0000000000014805
AUTHOR
ÁLvaro Pons
<em>El dibujado</em>: volver a la pared
The exhibition El dibujado by Paco Roca (IVAM, 2019) is an exploration of the paradigm shift brought forth by the abandonment of paper and reproducibility as a space for the dissemination of the comic strip. The exhibition hall of a museum (the Instituto Valenciano de Arte Moderno) becomes a space for formal and ephemeral experimentation at different levels, from the purely creative to the pondering about the unexplored possibilities of the language of the comic book. With this exhibition cartoonist Paco Roca poses a challenge to a spectator who is called to leave his/her role as a visitor and become the reader of an experience in which s/he becomes a part of the work’s own narrative. The a…
Effect of Color on Contrast Sensitivity with Two Different Accommodative Stimuli
We studied the influence of color and accommodation on the contrast sensitivity function (CSF). At the same time, we measured the effect of axial chromatic aberration (ACA) on the CSF. The CSF's of two observers were determined using red, green, blue, and white light, at 5- and 0.5-m viewing distances. At 5 m the CSF's were measured with natural vision and also with lenses which compensated the ACA. Results show that the effect of ACA on the CSF is to reduce the sensitivity to blue with respect to the red. The difference in sensitivity between these two colors is between 50 and 150% and varies with the frequency and the subject. When the ACA is compensated the influence of the color on the …
Micharmut: Más allá de la vanguardia
Micharmut: Más allá de la vanguardia
Influence of the luminance level on visual performance with a disposable soft cosmetic tinted contact lens.
The purpose of the present work was to study the effect on visual performance of wearing disposable soft tinted contact lenses for cosmetic purposes. Parameters such as contrast sensitivity (Vistech 6000), colour vision (Farnsworth-Munsell 100-Hue colour test), visual fields (static Goldmann perimetry) and subjective vision (what the wearer feels while wearing the lenses) were studied under different illumination levels in order to check for possible vision losses while wearing these contact lenses at low illumination levels. Sixteen emmetropic subjects were fitted consecutively with seven pairs of different colour lenses (Optima Colors lenses by BauschLomb), and the experimental parameters…
La industria del cómic en España: radiografía de ¿un mito o una realidad?
In spite of the importance of figures referred to published titles, or number of copies printed, which help to set publishing strategies and to really know the comic situation in Spain, there are no liable data. We are giving in this article, some enlightening data along with some explanations related to the evolution of the market from 2001 to 2009. The different titles are grouped considering the place they come from (Europe, Asia, United States…), along with their format (album, book, magazine, comic-book…). Using all this information, we can deduce evolution lines, tendencies, futures perspectives in an industry that, despite its precariousness, is facing an increasing number of copies …
Influence of the tear film on optical quality of the eye
The optical quality of the tear film of the eye was tested by measuring the retinal image before and after the break-up time (BUT). An objective method was used based on the evaluation of the retinal image of a point test projected onto the fovea. The loss of an entire tear film would result in a decrease in the optical quality because of corneal irregularities and the formation of an irregular tear lens after the BUT. Our results confirm the expected loss both of non-contact lens wearers and contact lens wearers. Also, the fact that the optical deterioration found after the BUT is greater for contact lens wearers confirms that soft contact lens wear produces a disruption of the tears.
Characterization of the human visual system threshold performance by a weighting function in the Gabor domain
Abstract As evidenced by many physiological and psychophysical reports, the receptive fields of the first-stage set of mechanisms of the visual process fit to two-dimensional (2D) compactly supported harmonic functions. The application of this set of band-pass filter functions to the input signal implies that the visual system carries out some kind of conjoint space/spatial frequency transform. Assuming that a conjoint transform is carried out, we present in this paper a new characterization of the visual system performance by means of a weighting function in the conjoint domain. We have called this weighting function (in the particular case of the Gabor transform) the Gabor stimuli Sensiti…
Contact lenses: do they really change the opticalperformance?
