Psychophysical Determination of the Relevant Colours That Describe the Colour Palette of Paintings

In an early study, the so-called “relevant colour” in a painting was heuristically introduced as a term to describe the number of colours that would stand out for an observer when just glancing at a painting. The purpose of this study is to analyse how observers determine the relevant colours by describing observers’ subjective impressions of the most representative colours in paintings and to provide a psychophysical backing for a related computational model we proposed in a previous work. This subjective impression is elicited by an efficient and optimal processing of the most representative colour instances in painting images. Our results suggest an average number of 21 subjective colours. This number is in close agreement with the computational number of relevant colours previously obtained and allows a reliable segmentation of colour images using a small number of colours without introducing any colour categorization. In addition, our results are in good agreement with the directions of colour preferences derived from an independent component analysis. We show that independent component analysis of the painting images yields directions of colour preference aligned with the relevant colours of these images. Following on from this analysis, the results suggest that hue colour components are efficiently distributed throughout a discrete number of directions and could be relevant instances to a priori describe the most representative colours that make up the colour palette of paintings.FEDER Funds by the Spanish Ministry of Science Innovation and Universities (MICINN, grant number RTI2018-094738-B-I00

Computational color analysis of paintings for different artists of the XVI and XVII centuries

We have performed a computational color analysis of images of paintings for six master painters: Titian, Rubens, El Greco, Velázquez, Rembrandt, and Vermeer. These painters show the evolution from the renaissance to the baroque style. Different first and second-order statistical parameters have been obtained and analyzed in order to fix which of them can be common for the different artists and which of them can be representative of a certain period of time or the evolution of the art. The firsts include the orientation and semi-axes ratio of the ellipses that define the gamut in the chromaticity diagram and the dependencies with the frequency of the power of the Fourier transforms. Most differences among artists can be found in the volume and area of the gamut, the number of discernible colors which is greater for Titian, El Greco and Rubens, compared to Velázquez, Rembrandt and Vermeer, the average value of L* and the number of dark pixels.Ministerio de Industria Economia y Competitividad for their support and grant in the project DPI 2015-6471_

Understanding the effect of correlated colour temperatures on spatio-chromatic properties of natural images

Despite the natural occurrence of global and local daylight changes in natural scenes, the human visual system typically adapts well to these changes and develops stable colour perception. In a previous study, the influence of daylight characterized by its Correlated Colour Temperatures (CCT) on different chromatic descriptors was analysed (Ojeda et al., 2017). The results showed that chromatic information is almost constant for CCT values above 14,000 K, with local extremes occurring in the range of low CCTs. The aim of this work is to extend the analysis of the CCT dependence of the illuminant to those that consider the spatio-chromatic structure, including second order descriptors (gradients, spectral slope, spectral signature, and PCA) and higher order descriptors (kurtosis, skewness, and number of relevant colours). Our results show that most of the descriptors exhibit horizontal asymptotic behaviour for CCTs above 15,000 K and local extremes in the range of 3,900 K-9,600 K. For those descriptors that could be analysed in CIELAB space, sufficient statistical evidence was obtained to consider skewness, kurtosis, and the independent spectral slopes of the L* channel as equal in the range of CCTs used. However, the slight variations in spectral signatures and the directions of the principal components when applying PCA to image patches are not statistically significant and cannot be considered equal under different illuminants. The number of relevant colours (NRC) exhibits sensitivity to temperature variations and behaves similarly to the other descriptors, due to its small number.Computational Colour and Spectral Imaging Erasmus+ master programme (610605-EPP-1-2019-1-NO-EPPKA1-JMD-MOB

