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At least 1,171 records · Page 65Linked to original sources
PubMed2003

Gaze-contingent multiresolutional displays: an integrative review.

Gaze-contingent multiresolutional displays (GCMRDs) center high-resolution information on the user's gaze position, matching the user's area of interest (AOI). Image resolution and details outside the AOI are reduced, lowering the requirements for processing resources and transmission bandwidth in demanding display and imaging applications. This review provides a general framework within which GCMRD research can be integrated, evaluated, and guided. GCMRDs (or "moving windows") are analyzed in terms of (a) the nature of their images (i.e., "multiresolution," "variable resolution," "space variant," or "level of detail"), and (b) the movement of the AOI (i.e., "gaze contingent," "foveated," or "eye slaved"). We also synthesize the known human factors research on GCMRDs and point out important questions for future research and development. Actual or potential applications of this research include flight, medical, and driving simulators; virtual reality; remote piloting and teleoperation; infrared and indirect vision; image transmission and retrieval; telemedicine; video teleconferencing; and artificial vision systems.

Data Display↗
PubMedDate not supplied

Vertical disparity pooling and the induced effect.

If the image received by one eye is vertically magnified by a small amount then an illusory tilt is perceived around the vertical axis through the fixation point. This is known as the induced effect and it can be explained by a recent computational theory of binocular vision which treats it as a side-effect of the use of vertical disparities to recover information about the distance to the fixation point and the angle of gaze. We have investigated the consequences of introducing vertical magnifications of some parts of a scene and not others and report here that there is a simple linear relationship between the size of the induced effect and the average vertical magnification. This suggests that a pooling strategy is adopted in the measurement of vertical disparities, a result which fits in well with expectations of the theory.

Computers↗
PubMedDate not supplied

Pediatric Vision Screener 2: pilot study in adults.

Amblyopia is a form of visual impairment caused by ocular misalignment (strabismus) or defocus in an otherwise healthy eye. If detected early, the condition can be fully treated, yet over half of all children with amblyopia under age 5 escape detection. We developed a Pediatric Vision Screener (PVS) to detect amblyopia risk factors. This instrument produces a binocularity score to indicate alignment and a focus score to indicate focus. The purpose of this study is to assess the performance of the PVS by testing adults who were fully cooperative for testing. The study group includes 40 subjects (20 controls, 20 patients) aged 22 to 79 years. 12 patients had constant strabismus (8 to 50Delta), and eight had variable strabismus (12 to 55Delta). All controls had binocularity scores >50%. Binocularity was <50% in 11/12 patients. The patient with binocularity >50% had a well-controlled intermittent exotropia and was not at risk for amblyopia. Focus scores were highly sensitive for good focus but not specific. The PVS shows high sensitivity and specificity for detection of strabismus in adults. Future studies will determine whether this performance can be achieved in preschool children, who are at greatest risk for vision loss.

Adult↗
PubMed1986

Computerized scoring and graphing of the Farnsworth-Munsell 100-hue color vision test.

The Farnsworth-Munsell 100-hue test is a sensitive and accurate test of color discrimination. A major disadvantage of the test is the laborious and time-consuming calculation needed to score the results and plot them on a chart for interpretation. We present a computer program, written in Microsoft's BASIC language, that performs the calculation and reports both the individual color cap error scores (from which the graph is plotted) and the total error score. If used with an IBM personal computer (or compatible) capable of graphics, the program plots a graph in a modified polar coordinate format that can be printed on a dot-matrix printer.

Color Perception↗
PubMed1998

A new computer program for mass screening of visual defects in preschool children.

