Dr. Gabriel Cristobal Profile

Dr. Gabriel Cristobal

Research Scientist at Instituto de Óptica "Daza de Valdés"

SPIE Involvement:

Conference Program Committee | Author | Editor

Publications (63)

Proceedings Article | 18 June 2024 Presentation + Paper

Microscopic image quality in few-shot GAN-generated cyanobacteria images and its impact on classification networks

Gloria Bueno, Lucia Sanchez, Elvira Perona, M. Angeles Muñoz-Martín, Alejandro Hiruelas, Jesus Salido, Gabriel Cristobal

Proceedings Volume 12998, 1299807 (2024) https://doi.org/10.1117/12.3017262

KEYWORDS: Image quality, Cyanobacteria, Image classification, Image processing

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Proceedings Article | 18 June 2024 Presentation + Paper

An ImageJ plugin for image fusion based on edge-preserving filtering

Harbinder Singh, Manuel Forero, Nuray Ağaoğlu, Gloria Bueno, Oscar Deniz, Gabriel Cristobal

Proceedings Volume 12998, 129980Q (2024) https://doi.org/10.1117/12.3017408

KEYWORDS: Image fusion, Tunable filters, Image quality, Image processing, Microscopy, Image analysis, Image filtering, Focus stacking, Image restoration, Image enhancement

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Proceedings Article | 24 May 2018 Presentation + Paper

Lights and pitfalls of convolutional neural networks for diatom identification

Anibal Pedraza, Gloria Bueno, Oscar Deniz, Jesus Ruiz-Santaquiteria, Carlos Sanchez, Saul Blanco, Maria Borrego-Ramos, Adriana Olenici, Gabriel Cristobal

Proceedings Volume 10679, 106790G (2018) https://doi.org/10.1117/12.2309488

KEYWORDS: Convolutional neural networks, Neural networks, Data processing, Image processing, Data acquisition, Algorithm development, Biomedical optics

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SPIE Journal Paper | 2 January 2018 Open Access

Low-cost oblique illumination: an image quality assessment

Jesús Ruíz-Santaquiteria, José Luis Espinosa-Aranda, Oscar Deniz, Carlos Sanchez, Maria Borrego-Ramos, Saúl Blanco, Gabriel Cristobal, Gloria Bueno

JBO, Vol. 23, Issue 01, 016001, (January 2018) https://doi.org/10.1117/12.10.1117/1.JBO.23.1.016001

KEYWORDS: Image quality, Image filtering, Microscopes, Visualization, Image resolution, Image analysis, Image processing, Image enhancement, 3D modeling, Image classification

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Proceedings Article | 29 April 2016 Paper

Image quality metrics applied to digital pathology

Ana Jiménez, Gloria Bueno, Gabriel Cristóbal , Oscar Déniz, David Toomey, Catherine Conway

Proceedings Volume 9896, 98960S (2016) https://doi.org/10.1117/12.2230655

KEYWORDS: Optical proximity correction, Image quality, Pathology, Image processing, Information visualization, Visualization, Quality measurement, Signal processing, Image analysis, Digital imaging, Distortion, Image quality, Speckle, Tissues, Breast, Algorithm development

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Proceedings Article | 22 September 2015 Paper

Analysis of the hand vein pattern for people recognition

R. Castro-Ortega, C. Toxqui-Quitl, G. Cristóbal, J. Victor Marcos, A. Padilla-Vivanco, R. Hurtado Pérez

Proceedings Volume 9599, 95992Q (2015) https://doi.org/10.1117/12.2188817

KEYWORDS: Veins, Image segmentation, Image acquisition, Image processing, Infrared imaging, Feature extraction, Image enhancement, Computing systems, Neural networks, Light sources

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Proceedings Article | 2 October 2014 Paper

Hurst exponent for fractal characterization of LANDSAT images

Juan Valdiviezo-N., Raul Castro , Gabriel Cristóbal , Anna Carbone

Proceedings Volume 9221, 922103 (2014) https://doi.org/10.1117/12.2060281

KEYWORDS: Landsat, Satellite imaging, Satellites, Fractal analysis, Earth observing sensors, Linear filtering, Ecosystems, Systems modeling, Thermography, Complex systems

