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A television image is formed by a series of parallel luminous lines called a raster. The visual prominence of the raster structure has been shown to interfere with the extraction of information from the image. However, the raster may be suppressed experimentally by a deflection process called spot wobble. Experiments were conducted to determine the effects of raster structure suppression on visual sine-wave contrast sensitivity thresholds, dynamic target acquisition performance using noise-free and noise-degraded imagery, and alphanumeric recognition performance using noisy and noise-free static displays. Results of the dynamic experiment indicate raster structure suppression and improvements in sine-wave threshold sensitivity are correlated and that a suppressed raster significantly improves target acquistion performance for noise-free conditions. Results of the static experiment were inconclusive, as no spot wobble effect was obtained, although display noise had a significant effect upon search time. Significant correlations with the modulation transfer functions area (MTFA) image quality metric were obtained, although the correlations were neither large nor consistent enough to be strongly advocated for detailed design evaluations.

This report contains the results of two experiments which investigated the effects of the quality of a televised image on eye movements and search-related dependent measures. The first experiment search task involved having subjects perform an air-to-ground search during a simulated flight. The quality of the image presented was varied by either passing, low-pass filtering, or attenuating the video signal and by adding electrical white noise to the video signal. The results of this experiment indicate that (1) at the highest level of electrical noise added, the percent of correct target acquisitions was decreased moderately, (2) the larger the target, the higher the percent correct responses, (3) the low-pass filtering of the video signal led to shorter ground ranges at acquisition for the large-sized targets, and (4) that the larger the target, the longer the fixation duration. Low to moderate correlations between modulation transfer function area (MTFA) and performance measures generally indicated that as MTFA increases performance improves, and that as MTFA increases fixation duration decreases. The search task of the second experiment consisted of having the subjects search for a designated letter or numeral across a televised picture of randomly positioned letters and numerals. The quality of the picture was varied by either passing, low-pass filtering, high-pass filtering, or attenuating the video signal and by adding electrical white noise to the video signal.

This report summarized the work performed during the first year, dealing with two tasks. The first task, entitled 'Human Engineering Survey and Analysis,' reviews the current flap panel display technologies, a summary of the human operator-critical characteristics of each technology, a technical summary of relevant human operator visual characteristics, and an evaluation of each technology by current visual display theoretical evaluation approches. The second task, entitled 'Hue/Luminance Contrast Tradeoffs,' involved laboratory research designed to develop a metric by which luminance contrast and chrominance contrast can be traded off in display design to provide a metric of total effective display contrast. Work to date on both these tasks is summarized in this report. (Author)

This report describes the results of two studies designed to measure dynamic noise, photometrically, on a raster-scan display. One study evaluated spot microphotometry of a single raster line; the other evaluated microdensitometric power spectral analysis of close-up photographs of raster lines. The spot microphotometry technique proved superior and very reliable, yielding results that are highly correlated with input noise spectra. (Author)

A new model for temporal and spatial encoding in the visual system is developed and presented. Three series of experiments were conducted to validate the model. The experiments used (1) a TV display of random, dynamic noise, and (2) a specially designed stimulus generator which produces very large homogeneous visual fields which can be easily modulated to reproduce a large variety of temporal waveforms having a rise time longer than 1 ms. The obtained results support the proposed model. The principal findings are: (1) Time integration of the eye is locally controlled at the retina and has very fast dynamics. (2) The obtained CFF curves suggest a correlation between the frequency at which maximum sensitivity is obtained and the sensitivity itself. (3) As predicted by the model, temporal bands are developed in the visual system for stimuli showing temporal discontinuity points. The width of the temporal bands was measured and a strong correlation was found between the temporal band width and the integration time. The width of the temporal bands is a function of the luminance level of the bands; the width is not dependent on the stimulus slope. The apparent brightness of the temporal band is, however, dependent on the slope of the stimulus.