AIMS: To test the effectiveness of a PC computer program for detecting vision disorders which could be used by non-trained personnel, and to determine the prevalence of visual impairment in a sample population of preschool children in the city of Beer-Sheba, Israel. METHODS: 292 preschool children, aged 4-6 years, were examined in the kindergarten setting, using the computer system and "gold standard" tests. Visual acuity and stereopsis were tested and compared using Snellen type symbol charts and random dot stereograms respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and kappa test were evaluated. A computer pseudo Worth four dot test was also performed but could not be compared with the standard Worth four dot test owing to the inability of many children to count. RESULTS: Agreement between computer and gold standard tests was 83% and 97.3% for visual acuity and stereopsis respectively. The sensitivity of the computer stereogram was only 50%, but it had a specificity of 98.9%, whereas the sensitivity and specificity of the visual acuity test were 81.5% and 83% respectively. The positive predictive value of both tests was about 63%. 27.7% of children tested had a visual acuity of 6/12 or less and stereopsis was absent in 28% using standard tests. Impairment of fusion was found in 5% of children using the computer pseudo Worth four dot test. CONCLUSIONS: The computer program was found to be stimulating, rapid, and easy to perform. The wide availability of computers in schools and at home allow it to be used as an additional screening tool by non-trained personnel, such as teachers and parents, but it is not a replacement for standard testing.

Child↗
PubMed1986

Formal connections between lightness algorithms.

The computational problem underlying color vision is to recover the invariant surface-spectral-reflectance properties of an object. Lightness algorithms, which recover an approximation to surface reflectance in independent wavelength channels, have been proposed as one method to compute color. This paper clarifies and formalizes the lightness problem by proposing a new formulation of the intensity equation on which lightness algorithms are based and by identifying and discussing two basic subproblems of lightness and color computation: spatial decomposition and spectral normalization of the intensity signal. Several lightness algorithms are reviewed, and a new extension (the multiple-scales algorithm) of one of them is proposed. The main computational result is that each of the lightness algorithms may be derived from a single mathematical formula, under different conditions, which, in turn, imply limitations for the implementation of lightness algorithms by man or machine. In particular, the algorithms share certain limitations on their implementation that follow from the physical constraints imposed on the statement of the problem and the boundary conditions applied in its solution.

Algorithms↗
PubMed2005

A vision-based surgical tool tracking approach for untethered surgery simulation and training.

This paper presents progress in the development of an untethered surgery simulation and training system. A surgical trainee interacts with the simulation in the most natural way possible-using standard, untethered surgical tools and hands. This natural interface requires innovations in tracking, haptic feedback, and visualization. This article describes the approach used for tool tracking with color cameras. A novel tracking algorithm is used to identify the type of tool, its position, and its orientation. Integration of the vision system with the tissue deformation and visualization modules is also discussed.

Algorithms↗
PubMed2003

[A case of giant frontal sinus osteoma].

Osteomas are the most frequent bone tumors of the facial bones, the most involving the frontal sinus and thus leading to symptoms of frontal sinusitis or associated complications. A twenty-one-year-old male patient presented with a growing swelling on the right side of the forehead. Examination revealed a slight facial asymmetry, a laterally shifted right orbital bulb, and disturbed vision. Cranial and orbital computed tomography showed a dense bony mass in the medial wall of the right orbit. The mass was excised totally following a bicoronal incision. The frontal and ethmoid sinuses were filled with fat tissue. Postoperatively, his vision improved to normal after two months and no complications or recurrences were detected in the sixth month.

Adult↗
PubMed2004

Virtual vision loss simulator.

Vision loss is common among people over the age of 65 and the condition is irreversible in most cases. Our simulator is a means to effectively and accurately inform people about the nature of common vision problems, initially limited to medically accurate simulations of cataract and macular degeneration. Using an eye tracker that continuously determines the subject's fixation point, a systematically degraded digital image displayed on an HMD can be a powerful educational tool. This article presents our Virtual Vision Loss (VVL) simulator and the developed simulation techniques based on calibration from 27 subjects.

Adult↗
PubMed2005

Biomimetic machine vision system.