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Proceedings Article | 15 May 2014 Paper

Texture descriptor approaches to level set segmentation in medical images

Jimena Olveres, Rodrigo Nava, Ernesto Moya-Albor, Boris Escalante-Ramírez, Jorge Brieva, Gabriel Cristóbal, Enrique Vallejo

Proceedings Volume 9138, 91380J (2014) https://doi.org/10.1117/12.2054527

KEYWORDS: Image segmentation, Blood, Medical imaging, Image processing algorithms and systems, Binary data, Signal attenuation, Computed tomography, Heart, Medical diagnostics, Image understanding

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Proceedings Article | 19 November 2013 Paper

A probabilistic model of emphysema based on granulometry analysis

J. Marcos, R. Nava, G. Cristobal, A. Munoz-Barrutia, B. Escalante-Ramírez, C. Ortiz-de-Solórzano

Proceedings Volume 8922, 892211 (2013) https://doi.org/10.1117/12.2035478

KEYWORDS: Emphysema, Lung, Tissues, Image segmentation, Statistical analysis, Lawrencium, Feature extraction, Analytical research, Binary data, Selenium

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Proceedings Article | 26 September 2013 Paper

Midbrain volume segmentation using active shape models and LBPs

Jimena Olveres, Rodrigo Nava, Boris Escalante-Ramírez, Gabriel Cristóbal, Carla María García-Moreno

Proceedings Volume 8856, 88561F (2013) https://doi.org/10.1117/12.2024396

KEYWORDS: Image segmentation, Binary data, Magnetic resonance imaging, Statistical modeling, Statistical analysis, Visualization, Image processing algorithms and systems, Volume rendering, Distance measurement, Brain

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SPIE Journal Paper | 17 July 2012 Open Access

Anisotropy-based robust focus measure for non-mydriatic retinal imaging

Andres Marrugo, María Millán, Hector Abril Baez, Gabriel Cristóbal, Salvador Gabarda

JBO, Vol. 17, Issue 7, 076021, (July 2012) https://doi.org/10.1117/12.10.1117/1.JBO.17.7.076021

KEYWORDS: Fermium, Frequency modulation, Eye, Cameras, Retinal scanning, Anisotropy, Imaging systems, Image processing, Nonlinear filtering, Image quality

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Proceedings Article | 1 May 2012 Paper

Image analysis in modern ophthalmology: from acquisition to computer assisted diagnosis and telemedicine

Andrés Marrugo, María Millán, Gabriel Cristóbal, Salvador Gabarda, Michal Sorel, Filip Sroubek

Proceedings Volume 8436, 84360C (2012) https://doi.org/10.1117/12.921299

KEYWORDS: Image quality, Image enhancement, Ophthalmology, Telemedicine, Point spread functions, Visualization, Image processing, Photography, Image restoration, Deconvolution

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Proceedings Article | 1 May 2012 Paper

A comprehensive study of texture analysis based on local binary patterns

Rodrigo Nava, Gabriel Cristóbal, Boris Escalante-Ramírez

Proceedings Volume 8436, 84360E (2012) https://doi.org/10.1117/12.923558

KEYWORDS: Binary data, Databases, Analytical research, Computer programming, Distance measurement, Statistical analysis, Light sources and illumination, Visualization, Feature extraction, Facial recognition systems

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One of the main goals of texture analysis is to provide a robust mathematical description of the spatial behavior of intensity values in any given neighborhood. These local distributions {called textures{ characterize object surfaces and are used for pattern identication and recognition of images. However, some spatial patterns may vary from quite simple stripes to randomness, where textures look like unstructured noise. Since textures can exhibit a large number of properties such as surface materials and geometry of the lighting sources, many dierent approaches have been proposed. A featured method is the modication of Wang's algorithm made by Ojala et al, the so-called local binary patterns (LBP). The LBP algorithm uses a 3×3 square mask named "texture spectrum" which represents a neighborhood around a central pixel. The values in the square mask are compared with the central pixel and then multiplied by a weighting function according with their positions. This technique has become popular due to its computational simplicity and more importantly for encoding a powerful signature for describing textures. Specially, it has gained increased importance in image classication, where the success not only depends on a robust classier but also relies in a good selection of the feature descriptors. However, Ojala's algorithm presents some limitations such as noise sensitivity and lack of invariance to rotational changes. This fact has fostered many extensions of the original LBP approach that in many cases are based on minor changes in order to attain e.g. illumination and rotational invariance or improving the robustness to noise. In this paper we present a detailed overview of the LBP algorithm and other recently modications. In addition, we perform a texture classication study with seven algorithms in presence of rotational changes, noise degradation, contrast information, and dierent sizes of LBP masks using the USC-SIPI database. The LBP histograms have been evaluated using the Kullback-Leibler distance. This study will be a valuable insight for establishing a robust and ecient texture descriptor to solve real world problems.

