We used a new method to measure the perceived quality of contrast-enhanced motion video. Patients with impaired vision �n=24 � and normally sighted subjects �n=6 � adjusted the level of MPEG-based enhancement of 8 videos (4 min each) drawn from 4 categories. They selected the level of enhancement that provided the preferred view of the videos, using a decreasing-step-size staircase procedure. Most patients made consistent selections of the preferred level of enhancement, indicating an appreciation of and a perceived benefit from the MPEG-based enhancement. The selections varied between patients and were correlated with letter contrast

ABSTRACT Traditional Thurstone scaling (1927) constructs a perceptual scale from pairwise comparisons without providing statistical inferences. We show that subjective preferences for moving video using pairwise comparisons can be analyzed to construct a perceptual scale and provide the statistical significance of preference differences. Two statistical methods (binary logistic regression and linear regression) are described. Data sets from two studies are used to demonstrate the perceptual scale construction from the traditional Thurstone method and from the described statistical methods. Both the studies showed videos on two side-by-side TVs. Four enhancement levels (Off, Low, Medium and High) were applied to the videos using a commercial device. Subjects made pairwise comparisons to indicate their preference of one video over another. The perceptual scales constructed from the three methods were comparable, except when there were cells missing from the preference matrix. Binary logistic regression easily permitted modeling of additional factors, such as side bias. Video quality can be systematically assessed using pairwise comparisons and statistical methods that permits construction of a perceptual scale and provide statistical significance for the compared levels.

We describe a technique to generate imagery with improved sharpness for individuals having refractive vision problems. Our method can reduce their dependence on corrective eyewear. It also benefits individuals with normal vision by improving visual acuity at a distance and of small details. Our approach does not require custom hardware. Instead, the calculated images can be shown on a standard computer display, on printed paper, or superimposed on a physical scene using a projector. Our technique uses a constrained total-variation method to produce a deconvolution result which upon observation appears sharp at the edges. We introduce a novel relative total variation term that enables controlling ringing reduction, contrast gain and sharpness. The end result is the ability to generate sharper appearing images, even for individuals with refractive vision problems including myopia, hyperopia, presbyopia, and astigmatism. Our approach has been validated in simulation, in camera-screen experiments, and in a study with human observers.

Image quality plays a key role in consumer purchasing decisions. In this study we manipulated image quality of videos using a consumer product that enhances digital video images in real time. Videos were presented on two HDTVs, enhanced by varying amounts and subjects made pairwise comparisons. Our results showed two distinct preference groups (“Sharp ” and “Smooth”) in our study subjects. Preferences for enhancement depended on the video content, particularly the presence or absence of a human face. 1.

Purpose. Exotropia in congenital homonymous hemianopia has been reported to provide field expansion that is more useful when accompanied with harmonious anomalous retinal correspondence (HARC). Torsional strabismus with HARC provides a similar functional advantage. In a subject with hemianopia demonstrating a field expansion consistent with torsion, we documented torsional strabismus and torsional HARC. Methods. Monocular visual fields under binocular fixation conditions were plotted using a custom dichoptic visual field perimeter. The dichoptic visual field was also modified to measure perceived visual directions under dissociated and associated conditions across the central 50 ° diameter field. The field expansion and retinal correspondence of a subject with torsional strabismus (along with exotropia and right hypertropia) with congenital homonymous hemianopia was compared with that of another exotropic subject with acquired homonymous hemianopia without torsion and to a control subject with minimal phoria. Torsional rotations of the eyes were calculated from fundus photographs and perimetry. Results. Torsional anomalous retinal correspondence documented in the subject with congenital homonymous hemianopia provided a functional binocular field expansion up to 18°. Normal retinal correspondence was mapped for the full 50 ° visual field in the control subject and for the seeing field of the acquired homonymous hemianopia subject, limiting the functional field expansion benefit.

Purpose. Volume scotomas are three-dimensional regions of space that are not visible to the observer. Volume perimetry maps volume scotomas. Volume scotomas predicted from combining monocular visual fields assume known fixation locus (mainly foveal). However, fixation loci are not always known, especially with central field loss (CFL). Here we demonstrate methods for measuring and calculating volume scotomas and discuss their practical implications. Methods. Three patients (bitemporal hemianopia, binasal scotoma, and CFL) were evaluated. Slices through the volume scotomas were measured at three distances: at the plane of fixation, at a plane anterior to fixation (representing anterior volume perimetry), and at a plane posterior to fixation (representing posterior volume perimetry). For anterior volume perimetry, patients fixated on a screen 100 cm away through a beamsplitter that reflected the perimetric stimulus (at 50 cm). For posterior volume perimetry, patients fixated on a near target (50 cm), while perimetric stimuli were presented on a screen 150 cm beyond fixation. At the plane of fixation, monocular visual fields under binocular viewing conditions were measured using a computerized dichoptic perimeter. Results. Posterior and anterior volume scotomas were documented in patients with bitemporal hemianopia and binasal scotomas, respectively. The CFL patient demonstrated both anterior and posterior volume scotomas. Scotoma magnitude was considered to determine its effect on visual function.