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Handwritten words can never complement printed words because the former are mostly written in either skewed or slanted form or in both. This very nature of handwriting adds a huge overhead when converting word images into machine-editable format through an optical character recognition system. Therefore, slope and slant corrections are considered as the fundamental pre-processing tasks in handwritten word recognition. For solving this, researchers have followed a two-pass approach where the slope of the word is corrected first and then slant correction is carried out subsequently, thus making the system computationally expensive. To address this issue, we propose a novel one-pass method, based on fitting an oblique ellipse over the word images, to estimate both the slope and slant angles of the same. Furthermore, we have developed three databases considering word images of three popular scripts used in India, namely Bangla, Devanagari, and Roman, along with ground truth information. The experimental results revealed the effectiveness of the proposed method over some state-of-the-art methods used for the aforementioned problem.

The projected image of a textured surface contains multiple texture cues to three-dimensional (3D) surface orientation. Previous studies have reported conflicting findings about the roles of various texture cues. We tested the influence of texture compression relative to other texture cues using a cue conflict paradigm. Observers viewed images of textured planar surfaces with varied slants (0°–70°) and estimated 3D slant by aligning their hand with the virtual surface. Conflicts between texture cues were created by stretching or compression the texture along the surface, which selectively changes the slant specified by texture compression. The texture distortions were relatively small (±10% or ±20%) to limit the size of the cue conflicts. Across three experiments, we varied the field of view (10° vs. 20°), texture regularity (circles vs. Voronoi), and availability of binocular cues. In monocular conditions, slant estimates were strongly affected by texture distortions. Analyses of cue weighting found that texture compression had more influence on slant settings than other texture cues and the relative influence of texture compression decreased with larger field of view and less regular textures. In binocular conditions, we also observed effects of texture distortion, and the influence of texture compression relative to information from stereo and other texture cues increased with slant. Our results provide evidence that texture compression contributes to perceived slant, in addition to other texture cues such as texture scaling. The observed effects of simulated slant, field of view, and texture regularity on cue weighting were all consistent with a model that integrates multiple sources of information according to their reliability.

As a generalization of slant submanifolds and semi-slant submanifolds, we introduce the notions of pointwise slant submanifolds and pointwise semi-slant sunmanifolds of an almost contact metric manifold. We obtain a characterization at each notion, investigate the topological properties of pointwise slant submanifolds, and give some examples of them. We also consider some distributions on cosymplectic, Sasakian, Kenmotsu manifolds and deal with some properties of warped product pointwise semi-slant submanifolds. Finally, we give some inequalities for the squared norm of the second fundamental form in terms of a warping function and a semi-slant function for warped product submanifolds of cosymplectic, Sasakian, Kenmotsu manifolds., 35 pages

Creating three-dimensional (3D) representations of the world from two-dimensional retinal images is fundamental to many visual guided behaviors including reaching and grasping. A critical component of this process is determining the 3D orientation of objects. Previous studies have shown that neurons in the caudal intraparietal area (CIP) of the macaque monkey represent 3D planar surface orientation (i.e., slant and tilt). Here we compare the responses of neurons in areas V3A (which is implicated in 3D visual processing and which precedes CIP in the visual hierarchy) and CIP to 3D oriented planar surfaces. We then examine whether activity in these areas correlates with perception during a fine slant discrimination task in which monkeys report if the top of a surface is slanted towards or away from them. Although we find that V3A and CIP neurons show similar sensitivity to planar surface orientation, significant choice-related activity during the slant discrimination task is rare in V3A but prominent in CIP. These results implicate both V3A and CIP in the representation of 3D surface orientation, and suggest a functional dissociation between the areas based on slant-related decision signals.Significance StatementSurface orientation perception is fundamental to visually guided behaviors such as reaching, grasping, and navigation. Previous studies implicate the caudal intraparietal area (CIP) in the representation of 3D surface orientation. Here we show that responses to 3D oriented planar surfaces are similar in CIP and V3A, which precedes CIP in the cortical hierarchy. However, we also find a qualitative distinction between the two areas: only CIP neurons show robust choice-related activity during a fine visual orientation discrimination task.