SPIE Journal Paper | 26 March 2012 Open Access

Autofocus evaluation for brightfield microscopy pathology

Rafael Redondo, Gabriel Cristóbal, Gloria Bueno Garcia, Oscar Deniz, Jesus Salido, Maria del Milagro Fernandez, Juan Vidal, Juan Carlos Valdiviezo, Rodrigo Nava, Boris Escalante-Ramírez, Marcial Garcia-Rojo

JBO, Vol. 17, Issue 03, 036008, (March 2012) https://doi.org/10.1117/12.10.1117/1.JBO.17.3.036008

KEYWORDS: Microscopy, Pathology, Tissues, Cell biology, Image analysis, Breast, Biopsy, Lung, Computing systems, Image processing

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Proceedings Article | 3 November 2011 Paper

Evaluation of autofocus measures for microscopy images of biopsy and cytology

R. Redondo, M. G. Bueno, J. C. Valdiviezo, R. Nava, G. Cristóbal, M. García, O. Déniz, B. Escalante-Ramírez

Proceedings Volume 8011, 801194 (2011) https://doi.org/10.1117/12.903314

KEYWORDS: Microscopy, Biopsy, Cell biology, Computing systems, Picosecond phenomena, Biological research, Image analysis, Tissues, Image acquisition, Breast

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Proceedings Article | 6 May 2010 Paper

A new Rényi entropy-based local image descriptor for object recognition

S. Gabarda, G. Cristóbal, P. Rodríguez, C. Miravet, J. M. del Cura

Proceedings Volume 7723, 772312 (2010) https://doi.org/10.1117/12.854901

KEYWORDS: Image processing, Object recognition, Clocks, Time-frequency analysis, Reconstruction algorithms, Detection and tracking algorithms, Solids, Tolerancing, Feature extraction, Databases

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Proceedings Article | 5 May 2010 Paper

Blind quality assessment of multi-focus image fusion algorithms

Rodrigo Nava, Boris Escalante-Ramírez, Gabriel Cristóbal

Proceedings Volume 7723, 77230F (2010) https://doi.org/10.1117/12.853899

KEYWORDS: Image fusion, Image quality, Image processing, Wavelets, Visualization, Image information entropy, Data processing, Signal to noise ratio, Quality measurement, Image registration

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Proceedings Article | 2 September 2009 Paper

Image denoising and quality assessment through the Rényi entropy

Salvador Gabarda, Raphael Redondo, Elena Gil, Gabriel Cristóbal

Proceedings Volume 7444, 744419 (2009) https://doi.org/10.1117/12.826153

KEYWORDS: Image quality, Denoising, Image denoising, Anisotropy, Synthetic aperture radar, Image filtering, Wavelets, Digital filtering, Image analysis, Anisotropic filtering

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Proceedings Article | 1 September 2009 Paper

Applications of the programmable two-dimensional optical fractional Fourier processor

José Rodrigo, Tatiana Alieva, Gabriel Cristóbal, María Calvo

Proceedings Volume 7442, 74420O (2009) https://doi.org/10.1117/12.825262

KEYWORDS: Fourier transforms, Spatial light modulators, Lenses, Phase retrieval, Phase shift keying, Modulation, Wavefront distortions, Signal generators, Telescopes, Data processing

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Proceedings Article | 28 May 2009 Paper