This report summarizes a research program which has investigated the effects of numerous design parameters of alphanumeric dot-matrix displays upon operator performance. Among the parameters investigated experimentally are dot size, dot shape, dot contrast (or modulation), dot spacing, matrix size, character size, word context, ambient illuminance, character (dot) luminance, and character font. Operator performance in reading and search tasks was predicted by a linear regression model and subsequently cross-validated by additional experiments. Evaluations of several specific flat panel displays were made, with operator performance predicted acceptably from the previously derived regression model of display quality. Optimal capital alphanumeric fonts were determined for 5 x 7, 7 x 9, and 9 x 11 matrices. (Author)

This report presents the results of an air-to-ground television target acquisition experiment which investigated the effects of mission profile, video system line rate and bandwidth, and video noise level. The target acquisition performance data are related to these variables and to a measure of display image quality, the Modulation Transfer Function Area (MTFA), which is measured microphotometrically at the display surface. The target acquisition performance results are largely as expected. For a camera field of view of 18.8 x 14.2 deg, the mean ground ranges of correctly acquired targets are 28,661, 24,376, and 12,171 ft, respectively, for mission profiles of 23 deg depression angle, 500 ft/s velocity; 23 deg, 3000 ft/s; and 45 deg, 500 ft/s. As depression angle decreased, there was a large decrease in acquisition range; as velocity increased, there was a smaller decrease in acquisition range. Altitude was 10,000 ft.

A computerized analysis technique was developed for the evaluation of eye movements. This techique, when applied to eye movement data of 1 millisecond temporal resolution, is considered useful to evaluate such eye movement parameters as fixation duration, interfixation distance, and number of fixations per trial. This analysis technique was evaluated for displays having a single target and up to 192 nontargets in a static display. The results indicate that fixation duration is unaffected by the density of nontargets, but that the mean interfixation distance decreases linearly with increases in nontarget density. Due to this decrease in interfixation distance, the search time and the number of fixations per trial increase linearly with the density of nontargets. An overall evaluation of the eye movement measuring device is offered. (Author)

This report summarizes the research on user performance and display quality metrics pertinent to flat-panel displays. The report is divided into five sections. Section 1 is a brief introduction. Section 2 provides a description of each of the current flat-panel technologies and compares the technologies based on nine display parameters. Section 3 summaries research investigating the effects of various display variables on user performance. The research described in this section is divided into three types; alphanumeric research, cartographic/symbolic research, and literal research. Section 4 defines and discusses different quality metrics which have been used by researchers to predict user performance. One purpose of this literature review was to determine variables requiring further investigation. Based on the findings, an experimental plan is presented in Section 5. An annotated bibliography of references pertinent to these topics is included at the end of the report. (Author)

Television displays generate an image composed of a number of parallel raster lines. These lines, when visible, act as an interfering pattern and detract from operator performance in obtaining information from the video system. One way to reduce line visibility is to deflect the scanning spot vertically as it scans; this technique is commonly termed spot wobble. An experiment was conducted which evaluated changes in operator performance as indicated by the ranges at which targets were acquired and the number of correct responses to target presentation in a simulated air-to-ground search task. These performance parameters were evaluated at four spot wobble amplitudes and three viewing distances. The main findings were that spot wobble had no significant effect on the number of correct responses, but that large-amplitude spot wobble significantly increased the ranges at which targets were acquired. Additionally, several subjective indicators of preferred image quality were evaluated, and show that there is wide variance among subjects as to what image characteristics they prefer.

A study was undertaken to test and evaluate the human factors design aspects of an automobile moving-map navigation system. The primary objective of the study was to assess the driver attentional demand required by the navigation system during vehicle operation. A secondary objective of the study was to assess design specifics and determine whether or not the design was optimal in terms of efficiency of use in an automotive environment. Thirty-two driver-subjects drove a specially instrumented 1985 Cadillac Sedan de Ville on public roadways for this research. A cross-section of driver-subjects (both genders, ages 18 to 73, and driving experience from 2,000 to 40,000 miles per year) participated, and a cross·section of roadway types (residential, two-lane state route, and limited·access four-lane) and traffic conditions (light and moderate) were used as part of this research. The driver-subjects were asked to perform a variety of tasks while operating the research vehicle. These tasks included navigation tasks normally performed while using the navigation system, as well as a wide variety of conventional automotive tasks (e.g., tuning the radio or reading the speedometer) normally performed during vehicle operation. The purpose of asking the driver-subjects to perform a variety of conventional automotive tasks was so that direct comparisons in attentional demand could be made between tasks performed daily in an automotive environment and the navigation tasks. Twenty-one performance and behavioral measures were collected and analyzed for this research. These measures included eye—scanning and dwell-time measures, task-completion-time measures, and a variety of measures indicating driver performance and behavior. The data analyses for these measures focused on two major goals. First, the analyses determined which tasks (both navigator and conventional) required the highest attentional demand. Second, the analyses were used to determine groups of tasks which, for all pr

