John W. Roberts

49.2: Rotating-Wheel Braille Display for Continuous Refreshable Braille

Refreshable Braille provides a critical path to display accessibility. High cost and reliability issues severely limit the market for existing Braille displays. A novel wheel-based design addresses reliability issues, and provides continuous Braille text with many-fold reduction in cost.

Display characteristics and the impact on usability for stereo

Over the past decade, the number of electronic display technologies available to consumers has risen dramatically, and the capabilities of existing technologies have been expanded. This proliferation of choices provides new opportunities for visual stereo presentation, but also new challenges. The methods of implementing stereo on an electronic display, optimized for the original capabilities of the original displays, may no longer be the best choices. Features such as response time, frame rate, aspect ratio, sync timing, pixel registration, and temporal modulation of grayscale and color can strongly influence the process of selecting an optimum presentation format for a given display technology. Display performance issues such as brightness, contrast, flicker, image distortion, defective pixels, and mura are more critical in 3D imagery than in 2D. Susceptibility to burn-in limits the implementation choices for a display that is to be used for both 3D and 2D applications. Resolution and frame rate establish the overall capability for representing depth, and also establish the performance requirements depth, and also establish the performance requirements for the engine providing the 3D material. This paper surveys the capabilities and characteristics of traditional displays such as CRT and LCD panel, and a broad assortment of newer display technologies, including color plasma, field emission, micromirror and other reflective systems, and the general classes of microdisplays. Relevance of display characteristics to various stereo presentation formats is discussed, with description of laboratory experimentation to provide hard numbers. Recommendations are made regarding the stereo formats to be used with various display technologies, and the display technologies to be used with various stereo formats.

Developing an interpretability scale for motion imagery

The motion imagery community would benefit from standard measures for assessing image interpretability. The National Imagery Interpretability Rating Scale (NIIRS) has served as a community standard for still imagery, but no comparable scale exists for motion imagery. Several considerations unique to motion imagery indicate that the standard methodology employed in the past for NIIRS development may not be applicable or, at a minimum, requires modifications. The dynamic nature of motion imagery introduces a number of factors that do not affect the perceived interpretability of still imagery—namely target motion and camera motion. We conducted a series of evaluations to understand and quantify the effects of critical factors. This paper presents key findings about the relationship of perceived interpretability to ground sample distance, target motion, camera motion, and frame rate. Based on these findings, we modified the scale development methodology and validated the approach. The methodology adapts the standard NIIRS development procedures to the softcopy exploitation environment and focuses on image interpretation tasks that target the dynamic nature of motion imagery. This paper describes the proposed methodology, presents the findings from a methodology assessment evaluation, and offers recommendations for the full development of a scale for motion imagery.

New technology enables many-fold reduction in the cost of refreshable Braille displays

By analysis of the primary cost factors for existing refreshable Braille displays, a team at NIST has pioneered a new technology that can reduce the cost of the electromechanical portions of a Braille display by an extremely large factor, and the overall cost of a Braille display by as much as a factor of ten. A massive cost reduction in displays creates a new model for the purchase and use of Braille displays by individuals, by employers, and by educators. Readability and user control issues are are addressed. It is hoped that this technology will open a significant new market for low cost, high performance refreshable Braille displays.

Factors affecting development of a motion imagery quality metric

The motion imagery community would benefit from the availability of standard measures for assessing image interpretability. The National Imagery Interpretability Rating Scale (NIIRS) has served as a community standard for still imagery, but no comparable scale exists for motion imagery. Several considerations unique to motion imagery indicate that the standard methodology employed in the past for NIIRS development may not be applicable or, at a minimum, require modifications. Traditional methods for NIIRS development rely on a close linkage between perceived image quality, as captured by specific image interpretation tasks, and the sensor parameters associated with image acquisition. The dynamic nature of motion imagery suggests that this type of linkage may not exist or may be modulated by other factors. An initial study was conducted to understand the effects target motion, camera motion, and scene complexity have on perceived image interpretability for motion imagery. This paper summarizes the findings from this evaluation. In addition, several issues emerged that require further investigation: - The effect of frame rate on the perceived interpretability of motion imagery - Interactions between color and target motion which could affect perceived interpretability - The relationships among resolution, viewing geometry, and image interpretability - The ability of an analyst to satisfy specific image exploitation tasks relative to different types of motion imagery clips Plans are being developed to address each of these issues through direct evaluations. This paper discusses each of these concerns, presents the plans for evaluations, and explores the implications for development of a motion imagery quality metric.