Anisotropic quality measurement applied to H.264 video compression

G. Callico, Sebastián Lopez, Salvador Gabarda, Elena Gil, Gabriel Cristobal, José Lopez, Roberto Sarmiento

Proceedings Volume 7363, 73630I (2009) https://doi.org/10.1117/12.821652

KEYWORDS: Image quality, Video compression, Anisotropy, Quality measurement, Video, Image compression, Image quality standards, Computer programming, Quantization, Visual system

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Proceedings Article | 3 September 2008 Paper

Image analysis through high-order entropy measures extracted from time-frequency representations

Salvador Gabarda, Gabriel Cristóbal

Proceedings Volume 7074, 70740Z (2008) https://doi.org/10.1117/12.797300

KEYWORDS: Image fusion, Image quality, Image information entropy, Anisotropy, Time-frequency analysis, Digital imaging, Image processing, Wavelets, Visualization, Image analysis

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Proceedings Article | 3 September 2008 Paper

Superresolution imaging: a survey of current techniques

G. Cristóbal, E. Gil, F. Šroubek, J. Flusser, C. Miravet, F. Rodríguez

Proceedings Volume 7074, 70740C (2008) https://doi.org/10.1117/12.797302

KEYWORDS: Super resolution, Lawrencium, Point spread functions, Image processing, Sensors, Deconvolution, Image resolution, Model-based design, Image registration, Linear filtering

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Proceedings Article | 19 May 2008 Paper

A novel multi-focus image fusion algorithm based on feature extraction and wavelets

Rodrigo Nava, Boris Escalante-Ramírez, Gabriel Cristóbal

Proceedings Volume 7000, 700028 (2008) https://doi.org/10.1117/12.781403

KEYWORDS: Image fusion, Wavelets, Feature extraction, Image filtering, Image processing, Image quality, Sensors, Image sensors, Image segmentation, Composites

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Proceedings Article | 25 April 2008 Paper

Image quality assessment through a logarithmic anisotropic measure

Salvador Gabarda, Gabriel Cristóbal

Proceedings Volume 7000, 70000J (2008) https://doi.org/10.1117/12.781370

KEYWORDS: Image quality, Anisotropy, Quality measurement, Image enhancement, Visualization, Image processing, Visual system, Signal to noise ratio, Statistical modeling, Information visualization

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Proceedings Article | 10 July 2007 Paper

The generalized Rényi image entropy as a noise indicator

S. Gabarda, G. Cristóbal

Proceedings Volume 6603, 66030K (2007) https://doi.org/10.1117/12.725086

KEYWORDS: Image information entropy, Digital imaging, Image quality, Image analysis, Anisotropy, Visualization, Image enhancement, Lab on a chip, Quality measurement, Image processing

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Proceedings Article | 22 May 2007 Paper

Quality evaluation of blurred and noisy images through local entropy histograms

S. Gabarda, G. Cristóbal

Proceedings Volume 6592, 659214 (2007) https://doi.org/10.1117/12.721952

KEYWORDS: Image quality, Anisotropy, Image resolution, Resolution enhancement technologies, Image processing, Quality measurement, Image enhancement, Image classification, Image analysis, Image information entropy

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Proceedings Article | 22 May 2007 Paper

Nonreference image fusion evaluation procedure based on mutual information and a generalized entropy measure

Rodrigo Nava, Gabriel Cristóbal, Boris Escalante-Ramírez

Proceedings Volume 6592, 659215 (2007) https://doi.org/10.1117/12.722844

KEYWORDS: Image fusion, Image quality, Image information entropy, Image processing, Data fusion, Discrete wavelet transforms, Signal to noise ratio, Wavelets, Image resolution, Visualization

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Proceedings Article | 25 August 2006 Paper

On the development of a high-order texture analysis using the PWD and Renyi entropy

S. Gabarda, G. Cristóbal

Proceedings Volume 6313, 63130V (2006) https://doi.org/10.1117/12.682135

KEYWORDS: Binary data, Image segmentation, Data analysis, Image processing, Performance modeling, Anisotropy, Image information entropy, Correlation function, Time metrology, Distance measurement

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Proceedings Article | 24 August 2006 Paper

A hybrid spatiotemporal and Hough-based motion estimation approach applied to magnetic resonance cardiac images

