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  • DISEÑO E IMPLEMENTACIÓN DE UN SISTEMA MULTIESPECTRAL EN EL RANGO ULTRAVIOLETA, VISIBLE E INFRARROJO. APLICACIÓN AL ESTUDIO Y CONSERVACIÓN DE OBRAS DE ARTE

     Herrera Ramirez, Jorge Alexis
    Defense's date: 2014-03-25
    Universitat Politècnica de Catalunya
    Theses

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    Los sistemas multiespectrales tienen la caracteristica principal de proporcionar acceso a informaci6n espectral de una muestra con alta resoluci6n espacial. En esta tesis, como principal objetivo, se ha disefiado e implementado un sistema multiespectral para aplicarlo al estudio de obras de arte. Este sistema comprende dos m6dulos: el m6dulo 1 UV-Vis, con una camara CCD con sensibilidad entre 370nm y930nm, acoplada a una fuente de diodos emisores de luz(LED) con 16 canales diferentes, es decir 16 1ongitudes de onda de emisi6n; yel m6dulo 2 IR, con una camara lnGaAs con sensibilidad entre 930nm y 1650nm, acoplada a una fuente LED con 71ongitudes de onda de emisi6n. Por tanto, el sistema completo abarca desde 370nm a 1650nm con un total de 23 canales.Se caracterizaron Ios elementos del sistema y se han realizado simulaciones para evaluar su rendimiento en la reconstrucci6n de reflectancias espectrales bajo condiciones ideales, condiciones de ruido de cuantificaci6n y aditivo. Su rendimiento se evalu6 empleando la formula de diferencia de color CIEDE2000,el error cuadratico medio (RMSE) y el coeficiente de bondad del ajuste (GFC). Los resultados de las simulaciones mostraron un buen rendimiento general del sistema, aunque con mejores resultados para el m6dulo 1 UV-Vis debido a la mayor cantidad de canales LED en su rango espectral.Paralelamente se implementaron Ios programas computacionales con sus respectivas interfaces graficas necesarias para el control del hardware usado y para el procesamiento de la informaci6n proporcionada por el sistema. Para la reconstrucci6n espectral empleamos un metodo de interpolaci6n directa basado en splines, y Ios metodos depseudoinversa indeterminada (PSE-l) y pseudoinversa simple (PSE) que necesitan de un entrenamiento con un conjunto de muestras con respuestas digitales del sistema y reflectancias espectrales conocidas. El equipo se evalu6 sobre muestras reales de la carta de colores Color Checker CCCR y sobre un conjunto de pinturas alfresco realizadas con pigmentos comunmente presentas en obras de arte. Los resultados de las metricas CIEDE2000,RMSE yGFC mostraron que Ios metodos de la PSE-1 y PSE tienen desempefios similares,con resultados ligeramente mejores para el segundo metodo. El metodo de interpolaci6n present6 un rendimiento ligeramente menor, aunque tiene el valor practico de no necesitar entrenamiento. Los resultados reales para el metodo del PSE fueron similares a Ios obtenidos mediante simulaci6n, y se mostr6 una vez m as que el m6dulo 2 IR tiene un rendimiento inferior. Se concluy6 que en general el desempefio delsistema era bueno, con valores CIEDE2000 y RMSE promedio para Ios metodos basados en PSE del orden de 1 unidad enambos casos.El sistema desarrollado fue aplicado a obras de arte en elmuseo de Monasterio de Pedralbes, en Barcelona, y Ias lglesias de Sant Pere, en Terrassa.En el Monasterio de Pedralbes se capturaron diferentes imagenes de pinturas murales de la capilla de San Miguel y se evalu6 el desempefio del sistema para esta aplicaci6n de museo, mostrando un desempeno similar al reportado en las pruebas de laboratorio. Tambien se accedi6 a la obra Virgen de la Leche que es un 61eo en tabla de gran formato. En esta obra se aprovech6 el diseno modular y de facil movimiento del sistema para generar por composici6n una imagen completa a partir de varias imagenes menores.En las iglesias de Sant Pere se exploraron pinturas murales que se estima datan de las epocas visigoda (siglos VI-VII) y romanica (siglos XII-XIII) para evaluar si existian caracteristicas en Ias pinturas que no fueran evidentes en el rango visible y que silo fueran en otros rangos espectrales. Para ello se implementaron algoritmos de realce de la informaci6n. Los resultados obtenidos en esta tesis doctoral ponen de manifiesto las potencialidades del sistema multiespecral desarrollado para la obtenci6n de informaci6n espectral en las regiones ultravioleta, visible e infrarrojo.

