Prey capture and accommodation in the sandlance, Limnichthyes fasciatus (Creediidae; Teleostei)

The eyes of the sandlance, Limnichthyes fasciatus (Creediidae. Teleostei) move independently and possess a refractive cornea, a convexiclivate fovea and a non-spherical lens giving rise to a wide separation of the nodal point from the axis of rotation of the eye much like that of a chameleon. To investigate this apparent convergence of the visual optics in these phylogenetically disparate species, we examine feeding behaviour and accommodation in the sandlance with special reference to the possibility that sandlances use accommodation as a depth cue to judge strike length. Frame-by-frame analysis of over 2000 strikes show a 100% success rate. Explosive strikes are completed in 50 ms over prey distances of four body lengths. Close-up video confirms that successful strikes can be initiated monocularly (both normally and after monocular occlusion) showing that binocular cues are not necessary to judge the length of a strike. Additional means of judging prey distance may also be derived from parallax information generated by rotation of the eye as suggested for chameleons. Using photorefraction on anaesthetised sandlances, accommodative changes were induced with acetylcholine and found to range between 120 D and 180 D at a speed of 600-720 D s(-1). The large range of accommodation (25% of the total power) is also thought to be mediated by corneal accommodation where the contraction of a unique cornealis muscle acts to change the corneal curvatures.

The minimum number of measurements for colour, sparkle, and graininess characterisation in gonio-apparent panels

Materials with new visual appearances have emerged over the last few years. In the automotive industry in particular there is a growing interest in materials with new effect finishes, such as metallic, pearlescent, sparkle, and graininess effects. Typically, for solid colours the mean of three measurements with repetitions is sufficient to obtain a representative measurement for colour characterisation. However, gonio-apparent panels have non-homogeneous colours, and there are no studies that recommend the minimum number of repetitions for colour, sparkle, and graininess characterisation of this type of panel. We assume that colour panels incorporating special-effect pigments in their colour recipes will require a higher minimum number of measurements than solid colour panels. Therefore, the purpose of this study is to verify this assumption by using a multiangle BYK-mac spectrophotometer, given that it is currently the only commercial device that can measure colour, sparkle, and graininess values simultaneously. In addition, a possible methodology is given for establishing the minimum number of measurements when characterising gonio-apparent materials using a specific instrument, able to be implemented in future instruments when determining multiple appearance attributes (colour, gloss, sparkle, etc.) for many coloration technologies. Thus, we studied the minimum number of measurements needed to characterise the colour, sparkle, and graininess of three types of sample with solid, metallic, and pearlescent coatings respectively. Twenty measurements were made at twenty random positions (different target areas) of 90 samples. The minimum number of measurements for all these variables was determined on the basis of the point at which the cumulative mean value became constant. Thus, applying new statistical tools, it is clearly shown that metallic and pearlescent panels require more colour measurements than solid panels, in particular when geometries are being measured in a specular direction. As regards texture (sparkle and graininess), more measurements are needed for graininess than for sparkle, and more for metallic panels than for pearlescent panels.

Optics of the developing fish eye: comparisons of Matthiessen's ratio and the focal length of the lens in the black bream Acanthopagrus butcheri (Sparidae, Teleostei)

Matthiessen's ratio (distance from centre of lens to retina: lens radius) was measured in developing black bream, Acanthopagrus butcheri (Sparidae, Teleostei). The value decreased over the first 10 days post-hatch from 3.6 to 2.3 along the nasal and from four to 2.6 along temporal axis. Coincidentally, there was a decrease in the focal ratio of the lens (focal length:lens radius). Morphologically, the accommodatory retractor lentis muscle appeared to become functional between 10-12 days post-hatch. The results suggest that a higher focal ratio compensates for the relatively high Matthiessen's ratio brought about by constraints of small eye size during early development. Combined with differences in axial length, this provides a means for larval fish to focus images from different distances prior to the ability to accommodate. (C) 1999 Elsevier Science Ltd. All rights reserved.

