Halloysite and Laponite Hybrid Pigments Synthesis with Copper Chlorophyll

Sustainable and green materials have been studied in dye and pigment productions to reduce their environment impacts from being produced and applied. Although natural dyes are an excellent choice to move from agrowaste, some improvements must be made before they are applied given their poor fastness. One way of improving natural dye properties is their adsorption into nanoclay structures to give hybrid pigments. This work used tubular halloysite and laminar laponite to adsorb and stabilize natural copper chlorophyll. With a statistical design of experiments, we observed interactions between synthesis factors, such as pH, ionic strength, and surfactant or silane modification. Cool hybrid pigments with high TSR (%) values and a wide color range were obtained by using dispersions with only distilled water at room temperature. Successful chlorophyll adsorption on both nanoclay surfaces took place by XRD and DTA analyses. The maximum natural dye absorption for both nanoclay types took place under acid conditions, pH 3–4, and in the presence of mordant. The TSR (%) improved by the silane pH interaction, and halloysite hybrid pigments obtained higher TSR values than the laponite ones. Finally, a wide chromatic green color range was obtained with the surfactant modification in both nanoclays, and the color fastening was also improved in the hybrid pigments application. The samples generated with 10% of hybrid pigments from both nanoclays and an Epoxy bioresin, show higher colorfastness than the sample with the natural chlorophyll, due to the nanoclays–dye interaction and protection.This research was funded by Spanish Ministry of Economy and Competitiveness (project RTI2018-096000-B-100)

Evaluating the Graininess Attribute by Visual Scaling for Coatings with Special-Effect Pigments

[EN] In our society, objects' visual appearance is an essential factor because it allows us to recognize and differentiate one object from another. In different industrial sectors like cosmetics, textiles and automotive, special-effect pigments are largely used to achieve attractive visual features. These pigments provide a color change with viewing and illumination direction, and visually provide texture. Depending on a finish's properties, and also on the viewing and illumination conditions, coatings exhibit sparkle or a graininess-like texture. Currently, not many scientific works on the visual perception of these texture effects can be found in the literature. In addition, choice of experimental method can influence the measurement scale obtained from visual data. For this reason, the purpose of this work was to analyze graininess visual scaling constructed by two different psychophysical methods. The experimental design was based on the rank-order and paired-comparison methods. The data analysis was conducted by following the law of comparative judgments to obtain a visual scale of the graininess attribute to compare it to instrumental data. A good correlation appeared between both magnitudes with a correlation coefficient close to 0.9. Both methods provided useful results with a reasonable correspondence between them, which ensures that data can be considered reliable, while the visual obtained scale can act as a good graininess scale perceived by the human visual system.This research was funded by EMRP, grant number 16NRM08, and by the Ministerio de Ciencia, Innovacion y Universidades, grant number RTI2018-096000-B-I00.Perales, E.; Micó-Vicent, B.; Huraibat, K.; Viqueira, V. (2020). Evaluating the Graininess Attribute by Visual Scaling for Coatings with Special-Effect Pigments. Coatings. 10(4):1-10. https://doi.org/10.3390/coatings10040316S11010

Using a video-based eye tracker to analyse the binocular near-reflex dynamics response

Purpose: This study presents a novel video-based eye-tracking system for analysing the dynamics of the binocular near-reflex response. The system enables the simultaneous measurement of convergence, divergence and pupillary size during accommodation and disaccommodation to aid the comprehensive understanding of the three-component near-reflex. Methods: A high-speed (90 Hz) video-based eye tracker was used to capture changes in eye gaze and pupil radius in 15 participants in response to altering stimulus conditions. An offline analysis involved separating the gaze vector components and pupil radius, which were fitted to a hyperbolic tangent function to characterise the dynamics of the near-reflex process. Results: Significant differences in the temporal parameters of the pupil radius were observed between the near-to-far and far-to-near vision changes, with faster miosis compared with mydriasis. Additionally, differences in response times were found between gaze angle components, with longer convergence times compared to changes in the vertical direction (saccades). The steady-state values of the gaze components and pupil radius were in line with theoretical expectations and previous reports. Conclusions: The proposed system provides a non-invasive, portable and cost-effective method for evaluating near-reflex dynamics under natural viewing conditions using a video-based eye tracker. The sampling rate ensures the accurate assessment of vergence eye movements and pupillary dynamics. By simultaneously measuring eye convergence, divergence and pupil size, the system offers a more comprehensive assessment of the near-reflex response. This makes it a valuable tool for clinical diagnosis, research studies and investigating the effects of near work on the visual system.This work was funded by Universidad de Alicante, participating CRUE-CSIC institution

Guías y materiales docentes en Moodle para el programa de postgrado en tecnología de color