The ability of human visual systems to estimate 3D surface orientation from 2D retinal images is critical. But the computation to calculate 3D orientation in real-world scenes is not fully understood. A Bayes optimal model grounded in natural statistics has explained 3D surface tilt estimation of human observers in natural scenes (Kim and Burge, 2018). However, the model is limited because it estimates only unsigned tilt (tilt modulo 180deg). We extend the model to predict signed tilt estimates and compared with human signed estimates. The model takes image pixels as input and produces optimal estimates of tilt as output, using the joint statistics of tilt and image cues in natural scenes. The image cues to tilt are the directions of luminance, texture, and disparity gradients in a local area on the image. To estimate signed tilt, the disparity cue is used as a signed tilt cue, and the luminance and texture cues are used as unsigned tilt cues. Given a particular set of local image cues, the model computes the minimum mean squared error (MMSE) estimate, which is equal to the posterior mean over signed tilt. We found that the signed MMSE estimates were well aligned with human signed tilt estimates on the identical set of stimuli. Next, we pooled the local MMSE estimates across the space to obtain a global tilt estimate. Given that local MMSE estimates are unbiased predictor of groundtruth tilt with nearly equal reliability, the global pooled estimates are also near-optimal. The global estimates even better explained human tilt estimation. We conclude that this computational model provides a tool to understand how human visual systems make the best use of 2D image information to compute local estimates and integrate a global estimate of 3D surface tilt in complex natural scenes using the local estimates.

Slant is the degree to which a surface recedes or slopes away from the observer about the horizontal axis. The perception of surface slant may be derived from static monocular cues, including linear perspective and foreshortening, applied to single shapes or to multi-element textures. It is still unclear the extent to which color vision can use these cues to determine slant in the absence of achromatic contrast. Although previous demonstrations have shown that some pictures and images may lose their depth when presented at isoluminance, this has not been tested systematically using stimuli within the spatio-temporal passband of color vision. Here we test whether the foreshortening cue from surface compression (change in the ratio of width to length) can induce slant perception for single shapes for both color and luminance vision. We use radial frequency patterns with narrowband spatio-temporal properties. In the first experiment, both a manual task (lever rotation) and a visual task (line rotation) are used as metrics to measure the perception of slant for achromatic, red–green isoluminant and S-cone isolating stimuli. In the second experiment, we measure slant discrimination thresholds as a function of depicted slant in a 2AFC paradigm and find similar thresholds for chromatic and achromatic stimuli. We conclude that both color and luminance vision can use the foreshortening of a single surface to perceive slant, with performances similar to those obtained using other strong cues for slant, such as texture. This has implications for the role of color in monocular 3D vision, and the cortical organization used in 3D object perception.

The main purpose of this article is to construct inequalities between a main intrinsic invariant (the normalized scalar curvature) and an extrinsic invariant (the Casorati curvature) for some submanifolds in a Sasakian manifold with a zero C-Bochner tensor.

Perceived three-dimensional shape can be systematically distorted by altering viewing conditions. Here we investigate whether such distortions are inconsistent or congruent among different surface properties (relative depth, orientation, and curvature). Participants matched two surfaces defined by different types of visual information (motion parallax, texture, or shading). Judgments of different surface properties elicited qualitatively different patterns of distortions. Adding multiple sources of information did not eliminate inconsistencies. This result indicates that 3D shape perception is not based on Euclidean representation. Moreover, models of cue integration that assume interpretation of information prior to fusion cannot account for such findings.

This paper provides a survey of the literature analyzing the political economy of news media. The survey discusses the effects of news media on political and public policy outcomes and the theory and evidence analyzing the distortions present in the market for news. I conclude by discussing some open research questions regarding the scope for public intervention in the market for news, and issues relative to the internet and new media.

In previous work [Meese et al. (1995). Vision Research, 35, 2879–2888)] we showed that one dimensional (1D) speed gradients are sufficient to produce a compelling impression of surface slant. Summing a 1D vertical shearing gradient or, less intuitively, a 1D horizontal shearing gradient with a random field of horizontally translating dots produces perceived slant about a horizontal axis. Similarly, a 1D vertical or horizontal compression gradient produces perceived slant about a vertical axis. Appropriately combining orthogonal 11) shears or compressions produces a purely deforming flow pattern. Here we asked whether both the vertical and horizontal components in such a stimulus contribute to perceived slant. Using a matching technique we found that for surfaces inclined about a vertical axis, this was indeed the case and that horizontal and vertical compression gradients contributed roughly equally to perceived slant. Similarly, for surfaces inclined about a horizontal axis, both vertical and horizontal shearing gradients contributed to the perceived slant, though here the horizontal gradient was given less weight than the vertical. We conclude that under appropriate conditions, the human visual system combines orthogonal speed gradients prior to the computation of slant from retinal flow.