Computational visual quality of digitally printed images

The problem of understanding how humans perceive the quality of a reproduced image is of interest to researchers of many fields related to vision science and engineering: optics and material physics, image processing (compression and transfer), printing and media technology, and psychology. A measure for visual quality cannot be defined without ambiguity because it is ultimately the subjective opinion of an “end-user” observing the product. The purpose of this thesis is to devise computational methods to estimate the overall visual quality of prints, i.e. a numerical value that combines all the relevant attributes of the perceived image quality. The problem is limited to consider the perceived quality of printed photographs from the viewpoint of a consumer, and moreover, the study focuses only on digital printing methods, such as inkjet and electrophotography. The main contributions of this thesis are two novel methods to estimate the overall visual quality of prints. In the first method, the quality is computed as a visible difference between the reproduced image and the original digital (reference) image, which is assumed to have an ideal quality. The second method utilises instrumental print quality measures, such as colour densities, measured from printed technical test fields, and connects the instrumental measures to the overall quality via subjective attributes, i.e. attributes that directly contribute to the perceived quality, using a Bayesian network. Both approaches were evaluated and verified with real data, and shown to predict well the subjective evaluation results.

A comunicação como barreira à inclusão de alunos com deficiência visual em aulas de mecânica

O presente artigo encontra-se inserido em um estudo que busca compreender as principais barreiras para a inclusão de alunos com deficiência visual no contexto do ensino de física. Focalizando aulas de mecânica, analisa as dificuldades comunicacionais entre licenciandos e discentes com deficiência visual. Para tal, enfatiza as estruturas empírica e semântico-sensorial das linguagens utilizadas, indicando fatores geradores de dificuldades de acessibilidade às informações veiculadas. Recomenda, ainda, alternativas que se destinam a dar condições à participação efetiva do discente com deficiência visual no processo comunicativo. Conclui afirmando que a comunicação representa a principal barreira à participação efetiva de alunos com deficiência visual em aulas de mecânica, e enfatiza a importância da criação de canais comunicacionais adequados como condição básica à inclusão desses alunos.

A comunicação como barreira à inclusão de alunos com deficiência visual em aulas de óptica

O presente artigo representa uma continuidade dos resultados apresentados em Camargo e Nardi (Revista Brasileira de Ensino de Física 29, 117 (2007)). Encontra-se inserido dentro de um estudo que busca compreender as principais barreiras para a inclusão de alunos com deficiência visual no contexto do ensino de física. Focalizando aulas de óptica, analisa as dificuldades comunicacionais entre licenciandos e discentes com deficiência visual. Para tal, enfatiza as estruturas empírica e semântico-sensorial das linguagens utilizadas, indicando fatores geradores de dificuldades de acessibilidade nas informações veiculadas. Recomenda, ainda, alternativas que visam dar condições à participação efetiva do discente com deficiência visual no processo comunicativo, das quais destacam-se: a identificação da estrutura semântico-sensorial dos significados veiculados, o conhecimento da história visual do aluno, a destituição da estrutura empírica audiovisual interdependente e a exploração das potencialidades comunicacionais das linguagens constituídas de estruturas empíricas de acesso visualmente independente. Conclui afirmando que a comunicação representa a principal barreira à participação efetiva de alunos com deficiência visual em aulas de óptica e enfatiza a importância da criação de canais comunicacionais adequados como condição básica à inclusão desses alunos.

O emprego de linguagens acessíveis para alunos com deficiência visual em aulas de Óptica

O presente artigo encontra-se inserido dentro de um estudo que busca compreender as principais alternativas para a inclusão de alunos com deficiência visual no contexto do ensino de física. Focalizando aulas de óptica, analisa as viabilidades comunicacionais entre licenciandos e discentes com deficiência visual. Para tal, enfatiza as estruturas empírica e semântico-sensorial das linguagens utilizadas, indicando fatores geradores de acessibilidade às informações veiculadas. Recomenda, ainda, alternativas que visam dar condições à participação efetiva do discente com deficiência visual no processo comunicativo, das quais se destacam: a identificação da estrutura semântico-sensorial dos significados veiculados, o conhecimento da história visual do aluno, a utilização de linguagens de estrutura empírica tátil-auditiva interdependente em contextos interativos, bem como, a exploração das potencialidades comunicacionais das linguagens constituídas de estruturas empíricas fundamental auditiva, e auditiva e visual independentes.

