Image quality of a mobile display under different illuminations

This study constructed the image quality models for a small mobile display under different ambient illumination levels using Group Method and Data Handling (GMDH) and described the relationship between perceived image quality and physical measurements. 33 college students took part in this experiment and were asked to evaluate the image quality under 1500 lux (typical indoor office illumination) and 7000 lux (simulated outdoor environment) in Stage One and Stage Two, respectively. In each stage, the participants had to evaluate 21 images. 17 sets of the data as a training set were used to build the model and four sets of the data as a testing set were used to verify the model. The results indicated that the effects of luminance, contrast, correlated color temperature (CCT), and resolution were significant on perceived image quality under 1500 lux. However, color temperature was not a significant physical characteristic, and an interaction between luminance and contrast was found below 7000 lux. From the results of the experiment, it is considered that the outdoor environment (7000 lux) is not suitable for using mobile displays. Finally, once a valid image quality model is built, the subjective image quality can be established when the measurements of significant physical characteristics are provided. The results of subjective ratings can also be provided for mobile display manufacturers to improve the product quality so that their products can meet customers' requirements.     

Eye movement control during scene viewing: Immediate degradation and enhancement effects of spatial frequency filtering

What controls how long the eyes remain fixated during scene perception? We investigated whether fixation durations are under the immediate control of the quality of the current scene image. Subjects freely viewed photographs of scenes in preparation for a later memory test while their eye movements were recorded. Using the saccade-contingent display change method, scenes were degraded (Experiment 1) or enhanced (Experiment 2) via blurring (low-pass filtering) during predefined saccades. Results showed that fixation durations immediately after a display change were influenced by the degree of blur, with a monotonic relationship between degree of blur and fixation duration. The results also demonstrated that fixation durations can be both increased and decreased by changes in the degree of blur. The results suggest that fixation durations in scene viewing are influenced by the ease of processing of the image currently in view. The results are consistent with models of saccade generation in scenes in which moment-to-moment difficulty in visual and cognitive processing modulates fixation durations.     

Visible Speech as a Function of Image Quality: Effects of Display Parameters on Lipreading Ability

Two experiments are reported that examine effects of certain visual display parameters on subjects' ability to lipread numbers. The quality of the image of the speaker's face is altered by varying temporal resolution (frame rate), spatial resolution (number of pixels) and contrast resolution (number of grey scale levels). In Experiment 1, combinations of these variables are examined in a repeated measures design and reliable effects of reducing both frame rate and number of grey levels are evident. In Experiment 2, the frame rate and grey scale settings are factorially combined on a between-subjects basis, and practice is given so that subjects can adapt to the display conditions to which they are exposed. Effects of frame rate and grey scale are again statistically significant, and additive. Lipreading performance improves over the short duration of the experiment, but both image variables continue to affect performance. The effect size of the grey scale factor decreases with practice, but not that of frame rate. The results are discussed with regard to the kinds of relevant visual cues that may be affected by image degradation. Implications for the planned development of low cost digital communication are also considered. Trading off one image variable at the expense of another may be necessary to meet bandwidth limitations, and data such as those presented will be necessary to decide on a combination of parameter values to satisfy human performance and technical criteria.     

Stereoscopic visual displays: Principles,viewing devices,alignment procedures

The principle of binocular (stereoscopic) depth perception is that the visual system interprets the slight differences between the views seen by the two eyes as depth cues. In computer-generated displays, two slightly different images are produced on the left and right halves of the display surface and viewed by a prism, mirror, or binoculars system that delivers the appropriate image to each eye. The prism system is the simplest, the mirror system gives the best optical quality, and the binoculars system is useful for producing large apparent images from small display surfaces. All three systems can be adapted for group viewing and all require careful alignment (null adjustment of accommodative distance and vergence distance). Objective and subjective methods of alignment are described.     