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    Portable multispectral imaging system based on light-emitting diodes for spectral recovery from 370 to 1630 nm  Open access

     Herrera Ramirez, Jorge Alexis; Vilaseca Ricart, Meritxell; Pujol Ramo, Jaume
    Applied optics
    Date of publication: 2014-05-10
    Journal article

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    To expand and investigate the potential of spectral imaging, we developed a portable multispectral system using light-emitting diodes. This system recovers spectral information from the UV to the near IR over a large area using two different image sensors synchronized with 23 bands of illumination. The system was assessed for spectral reconstruction through simulations and experimental measurements by means of two methods of spectral reconstruction and three different evaluation metrics. The results over a Macbeth ColorChecker chart and other samples, including pigments usually employed in art paintings, are compared and discussed. The portable multispectral system using LEDs constitutes a cost-effective and versatile method for spectral imaging.

    To expand and investigate the potential of spectral imaging, we developed a portable multispectral system using light-emitting diodes. This system recovers spectral information from the UV to the near IR over a large area using two different image sensors synchronized with 23 bands of illumination. The system was assessed for spectral reconstruction through simulations and experimental measurements by means of two methods of spectral reconstruction and three different evaluation metrics. The results over a Macbeth ColorChecker chart and other samples, including pigments usually employed in art paintings, are compared and discussed. The portable multispectral system using LEDs constitutes a cost-effective and versatile method for spectral imaging.

  • Diagnosis of skin cancer using optics

     Vilaseca Ricart, Meritxell; Pujol Ramo, Jaume; Ares Rodriguez, Miguel; Riu Gras, Jordi; Azcona Guerrero, Francisco Javier; Herrera Ramirez, Jorge Alexis; Delpueyo Español, Xana; Jha, Ajit; Royo Royo, Santiago
    Participation in a competitive project

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  • Reconstruction of CIE standard illuminants with an LED-based spectrally tuneable light source

     Burgos Fernandez, Francisco Javier; Perales Romero, Esther; Herrera Ramirez, Jorge Alexis; Vilaseca Ricart, Meritxell; Martínez Verdú, Francisco Miguel; Pujol Ramo, Jaume
    International AIC Colour Congress
    Presentation's date: 2013-07-12
    Presentation of work at congresses

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  • Generación de iluminantes estándar a partir de una fuente de luz espectral y sintonizable basada en LEDs

     Burgos Fernandez, Francisco Javier; Perales Romero, Esther; Herrera Ramirez, Jorge Alexis; Vilaseca Ricart, Meritxell; Martínez Verdú, Francisco Miguel; Pujol Ramo, Jaume
    Congreso Nacional del Color
    Presentation's date: 2013-06-28
    Presentation of work at congresses

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  • Colour and Space in cultural Heritage (COSCH)

     Vilaseca Ricart, Meritxell; Royo Royo, Santiago; Pujol Ramo, Jaume; Ares Rodriguez, Miguel; Arjona Carbonell, Maria Montserrat; Herrera Ramirez, Jorge Alexis
    Participation in a competitive project

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  • Studying Art Paintings through a Multispectral Imaging System Composed of Light-Emitting Diodes Covering the Spectral Range from 370 to 1600 nm

     Herrera Ramirez, Jorge Alexis; Vilaseca Ricart, Meritxell; Burgos, Francisco Javier; Font, Lídia; Senserrich, Rosa; Pujol Ramo, Jaume
    Interim Meeting of the International Color Association
    Presentation's date: 2012-09
    Presentation of work at congresses

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    Multispectral systems are implemented in many ways and are intended for different purposes. Some of them have been used for the study of art work but they have been mostly based on filters. In this work we assess the feasibility of a multispectral system based on Light-Emitting Diodes (LED) for the study of art work paintings. This system is comprised of two cameras and two sets of LEDs with different peak wavelengths of emission. Images from the 23 channels of the system give access to pixel-wise information of color and spectrum in the range of 370nm to 1600nm. The spectrum for each pixel is calculated via two methods: the pseudo-inverse estimation method using a training set of samples and the interpolation method using splines. The performance of the system in terms of color and spectral reconstruction is evaluated using three different metrics. The results obtained in spectral estimation shows a good performance of the system. In addition, some of the possibilities that the system offers are shown with images and spectra estimation of pixels for real wall paintings.