Dificuldades e alternativas encontradas por licenciandos para o planejamento de atividades de ensino de óptica para alunos com deficiência visual

Partial outcomes of a study aimed to verify future High School teachers performance during the development of a Teaching Practice undergraduate course. The student teachers were asked to plan, elaborate and teach, in a classroom situation, optics topics to a class which included visual handicapped pupils. Data analysis shows that the main difficulties found by the student physics' teachers are related to which approach will be used to perceive phenomena dependent on vision and also to the need to break away from traditional pedagogy.. On the other hand, as alternatives, future teachers have shown creativity in order to overcome passive aptitudes related to this educational problem, working out methodological strategies that do not require the knowing/seeing relation, as well as, emphasizing oral communication within the physics teaching context. Copyright by the Sociedade Brasileira de Física.

Influence of loupes and age on the near visual acuity of practicing dentists

We evaluated the near visual acuity of 40 dentists and its improvement by using different magnification devices. The acuity was tested with miniaturized E-optotype tests on a negatoscope under the following conditions: 1. natural visual acuity, 300 mm; 2. single lens loupe, 2×, 250 mm; 3. Galilean loupe, 2.5×, 380 mm; and 4. Keplerian loupe, 4.3×, 400 mm. In part 1, the influence of the magnification devices was investigated for all dentists. The Keplerian loupe obtained the highest visual acuity (4.64), followed by the Galilean loupe (2.43), the single lens loupe (1.42), and natural visual acuity (1.19). For part 2, the dentists were classified according to their age (visual acuity with all magnification devices (p<0.001). For part 3, the dentists were grouped according to their natural visual acuity. The group with the higher natural visual acuity achieved significantly higher visual acuity with all magnification devices than did the group of dentists with the lower natural visual acuity (p<0.01). It can be concluded that near visual acuity varies highly between individuals and decreases during the lifetime. Independent of age or natural vision, visual acuity can be significantly improved by using magnification devices.

Reading on LCD vs e-Ink displays: effects on fatigue and visual strain

Purpose:  Most recently light and mobile reading devices with high display resolutions have become popular and they may open new possibilities for reading applications in education, business and the private sector. The ability to adapt font size may also open new reading opportunities for people with impaired or low vision. Based on their display technology two major groups of reading devices can be distinguished. One type, predominantly found in dedicated e-book readers, uses electronic paper also known as e-Ink. Other devices, mostly multifunction tablet-PCs, are equipped with backlit LCD displays. While it has long been accepted that reading on electronic displays is slow and associated with visual fatigue, this new generation is explicitly promoted for reading. Since research has shown that, compared to reading on electronic displays, reading on paper is faster and requires fewer fixations per line, one would expect differential effects when comparing reading behaviour on e-Ink and LCD. In the present study we therefore compared experimentally how these two display types are suited for reading over an extended period of time. Methods:  Participants read for several hours on either e-Ink or LCD, and different measures of reading behaviour and visual strain were regularly recorded. These dependent measures included subjective (visual) fatigue, a letter search task, reading speed, oculomotor behaviour and the pupillary light reflex. Results:  Results suggested that reading on the two display types is very similar in terms of both subjective and objective measures. Conclusions:  It is not the technology itself, but rather the image quality that seems crucial for reading. Compared to the visual display units used in the previous few decades, these more recent electronic displays allow for good and comfortable reading, even for extended periods of time.

An approach to visual cortex operation: optical neuron model

Several works have been published in the last years concerning the modelling and implementation of the visual cortex operation. Most of them present simple neurons with just two different responses, namely inhibitory and excitatory. Some of the different types of visual cortex cells are simulated in these configurations.

