Thesis (M.S.)--Florida State University, 2006. / Advisor: Amy B. Chan-Hilton, Florida State University, College of Engineering, Dept. of Civil and Environmental Engineering. Title and description from dissertation home page (viewed Sept. 18, 2006). Document formatted into pages; contains xiii, 116 pages. Includes bibliographical references.

No description available.

W.T. Dyall. / "January 16, 1948." Based on a thesis submitted to M.I.T. Dept. of Physics, 1948. / Bibliography: p. 102-104. / Army Signal Corps Contract No. W-36-039 sc-32037.

Thesis (M.S.)--Rochester Institute of Technology, 1988. / Includes bibliographical references (leaves 38-39).

Thesis (M.S.)--Rochester Institute of Technology, 1992. / Typescript. Includes bibliographical references (leaves [152]-164).

This research was conducted to achieve four objectives. The first objective was to develop an analytic model to predict the expected luminance distribution through the shadow mask structure on a color CRT display system. The model incorporates functions to describe the unique features of a color CRT, that is, the discrete sampling imposed by the shadow mask/ phosphor-dot arrangement as well as the electron beam phase relationships. The model also includes a flexible beam profile which allows the user to specify the desired shape of the beam profile, that is, whether the profile is described with a Gaussian, leptokurtic, or platykurtic distribution. This objective was fully satisfied with a computer program written in Lightspeed C which runs efficiently on Macintosh computers. The second objective was to determine detection thresholds for various levels of misconvergence of the three electron guns. When the three guns are properly registered, the luminance profiles converge and one perceives a color combination rather than the separate red, green, and blue luminances. Misconvergence is perceived by a change in the overall color or by color fringes, for example, a red edge to a yellow line. Past research has shown that threshold detection of misconvergence occurs when the primary beams are misconverged by 1 to 2 visual arcminutes of separation. This finding was replicated in this research for the two-color beam combinations which have previously been investigated, as well as for a white pixel, which involves all three guns. The third objective was to demonstrate the effect of misconvergence on the performance of a visual task and on subjective estimates of image quality. While subjective quality and threshold detection have previously been investigated for some color combinations, the three tasks (i.e., threshold detection, visual task performance, and subjective estimates) have not been systematically combined within the same data set for a variety of misconvergence conditions. This research provides such a composite data set. The subjective quality estimates were significantly correlated with the threshold detection data. In other words, as misconvergence of the display image increased, the probability of detection of misconvergence increased and the subjective quality rating decreased. However, the selected visual task (a short reading task with average reading time of 6.5 s) was not significantly affected by very large levels of misconvergence. Rather than conclude that the levels of misconvergence used in this research do not affect reading task performance, a more comprehensive visual task (e.g., a longer editing task, a random search task, or a map reading task) should be evaluated. The final objective was to evaluate the ability of selected image quality metrics which are computed from the model to predict threshold detection, subjective quality ratings, or visual task performance. The three metrics computed in this model (MTF Area, MTFA, and SQRI) are all based upon the modulation transfer function (MTF) of the display. These three computed metrics were for all practical purposes constant across the range of misconvergence. While this result was unexpected, it does suggest (1) that a model based only on luminance may be deficient because of the omission of chromaticity, and (2) that MTF-based metrics may not be an appropriate representation because misconvergence does not change the display’s ability to transmit information, but is a phase shift along the shadow mask. As summarized, this research successfully met three of the stated objectives. Further, it points toward future research opportunities to further this type of modelling effort and to successfully develop image quality metrics for color displays. / Ph. D.

A study was conducted to investigate the effects of color CRT misconvergence and display luminance on reading performance and perceived image quality. The objectives of this study were (1) to determine the effects of color CRT misconvergence on reading time and errors, (2) to determine the effects of color CRT misconvergence on subjective ratings of image quality, and (3) to examine the interaction between color CRT misconvergence and display luminance upon reading performance and subjective ratings of image quality. Ten participants performed a Tinker Speed of Reading Test on a shadow-mask, color CRT computer workstation. Both search time to find the out-of-context word and errors were recorded. Following the reading task, each participant rated the image quality of the display using a 9-point subjective scale. Reading performance was not affected by CRT misconvergence or character luminance. Increasing misconvergence did result in lower image quality ratings; however, it was found that participants perceived the more luminous displays to have higher image quality. Also, it was determined that image quality ratings were lowest for magenta misconvergence. However, using normalized ratings, it was found that image quality ratings decreased quickest for the yellow characters with increasing misconvergence. These findings indicate that lower levels of misconvergence (1 to 2.5 arcmin) may not affect reading performance adversely. However, since individuals perceive display quality to be poor at these levels of misconvergence, color CRTs should be used only when application absolutely requires them. / Master of Science

Our information-oriented society relies on the widespread use of color CRT displays. Misconvergence of the primary colors of a shadow-mask CRT is a problem with this technology that deserves human factors engineering consideration. The purpose of this research was as follows: (1) to determine the effects of misconvergence type and amount and font type on reading performance (time required and errors made), (2) to determine the effects of misconvergence type and amount and font type on subjective image quality ratings, (3) to determine the role of luminance and chrominance contrasts in predicting performance or subjective ratings. Ten participants performed a simple reading task and rated the image quality of the text they had just seen using a nine-point scale. The text was presented on a shadow-mask CRT. Different misconvergence types and amounts and different font types were presented. Neither font type, misconvergence type, nor misconvergence amount affected the time required to perform the reading task. Only misconvergence type affected the rate at which errors occurred, with blue misconvergence of a white character resulting in the most errors and cyan misconvergence resulting in the fewest errors. Font type, misconvergence type, misconvergence amount, and the misconvergence type and amount interaction all affected subjective ratings, with 1 to 2 arcmin being the largest acceptable misconvergence amounts. The Yu'v’ chrominance contrast between the stationary misconvergence fringe and the background was positively correlated with subjective preference ratings. / Master of Science

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