Methodology study for development of a motion imagery quality metric

The motion imagery community would benefit from the availability of standard measures for assessing image interpretability. The National Imagery Interpretability Rating Scale (NIIRS) has served as a community standard for still imagery, but no comparable scale exists for motion imagery. Several considerations unique to motion imagery indicate that the standard methodology employed in the past for NIIRS development may not be applicable or, at a minimum, requires modifications. The dynamic nature of motion imagery introduces a number of factors that do not affect the perceived interpretability of still imagery - namely target motion and camera motion. A set of studies sponsored by the National Geospatial-Intelligence Agency (NGA) have been conducted to understand and quantify the effects of critical factors. This study discusses the development and validation of a methodology that has been proposed for the development of a NIIRS-like scale for motion imagery. The methodology adapts the standard NIIRS development procedures to the softcopy exploitation environment and focuses on image interpretation tasks that target the dynamic nature of motion imagery. This paper describes the proposed methodology, presents the findings from a methodology assessment evaluation, and offers recommendations for the full development of a scale for motion imagery.

Measurements of static noise in display images

The appearance of noise on a display is an important usability issue. Sources of noise include electrical interference, display driver artifacts, resampling artifacts, transmission artifacts, compression artifacts, and any intrinsic noise artifacts produced within a display device. Issues for the severity of the noise problem include total magnitude of noise, noise spatial frequencies, proximity of the noise spatial frequencies of the desired information content and the human-eye response to that information content, uniformity of the distribution of noise, and appearance of any visible or regular patterns in the noise. Whatever the source, an accurate method to measure noise may be required to properly assess the influence of the noise. We investigate the intricacies of using a digital camera to accurately measure noise in a static image on a flat panel display (FPD). The electro- optical transfer function of the FPD is measured. A known noise pattern is displayed and measured using the digital camera whereby the predicted noise is compared to the measured noise. Complications and limitations in the metrology will be discussed.

Quantifying interpretability for motion imagery: Applications to image chain analysis

The motion imagery community will benefit from the availability of standard measures for assessing image interpretability. The national imagery interpretability rating scale (NIIRS) has served as a community standard for still imagery, but no comparable scale exists for motion imagery. We conducted a series of user evaluations to understand and quantify the effects of critical factors affecting the perceived interpretability of motion imagery. These evaluations provide the basis for relating perceived image interpretability to image parameters, including ground sample distance (GSD) and frame rate. The first section of this paper presents the key findings from these studies. The second portion is a new study applying these methods to quantifying information loss due to compression of motion imagery. We conducted an evaluation of several methods for video compression (JPEG2000, MPEG-2, and H.264) at various bitrates. A set of objective image quality metrics (structural similarity, peak SNR, an edge localization metric, and edge strength) were computed for the parent video clip and the various compressed products. In an evaluation, imagery analysts rated each clip relative to image interpretability tasks. The analysis quantifies the interpretability loss associated with the various compression methods and bitrates. We present the evaluation results and explore their relationship to the objective image quality metrics. The findings indicate the compression rates at which image interpretability declines significantly. These findings have implications for sensor system design, systems architecture, and mission planning.

Metrics to estimate image quality in compressed video sequences

A fundamental problem in image processing is finding objective metrics that parallel human perception of image quality. In this study, several metrics were examined to quantify compression algorithms in terms of perceived loss of image quality. In addition, we sought to describe the relationship of image quality as a function of bit rate. The compression schemes used were JPEG2000, MPEG2, and H.264. The frame size was fixed at 848x480 and the encoding varied from 6000 k bps to 200 k bps. The metrics examined were peak signal to noise ratio (PSNR), structural similarity (SSIM), edge localization metrics, and a blur metric. To varying degrees, the metrics displayed desirable properties, namely they were monotonic in the bit rate, the group of pictures (GOP) structure could be inferred, and they tended to agree with human perception of quality degradations. Additional work is being conducted to quantify the sensitivity of these measures with respect to our Motion Imagery Quality Scale.

Perceived interpretability of motion imagery: implications for scale development

The motion imagery community would benefit from the availability of standard measures for assessing image interpretability. The National Imagery Interpretability Rating Scale (NIIRS) has served as a community standard for still imagery, but no comparable scale exists for motion imagery. Previous studies have explored the factors affecting the perceived interpretability of motion imagery and the ability to perform various image exploitation tasks. More recently, a study demonstrated an approach for adapting the standard NIIRS development methodology to motion imagery. This paper presents the first step in implementing this methodology, namely the construction of the perceived interpretability continuum for motion imagery. We conducted an evaluation in which imagery analysts rated the interpretability of a large number of motion imagery clips. Analysis of these ratings indicates that analysts rate the imagery consistently, perceived interpretability is unidimensional, and that interpretability varies linearly with log(GSD). This paper presents the design of the evaluation, the analysis and findings, and implications for scale development.