  • Trabajos de investigación en óptica visual y tecnología del color en el CD6

     Pujol Ramo, Jaume; Arjona Carbonell, Maria Montserrat; Vilaseca Ricart, Meritxell; Aldaba Arevalo, Mikel; Diaz Douton, Fernando; Luque, Sergio Oscar; Zuluaga Duque, Harold; Herrera Ramirez, Jorge Alexis; Sanabrial, F.; Ferrer Serrano, Edgar; Martinez Roda, Juan Antonio; Ondategui Parra, Juan Carlos; Burgos, Francisco Javier; Giner Tort, Anna; Torrecilla Ribalta, Elena
    Reunión Nacional de Óptica
    Presentation's date: 2012-09-05
    Presentation of work at congresses

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  • Sistema multiespectral basado en LEDs en los rangos ultravioleta, visible e infrarrojo. Aplicación al estudio y conservación de obras de arte

     Vilaseca Ricart, Meritxell; Burgos Fernandez, Francisco Javier; Senserrich, Rosa; Font, Lídia; Pujol Ramo, Jaume; Herrera Ramirez, Jorge Alexis
    Reunión Nacional de Óptica
    Presentation's date: 2012-09
    Presentation of work at congresses

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    Sistema multiespectral basado en LEDS para el estudio de obras de arte en el rango espectral desde los 370 a los 1600nm  Open access

     Herrera Ramirez, Jorge Alexis; Vilaseca Ricart, Meritxell; Burgos, Francisco Javier; Senserrich, Rosa; Font, Lídia; Pujol Ramo, Jaume
    Red temática "Ciencia y tecnología del color"
    Presentation's date: 2012-03-22
    Presentation of work at congresses

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    Este trabajo muestra el diseño e implementación de un sistema de imágenes multiespectral basado en diodos e misores de luz (LED) que cubre los rangos de longitudes de onda desde los 370 nm a los 1600 nm. El sistema permite la estimación del espectro de reflectancia píxel a píxel, a partir de la infonnación de 23 canales espectrales dados por una iluminación LED multiplexada. La infonnación de reflectancia se estima usando dos métodos diferentes: a través de interpolación a partir de las respuestas digitales de los sensores de imagen y por medio del método de la pseudoinversa. Los resultados desimulaciones y de medidas experimentales fueron validados mediante métricas de ajuste entre espectros y diferencias de color, mostrando la cercanía entre las simulaciones y las mediciones y un buen desempeño del equipo. Este sistema está siendo usado para el estudio de las pinturas al fresco de la Capilla de San Miguel del Museo-Monasterio de Pedralbes en la ciudad de Barcelona.

  • Iris Color and Texture: A Comparative Analysis of Real Irises, Ocular Prostheses, and Colored Contact Lenses

     Herrera Ramirez, Jorge Alexis; Vilaseca Ricart, Meritxell; Düll, Jochen; Arjona Carbonell, Maria Montserrat; Torrecilla Ribalta, Elena; Pujol Ramo, Jaume
    Color research and application
    Date of publication: 2011-10
    Journal article

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  • NUEVOS DESARROLLOS EN ÓPTICA VISUAL Y TECNOLOGÍA DEL COLOR CON ALTO IMPACTO SOCIAL E INDUSTRIAL

     Pujol Ramo, Jaume; Vilaseca Ricart, Meritxell; Arjona Carbonell, Maria Montserrat; Martinez Roda, Juan Antonio; Ondategui Parra, Juan Carlos; Aldaba Arevalo, Mikel; Zuluaga Duque, Harold; Herrera Ramirez, Jorge Alexis; Ferrer Serrano, Edgar
    Participation in a competitive project

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  • Multispectral imaging system with multiplexed illumination for spectral and color measurements

     Herrera Ramirez, Jorge Alexis; Vilaseca Ricart, Meritxell; Pujol Ramo, Jaume
    Interim Meeting of the International Color Association
    Presentation's date: 2011-06-07
    Presentation of work at congresses

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  • Evaluation of the repeatability and reproducibility levels for colour measurement obtained by digital imaging capture devices

     Chorro, Elisabeth; Vilaseca Ricart, Meritxell; Herrera Ramirez, Jorge Alexis; Perales Romero, Esther; Martínez Verdú, Francisco Miguel; Pujol Ramo, Jaume
    European Conference on Colour in Graphics, Imaging and Vision
    Presentation's date: 2010-06-14
    Presentation of work at congresses

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    Conventional and multi-spectral digital imaging capture devices can be used for colorimetric measurements. However, a preliminary study of their repeatability and reproducibility is very advisable if they want to be used for this purpose. In this work, a methodology to study the repeatability and reproducibility of such systems is proposed and two digital imaging capture devices working as spectroradiometers with three and seven filters, respectively, are analyzed with respect to a reference tele-spectra-colorimeter. The results of the statistical test show that both have good levels of repeatability, although not the same conclusion is reached regarding the reproducibility, due to some systematic errors.

