artificial reproduction of human visual perception.