Some relations between visual perception and non-linear photonic structures

The main objective of this work is to present a way to emulate some functions of the mammalian visual system and a model to analyze subjective sensations and visual illusions

Color uniformity in spotligths - visual perception and system design

La iluminación con diodos emisores de luz (LED) está reemplazando cada vez en mayor medida a las fuentes de luz tradicionales. La iluminación LED ofrece ventajas en eficiencia, consumo de energía, diseño, tamaño y calidad de la luz. Durante más de 50 años, los investigadores han estado trabajando en mejoras LED. Su principal relevancia para la iluminación está aumentando rápidamente. Esta tesis se centra en un campo de aplicación importante, como son los focos. Se utilizan para enfocar la luz en áreas definidas, en objetos sobresalientes en condiciones profesionales. Esta iluminación de alto rendimiento requiere una calidad de luz definida, que incluya temperaturas ajustables de color correlacionadas (CCT), de alto índice de reproducción cromática (CRI), altas eficiencias, y colores vivos y brillantes. En el paquete LED varios chips de diferentes colores (rojo, azul, fósforo convertido) se combinan para cumplir con la distribución de energía espectral con alto CRI. Para colimar la luz en los puntos concretos deseados con un ángulo de emisión determinado, se utilizan blancos sintonizables y diversos colores de luz y ópticas secundarias. La combinación de una fuente LED de varios colores con elementos ópticos puede causar falta de homogeneidad cromática en la distribución espacial y angular de la luz, que debe resolverse en el diseño óptico. Sin embargo, no hay necesidad de uniformidad perfecta en el punto de luz debido al umbral en la percepción visual del ojo humano. Por lo tanto, se requiere una descripción matemática del nivel de uniformidad del color con respecto a la percepción visual. Esta tesis está organizada en siete capítulos. Después de un capítulo inicial que presenta la motivación que ha guiado la investigación de esta tesis, en el capítulo 2 se presentan los fundamentos científicos de la uniformidad del color en luces concentradas, como son: el espacio de color aplicado CIELAB, la percepción visual del color, los fundamentos de diseño de focos respecto a los motores de luz y ópticas no formadoras de imágenes, y los últimos avances en la evaluación de la uniformidad del color en el campo de los focos. El capítulo 3 desarrolla diferentes métodos para la descripción matemática de la distribución espacial del color en un área definida, como son la diferencia de color máxima, la desviación media del color, el gradiente de la distribución espacial de color, así como la suavidad radial y axial. Cada función se refiere a los diferentes factores que influyen en la visión, los cuales necesitan un tratamiento distinto que el de los datos que se tendrán en cuenta, además de funciones de ponderación que pre- y post-procesan los datos simulados o medidos para la reducción del ruido, la luminancia de corte, la aplicación de la ponderación de luminancia, la función de sensibilidad de contraste, y la función de distribución acumulativa. En el capítulo 4, se obtiene la función de mérito Usl para la estimación de la uniformidad del color percibida en focos. Se basó en los resultados de dos conjuntos de experimentos con factor humano realizados para evaluar la percepción visual de los sujetos de los patrones de focos típicos. El primer experimento con factor humano dio lugar al orden de importancia percibida de los focos. El orden de rango percibido se utilizó para correlacionar las descripciones matemáticas de las funciones básicas y la función ponderada sobre la distribución espacial del color, que condujo a la función Usl. El segundo experimento con factor humano probó la percepción de los focos bajo condiciones ambientales diversas, con el objetivo de proporcionar una escala absoluta para Usl, para poder así sustituir la opinión subjetiva personal de los individuos por una función de mérito estandarizada. La validación de la función Usl se presenta en relación con el alcance de la aplicación y condiciones, así como las limitaciones y restricciones que se realizan en el capítulo 5. Se compararon los datos medidos y simulados de varios sistemas ópticos. Se discuten los campos de aplicación , así como validaciones y restricciones de la función. El capítulo 6 presenta el diseño del sistema de focos y su optimización. Una evaluación muestra el análisis de sistemas basados en el reflector y la lente TIR. Los sistemas ópticos simulados se comparan en la uniformidad del color