Actualmente la medida y gestión de la calidad de color de materiales gonio-aparentes es compleja, pero altamente demandada desde varios sectores industriales, como en automoción. En particular, en los últimos años, ha habido una gran demanda de titulados con una buena formación en Tecnología de Color. Por tal motivo, para satisfacer las competencias demandas por la industria, desde el Grupo de Visión y Color de la Universidad de Alicante, se está trabajando en la articulación de un programa de postgrado que oferte a estudiantes, titulados y no titulados, de una amplia y completa formación en Tecnología de Color. Por tanto, el objetivo principal de este trabajo es la elaboración del diseño curricular y materiales docentes para el programa de postgrado propuesto. En una primera fase, el trabajo se centra en la elaboración de la guía docente de cada una de las asignaturas. La segunda fase se centra en la gestión de los materiales docentes mediante la plataforma Moodle que permitirá el seguimiento por parte del alumno a distancia (b-learning). De esta forma, mediante este programa de postgrado se pretende aportar mayores vías de empleabilidad laboral a unos postgraduados en un sector industrial de gran importancia socio-económica a nivel mundial

Design of online practical lessons in colorimetry

Applied colorimetry is an important module in the program of the elective subject "Colour Science: industrial applications”. This course is taught in the Optics and Optometry Degree and it has been used as a testing for the application of new teaching and assessment techniques consistent with the new European Higher Education Area. In particular, the main objective was to reduce the attendance to lessons and encourage the individual and collective work of students. The reason for this approach is based on the idea that students are able to work at their own learning pace. Within this dynamic work, we propose online lab practice based on Excel templates that our research group has developed ad-hoc for different aspects of colorimetry, such as conversion to different colour spaces, calculation of perceptual descriptors (hue, saturation, lightness), calculation of colour differences, colour matching dyes, etc. The practice presented in this paper is focused on the learning of colour differences. The session is based on a specific Excel template to compute the colour differences and to plot different graphs with these colour differences defined at different colour spaces: CIE ΔE, CIE ΔE94 and the CIELAB colour space. This template is implemented on a website what works by addressing the student work at a proper and organized way. The aim was to unify all the student work from a website, therefore the student is able to learn in an autonomous and sequential way and in his own pace. To achieve this purpose, all the tools, links and documents are collected for each different proposed activity to achieve guided specific objectives. In the context of educational innovation, this type of website is normally called WebQuest. The design of a WebQuest is established according to the criteria of usability and simplicity. There are great advantages of using WebQuests versus the toolbox “Campus Virtual” available in the University of Alicante. The Campus Virtual is an unfriendly environment for this specific purpose as the activities are organized in different sectors depending on whether the activity is a discussion, an activity, a self-assessment or the download of materials. With this separation, it is more difficult that the student follows an organized sequence. However, our WebQuest provides a more intuitive graphical environment, and besides, all the tasks and resources needed to complete them are grouped and organized according to a linear sequence. In this way, the student guided learning is optimized. Furthermore, with this simplification, the student focuses on learning and not to waste resources. Finally, this tool has a wide set of potential applications: online courses of colorimetry applied for postgraduate students, Open Course Ware, etc

Machine-readable universal data format for bidirectional reflectance distribution function and BiRDview—An open-source web-based application for viewing and comparing bidirectional reflectance data

Modern studies of bidirectional reflectance distribution function (BRDF) and its applications using data and machine-driven science require formatting of BRDF data according to Findable, accessible, interoperable and reusable (FAIR) data principles. As a solution a FAIR universal BRDF file-format based on Java Script Object Notation (JSON) is proposed. JSON principles as well as file structure are explained and examples are given. Automatic validation of universal BRDF file format is realized with the help of JSON schema. Furthermore, the source code and accompanying documentation are presented in dedicated supporting material files. It is expected that after its wide adoption, the proposed BRDF file format will enhance collaboration between different research groups and benefit machine-driven science. The uptake is facilitated by introducing a BiRDview—a modern open-source web-based application for BRDF visualization.This work has been done in the frame of the projects 16NRM08 BiRD and 18SIB03 BxDiff, that have received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme. The work has also been supported by the Academy of Finland Flagship Programme, Photonics Research and Innovation (PREIN), decision number: 320167

Diseño curricular y elaboración de materiales para el programa de postgrado en tecnología de color utilizando la plataforma Moodle

En los últimos años, la investigación realizada por el grupo de Visión y Color nos ha permitido conocer la demanda existente en el mercado laboral de expertos en tecnología y reproducción del color, especialmente relacionado con los materiales gonio-aparentes, materiales que ofrecen atractivos atributos para el sector del automóvil, entre otros. Por esta razón, miembros del Grupo de Visión y Color de la Universidad de Alicante nos hemos involucrado en esta red cuyo objetivo principal es ofrecer un programa de postgrado para titulados y no titulados, con una amplia y completa formación en Tecnología de Color. En particular, esta red se ha centrado en el diseño curricular y la elaboración de materiales docentes para este programa de postgrado. En primer lugar, se han desarrollado las guías docentes de cada una de las asignaturas propuestas con el fin de planificar cada una de ellas y poder desarrollar los materiales docentes adecuados. Dado las características de este programa de postgrado, todos los materiales se han elaborado en la plataforma Moodle ya que permite el seguimiento por parte del alumno a distancia (b-learning)