A multichannel PC tachistoscope with high resolution and fast display change capability

The number of channels that PC tachistoscopes can have has increased recently (Bokhorst, 1995; Myors, 1998); however, neither the quality of display nor speed of image switching has been improved. This article shows the capability of VESA’s VBE 3.0 standard (1998) for increasing the number of channels of high-quality images. And the refresh rate can be set to the fastest cathode ray tube (CRT) scanning rate the monitor can tolerate in order to reduce the timing delay of changing display. A PCTSCOPE library was written in C to provide these capabilities, which is compatible with conventional DOS real mode. The PC tachistoscope can have numbers of channels with various resolutions and colors and different refresh rates. For example, 25 images with the resolution of 640 × 480 pixels and 256 colors can be loaded to video memory, and vertical refresh rate can be set to 180 Hz. It takes less than 6 msec to change the display among 25 channels in synchronizing with the start of the video scanning frame. In this library, the number of channels, the resolution of the images, and the speed of changing display all are improved. The multichannel PC tachistoscope with this technique is especially suitable for research requiring high-quality images and rapid successive presentation of stimuli.     

Facial Wipes don't Wash: Facial Image Comparison by Video Superimposition Reduces the Accuracy of Face Matching Decisions

In cases of disputed CCTV identification, expert testimony based on the results of analysis by facial image comparison may be presented to the Jury. However, many of the techniques lack empirical data to support their use. Using a within‐participants design, we compared the accuracy of face‐matching decisions when images were presented using a ‘facial wipe’ technique (where one image is superimposed on another and the display gradually ‘wipes’ between the two) with decisions based on static images. Experiment 1 used high‐quality image pairs; Experiment 2 used disguised target images; and Experiment 3 used degraded target images. Across all three experiments, rather than optimising performance, facial wipes reduced accuracy relative to static presentations. Further, there is evidence that video wipes increase false positives and therefore may increase the likelihood that images of two different people will be incorrectly judged to show the same individual.Copyright © 2016 John Wiley & Sons, Ltd.     

Axiomatic Quantum Theory

The basis of a rigorous formal axiomatization of quantum mechanics is constructed, built upon Dirac's bra–ket notation. The system is three-sorted, with separate variables for scalars, vectors and operators. First-order quantification over all three types of variable is permitted. Economy in the axioms is effected by, e.g., assigning a single logical function * to transform (i) a scalar into its complex conjugate, (ii) a ket vector into a bra and a bra into a ket, (iii) an operator into its adjoint. The system is accompanied by a formal semantics. Further papers will deal with vector subspaces and projection operators, operators with continuous spectra, tensor products, observables, and quantum mechanical probabilities.     

The relationship between self-reported vividness and latency during mental size scaling of everyday items: phenomenological evidence of different types of imagery

We examined how the relationship between ratings of vividness (or image strength) and image latency might reflect the concerted action of two visual imagery pathways hypothesized by Kosslyn (1994): the ventral pathway, processing object properties, and the dorsal pathway, processing locative properties of mental images. Participants formed their images at small or large angular display sizes, varying the amount of size scaling needed. In Experiment 1, display size varied between participants, and images were trial unique. The higher the vividness, the faster the generation of small images (requiring size scaling of less than 10 degrees), which would recruit mainly the ventral pathway. This vivid-is-fast relationship changed for large images (requiring size scaling of 10 degrees or more), which would recruit mainly the dorsal pathway. The size-dependent alteration of the vivid-is-fast relationship was replicated in the first block of Experiment 2. However, when repeated over 3 consecutive blocks, image generation sped up, and gradually the vivid-is-fast relationship tended to occur for all display sizes until complete automatization of image generation occurred. The findings suggest that differential patterns of vividness-latency relationship can reflect the types of images involved, their relative ventral and dorsal contributions, and the involvement of working memory.     

A set of high quality colour images with Spanish norms for seven relevant psycholinguistic variables: the Nombela naming test

This paper presents a new corpus of 140 high quality colour images belonging to 14 subcategories and covering a range of naming difficulty. One hundred and six Spanish speakers named the items and provided data for several psycholinguistic variables: age of acquisition, familiarity, manipulability, name agreement, typicality and visual complexity. Furthermore, we also present lexical frequency data derived internet search hits. Apart from the large number of variables evaluated, these stimuli present an important advantage with respect to other comparable image corpora in so far as naming performance in healthy individuals is less prone to ceiling effect problems. Reliability and validity indexes showed that our items display similar psycholinguistic characteristics to those of other corpora. In sum, this set of ecologically valid stimuli provides a useful tool for scientists engaged in cognitive and neuroscience-based research.     