Usl, sensibilidad a las sombras coloreadas, eficiencia e intensidad luminosa máxima. Se ha comprobado que no hay un sistema único que obtenga los mejores resultados en todas las categorías, y que una excelente uniformidad de color se pudo alcanzar por la conjunción de dos sistemas diferentes. Finalmente, el capítulo 7 presenta el resumen de esta tesis y la perspectiva para investigar otros aspectos. ABSTRACT Illumination with light-emitting diodes (LED) is more and more replacing traditional light sources. They provide advantages in efficiency, energy consumption, design, size and light quality. For more than 50 years, researchers have been working on LED improvements. Their main relevance for illumination is rapidly increasing. This thesis is focused on one important field of application which are spotlights. They are used to focus light on defined areas, outstanding objects in professional conditions. This high performance illumination required a defined light quality including tunable correlated color temperatures (CCT), high color rendering index (CRI), high efficiencies and bright, vivid colors. Several differently colored chips (red, blue, phosphor converted) in the LED package are combined to meet spectral power distribution with high CRI, tunable white and several light colors and secondary optics are used to collimate the light into the desired narrow spots with defined angle of emission. The combination of multi-color LED source and optical elements may cause chromatic inhomogeneities in spatial and angular light distribution which needs to solved at the optical design. However, there is no need for perfect uniformity in the spot light due to threshold in visual perception of human eye. Therefore, a mathematical description of color uniformity level with regard to visual perception is required. This thesis is organized seven seven chapters. After an initial one presenting the motivation that has guided the research of this thesis, Chapter 2 introduces the scientific basics of color uniformity in spot lights including: the applied color space CIELAB, the visual color perception, the spotlight design fundamentals with regards to light engines and nonimaging optics, and the state of the art for the evaluation of color uniformity in the far field of spotlights. Chapter 3 develops different methods for mathematical description of spatial color distribution in a defined area, which are the maximum color difference, the average color deviation, the gradient of spatial color distribution as well as the radial and axial smoothness. Each function refers to different visual influencing factors, and they need different handling of data be taken into account, along with weighting functions which pre- and post-process the simulated or measured data for noise reduction, luminance cutoff, the implementation of luminance weighting, contrast sensitivity function, and cumulative distribution function. In chapter 4, the merit function Usl for the estimation of the perceived color uniformity in spotlights is derived. It was based on the results of two sets of human factor experiments performed to evaluate the visual perception of typical spotlight patterns by subjects. The first human factor experiment resulted in the perceived rank order of the spotlights. The perceived rank order was used to correlate the mathematical descriptions of basic functions and weighted function concerning the spatial color distribution, which lead to the Usl function. The second human factor experiment tested the perception of spotlights under varied environmental conditions, with to objective to provide an absolute scale for Usl, so the subjective personal opinion of individuals could be replaced by a standardized merit function. The validation of the Usl function is presented concerning the application range and conditions as well as limitations and restrictions in carried out in chapter 5. Measured and simulated data of various optical several systems were compared. Fields of applications are discussed as well as validations and restrictions of the function. Chapter 6 presents spotlight system design and their optimization. An evaluation shows the analysis of reflector-based and TIR lens systems. The simulated optical systems are compared in color uniformity Usl , sensitivity to colored shadows, efficiency, and peak luminous intensity. It has been found that no single system which performed best in all categories, and that excellent color uniformity could be reached by two different system assemblies. Finally, chapter 7 summarizes the conclusions of the present thesis and an outlook for further investigation topics.

