Raster Display Research Articles

Annals of Neurology: Volume 83, Number 2, February 2018

A raster display of repeated motor cortical evoked potentials with single pulses of deep brain stimulation in the globus pallidus, pars interna in a patient with cervical dystonia. Each line represents a single trial, with stimulation beginning at the left margin, and the length of each line equivalent to 50 msec of recording. Dark blue = 0 mV, lighter blue‐green colors = negative voltage, purple‐red colors = positive voltage. Note that the evoked potential is negative at about 10 msec, positive at about 25 msec, and then near zero again at 50 msec. See Ni et al., pp 352–362, this issue. Ann Neurol 2018;83:1–1

Bidirectional raster scanning to increase time for vector writing in avionics see‐through displays

AbstractSee‐through displays (STD) like head‐up displays (HUD) play major role in providing aircraft data to pilot through a visual interface. The data is displayed in form of symbology in pilot's line of sight using vector scanning technique and is deciphered to get flight and mission information. Contrast ratio required to see against bright sunlight at high altitudes is given only by luminance of cathode ray tube (CRT). Therefore, CRT is still used as display source in avionic HUDs, although other devices are also being explored for these applications. Aircraft's night mode operation requires raster display of external scene information along with vector data display due to low visibility during night. It reduces time available for writing vector data during night mode resulting in reduced symbology. Conventionally used raster scanning methods are unidirectional scanning methods. Bidirectional raster scanning (BRS) is an unconventional approach which scans display screen from both directions. In present work, an algorithm for BRS has been developed in VHDL providing more time for vector writing by increasing vertical retrace period (VRP) of raster scanning. Functional verification of design has been performed by simulations carried out through test‐bench and VRP is increased to 5.8304 ms from conventional 1.2800 ms per field.

Low‐voltage activated Kv1.1 subunits are crucial for the processing of sound source location in the lateral superior olive in mice

Voltage-gated potassium (Kv) channels containing Kv1.1 subunits are strongly expressed in neurons that fire temporally precise action potentials (APs). In the auditory system, AP timing is used to localize sound sources by integrating interaural differences in time (ITD) and intensity (IID) using sound arriving at both cochleae. In mammals, the first nucleus to encode IIDs is the lateral superior olive (LSO), which integrates excitation from the ipsilateral ventral cochlear nucleus and contralateral inhibition mediated via the medial nucleus of the trapezoid body. Previously we reported that neurons in this pathway show reduced firing rates, longer latencies and increased jitter in Kv1.1 knockout (Kcna1−/−) mice. Here, we investigate whether these differences have direct impact on IID processing by LSO neurons. Single-unit recordings were made from LSO neurons of wild-type (Kcna1+/+) and from Kcna1−/− mice. IID functions were measured to evaluate genotype-specific changes in integrating excitatory and inhibitory inputs. In Kcna1+/+ mice, IID sensitivity ranged from +27 dB (excitatory ear more intense) to −20 dB (inhibitory ear more intense), thus covering the physiologically relevant range of IIDs. However, the distribution of IID functions in Kcna1−/− mice was skewed towards positive IIDs, favouring ipsilateral sound positions. Our computational model revealed that the reduced performance of IID encoding in the LSO of Kcna1−/− mice is mainly caused by a decrease in temporal fidelity along the inhibitory pathway. These results imply a fundamental role for Kv1.1 in temporal integration of excitation and inhibition during sound source localization.

Motor Cortex Gates Vibrissal Responses in a Thalamocortical Projection Pathway

Higher-order thalamic nuclei receive input from both the cerebral cortex and prethalamic sensory pathways. However, at rest these nuclei appear silent due to inhibitory input from extrathalamic regions, and it has therefore remained unclear how sensory gating of these nuclei takes place. In the rodent, the ventral division of the zona incerta (ZIv) serves as a relay station within the paralemniscal thalamocortical projection pathway for whisker-driven motor activity. Most, perhaps all, ZIv neurons are GABAergic, and recent studies have shown that these cells participate in a feedforward inhibitory circuit that blocks sensory transmission in the thalamus. The present study provides evidence that the stimulation of the vibrissa motor cortex suppresses vibrissal responses in ZIv via an intra-incertal GABAergic circuit. These results provide support for the proposal that sensory transmission operates via a top-down disinhibitory mechanism that is contingent on motor activity.