Abstract In this investigation the quality of two types of optical correction, hydrogel contact lenses and ophthalmic lenses, wascompared by measuring the modulation transferfunction (MTF) of the correcting lens plus visual optics system using an objective method. A merit function was defined in order to allow the direct comparison between the optical performance with the two corrections. A study on 10 subjects was undertaken, measuring the MTF of both corrections by using the double pass method. The results show that the optical quality of contact lenses was higher than that with ophthalmic lenses. The contrast sensitivity function (CSF) and visual acuity (VA) were determined as subjective…
Symptomatic accommodative and binocular dysfunctions from the use of flat-panel displays
AIM: To determine the presence of symptomatic accommodative and non-strabismic binocular dysfunctions (ANSBD) in a non-presbyopic population of video display unit (VDU) users with flat-panel displays. METHODS: One hundred and one VDU users, aged between 20 to 34y, initially participated in the study. This study excluded contact-lens wearers and subjects who had undergone refractive surgery or had any systemic or ocular disease. First, subjects were asked about the type and nature of eye symptoms they experienced during VDU use. Then, a thorough eye examination excluded those subjects with a significant uncorrected refractive error or other problem, such as ocular motility disorders, vertica…
Optical quality of the diabetic eye: a review
Diabetes mellitus is a metabolic disorder characterized by the presence of chronic hyperglycaemia. Several structural, morphological, and physiological changes in each of ocular component have been described in detail during the past decades. Due to these abnormalities, the diabetic patient undergoes a degradation of the retinal image by an increase of higher ocular aberrations and ocular scattering coming from mainly tear film, cornea, and crystalline lens. This review aims to provide an overview of current knowledge about the effects of diabetes mellitus in these optical phenomena and its consequence on the visual quality of the diabetic patient.
Human contrast sensitivity in coherent Maxwellian view: effect of coherent noise and comparison with speckle.
Lasers have been used in vision for measuring the neural contrast sensitivity function (CSF) by forming interference fringes on the retina. We distinguish among three kinds of illumination with lasers: incoherent (without noise), Maxwellian or coherent (with coherent noise), and diffuse coherent (with speckle). The three have different characteristics and different CSF's. A coherent imaging system is designed to measure the CSF with fully coherent illumination. This is the CSF of the whole visual system, although it is measured with gratings imaged on the retina. It therefore differs from the neural CSF's measured by other authors with partially coherent illumination. However, the neural CS…
Visual and ocular effects from the use of flat-panel displays
AIM: To evaluate the prevalence of eye symptoms in a non-presbyopic population of video display unit (VDU) users with flat-panel displays. METHODS: One hundred and sixteen VDU users with flat-panel display from an urban population participated in the study; their ages ranging from 20 to 34y. There were 60 females and 56 males. An eye examination to rule out the presence of significant uncorrected refractive errors, general binocular dysfunctions and eye conditions was carried out. In order to determine and quantify the type and nature of eye symptoms, participants were asked to answer written questionnaire and the results were grouped by gender, age and number of hours a day spent using a V…
Subjective image fidelity metric based on bit allocation of the human visual system in the DCT domain
Until now, subjective image distortion measures have partially used diverse empirical facts concerning human perception: non-linear perception of luminance, masking of the impairments by a highly textured surround, linear filtering by the threshold contrast frequency response of the visual system, and non-linear post-filtering amplitude corrections in the frequency domain. In this work, we develop a frequency and contrast dependent metric in the DCT domain using a fully non-linear and suprathreshold contrast perception model: the Information Allocation Function (IAF) of the visual system. It is derived from experimental data about frequency and contrast incremental thresholds and it is cons…
Refractive analysis of the human cornea through propagated fields
A new technique for analysing the optical quality of the human cornea is presented. Corneal maps are obtained through keratographies and then converted into phase maps. The propagated fields generated from this surface are plotted and studied. It is shown that any irregularity in the cornea affects the propagated field and the energy distribution at the focal plane. Simple applications are also indicated.
Influence of the gaze-stabilizing eye movements on the quality of the retinal image of the human eye
In this work we have studied the influence of the gaze stabilizing movements of the eye on the quality of the retinal image of the human eye obtained by double pass methods. The results obtained agree with the expected differences between the coherent and incoherent behaviour of the optical system of the eye. The movements-free retinal image is obtained from a typical retinal image by considering a filter function in the frequency domain which characterizes the effect of the considered movements.
Image quality metric based on multidimensional contrast perception models
Abstract The procedure to compute the subjective difference between two input images should be equivalent to a straightforward difference between their perceived versions, hence reliable subjective difference metrics must be founded on a proper perception model. For image distortion evaluation purposes, perception can be considered as a set of signal transforms that successively map the original image in the spatial domain into a feature and a response space. The properties of the spatial pattern analyzers involved in these transforms determine the geometry of these different signal representation domains. In this work the general relations between the sensitivity of the human visual system…
How Do Different Digital Displays Affect the Ocular Surface?