When periodic stimuli, such as vertical sinewave gratings, are presented to the two eyes, the initial stage of disparity estimation yields multiple solutions stacked in at multiple depths. The solutions are all frontoparallel when the sinewaves have the same spatial frequency;. They are all slanted when the sinewaves have quite different frequencies. Despite the multiple solutions, humans perceive only one depth in each visual direction: a single frontoparallel plane when the frequencies are the same and a series of small slanted planes—Venetian blinds—when the frequencies are quite different. These percepts are consistent with a preference for solutions that minimize absolute disparity or that minimize overall slant. We conducted two psychophysical experiments to determine whether the preference is for minimum disparity or and for minimum slant are identical for gaze at zero eccentricity., We dissociated the predictions of the two by measuring the occurrence of Venetian blinds when the stimuli were viewed in eccentric gaze. The results were generally quite consistent with a zero-disparity preference (experiment 1), but we also observed a shift toward a zero-slant preference when the edges of the stimulus had zero slant (experiment 2). These observations provide useful insights into how the visual system constructs depth percepts from a multitude of possible depths.

Estimating three-dimensional (3D) surface orientation (slant and tilt) is an important first step toward estimating 3D shape. Here, we examine how three local image cues from the same location (disparity gradient, luminance gradient, and dominant texture orientation) should be combined to estimate 3D tilt in natural scenes. We collected a database of natural stereoscopic images with precisely co-registered range images that provide the ground-truth distance at each pixel location. We then analyzed the relationship between ground-truth tilt and image cue values. Our analysis is free of assumptions about the joint probability distributions and yields the Bayes optimal estimates of tilt, given the cue values. Rich results emerge: (a) typical tilt estimates are only moderately accurate and strongly influenced by the cardinal bias in the prior probability distribution; (b) when cue values are similar, or when slant is greater than 40°, estimates are substantially more accurate; (c) when luminance and texture cues agree, they often veto the disparity cue, and when they disagree, they have little effect; and (d) simplifying assumptions common in the cue combination literature is often justified for estimating tilt in natural scenes. The fact that tilt estimates are typically not very accurate is consistent with subjective impressions from viewing small patches of natural scene. The fact that estimates are substantially more accurate for a subset of image locations is also consistent with subjective impressions and with the hypothesis that perceived surface orientation, at more global scales, is achieved by interpolation or extrapolation from estimates at key locations.

We report on the ability of human observers to discriminate local second-order shape of quadratic stereo-defined surfaces. Local second-order shape can be specified by two parameters: the curvedness (a scale-dependent quantity describing overall curvature of a shape) and the shape index (a scale-independent quantity describing the shape's appearance). We measured shape index discrimination thresholds of shapes subject to attitude and curvedness transformations. Results show that neither slant nor curvedness manipulations affect or bias observers' judgements of surface shape. Furthermore, ideal detector simulations show that observers do not perform optimally: they do not exploit all available information.

Under the assumption of a general viewpoint, particular image properties, such as cotermination, straightness, and parallelism, can be used to infer, more or less reliably, the corresponding characteristics in the world. In this paper, the literature about these nonaccidental properties (NAPs) is reviewed to trace its historical roots, to list the properties that function as NAPs, and to discuss the psychological evidence for their detection and use. Against this background, four experiments are reviewed and four are fully described that were designed to test the perceptual use of skewed symmetry (SS), which results from orthographic projection of planar bilateral or mirror symmetry (BS). Despite the large symmetry advantage obtained in all experiments, ss is only perceived as BS-in-depth in cases of closed polygons or dot patterns with higher-order types of symmetry. In all random dot patterns and in some symmetric patterns with low "Gestalt", subjects relied on more local groupings which are qualitatively affine invariant, such as clusters based on proximity or curvilinearity. Based on previous approaches in the literature and these new findings, I suggest some distinctions between different ways of using NAPs, which might foster further research. ispartof: Canadian Journal of Psychology vol:46 issue:2 pages:236-279 ispartof: location:Canada status: published

Total electron content (TEC) measurements from ground stations to Global Positioning System (GPS) satellites provide a rich source of information about the Earth's ionosphere. These data comprise a significant part of the typical data set used by various data ingestion and assimilation models of the ionosphere. For example, the Utah State University (USU) Global Assimilation of Ionospheric Measurements (GAIM) data assimilation model uses slant TEC, along with various other types of data, to obtain a global reconstruction of the ionosphere. There are presently two different USU GAIM models: the Gauss‐Markov Kalman Filter (GAIM‐GM), which is operational at the NASA Community Coordinated Modeling Center and the Air Force Weather Agency; and the Full‐Physics Kalman Filter (GAIM‐FP), which is presently run for scientific studies. TEC is the integrated electron density along the path from the ground to the GPS satellites, which orbit at approximately 20,200 km. The GAIM‐FP modeled space ranges up to 30,000 km in altitude, so the entire TEC raypath is contained within the model space. Many ionosphere models do not model this entire region. For example, the GAIM‐GM extends up to an altitude of 1400 km. It is necessary to account for the portion of TEC that is not modeled by some means. There are basically two simple techniques that are in common use: (1) correct the measured TEC by using a model of the upper ionosphere and plasmasphere to subtract their contributions, or (2) ignore the effect and assign the full measured TEC to the ionosphere within the assimilation model space. We present the effect of assimilating TEC measurements into the GAIM‐GM using both the techniques mentioned above. It is found that derived quantities such as N m F 2 are significantly degraded by ignoring the upper ionospheric contribution to TEC. This degradation is seen at all local times. The effect is most pronounced at night, when the F region densities are small and the upper ionospheric contribution to TEC is relatively large.