Designing Graphics Programming Interfaces for Mobile Devices

Mobile devices have evolved to a point where interactive 3D graphics is becoming feasible. The first standardized 3D programming interfaces for mobile devices - OpenGL ES for native C/C++ and Mobile 3D Graphics (M3G) for Java applications - are now available to hardware vendors and application developers. The interfaces complement rather than compete with each other and can share the same underlying rendering engine, whether implemented in hardware or software. Three-dimensional graphics on mobile devices is still about converting descriptions of geometry, material, and illumination into pixels shown on a raster display, using the same fundamental algorithms as elsewhere. However, mobile devices' limited capabilities must be reflected in the realizations of those algorithms, as well as in the overall graphics system design. In this article, we describe a design that attempts to take on that challenge, consisting of OpenGL ES, a low-level API, and M3G (also known as JSR-184), a high-level API for Java. We describe how the two interfaces relate to each other and existing graphics architectures on the desktop, and how they attempt to provide optimal features and performance across the whole gamut of different devices. OpenGL ES and M3G, as well as our presentation of them in this article, derive from a long tradition of graphics systems design.

휴대장치용 새로운 자기 스프링 액추에이터의 해석

SLA(Scanned Linear Array) is a portable display unit for implementing next-generation virtual realities, utilizes a design that light generated by a line of LEDs is reflected from the rapidly oscillating mirror to generate a raster display. Reaction forces generated by the motions of the mirror and counter-balance mass cancel each other at the device base, reducing vibration. Metal leaf springs have been extensively applied in such portable units. Magnetic springs have been developed and adopted that can replace the metal spring and can avoid many disadvantages of metal springs. We model and analyze the dynamics of the structure with magnetic springs and present the simulation and experimental analysis results, which can be utilized for identifying and eliminating possible problem sources in removing shaking forces and moments, and oscillating the mirror at the required amplitude and frequency. Finally, we present the improved novel magnetic actuator model which can be applied in portable display units.br/

Slow Oscillation in Non-Lemniscal Auditory Thalamus

In the present study, we investigated the oscillatory behavior of the auditory thalamic neurons through in vivo intracellular and extracellular recordings in anesthetized guinea pigs. Repeated acoustic stimulus and cortical electrical stimulation were applied to examine their modulatory effects on the thalamic oscillation. The time course of the spike frequency over each trial was obtained by summing all spikes in the onset period and/or the last time period of 100 or 200 msec in the raster display. Spectral analysis was made on the time course of the spike frequency. A slow-frequency oscillation ranging from 0.03 to 0.25 Hz (mean +/- SD, 0.11 +/- 0.05 Hz) was found in the medial geniculate body (MGB) together with a second rhythm of 5-10 Hz. The oscillation neurons had a mean auditory response latency of 17.3 +/- 0.3 msec, which was significantly longer than that of the non-oscillation neurons in lemniscal MGB (9.0 +/- 1.5 msec, p < 0.001, ANOVA) and similar to the non-oscillation neurons in the non-lemniscal MGB (17.6 +/- 5.4 msec, p = 0.811). They were located in the non-lemniscal nuclei of the auditory thalamus. Cortical stimulation altered the thalamic oscillation, leading to termination of the oscillation or to acceleration of the rhythm of the oscillation (the average rhythm changed from 0.07 +/- 0.03 to 0.11 +/- 0.04 Hz, n = 8, p = 0.066, t test). Acoustic stimulation triggered a more regular rhythm in the oscillation neurons. The present results suggest that only the non-lemniscal auditory thalamus is involved in the slow thalamocortical oscillation. The auditory cortex may control the oscillation of the auditory thalamic neurons.

Image Processing Algorithms and the Digital Image Path

The digital image path encompasses a multiplicity of functions such as scanning, importing, printing, copying, and faxing of images. As such, a variety of computations is required to transform such diverse inputs to a form suitable for output on a raster display or printer. These computations frequently involve colorimetric and spatial image processing algorithms such as color calibration, color transformation, segmentation, compression, filtering, halftoning, rasterization, etc. This talk examines a number of representative pathways through the digital image processing pipe and elaborates on some of the more typical algorithms involved.