Visual preferences for sex and status in female rhesus macaques

Most primates are both highly visual and highly social. These qualities predict that visual cues to social variables, such as identity, sex, social status, and reproductive quality, would be intrinsically valuable and systematically attract attention. Supporting this idea, thirsty male rhesus macaques (Macaca mulatta) will forego fluid reward to view images of the faces of high-ranking males and the sexual skin of females. Whether female rhesus macaques, who experience dramatically different social pressures and reproductive costs than male macaques, also systematically and spontaneously value visual cues to social information remains untested experimentally. We probed the preferences of female rhesus macaques, given the opportunity to display an image from a known class of social stimuli or touch a second target to display a blank screen. We found that females preferred faces of high-status males and also images of the perinea of both males and females, but were not motivated to display images of subordinate males or control stimuli. These findings endorse the view that both male and female rhesus macaques—and presumably other highly social primates—seek information about other individuals in a way that matches the adaptive value of that information for guiding social behavior.     

A set of high quality colour images with Spanish norms for seven relevant psycholinguistic variables: The Nombela naming test

ABSTRACT

This paper presents a new corpus of 140 high quality colour images belonging to 14 subcategories and covering a range of naming difficulty. One hundred and six Spanish speakers named the items and provided data for several psycholinguistic variables: age of acquisition, familiarity, manipulability, name agreement, typicality and visual complexity. Furthermore, we also present lexical frequency data derived internet search hits. Apart from the large number of variables evaluated, these stimuli present an important advantage with respect to other comparable image corpora in so far as naming performance in healthy individuals is less prone to ceiling effect problems. Reliability and validity indexes showed that our items display similar psycholinguistic characteristics to those of other corpora. In sum, this set of ecologically valid stimuli provides a useful tool for scientists engaged in cognitive and neuroscience-based research.     

Social Context Effects in the Display of Emotion: Accountability in a Simulated Organization1

Emotional labor involves employees' displays of appropriate emotions done to comply with emotional display rules created to attain organizational goals. This study examined whether display rules operationalized as process accountability (being held accountable for the quality of emotional displays during social interactions) and as outcome accountability (being held responsible for producing desired outcomes in others) would affect participants' emotional labor. In a simulated job interview, process accountability increased emotional labor; this occurred only in the absence of outcome accountability. The findings imply that display rules that encourage attention to sustaining quality interactions are likely to be more successful in achieving organizational goals than are rules that focus directly on producing predetermined outcomes.     

Mental imagery and the third dimension

What sort of medium underlies imagery for three-dimensional scenes? In the present investigation, the time subjects took to scan between objects in a mental image was used to infer the sorts of geometric information that images preserve. Subjects studied an open box in which five objects were suspended, and learned to imagine this display with their eyes closed. In the first experiment, subjects scanned by tracking an imaginary point moving in a straight line between the imagined objects. Scanning times increased linearly with increasing distance between objects in three dimensions. Therefore metric 3-D information must be preserved in images, and images cannot simply be 2-D "snapshots." In a second experiment, subjects scanned across the image by "sighting" objects through an imaginary rifle sight. Here scanning times were found to increase linearly with the two-dimensional separations between objects as they appeared from the original viewing angle. Therefore metric 2-D distance information in the original perspective view must be preserved in images, and images cannot simply be 3-D "scale-models" that are assessed from any and all directions at once. In a third experiment, subjects mentally rotated the display 90 degrees and scanned between objects as they appeared in this new perspective view by tracking an imaginary rifle signt, as before. Scanning times increased linearly with the two-dimensional separations between objects as they would appear from the new relative viewing perspective. Therefore images can display metric 2-D distance information in a perspective view never actually experiences, so mental images cannot simply be "snapshot plus scale model" pairs. These results can be explained by a model in which the three-dimensional structure of objects is encoded in long-term memory in 3-D object-centered coordinate systems. When these objects are imagined, this information is then mapped onto a single 2-D "surface display" in which the perspective properties specific to a given viewing angle can be depicted. In a set of perceptual control experiments, subjects scanned a visible display by (a) simply moving their eyes from one object to another, (b) sweeping an imaginary rifle sight over the display, or (c) tracking an imaginary point moving from one object to another. Eye-movement times varied linearly with 2-D interobject distance, as did time to scan with an imaginary rifle sight; time to tract a point varied independently with the 3-D and 2-D interobject distances. These results are compared with the analogous image scanning results to argue that imagery and perception share some representational structures but that mental image scanning is a process distinct from eye movements or eye-movement commands.     

