Search results for "VISION"
showing 10 items of 5066 documents
Angiocardiographic digital still images compressed via irreversible methods: concepts and experiments.
1997
Abstract We defined, implemented and tested two new methods for irreversible compression of angiocardiographic still images: brightness error limitation (BEL) and pseudo-gradient adaptive brightness and contrast error limitation (PABCEL). The scan path used to compress the digital images is based on the Peano–Hilbert plane-filling curve. The compression methods limit, for each pixel, the brightness errors introduced when approximating the original image (i.e. the difference between the values of corresponding pixels as grey levels). Additional limitations are imposed to the contrast error observed when considering along the scan path consecutive pixels of both the original and the reconstru…
Corresponding-pair procedure: a new approach to simulation of dichromatic color perception.
2004
The dichromatic color appearance of a chromatic stimulus T can be described if a stimulus S is found that verifies that a normal observer experiences the same sensation viewing S as a dichromat viewing T. If dichromatic and normal versions of the same color vision model are available, S can be computed by applying the inverse of the normal model to the descriptors of T obtained with the dichromatic model. We give analytical form to this algorithm, which we call the corresponding-pair procedure. The analytical form highlights the requisites that a color vision model must verify for this procedure to be used. To show the capabilities of the method, we apply the algorithm to different color vi…
Lit environments quality: A software for the analysis of luminance maps obtained with the HDR imaging technique
2013
Abstract Energy performance of lighting systems has assumed a significant role in the assessment of buildings’ consumptions and consequently lighting design is aimed to reduce installed power but at the same time to achieve an excellent lighting quality both for visual and health purposes. Lighting design is nowadays essentially based on illuminance values on visual tasks and surrounding areas, but today designers’ and researchers’ interest is focused on the analysis of luminance maps obtained through video luminance meters or with numeric simulation tools. Luminance maps availability focus the attention on a more accurate study of the light reaching the eyes (luminance), rather than on the…
Brightness and contrast do not affect visually induced motion sickness in a passively-flown fixed-base flight simulator
2016
Abstract Background Visually Induced Motion Sickness (VIMS) or simulator sickness is often elicited by a visual stimulus that lacks the appropriate vestibular or proprioceptive feedback. In this study, we chose to investigate the effects of brightness and contrast of the visual scene on VIMS. Hypothesis We hypothesized that visual environments differing in brightness or contrast would differentially induce VIMS. The symptoms of VIMS should be most severe for the combination of high brightness and high contrast and conversely lowest for the low brightness and low contrast condition. Methods 33 healthy subjects were tested in a fixed-base flight simulator. Each subject flew in four consecutiv…
Personalized multimedia touristic services for hybrid broadcast/broadband mobile receivers
2010
This paper presents the topology of a multimedia tourism service that targets mobile devices equipped with broadband and either multicast or broadcast access capabilities. Multicast / Broadcast access is used to handle the delivery of multimedia data to many simultaneous users in the service area. The solution adopted is based on existing standards for mobile TV services, but introducing features that enable the provision of generic multimedia services on top of mobile hybrid broadband and broadcast networks. Furthermore, this paper shows how to use standardized interfaces originally defined for interactive mobile TV broadcasting to build personalized mobile multimedia services that do not …
Trends in Prevalence of Blindness and Distance and Near Vision Impairment Over 30 Years and Contribution to the Global Burden of Disease in 2020
2020
Background: The Vision Loss Expert Group and Global Burden of Disease Study have extensively updated estimates of global vision loss burden in 2020, temporal changeover 3 decades and forecasts for 2050. Methods: A systematic review and meta-analysis was conducted of population-based datasets relevant to vision impairment (VI) from January 1980 to October 2018. Hierarchical models were fitted to estimate 2020 prevalence (with 95% uncertainty intervals, UI) of (1) mild VI (presenting visual acuity [PVA] 6/12). Findings: In 2020, an estimated 43.2 million (95% UI: 37.5-48.2 million; 55% female) people were blind, 295.3 (95% UI 267.0-325.5) million had MSVI, 257.3 (95% UI 232.2-284.7) million h…
A Geometric Algorithm for Ray/Bézier Surfaces Intersection Using Quasi-Interpolating Control Net
2008
In this paper, we present a new geometric algorithm to compute the intersection between a ray and a rectangular Bezier patch. The novelty of our approach resides in the use of bounds of the difference between a Bezier patch and its quasi-interpolating control net. The quasi-interpolating polygon of a Bezier surface of arbitrary degree approximates the limit surface within a precision that is function of the second order difference of the control points, which allows for very simple projections and 2D intersection tests to determine sub-patches containing a potential intersection. Our algorithm is simple, because it only determines a 2D parametric interval containing the solution, and effici…
Surface Reconstruction Based on a Descriptive Approach
2000
The design of complex surfaces is generally hard to achieve. A natural method consists in the subdivision of the global surface into basic surface elements. The different elements are independently designed and then assembled together to represent the final surface. This method requires a classification and a formal description of the basic elements. This chapter presents a general framework for surface description, based on a constructive tree approach. In this tree the leaves are surface primitives and the nodes are constructive operators.
Cover Feature: Palladium‐Catalyzed Electrophilic C–H‐Bond Fluorination: Mechanistic Overview and Supporting Evidence (Eur. J. Org. Chem. 2‐3/2019)
2018
A Fuzzy Logic C-Means Clustering Algorithm to Enhance Microcalcifications Clusters in Digital Mammograms
2011
The detection of microcalcifications is a hard task, since they are quite small and often poorly contrasted against the background of images. The Computer Aided Detection (CAD) systems could be very useful for breast cancer control. In this paper, we report a method to enhance microcalcifications cluster in digital mammograms. A Fuzzy Logic clustering algorithm with a set of features is used for clustering microcalcifications. The method described was tested on simulated clusters of microcalcifications, so that the location of the cluster within the breast and the exact number of microcalcifications is known.