Eight-Channel Multispectral Image Database for Saliency Prediction

Saliency prediction is a very important and challenging task within the computer vision community. Many models exist that try to predict the salient regions on a scene from its RGB image values. Several new models are developed, and spectral imaging techniques may potentially overcome the limitations found when using RGB images. However, the experimental study of such models based on spectral images is difficult because of the lack of available data to work with. This article presents the first eight-channel multispectral image database of outdoor urban scenes together with their gaze data recorded using an eyetracker over several observers performing different visualization tasks. Besides, the information from this database is used to study whether the complexity of the images has an impact on the saliency maps retrieved from the observers. Results show that more complex images do not correlate with higher differences in the saliency maps obtained.Spanish Ministry of Science, Innovation, and Universities (MICINN) RTI2018-094738-B-I00European Commissio

Colorimetric analysis of outdoor illumination across varieties of atmospheric conditions

© 2016 [year] Optical Society of America.]. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited.Solar illumination at ground level is subject to a good deal of change in spectral and colorimetric properties. With an aim of understanding the influence of atmospheric components and phases of daylight on colorimetric specifications of downward radiation, more than 5,600,000 spectral irradiance functions of daylight, sunlight, and skylight were simulated by the radiative transfer code, SBDART [Bull. Am. Meteorol. Soc. 79, 2101 (1998).], under the atmospheric conditions of clear sky without aerosol particles, clear sky with aerosol particles, and overcast sky. The interquartile range of the correlated color temperatures (CCT) for daylight indicated values from 5712 to 7757 K among the three atmospheric conditions. A minimum CCT of ∼3600 K was found for daylight when aerosol particles are present in the atmosphere. Our analysis indicated that hemispheric day-light with CCT less than 3600 K may be observed in rare conditions in which the level of aerosol is high in the atmosphere. In an atmosphere with aerosol particles, we also found that the chromaticity of daylight may shift along the green–purple direction of the Planckian locus, with a magnitude depending on the spectral extinction by aerosol particles and the amount of water vapor in the atmosphere. The data analysis showed that an extremely high value of CCT, in an atmosphere without aerosol particles, for daylight and skylight at low sun, is mainly due to the effect of Chappuis absorption band of ozone at ∼600 nm. In this paper, we compare our data with well-known observations from previous research, including the ones used by the CIE to define natural daylight illuminants.Andalusian Regional Government (P12-RNM-2409); Spanish Ministry of Science and Technology (CGL2013-45410-R); EU via the ACTRIS project (EU INFRA-2010-1.1.16-262254); Spanish Ministry of Economy and Competitiveness (DPI2011-23202)

Characterization of the evolution of indigo blue by multispectral imaging

FEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento, Grant/Award Number: A-HUM-164-UGR18; Ministry of Economy and Competitiveness of Spain, Grant/Award Number: DPI2015-64571-R; Spanish Ministry of Economy and Competitiveness, Grant/Award Number: Ramon y Cajal program; Ministry of Economy and Competitiveness; Junta de Andalucia; FEDER (European Regional Development Fund).Indigo blue is a natural organic color from the Indigofera tinctoria plant. It is insoluble in water and does not require mordant to fix the color; therefore, due to its nature it can be considered as a pigment or dye. The identification of indigo in cultural heritage is very difficult due to the complexity of its chemical formula and the changes that it can undergo in certain conservation and exposition conditions. For this reason, characterization of possible degradation, transformation, and reaction processes is essential for its identification. In this study, multispectral imaging has been used for the first time as noninvasive technique to characterize the aging state of indigo blue using samples aged in a controlled climate chamber under extreme conditions of humidity, temperature, and light. The technique has proven to be very promising for this application, together with classification techniques based on machine learning approaches.FEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento A-HUM-164-UGR18Ministry of Economy and Competitiveness of Spain DPI2015-64571-RSpanish Ministry of Economy and CompetitivenessMinistry of Economy and CompetitivenessJunta de AndaluciaEuropean Commissio

Omic approaches in environmental risk assessment

Resumen de la comunicación presentada al XX Congreso de la Sociedad Española de Mutagénesis Ambiental – Córdoba 201