N. Carranza, G. Cristóbal, F. Sroubek, M. J. Ledesma-Carbayo, A. Santos

Proceedings Volume 6312, 631219 (2006) https://doi.org/10.1117/12.682149

KEYWORDS: Optical flow, Motion estimation, Magnetism, Motion analysis, Hough transforms, Fourier transforms, Heart, Spatial frequencies, 3D image processing, Motion measurement

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Proceedings Article | 17 September 2005 Paper

Spectral modeling of nonstationary clouds

Lorenzo Galleani, Leon Cohen, Gabriel Cristobal, Bruce Suter

Proceedings Volume 5910, 591017 (2005) https://doi.org/10.1117/12.623606

KEYWORDS: Clouds, Spectral models, Filtering (signal processing), Denoising, Convolution, Algorithm development, Analytical research, Roads, Humidity, Fourier transforms

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Proceedings Article | 16 September 2005 Paper

The Rényi entropy as a decision measure for a pseudo-Wigner distribution image fusion framework

Salvador Gabarda, Gabriel Cristobal

Proceedings Volume 5910, 59100E (2005) https://doi.org/10.1117/12.617269

KEYWORDS: Image fusion, Image quality, Image enhancement, Time-frequency analysis, Image processing, Visualization, Image information entropy, Digital cameras, Biomedical optics, Signal processing

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Proceedings Article | 16 September 2005 Paper

Multifocus fusion with multisize windows

R. Redondo, F. Sroubek, S. Fischer, G. Cristóbal

Proceedings Volume 5909, 59091B (2005) https://doi.org/10.1117/12.619263

KEYWORDS: Image fusion, Speckle, Transform theory, Image processing, Image segmentation, Wavelets, Information operations, Image quality, Fusion energy, Data fusion

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Proceedings Article | 29 June 2005 Paper

Blind image deconvolution using an evolutionary algorithm and image fusion

Salvador Gabarda, Gabriel Cristobal

Proceedings Volume 5839, (2005) https://doi.org/10.1117/12.608401

KEYWORDS: Image fusion, Evolutionary algorithms, Image quality, Point spread functions, Image enhancement, Image deconvolution, Deconvolution, Image processing, Stochastic processes, Optimization (mathematics)

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Proceedings Article | 29 June 2005 Paper

Sparse Gabor wavelets by local operations

Sylvain Fischer, Rafael Redondo, Laurent Perrinet, Gabriel Cristobal

Proceedings Volume 5839, (2005) https://doi.org/10.1117/12.608403

KEYWORDS: Wavelets, Transform theory, Image compression, Image filtering, Denoising, Quantization, Image enhancement, Head, Image denoising, Wavelet transforms

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Proceedings Article | 29 June 2005 Paper

Multifocus fusion with oriented windows

F. Sroubek, S. Gabarda, R. Redondo, S. Fischer, G. Cristobal

Proceedings Volume 5839, (2005) https://doi.org/10.1117/12.608399

KEYWORDS: Image fusion, Wavelets, Image segmentation, Image quality, Signal to noise ratio, 3D image reconstruction, Fusion energy, Volume rendering, Image processing, Wavelet transforms

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SPIE Journal Paper | 1 April 2005

Multifocus image fusion through pseudo-Wigner distribution

Salvador Gabarda, Gabriel Cristóbal-Perez

OE, Vol. 44, Issue 04, 047001, (April 2005) https://doi.org/10.1117/12.10.1117/1.1881412

KEYWORDS: Image fusion, Image enhancement, Image processing, Distance measurement, Image restoration, Optical engineering, Binary data, Convolution, Smoothing, Signal to noise ratio

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Proceedings Article | 2 November 2004 Paper

Volumetric image fusion using the pseudo-Wigner distribution

Salvador Gabarda, Gabriel Cristobal, Sylvain Fischer, Rafael Redondo, Lorenzo Galleani, Leon Cohen

Proceedings Volume 5558, (2004) https://doi.org/10.1117/12.561108

KEYWORDS: Image fusion, Image enhancement, Image processing, Distance measurement, Image restoration, Image quality, Image resolution, Cameras, Quality measurement, Microorganisms