  • Evaluación del nivel de repetibilidad para medidas de color obtenidas mediante dos sistemas de captura digital de imagen

     Chorro, Elisabeth; Vilaseca Ricart, Meritxell; Herrera Ramirez, Jorge Alexis; Perales Romero, Esther; Martínez Verdú, Francisco Miguel; Pujol Ramo, Jaume
    Congreso Nacional del Color
    Presentation's date: 2010-06-30
    Presentation of work at congresses

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  • Iris color evaluation with a digital color camera

     Herrera Ramirez, Jorge Alexis; Vilaseca Ricart, Meritxell; de Lasarte, Marta; Düll, Jochen; Pujol Ramo, Jaume
    Congress of the International Color Association (AIC 2009)
    Presentation's date: 2009-09-27
    Presentation of work at congresses

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    In this work we measure and evaluate the color of irises, prostheses and cosmetic colored contact lenses with a system based on a digital RGB color camera. Using multispectral tools, the CIE L*a*b* colorimetric coordinates are computed from the RGB digital values of the acquired images. With the statistical analysis of the L*a*b* values, the color gamuts and the CIEDE2000 color differences, a comparison of the color associated to each set of samples is performed. Specifically, the samples are classified in three major groups: brown, blue and green, using a new algorithm developed for this purpose. In the same way, the irises color reproduction achieved by prostheses and contact lenses is analysed, obtaining closer results in prostheses than in contact lenses. Besides, a preliminary analysis of the color spatial distribution of the irises, prostheses and cosmetic colored contact lenses by means of an algorithm based on co-occurrence matrices is also performed. The results obtained suggest that the color spatial distribution and therefore, the texture associated to each kind of samples, is very different. This study provides useful information on the color and texture of irises and may help improving the techniques used in the manufacturing process of prostheses and colored contact lenses in order to obtain a better and more realistic appearance.

  • Líneas de Investigación en Óptica Visual y Tecnología del Color en el CD6

     Pujol Ramo, Jaume; Vilaseca Ricart, Meritxell; Arjona Carbonell, Maria Montserrat; Aldaba Arevalo, Mikel; Herrera Ramirez, Jorge Alexis; Ondategui Parra, Juan Carlos; de Lasarte, Marta; Zuluaga Duque, Harold; Diaz Douton, Fernando; Luque, Sergio Oscar; Sanàbria Ortega, Ferran
    Reunión Nacional de Óptica
    Presentation of work at congresses

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  • Texture analysis the evaluation of human irises reproduction in ocular prostheses and colored contact lenses

     Herrera Ramirez, Jorge Alexis; Vilaseca Ricart, Meritxell; Arjona Carbonell, Maria Montserrat; Pujol Ramo, Jaume
    Red temática "Ciencia y tecnología del color"
    Presentation's date: 2009-11
    Presentation of work at congresses

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    This work takes advantage of multispectral data from human irises, ocular prostheses and colored contact lenses to compare them accounting for their texture features. For this aim, several procedures from image processing were implemented: image segmentation algorithms to extract the areas of interest, statical texture analysis tools for texture description, and statistical classifiers for samples discrimination from texture descriptors. For the texture study two approaches were implemented, firstorder statistical study of the image histogram and second order statistical analysis through co-occurrence matrices. The results of the samples classification regarding the texture show differences in color distribution among samples. Thus, it can be stated that the comparison of just color features of the samples are not enough to conclude whether a contact lens or ocular prosthesis is a good reproduction of an iris sample, and therefore, it is necessary to include the texture in such comparisons.

  • Evaluación del color del iris mediante una cámara digital

     Herrera Ramirez, Jorge Alexis; Vilaseca Ricart, Meritxell; de Lasarte, Marta; Düll, Jochen; Pujol Ramo, Jaume
    Reunión Nacional de Óptica
    Presentation's date: 2009-09-14
    Presentation of work at congresses

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    Iris color evaluation through multispectral systems  Open access

     Herrera Ramirez, Jorge Alexis; Vilaseca Ricart, Meritxell; Pujol Ramo, Jaume; Arjona Carbonell, Maria Montserrat; de Lasarte, Marta
    Red temática "Ciencia y tecnología del color"
    Presentation's date: 2008-09-24
    Presentation of work at congresses

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