Digital display use has been accepted as a contributing factor to dry eye disease. Nowadays, plenty of new models of digital displays have been developed, and the differences in their nature and the ways in which they are set and used may contribute to differences in the eye-related problems they cause.This study aimed to analyze the differences in ocular surface, tear film, and visual fatigue parameters after reading on different digital displays, with and without initial instillation of artificial tears.Thirty-one healthy individuals ranging in age from 20 to 26 years (mean ± standard deviation, 21.26 ± 1.73 years) were included in this prospective clinical study. Subjects' ocular surface…
In vitro optical quality differences between multifocal apodized diffractive intraocular lenses.
Purpose To compare the in vitro optical quality of multifocal apodized intraocular lenses (IOLs) at different focal points. Setting University of Valencia, Valencia, Spain. Design Experimental study. Methods The Acrysof Restor +3.0 diopter (D) multifocal IOL with 2 main foci (bifocal IOL) and the Finevision multifocal IOL with 3 main foci (trifocal IOL) were evaluated. The optical quality was quantified using the modulation transfer function (MTF) at 7 focal points and for 3.0 mm and 4.5 mm apertures. The through-focus MTF at 10 focal points of the IOLs was also recorded. Results For the 0.0 D and −2.5 D focal points, the bifocal IOL showed the highest MTF values for pupil sizes as well as …
Determination of scattering in intraocular lenses by spectrophotometric measurements.
This study presents a method for measuring scattering in explanted intraocular lenses (IOLs). Currently, determining scattering in IOLs is usually performed by Scheimpflug cameras and the results are expressed in the units used by this apparatus. The method we propose uses a spectrophotometer and this makes it possible to measure the total transmission of the IOL by using an integrating sphere; the direct transmission is determined by the double-beam mode. The difference between these two transmissions gives a value of the scattering in percentage values of light lost. In addition, by obtaining the spectral transmission curve, information about the most scattered wavelengths is also obtaine…
EL RETO DE LA POESÍA GRÁFICA: ANÁLISIS DE LA OBRA DE BEGOÑA GARCÍA-ALÉN
La poesía gráfica se ha consolidado en los últimos años como uno de los campos de experimentación del cómic más activo y fructífero. La exploración de las posibilidades del cómic alejadas de la tradicional narratividad secuencial ha permitido entroncar la narración visual con la poesía concreta y caligramática, encontrando una relación cuya naturalidad y potencialidad resulta sorprendente (McHale, 2010). Aunque las primeras experiencias de la poesía gráfica pueden ser rastreadas en la obra de George Herriman y en la fundacional Poema en viñetas de Dino Buzzatti, en la última década se ha producido un desarrollo espectacular desde el espacio de libertad que representa la autoedición y el fan…
Influence of the luminance spatial non-homogeneities of a display monitor on the contrast sensitivity function determination
Abstract The application of computer devices equipped with video monitors both in clinical practice and human vision research has become widespread. These devices offer great advantages over other traditional methodologies (such as printed tests) because they facilitate the variation of the experimental parameters or the design of new psychophysical experiences. The aim of this paper is to determine the degree to which spatial inhomogeneity affects the generation of sinusoidal gratings on a video display. Knowing this degree of tolerance will enable us to determine the minimum demands that can be made on the graphic board and the video screens for their implementation in assessing contrast …
Influence of the type of illumination on the measurement of the modulation transfer function in the living human eye: A theoretical study
Abstract Applications such as refractive surgery demand an objective appraisal of the retinal image quality. The modulation transfer function (MTF) provides that information when measured directly. Moreover, the MTF obtained using a simple and objective method such as that described in this paper allows the neural contrast sensitivity function (CSF) to be obtained from the global CSF and the MTF. When calculating the MTF it must be borne in mind whether the applicable theory is coherent or incoherent. In the literature, the developed theory presents some approximations and incongruities. Also, it is interesting to note that the method of recording the MTF (short or long time of integration,…
La nueva escuela valenciana. Un ejemplo de renovación formal desde la tradición de la historieta
[ES] La conocida como “Nueva Escuela Valenciana” fue un movimiento historietístico de gran proyección en los años 80 que reunió a una serie de autores profundamente comprometidos con la renovación formal del medio sin dejar de lado el respeto a la tradición tebeística que había vivido el País Valenciano durante las décadas anteriores. Durante los años del boom de las revistas, esta generación representó como pocas las ansias de libertad creativas que tenían los autores españoles y su capacidad para transformación insurgente