An artefact desynchroniser for use with visual evoked potential stimulators.

When recording visual evoked potentials elicited by a CRT raster display, driven from a frame-synchronised stimulus generator, artefacts caused by magnetic fields originating from the CRT field coils may seriously contaminate the recordings. This interference cannot be removed by signal averaging as it is time locked to the frame rate of the CRT. The circuit described here effectively desynchronises the interference, enabling the signal averaging process to reduce the artefact without the bandwidth restriction and resultant distortion of the recording which would be caused by lowpass filtering.

Requirements for Hud Raster Image Modulation in Daylight

Head-up displays (HUDs) represent the leading candidate display technology for inclusion in an enhanced or synthetic vision system (EVS or SVS) for commercial transport aircraft. One common EVS concept assumes the raster display of raw or processed sensor (radar or IR) data. However, experience with the use of raster rather than stroke display modes has been largely limited to the presentation of images captured by IR sensitive and image-intensified cameras during night flying conditions when the luminance of the forward scene over which the image will be superimposed is much lower than in daytime. The objective of this work is to generate a specification for minimum HUD raster image modulation assuming real-world luminance values typically found in low-visibility, daylight flight. Six Honeywell pilots rated the image quality and utility of flight video as presented through a military-style HUD in a transport cockpit mockup. Flight video came from daylight FLIR and daylight CCD cameras. The luminance of the forward scene against which the HUD image was superimposed was varied among nine levels ranging from 5 fL to 10,000 fL. The results indicate that HUD raster luminance must be approximately 50% external scene luminance to promote good pilot awareness of general terrain. To maintain good utility and visibility of standard, high-contrast runway markings, runway center line, and runway edges, HUD raster luminance must be approximately 15% of the forward scene luminance.

Use of a computer-controlled raster display for rapid screening of colour vision

Use of a computer-controlled raster display for rapid screening of colour vision

Gaze-directed volume rendering

We direct our gaze at an object by rotating our eyes or head until the object's projection falls on the fovea, a small region of enhanced spatial acuity near the center of the retina. In this paper, we explore methods for encorporating gaze direction into rendering algorithms. This approach permits generation of images exhibiting continuously varying resolution, and allows these images to be displayed on conventional television monitors. Specifically, we describe a ray tracer for volume data in which the number of rays cast per unit area on the image plane and the number of samples drawn per unit length along each ray are functions of local retinal acuity. We also describe an implementation using 2D and 3D mip maps, an eye tracker, and the Pixel-Planes 5 massively parallel raster display system. Pending completion of Pixel-Planes 5 in the spring of 1990, we have written a simulator on a Stellar graphics supercomputer. Preliminary results indicate that while users are aware of the variable-resolution structure of the image, the high-resolution sweet spot follows their gaze well and promises to be useful in practice.

Scan line display of algebraic surfaces

A robust algorithm is presented for scan line display of algebraic surfaces of arbitrary degree and topology. The algorithm correctly displays singularities of any complexity, even those missed by ray tracing or polygonization, and (for surfaces of degree less than eight) offers a significant speed improvement over ray tracing. Antialiasing can generally be accomplished very quickly. In addition to its typical function of shaded raster display, the algorithm is particularly adept at quickly plotting silhouette and intersection curves. A practical use for the algorithm is to display boolean combinations of algebraic half spaces, including blend surfaces.A new polynomial basis is introduced, referred to as the Bernstein pyramid polynomial basis, which enhances numerical stability and which simplifies several computations such as scan planesurface intersection and silhouette detection.

Stereopsis in Cockpit Display — A Part-Task Test

The benefit of adding retinal disparity to color raster display was tested with two formats. Six pilots flew a tracking task and periodically responded to “failures” in the two represented systems, providing a total of 4320 trials. Response time and error frequency were both reduced when disparity augmented monocular cues to “real world” depth. Response time and error frequency were not affected when disparity was used to make an element of an otherwise flat display more noticeable.