The limits of visual resolution in natural scene viewing

We examined the limits of visual resolution in natural scene viewing, using a gaze-contingent multiresolutional display having a gaze-centred area-of-interest and decreasing resolution with eccentricity. Twelve participants viewed high-resolution scenes in which gaze-contingent multiresolutional versions occasionally appeared for single fixations. Both detection of image degradation (five filtering levels plus a no-area-of-interest control) in the gaze-contingent multiresolutional display, and eye fixation durations, were well predicted by a model of eccentricity-dependent contrast sensitivity. The results also illuminate the time course of detecting image filtering. Detection did not occur for fixations below 100 ms, and reached asymptote for fixations above 200 ms. Detectable filtering lengthened fixation durations by 160 ms, and interference from an imminent manual response occurred by 400-450 ms, often lengthening the next fixation. We provide an estimate of the limits of visual resolution in natural scene viewing useful for theories of scene perception, and help bridge the literature on spatial vision and eye movement control.     

Luminance gradient can break background-independent lightness constancy

A display with a luminance gradient was shown to induce a strong lightness illusion (Logvinenko, 1999 Perception 28 803-816). However, a 3-D cardboard model of this display was found to produce a much weaker illusion (less than half that in the pictorial version) despite the fact that its retinal image is practically the same. This is in line with the hypothesis that simultaneous lightness contrast is solely a phenomenon of pictorial perception (Logvinenko et al, 2002 Perception 31 73-82). The residual lightness illusion in the 3-D model can be accounted for by the fact that this model is a hybrid display. Specifically, while it is a real object, a pictorial representation (of the illumination gradient) is superimposed on it. Thus, lightness in the 3-D display is a compromise between two opposite tendencies: the background-independent lightness constancy and the lightness illusory shift induced by the luminance gradient.     

Effect of stationary objects on illusory forward self-motion induced by a looming display

It has previously been shown that when a moving and a stationary display are superimposed, illusory self-rotation (circular vection) is induced only when the moving display appears as the background. Three experiments are reported on the extent to which illusory forward self-motion (forward vection) induced by a looming display is inhibited by a superimposed stationary display as a function of the size and location of the stationary display and of the depth between the stationary and looming displays. Results showed that forward vection was controlled by the display that was perceived as the background, and background stationary displays suppressed forward vection by about the same amount whatever their size and eccentricity. Also, the perception of foreground-background properties of competing displays determined which controlled forward vection, and this control was not tied to specific depth cues. The inhibitory effect of a stationary background on forward vection was, however, weaker than that found with circular vection. This difference makes sense because, for forward body motion, the image of a distant scene is virtually stationary whereas, when the body rotates, it is not.     

A new approach to the generation of visual stimuli for eye-movement research

An interactive, computer-controlled, visual stimulus generator is described, suitable for both psychophysical and neurophysiological experimentation on human subjects. The system core is a wide-screen electrostatic cathode-ray tube, which can be used both as a television monitor, to display standard video pictures, and as anx-y oscilloscope, so that a bright dot can be moved around the display by electrical signals. In addition, a third working mode is provided, according to which a time-compressed video picture of limited size (fast picture) plays the role that is typical of the spot in a standard oscilloscope. Through computer-assisted time compression, the frame period of the video signal is reduced to about one tenth of its standard value. The fast picture can accordingly be driven by even the fastest eye movements, and it can be displayed as a stabilized image, or, more generally, in the altered retinal feedback condition. Moreover, as compared with a standard video picture, the fast image can be “flashed” over much shorter time periods. Since a standard input video signal is used for both standard and fast video pictures, all the image processing facilities of commercial videographic systems can be fully exploited by the proposed device.     

Seeing with the skin

A system for converting an optical image into a tactile display has been evaluated to see what promise it has as a visual substitution system. After surprisingly little training, Ss are able to recognize common objects and to describe their arrangement in three-dimensional space. When given control of the sensing and imaging device, a television camera, Ss quickly achieve external subjective localization of the percepts. Limitations of the system thus far appear to be more a function of display resolution than limitations of the skin as a receptor surface. The acquisition of skill with the device has been remarkably similar for blind and sighted Ss.