Objective Prediction of Human Visual Acuity Using Image Quality Metrics

This work addresses the objective prediction of human uncorrected decimal visual acuity, an unsolved challenge due to the contribution of both physical and neural factors. An alternative approach to assess the image quality of the human visual system can be addressed from the image and video processing perspective. Human tolerance to image degradation is quantified by mean opinion scores, and several image quality assessment algorithms are used to maintain, control, and improve the quality of processed images. The aberration map of the eye is used to obtain the degraded theoretical image from a set of natural images. The amount of distortion added by the eye to the natural image was quantified using different image processing metrics, and the correlation between the result of each metric and subjective visual acuity was assessed. The correlation obtained for a model based on a linear combination of the normalized mean square error metric and the feature similarity index metric was very good. It was concluded that the proposed method could be an objective way to determine subjects’ monocular and uncorrected decimal visual acuity with low uncertainty

Visual and instrumental correlation of sparkle by the magnitude estimation method

Most real surfaces and objects show variations in appearance with viewing and illumination directions. Besides angular dependency, they also show spatial variation in color, i.e., they exhibit some sort of texture. Of the surfaces we see, surfaces colored by special-effect pigments produce several complex visual effects, like change in color and lightness with viewing and illumination angles, and effects like sparkle and gloss on other textures. In the last two decades, different commercial devices have appeared to help ensure the proper characterization of materials with special-effect pigments. However, the instrumental characterization of sparkle is currently available only by a commercial device integrated into a multi-angle spectrophotometer. As it is difficult to find complete open original studies about the sparkle effect for designing and calibrating this commercial instrument, the main objective of this work was to check whether a good visual and instrumental correlation exists between the sparkle that the observer perceives and the sparkle value provided by the device using some subsets of goniochromatic samples with different types of special-effect pigments and colors. Visual assessments were made by a conventional magnitude estimation method in a directional lighting booth, which belonged to the same company owner of the sparkle instrument, in different geometries and at distinct illuminance levels. The results revealed that there was a good visual correlation of the sparkle grade value. By separately analyzing the factors used in its instrument algorithm, such as sparkle intensity and sparkle area values, it was clearly shown that the correlation was not good or simply did not exist. Consequently, and perhaps in regards to the choice of new special-effect pigments, such as synthetic mica and other future ones, we generated herein even more questions about current mathematical algorithms, and only recognized calculating this texture effect at the industrial level.The authors are grateful to the EMRP for funding the project “Multidimensional Reflectometry for Industry”. The EMRP is jointly funded by EMRP participating countries within EURAMET and the European Union. We thank the Spanish Ministry of Economy and Competitiveness for the coordinated project DPI2011-30090-C02 and project DPI-2015-68514 and University of Alicante for project GRE13-28. Omar Gómez Lozano would also like to thank the above-cited ministry for his pre-doctoral fellowship (FPI BES-2012-053080)

Strategies for continuous improvement in the master's degree in "Colour Technology for the automotive sector" based on feedback from graduates

[ES] The first edition of the Master's Degree in "Color Technology for the Automotive Sector" was held during the last academic year. The academic results in terms of qualifications, achievement and learning were good. In spite of the good sensations, there are aspects to be improved, both in methodology and the development of the subjects, timing of the contents, organization or communication channels. Following this line, the Academic, agreed on a plan of continuous improvement based on the feedback provided by the graduate surveys. A specific survey was carried out to gather their specific experience of the course in order to be able to modify the general strategy of the master's degree at the teaching and organisational level. The objectives were to adapt the teaching methodology to facilitate a more reflexive, participative and autonomous learning with a high degree of involvement and motivation of the students, to improve the academic results in terms of learning and satisfaction, to simplify and improve the logistic management of the course, etc. Thus, the survey included questions relating to the usefulness of the master's degree, methodology, organisation and planning of teaching, as well as a final question relating to the overall satisfaction of the course. A short survey was chosen with only 10 questions that the student rated from 1 to 5 on a scale from "strongly disagree" to "strongly agree". From the analysis of the responses, some important weaknesses were detected, such as the lack of content developed in video format, and the slowness of feedback on the results obtained in the proposed tasks. Based on these results, it was proposed an improvement plan that included the incorporation of videos to teaching materials, flexibility in the deadlines for activities, and the periodic monitoring of student learning and concerns through "Adobe Connect".Perales, E.; Micó-Vicent, B.; Viqueira, V.; Huraibat, K.; Martínez-Verdú, FM. (2019). Strategies for continuous improvement in the master's degree in "Colour Technology for the automotive sector" based on feedback from graduates. En INNODOCT/18. International Conference on Innovation, Documentation and Education. Editorial Universitat Politècnica de València. 165-174. https://doi.org/10.4995/INN2018.2018.8846OCS16517