Luz industrial e imagen tecnificada: de Moholy Nagy al C.A.V.S. (Center for Advanced Visual Studies)

El desarrollo de la tecnología de la luz implicará la transformación de la vida social, cultural y económica. Tanto las consideraciones espaciales del Movimiento Moderno, como los efectos producidos por la segunda Guerra Mundial, tendrán efectos visibles en las nuevas configuraciones espaciales y en la relación simbiótica y recíproca que se dará entre ideología y tecnología. La transformación en la comprensión de la articulación espacial, asociada al desarrollo tecnológico, afectará al modo en que este espacio es experimentado y percibido. El espacio expositivo y el espacio escénico se convertirán en laboratorio práctico donde desarrollar y hacer comprensible todo el potencial ilusorio de la luz, la proyección y la imagen, como parámetros modificadores y dinamizadores del espacio arquitectónico. Esta experimentación espacial estará precedida por la investigación y creación conceptual en el mundo plástico, donde los nuevos medios mecánicos serán responsables de la construcción de una nueva mirada moderna mediatizada por los elementos técnicos. La experimentación óptica, a través de la fotografía, el cine, o el movimiento de la luz y su percepción, vinculada a nuevos modos de representación y comunicación, se convertirá en elemento fundamental en la configuración espacial. Este ámbito de experimentación se hará patente en la Escuela de la Bauhaus, de la mano de Gropius, Schlemmer o Moholy Nagy entre otros; tanto en reflexiones teóricas como en el desarrollo de proyectos expositivos, arquitectónicos o teatrales, que evolucionarán en base a la tecnología y la modificación de la relación con el espectador. El espacio expositivo y el espacio escénico se tomarán como oportunidad de investigación espacial y de análisis de los modos de percepción, convirtiéndose en lugares de experimentación básicos para el aprendizaje. El teatro se postula como punto de encuentro entre el arte y la técnica, cobrando especial importancia la intersección con otras disciplinas en la definición espacial. Las múltiples innovaciones técnicas ligadas a los nuevos fundamentos teatrales en la modificación de la relación con la escena, que se producen a principios del siglo XX, tendrán como consecuencia la transformación del espacio en un espacio dinámico, tanto física como perceptivamente, que dará lugar a nuevas concepciones espaciales, muchas de ellas utópicas. La luz, la proyección y la creación de ilusión en base a estímulos visuales y sonoros, aparecen como elementos proyectuales efímeros e inmateriales, que tendrán una gran incidencia en el espacio y su modo de ser experimentado. La implicación de la tecnología en el arte conllevará modificaciones en la visualización, así como en la configuración espacial de los espacios destinados a esta. Destacaremos como propuesta el Teatro Total de Walter Gropius, en cuyo desarrollo se recogen de algún modo las experiencias espaciales y las investigaciones desarrolladas sobre la estructura formal de la percepción realizadas por Moholy Nagy, además de los conceptos acerca del espacio escénico desarrollados en el taller de Teatro de la Bauhaus por Oskar Schlemmer. En el Teatro Total, Gropius incorporará su propia visión de cuestiones que pertenecen a la tradición de la arquitectura teatral y las innovaciones conceptuales que estaban teniendo lugar desde finales del s.XIX, tales como la participación activa del público o la superación entre escena y auditorio, estableciendo en el proyecto una nueva relación perceptual entre sala, espectáculo y espectador; aumentando la sensación de inmersión, a través del uso de la física, la óptica, y la acústica, creando una energía concéntrica capaz de extenderse en todas direcciones. El Teatro Total será uno de los primeros ejemplos en los que desde el punto de partida del proyecto, se conjuga la imagen como elemento comunicativo con la configuración espacial. Las nuevas configuraciones escénicas tendrán como premisa de desarrollo la capacidad de transformación tanto perceptiva, como física. En la segunda mitad del s.XX, la creación de centros de investigación como el CAVS (The Center for Advanced Visual Studies,1967), o el EAT (Experiments in Art and Technology, 1966), favorecerán la colaboración interdisciplinar entre arte y ciencia, implicando a empresas de carácter tecnológico, como Siemens, HP, IBM o Philips, facilitando soporte técnico y económico para el desarrollo de nuevos sistemas. Esta colaboración interdisciplinar dará lugar a una serie de intervenciones espaciales que tendrán su mayor visibilidad en algunas Exposiciones Universales. El resultado será, en la mayoría de los casos, la creación de espacios de carácter inmersivo, donde se establecerá una relación simbiótica entre espacio, imagen, sonido, y espectador. La colocación del espectador en el centro de la escena y la disposición dinámica de imagen y sonido, crearán una particular narrativa espacial no lineal, concebida para la experiencia. Desde las primeras proyecciones de cine a la pantalla múltiple de los Eames, las técnicas espaciales de difusión del sonido en Stockhausen, o los experimentos con el movimiento físico interactivo, la imagen, la luz en movimiento y el sonido, quedan inevitablemente convertidos en material arquitectónico. ABSTRACT. Light technology development would lead to a social, cultural and economic transformation. Both spatial consideration of “Modern Movement” and Second World War effects on technology, would have a visible