An algorithm for visible-line and visible-surface display of CSG models

An algorithm is presented for display of Constructive Solid Geometry (CSG) models, in which Boolean evaluation of a model is done during image generation only for the visible parts of the model. The algorithm is based on Atherton's CSG scan-line algorithm. It involves, however, dividing the image plane into strips of varying width, inside which areas are determined where only one face is visible. This may involve subdivision of an area into smaller areas. Two versions of the algorithm are presented: an efficient visible-line version for a raster display, and a visible-surface version, which turns out to be an improved variant for simple models of Atherton's algorithm. Sample images and CPU times for some models are given to show the efficiency of the algorithm.

Image Composition via Lookup Table Manipulation

The Image Composition Language provides a convenient way for programmers of interactive graphics application programs to define how the video lookup table of a raster display system is to be loaded. ICL allows one or several images stored in the frame buffer to be combined or modified in a variety of ways. ICL treats these images as variables, and provides arithmetic, relational, and conditional operators to combine the images, scalar variables, and constants in such image composition expressions as old_image*t+new_image*(1.0-t) and ifimager>0.5thenimage - {0.5,0,0,} else image endif. Use of the Image Composition Language relieves programmers of the tedium usually associated with loading the video lookup table to do simple image composition and modification.

Individual Differences in Responses of Untrained Observers to Stroboscopic Apparent Motion

Two large groups of inexperienced subjects (n = 208 and n = 50) and a small group of experienced subjects (n = 5) were tested using time-till-breakdown as a measure of long-range apparent motion across a range of temporal frequencies. One group of inexperienced subjects was retested after one week and demonstrated quite stable patterns of response. Large intersubject variability was observed in terms of the amount of motion seen, with most inexperienced subjects reporting very little apparent motion. A raster display produced a peak frequency 1 Hz higher than a standard tachistoscope display. The role of experience was also examined with a small group of inexperienced subjects (n = 8) tested once daily over five consecutive days. There was high intersubject variability and intrasubject consistency, demonstrating little influence of learning and experience. The results are discussed in terms of current ideas on the breakdown effect.

Theoretical and methodological approaches to apparent movement of short-range process and pattern perception

A variable raster and vector display processor interfaced with a PDP-11/23 computer is briefly described. Several experiments using random-dot cinematograms (RDCs) (raster display) and line segments (vector display) are discussed. The experiments on cooperative processes of apparent movement of RDCs and spatial-frequency-filtered RDCs showed that the average cooperative neighborhood of neural interaction is about 15 min arc of visual angle. In pattern perception, based on Julesz’s texton theory (1981) and Shaw’s attention model (1980), this study showed that the aperture of attention in serial and parallel processing is a function of feature gradient, set size, and eccentricity.

A differential compiler for computer animation

A program for the real-time display of computer animation on a bit-mapped raster display is presented. The differential compiler performs temporal domain image data compression using frame replenishment coding on successive frames of animation stored in memory as bitmaps and saves only the differences. A small run-time interpreter then retrieves and displays the differences in real-time to create the animated effect. This results in a significant reduction in storage requirements, and allows animation on general purpose computers which would otherwise be too slow or have insufficient memory. Frame creation is both device and method independent. An animation environment supports interactive editing capabilities, reconstructing any arbitrary desired frame for later modification. Frames can be added, modified, or deleted, and the animated sequence can be viewed at any point during the session. The compiler is automatically called as needed; its operation is transparent to the user. The compiler is described in detail, both in terms of data compression and the requirements of interactive animation editing.

Raster versus calligraphic display devices for assessing visual performance: The influence of stimulus area and uncertainty

Sixty-hertz raster scan monitors provide relatively inexpensive solutions to problems associated with presenting complex visual stimuli. However, they restrict the user to displays in which stimulus characteristics cannot be changed more often than once every 16.67 msec. Calligraphic monitors allow very high frame rates, but not the generation of complex or chromatic images (unless very expensive monitors are purchased). A method is reported for increasing the frame rate of some raster monitors at the expense of the number of lines that are painted. Also, data relating to the influence of such a modification on visual performance is presented.