We measure the performance of five subjects in a two-alternative-forced-choice slant-discrimination task for differently textured planes. As textures we used uniform lattices, randomly displaced lattices, circles (polka dots), Voronoi tessellations, plaids, 1/f noise, "coherent" noise and a leopard skin-like texture. Our results show: (1) Improving performance with larger slants for all textures, (2) and some cases of "non-symmetrical" performance around a particular orientation. (3) For orientations sufficiently slanted, the different textures do not elicit major differences in performance, (4) while for orientations closer to the vertical plane there are marked differences among them. (5) These differences allow a rank-order of textures to be formed according to their "helpfulness"--that is, how easy the discrimination task is when a particular texture is mapped on the plane. Polka dots tend to allow the best slant discrimination performance, noise patterns the worst. Two additional experiments were conducted to test the generality of the obtained rank-order. First, the tilt of the planes was rotated by 90 degrees. Second, the task was changed to a slant report task via probe adjustment. The results of both control experiments confirmed the texture rank-order previously obtained. We then test a number of spatial-frequency-based slant-from-texture models and discuss their shortcomings in explaining our rank-order. Finally, we comment on the importance of these results for depth-perception research in general, and in particular the implications our results have for studies of cue combination (sensor fusion) using texture as one of the cues involved. Afdeling Experimentele en kwantitatieve psychologie. Laboratorium voor Experimentele psychologie. ispartof: Vision research vol:44 issue:13 pages:1511-1535 ispartof: location:SCOTLAND, GLASGOW status: published

By presenting oriented Gabor patches either monocularly or binocularly, we dissociated retinal orientation from perceived tilt and perceived slant. After adapting to binocular patches, with zero apparent tilt and non-zero slant, small tilt after-effects (TAEs) and large slant after-effects (SAE) were measured. Adapting to monocular patches with non-zero tilt and zero slant produced large TAEs and smaller SAEs. This pattern of results suggests that a common, low-level adaptation to monocular orientation is involved in slant and tilt after-effects. However, the incomplete transfer between slant and tilt makes it clear that higher-level adaptation is also involved, perhaps at the level of surface representation.

Texture information about surface shape can be decomposed into three constituents: compression, density and scaling. Blake, Biilthoff and Sheinberg's (1993,Vision Research, 33, 1723–1737) Ideal Observer theory of slant from texture predicts that the relative contribution of compression and density to the percept of planar surface slant should vary with field of view (FOV). The contribution of compression and density should both increase as FOV increases but statistical analysis shows that the reliability, and hence the expected contribution, of density increases at a greater rate than compression with increasing FOV. Specific predictions are that at FOV 20 deg compression should be more effective than density, at FOV ≈ 20 deg, compression and density should be equally effective, and at FOV > 20 deg, compression should be less effective than density. These predictions were tested by pitting these components of texture against one another. The method used was similar to that described in Frisby and Buckley [1992 In Orban, G. Nagel H.-H. (Eds)Artificial and biological visual systems. Berlin: Springer]: observers judged binocularly the slant of a large table on to which was projected a texture created using computer graphics to contain various texture component cues to slant. The size of the projected texture patch determined the FOV which was by this means set to either 10, 20 or 30 deg. It was found that compression was the dominant cue irrespective of FOV, even if it was perturbed by noise. Possible reasons for this divergence of human observers from predictions of the Ideal Observer theory of slant from texture are discussed.

Three dimensional (3D) ion beam lithography (IBL) is used to directly pattern 3D photonic crystal (PhC) structures in crystalline titania. The process is maskless and direct write. The slanted pore 3D structures with pore diameters of 100 nm having aspect ratio of 8 were formed. It is shown that chemical enhancement of titania removal up to 5.2 times is possible in XeF2 gas for the closest nozzle-to-sample distance; the enhancement was ∼ 1.5 times for the actual 3D patterning due to a sample tilt. Tolerances of structural parameters and optimization of IBL processing required for the fabrication of PhCs with full photonic bandgap in visible spectral range in rutile are outlined. Application potential of 3D-IBL is discussed.