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Proceedings Article | 1 November 2004 Paper

Compression of volumetric data sets using motion-compensated temporal filtering

Raphael Redondo, Joeri Barbarien, Adrian Munteanu, Gabriel Cristobal, Peter Schelkens

Proceedings Volume 5607, (2004) https://doi.org/10.1117/12.573888

KEYWORDS: Motion estimation, Video, Video coding, Wavelet transforms, Video compression, Wavelets, Motion models, Computer programming, Data compression, Distortion

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Proceedings Article | 26 October 2004 Paper

Texture segmentation and analysis for tissue characterization

Rafael Redondo, Sylvain Fischer, Gabriel Cristobal, Manuel Forero, Andres Santos, Javier Hormigo, Salvador Gabarda

Proceedings Volume 5559, (2004) https://doi.org/10.1117/12.561112

KEYWORDS: Image segmentation, Principal component analysis, Bone, Filtering (signal processing), Image filtering, Linear filtering, Anisotropy, Tissues, Signal analyzers, Bandpass filters

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Proceedings Article | 25 May 2004 Paper

Cloud denoising

Salvador Gabarda, Gabriel Cristobal, Lorenzo Galleani, Leon Cohen

Proceedings Volume 5467, (2004) https://doi.org/10.1117/12.547635

KEYWORDS: Clouds, Image fusion, Denoising, Spatial frequencies, Cameras, Image registration, Image enhancement, Fluctuations and noise, Biomedical optics, Image filtering

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Proceedings Article | 30 December 2003 Paper

On the 1/f model for cloud generation

Lorenzo Galleani, Leon Cohen, Gabriel Cristobal, Bruce Suter

Proceedings Volume 5200, (2003) https://doi.org/10.1117/12.506854

KEYWORDS: Clouds, Differential equations, Fourier transforms, Systems modeling, Numerical simulations, Analytical research, Roads, Evolutionary algorithms, Stochastic processes, Neural networks

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Proceedings Article | 30 December 2003 Paper

Automatic screening and multifocus fusion methods for diatom identification

Manuel Forero, Filip Sroubek, Jan Flusser, Rafael Redondo, Gabriel Cristobal

Proceedings Volume 5200, (2003) https://doi.org/10.1117/12.506841

KEYWORDS: Image fusion, Image segmentation, Wavelets, Feature extraction, Water, Image processing, Detection and tracking algorithms, Fusion energy, Visualization, Mahalanobis distance

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Proceedings Article | 19 November 2003 Paper

Texture discrimination using the Wigner-Ville distribution

Javier Hormigo, Gabriel Cristobal, Leon Cohen, Lorenzo Galleani, Bruce Suter

Proceedings Volume 5203, (2003) https://doi.org/10.1117/12.506881

KEYWORDS: Principal component analysis, Image segmentation, Signal analyzers, Image analysis, Filtering (signal processing), Medical imaging, Data compression, Image classification, Neural networks, Smoothing

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Proceedings Article | 19 November 2003 Paper

Automatic identification techniques of tuberculosis bacteria

Manuel Forero, Gabriel Cristobal, Josue Alvarez-Borrego

Proceedings Volume 5203, (2003) https://doi.org/10.1117/12.506800

KEYWORDS: Image segmentation, Bacteria, Image processing, Error analysis, Statistical analysis, Luminescence, Image analysis, Shape analysis, Image classification, Particles

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Proceedings Article | 18 April 2003 Paper

Novel theory on mach-bands and gradient formation in early vision

Matthias Keil, Gabriel Cristobal, Heiko Neumann

Proceedings Volume 5119, (2003) https://doi.org/10.1117/12.499072

KEYWORDS: Diffusion, Visual system, Neurons, Visualization, Nonlinear filtering, Reflectivity, Image restoration, Computer architecture, Complex systems, Retina

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SPIE Journal Paper | 1 February 2003

Automatic object identification irrespective of geometric changes

Jose Pech-Pacheco, Josue Alvarez-Borrego, Gabriel Cristobal, Matthias Keil

OE, Vol. 42, Issue 02, (February 2003) https://doi.org/10.1117/12.10.1117/1.1531189