The purpose of this report is to present in orderly fashion the key factors in the design, analysis, and characterization of low-light-level devices. The parameters of interest are those that have the greatest effect on the transfer of information from the scene before the lens of the television camera to the human looking at the picture tube. Part I examines specifications for low-light-level devices. Part 2 discusses criteria for image quality. Part 3 examines the human visual process and optical aids to that process under conditions of low illumination. Part 4 discusses the image intensifier as a device to aid vision at low light levels and lists the parameters of a variety of available image intensifiers. Part 5 introduces television camera tubes and develops the concepts leading to display signal-to-noise ratio, Rosell's signal- to-noise ratio at the display. It is this, the authors believe, that is the most powerful means of evaluating 'resolution,' a term usually used loosely and incorrectly. Part 6 compares camera tubes on the basis of lag and display signal-to-noise ratio and discusses adverse factors such as 'burning' and 'blooming.' Part 7 sums up with some brief comments on important tube parameters and their specification., Prepared in cooperation with Westinghouse Defense and Space Center, Baltimore, Md. and Virginia Polytechnic Inst., Blacksburg.

Two modes of gun turret operation were compared in a study of facilitating tracking performance. Twenty subjects were used, arranged in two separate groups of ten subjects. One group was assigned to each mode of gun turret operation. One mode of turret operation was termed fully articulated; the manned turret moved both in azimuth and elevation in response to operator hand control movements. The second mode of turret operation was termed partially articulated; the manned turret moved in azimuth, but the sight alone moved in elevation. The results of the data analysis indicated that, over the 56 target runs each subject tracked, there were no significant differences in tracking performance between the two modes of turret operation. However, the interaction between mode and trials was et operation on tracking performance. Turrets which move in Azimuth and elevation vs. those which move in Azimuth only, using the sight for elevation. No significant differences in performance noted. (Study 2.)

The paper deals with aliasing, an important effect of one-and two- dimensional sampling on image quality. Aliasing changes the normal criteria of utility of the modulation transfer function (MTF) as a measure of system quality. Aliasing can be eliminated by letting the MTF fall to zero at one-half the sampling frequency. This, of course, markedly reduces the signal-to-noise ratio at the display (SNR(D)) near cutoff and thus reduces operator performance. Several factors control the amount of information an observer extracts from an image and the rate at which he extracts it. The paper presents the results of a series of experimental programs relating observer performance to the modulation transfer function area (MTFA) and to the SNR(D) and derives the relationship between MTFA and SNR(D). The paper discusses the tradeoffs as they are presently understood.

A laboratory simulation experiment was performed to determine the effect of the TV camera lens field of view upon air-to-ground target recognition by closed-circuit television. Measures of performance were probability of correct target recognition, range of correct recognition, and number of errors committed. It was found that, as the field of view decreased (1) probability of correct recognition decreased, (2) range of correct recognition increased, (3) incorrect target recognitions did not vary, and (4) number of no-response targets increased. The results were discussed in terms of their applicability to tactical airborne situations. (Author)

This item is from the William Crawford Gorgas Papers. It includes correspondence, articles, and other items that document the numerous awards and tributes Gorgas received during his life, collected by his widow, Marie Gorgas for her book, William Crawford Gorgas: his life and work., The digitization of this collection was funded by a gift from EBSCO Industries.