aftereffect on spatial configuration and on the symbiotic and mutual relationship between ideology & technology. Comprehension adjustment on the articulation of space together with technology development, would impact on how space is perceived and felt. Exhibition space and scenic space would turn into a laboratory where developing and making comprehensive all illusory potential of light, projection and image. These new parameters would modify and revitalize the architectonic space. as modifying and revitalizing parameters of architectonic space. Spatial experimentation would be preceded by conceptual creation and investigation on the sculptural field, where new mechanic media would be responsible for a fresh and modern look influenced by technical elements. Optical experimentation, through photography, cinema or light movement and its perception, would turn into essential components for spatial arrangement linked to new ways of performance and communication. This experimentation sphere would be clear at The Bauhaus School, by the hand of Gropius, Schlemmer or Moholy Nag among others; in theoretical, theatrical or architectural performance’s projects, that would evolve based on technology and also based on the transformation of the relationship with the observer. Exhibition and perfor-mance areas would be taken as opportunities of spatial investigation and for the analysis of the different ways of perception, thus becoming key places for learning. Theater is postulated as a meeting point between art and technique, taking on a new significance at its intersection with other disciplines working with spatial definition too. The multiple innovation techniques linked to the new foundations for the theater regarding stage relation, would have as a consequence the regeneration of the space. Space would turn dynamic, both physically and perceptibly, bringing innovative spatial conceptions, many of them unrealistic. Light, projection and illusory creation based on sound and visual stimulus would appear as intangible and momentary design components, which would have a great impact on the space and on the way it is experienced. Implication of technology in art would bring changes on the observer as well as on the spatial configuration of the art spaces2. It would stand out as a proposal Walter Groupis Total Theater, whose development would include somehow the spatial experiments and studies about formal structure of perception accomplished by Moholy Nagy besides the concepts regarding stage space enhanced at the Bauhaus Theater Studio by Oskar Schlemmer. Within Total Theater, Groupis would incorporate his own view about traditional theatric architecture and conceptual innovations that were taking place since the end of the nineteenth century, such as active audience participation or the diffusing limits between scene and audience, establishing a new perception relationship between auditorium, performance and audience, improving the feeling of immersion through the use of physics, optics and acoustics, creating a concentric energy capable of spreading in all directions. Total Theater would be one of the first example in which, from the beginning of the Project, image is combined as a communicating element with the spatial configuration. As a premise of development, new stage arrangement would have the capacity of transformation, both perceptive and physically. During the second half or the twentieth century, the creation of investigation centers such as CAVS (Center for Advanced Visual Studies, 1967) or EAT (Experiments in Art and Technology, 1966), would help to the interdisciplinary collaboration between art and science, involving technology companies like Siemens, HP, IBM or Philips, providing technical and economic support to the development of new systems. This interdisciplinary collaboration would give room to a series of spatial interventions which would have visibility in some Universal Exhibitions. The result would be, in most cases, the creation of immersive character spaces, where a symbiotic relationship would be stablished between space, image, sound and audience. The new location of the audience in the middle of the display, together with the dynamic arrangement of sound and image would create a particular, no lineal narrative conceived to be experienced. Since the first cinema projections, the multiple screen of Eames, the spatial techniques for sound dissemination at Stockhausen or the interactive physical movement experimentation, image, motion light and sound would turn inevitably into architectural material.

Retinal image quality assessment through a visual similarity index

Retinal image quality is commonly analyzed through parameters inherited from instrumental optics. These parameters are defined for ‘good optics’ so they are hard to translate into visual quality metrics. Instead of using point or artificial functions, we propose a quality index that takes into account properties of natural images. These images usually show strong local correlations that help to interpret the image. Our aim is to derive an objective index that quantifies the quality of vision by taking into account the local structure of the scene, instead of focusing on a particular aberration. As we show, this index highly correlates with visual acuity and allows inter-comparison of natural images around the retina. The usefulness of the index is proven through the analysis of real eyes before and after undergoing corneal surgery, which usually are hard to analyze with standard metrics.