Real-time application of digital imaging for use in machine vision systems has proven to be prohibitive when used within control systems that employ low-power single processors without compromising the scope of vision or resolution of captured images. Development of a real-time machine analog vision system is the focus of research taking place at the University of Wyoming. This new vision system is based upon the biological vision system of the common house fly. Development of a single sensor is accomplished, representing a single facet of the fly's eye. This new sensor is then incorporated into an array of sensors capable of detecting objects and tracking motion in 2-D space. This system "preprocesses" incoming image data resulting in minimal data processing to determine the location of a target object. Due to the nature of the sensors in the array, hyperacuity is achieved thereby eliminating resolutions issues found in digital vision systems. In this paper, we will discuss the biological traits of the fly eye and the specific traits that led to the development of this machine vision system. We will also discuss the process of developing an analog based sensor that mimics the characteristics of interest in the biological vision system. This paper will conclude with a discussion of how an array of these sensors can be applied toward solving real-world machine vision issues.

Algorithms↗
PubMed1997

[Stimulation parameters for automatic examination of color vision].

PURPOSE: We have developed a polyvalent computer controlled instrument, which uses the "two equation method" (Rayleigh and Moreland equations) to measure human colour vision. This "colorimeter" (or anomaloscope) was used to determine the influence of some important stimulation parameters. METHODS: The influence of stimulus exposure time, observation field size, absolute stimulus luminance, saturation and luminance mismatches between mixture and reference stimuli were measured on our computer controlled colorimeter. All subjects were normal observers. RESULTS: 1) An exposure time of 2s was found to be optimal for clinical work. 2) The Moreland equation on a 7 degrees observation field yields results in which population variability is comparable to a Rayleigh equation on a 2 degrees field. 3) A retinal illuminance between 40 and 1000 trolands can be used for automated Moreland matches. 4) The saturation of the reference field for the Moreland match can be preset to a fixed value. 5) It is important to vary automatically the radiance of the reference field to provide an approximate luminance match as the ratio of primaries in the mixture field is changed. CONCLUSION: These measurements allows us to determine optimal conditions for automated colour vision examinations and to make recommendations for an international standard.

Color Perception Tests↗
PubMed1993

Binocular vision in a virtual world: visual deficits following the wearing of a head-mounted display.

The short-term effects on binocular stability of wearing a conventional head-mounted display (HMD) to explore a virtual reality environment were examined. Twenty adult subjects (aged 19-29 years) wore a commercially available HMD for 10 min while cycling around a computer generated 3-D world. The twin screen presentations were set to suit the average interpupillary distance of our subject population, to mimic the conditions of public access virtual reality systems. Subjects were examined before and after exposure to the HMD and there were clear signs of induced binocular stress for a number of the subjects. The implications of introducing such HMDs into the workplace and entertainment environments are discussed.

Computer Simulation↗
PubMedDate not supplied

A review of computer-aided body surface area determination: SAGE II and EPRI's 3D Burn Vision.

Estimates of percent body surface area (%BSA) burns correlate well with fluid needs, nutritional requirements, and prognosis. Most burn centers rely on the Lund Browder chart and "rule of nines," to calculate the %BSA. Computer-based methods may improve precision and data analysis. We studied two new methods of determining %BSA: a two-dimensional Web-based program (Sage II) and a three-dimensional computer-aided design program (EPRI 3D Burn Vision). Members of our burn team found the Sage II program easy to use and found many of the features useful for patient care. The EPRI program has the advantage of 3D images and different body morphologies but required training to use. Computer-aided methods offer the potential for improved precision and data analysis of %BSA measurements.

Adult↗
PubMed2003

User-centered development of a Web-based preschool vision screening tool.

Although amblyopia is most successfully treated when detected in early childhood, many preschool-aged children are not being screened. This project explored the delivery of Web-based vision screenings, integrated with patient education, to parents and children, aged 3 to 6 years. Through a user-centered design methodology involving requirements gathering, iterative prototype development, and usability testing, a highly usable screening Website was created. Interviewing and testing parents and children in the home were essential in gathering accurate data about environments where the tool would actually be used. Frequent iterations of designing, testing, and modifying the tool were useful in identifying and correcting usability problems. Usability goals were set early in the project, and in the final phase a satisfaction questionnaire was administered to participants. Twenty-one out of 22 final usability objectives were achieved and the feasibility of Web-based vision screening was demonstrated.

Amblyopia↗