Características epidemiológico-clínicas y resultados del manejo de plastrón apendicular en pacientes adultos de un hospital de referencia del Perú: Epidemiological-clinical characteristics and results of appendiceal plastron management in adult patients from a reference hospital in Peru

Introduction: Appendicular plastron is considered a progressive form of acute appendicitis, with a national prevalence of 2-10%. Currently management is often controversial. It is that from this context, it seeks to promote studies that can elucidate the variables associated with the management of this condition. Objective: to determine the epidemiological-clinical characteristics associated with the results of the management of the appendiceal plastron in adult patients in a reference hospital in Peru. Methods: Non-experimental study, with a quantitative approach, observational, analytical and cross-sectional design, whose sample consisted of 100 patients with a diagnosis of appendicular plastron. The data collection sheet was applied as an instrument. Likewise, a Poisson regression model was used to respond to the objectives. Results: The multivariate analysis showed that alcohol consumption (p<0.05 RPa=1.12), nausea and vomiting (p<0.05, RPa=1.48), diarrhea (p<0.05; RPa=1.08), duration of symptoms before admission between 3 and 5 days (p<0.05; RPa=1.09), appendiceal mass (p<0.05, RPa=1.18) and bandemia (p<0.05, RPa=1.12) were significantly associated with unsuccessful management results of the appendiceal plastron. Conclusion: There are epidemiological and clinical characteristics associated with the results of the management of the appendicular plastron.Introducción: El plastrón apendicular se considera una forma progresiva de apendicitis aguda, teniendo una prevalencia a nivel nacional de 2-10%. Actualmente el manejo suele ser controversial. Ante lo expuesto, se busca promover estudios que puedan dilucidar las variables asociadas al manejo de esta condición. Objetivo: determinar las características epidemiológico-clínicas asociadas a los resultados del manejo del plastrón apendicular en pacientes adultos en un hospital de referencia del Perú. Métodos: Estudio no experimental, de enfoque cuantitativo, diseño observacional, analítico y transversal, cuya muestra estuvo conformada por 100 pacientes con diagnóstico de plastrón apendicular. Se aplicó como instrumento la ficha de recolección de datos. Asimismo, se utilizo un modelo de regresión de Poisson para responder a los objetivos. Resultados: El análisis multivariado evidenció que el consumo de alcohol (p<0.05 RPa=1.12), las náuseas y vómitos (p<0.05, RPa=1.48), diarrea (p<0.05; RPa=1.08), duración de síntomas antes del ingreso entre 3 y 5 días (p<0.05; RPa=1.09), masa apendicular (p<0.05, RPa=1.18) y bandemia (p<0.05, RPa=1.12) se asociaron significativamente a resultados de manejo no exitosos de plastrón apendicular. Conclusión: Existe características epidemiológicas y clínicas asociadas a resultados del manejo de plastrón apendicular

Band selection pipeline for maturity stage classification in bell peppers: From full spectrum to simulated camera data

This paper describes a workflow for classifying the maturity of bell peppers using hyperspectral imaging and machine learning. The approach involves using spectral reflectance to determine the number of maturity stages, followed by a classification task using the optimal bands for accurate classification. The study explores a realistic scenario using simulated camera responses and investigates the use of real sensors with their spectral sensitivities and noise. Four classifier algorithms (RBFNN, PLS-DA, SVM, and LDA) were employed to predict the maturity stage based on spectral reflectance. The best results were achieved with the LDA algorithm, which was used in the optimization process for band selection. The optimized bands in the VISNIR range (400–1000 nm) were found to be [783.5, 844.1, and 905.4] nm, with an accuracy of 90.67% for spectral data. For camera responses with intermediate-level noise, the best bands were [760, 820, and 900 nm], achieving an accuracy of 81%. Overall, using three bands yielded satisfactory and practical results for real-world implementation.Universidad de Granada/CBU

Proteómica para la identificación de biomarcadores en estudios medioambientales

Comunicaciones a congreso