KEYWORDS: Phase only filters, Image processing, Image filtering, Fourier transforms, Optical engineering, Image registration, Visualization, Optical filters, Organisms, Convolution

Proceedings Article | 6 December 2002 Paper

Phase-amplitude study of clouds

Lorenzo Galleani, Leon Cohen, Gabriel Cristobal, Bruce Suter

Proceedings Volume 4791, (2002) https://doi.org/10.1117/12.456491

KEYWORDS: Clouds, Denoising, Fourier transforms, Filtering (signal processing), Image analysis, Analytical research, Roads, Signal processing, Linear filtering, Optical inspection

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Proceedings Article | 21 November 2002 Paper

Study of 21 fragmented fossil diatoms using a digital invariant correlation

C. Elizabeth Villalobos-Flores, Josue Alvarez-Borrego, Vitaly Kober, Gabriel Cristobal-Perez, Ernestina Castro-Longoria

Proceedings Volume 4790, (2002) https://doi.org/10.1117/12.452180

KEYWORDS: Organisms, Phase only filters, Statistical analysis, System identification, Ecology, Oceanography, Climate change, Climatology, Data conversion, Digital image processing

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Proceedings Article | 21 November 2002 Paper

Automatic diatom recognition on digital images

Manuel Forero-Vargas, Jorge Alvarado, Andres Luna-Tamayo, Gabriel Cristobal-Perez

Proceedings Volume 4790, (2002) https://doi.org/10.1117/12.452410

KEYWORDS: Image segmentation, Image processing, Pattern recognition, Organisms, Detection and tracking algorithms, Microscopes, Silica, Ecosystems, Image classification, Digital image processing

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Proceedings Article | 15 November 2002 Paper

Segmentation, autofocusing, and signature extraction of tuberculosis sputum images

Manuel Forero-Vargas, Filip Sroubek, Josue Alvarez-Borrego, Norberto Malpica, Gabriel Cristobal, Andres Santos, Luis Alcala, Manuel Desco, Leon Cohen

Proceedings Volume 4788, (2002) https://doi.org/10.1117/12.451665

KEYWORDS: Image segmentation, Bacteria, Colorimetry, Image processing, Luminescence, Optical filters, Color image processing, Feature extraction, Mathematical morphology, Fuzzy logic

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SPIE Journal Paper | 1 April 2002

Invariant recognition of polychromatic images of Vibrio cholerae 01

Josue Alvarez-Borrego, Rosa Mourino-Perez, Gabriel Cristobal, Jose Pech-Pacheco

OE, Vol. 41, Issue 04, (April 2002) https://doi.org/10.1117/12.10.1117/1.1456539

KEYWORDS: Bacteria, Organisms, Fourier transforms, Image filtering, Polymer optical fibers, Optical filters, Phase only filters, Optical engineering, Climate change, Climatology

Proceedings Article | 13 November 2001 Paper

Identification of a red tide blooming species through an automatic optical-digital system

Jose Pech-Pacheco, Josue Alvarez-Borrego, Gabriel Cristobal-Perez

Proceedings Volume 4471, (2001) https://doi.org/10.1117/12.449342

KEYWORDS: Organisms, Optical signal processing, Microscopes, LCDs, Interfaces

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Proceedings Article | 13 November 2001 Paper

Automatic sputum color image segmentation for tuberculosis diagnosis

Manuel Forero-Vargas, Eduard Sierra-Ballen, Josue Alvarez-Borrego, Jose Pech-Pacheco, Gabriel Cristobal-Perez, Luis Alcala, Manuel Desco

Proceedings Volume 4471, (2001) https://doi.org/10.1117/12.449343

KEYWORDS: Image segmentation, Fuzzy logic, Bacteria, Image filtering, Image analysis, Particles, Luminescence, RGB color model, Phase only filters, Color image segmentation

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Proceedings Article | 14 August 2001 Paper

Fragmented fossil diatoms using an invariant correlation method

C. Elizabeth Villalobos-Flores, Josue Alvarez-Borrego, Jose Pech-Pacheco, Gabriel Cristobal, Ernestina Castro-Longoria

Proceedings Volume 4419, (2001) https://doi.org/10.1117/12.437080

KEYWORDS: Organisms, Statistical analysis, Phase only filters, Ocean optics, System identification, Ecology, Oceanography, Climate change, Climatology, Biomedical optics

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Proceedings Article | 2 November 2000 Paper

Power cepstral image analysis through the scale transform

Jose Pech-Pacheco, Gabriel Cristobal, Josue Alvarez-Borrego, Leon Cohen

Proceedings Volume 4113, (2000) https://doi.org/10.1117/12.405864

KEYWORDS: Image registration, Particles, Fourier transforms, Image processing, Image analysis, Image restoration, Current controlled current source, Image fusion, Digital filtering, Microscopy

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Proceedings Article | 21 March 2000 Paper

Eggshell defects detection based on color processing

Maria Garcia-Alegre, Angela Ribeiro, Domingo Guinea, Gabriel Cristobal

Proceedings Volume 3966, (2000) https://doi.org/10.1117/12.380082

KEYWORDS: Image processing, Inspection, Machine vision, Algorithm development, Cameras, Binary data, Defect detection, Visualization, Blood, CCD cameras

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Proceedings Article | 2 November 1999 Paper

Denoising using time-frequency and image processing methods

Douglas Nelson, Gabriel Cristobal, Vitaly Kober, Fehret Cakrak, Patrick Loughlin, Leon Cohen

Proceedings Volume 3807, (1999) https://doi.org/10.1117/12.367673

KEYWORDS: Interference (communication), Electronic filtering, Fourier transforms, Time-frequency analysis, Frequency modulation, Fermium, Transform theory, Signal processing, Optical filters, Filtering (signal processing)

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Proceedings Article | 1 November 1999 Paper

How is luminance information passed into the cortex: emergent multifunctional behavior of a simple cell model

Matthias Keil, Gabriel Cristobal

Proceedings Volume 3812, (1999) https://doi.org/10.1117/12.367687

KEYWORDS: Visual process modeling, Visual system, Visual cortex, Information operations, Solids, Retina, Visualization, Space operations, Sensors, Circuit switching

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Proceedings Article | 18 October 1999 Paper

Rank order filtering based on accelerated algorithm of local histogram calculation

Vitaly Kober, Gabriel Cristobal

Proceedings Volume 3808, (1999) https://doi.org/10.1117/12.365878

KEYWORDS: Filtering (signal processing), Satellite imaging, Earth observing sensors, Satellites, Image filtering, Signal processing, Digital filtering, Image contrast enhancement, Electronic filtering, Synthetic aperture radar

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Proceedings Article | 14 October 1997 Paper

Global and local translation and magnification

S. Umesh, Aibing Rao, Gabriel Cristobal, Leon Cohen, Jos van Deemter

Proceedings Volume 3167, (1997) https://doi.org/10.1117/12.290274

KEYWORDS: Fourier transforms

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Proceedings Article | 23 October 1996 Paper

Wavelet-based denoising methods: a comparative study with applications in microscopy

Gabriel Cristobal, Monica Chagoyen, Boris Escalante-Ramirez, Juan Lopez

Proceedings Volume 2825, (1996) https://doi.org/10.1117/12.255299

KEYWORDS: Denoising, Wavelets, Image processing, Filtering (signal processing), Linear filtering, Microscopy, Nonlinear filtering, Digital filtering, Acquisition tracking and pointing, Signal processing

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Proceedings Article | 22 October 1996 Paper

Scale in images

Gabriel Cristobal, Leon Cohen

Proceedings Volume 2846, (1996) https://doi.org/10.1117/12.255438

KEYWORDS: Fourier transforms, Cameras, Optical filters, Denoising, Signal processing, Linear filtering, Image resolution, Fractal analysis, Vibrometry, Multidimensional signal processing

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Proceedings Article | 8 October 1996 Paper

Signal reconstruction with a small set Gabor filters

Jos van Deemter, Gabriel Cristobal

Proceedings Volume 2823, (1996) https://doi.org/10.1117/12.253440

KEYWORDS: Signal to noise ratio, Image filtering, Image quality, Bandpass filters, Linear filtering, Electronic filtering, Fourier transforms, Gaussian filters, Reconstruction algorithms, Optical filters

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