Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 21 for “"luminance contrast"”.
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The effects of luminance contrast, raster modulation, and ambient illumination on text readability and subjective image quality
This thesis examined the effects of luminance contrast, raster modulation, and ambient illumination on readability and image quality of text presented on a CRT display. Participants read a Tinker Speed of Reading text passage on the monitor and then responded when they found the out-of-context word …
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The Effects of Stimuli Type, Size, and Articulation on Estimating the Luminance Contrast of Real and CRT Targets
The goal of this thesis was to examine how luminance contrast estimates were affected by varying conditions of stimuli type, size, and articulation. Based on previous research, it was expected that lightness constancy would increase as stimuli moved from a spotlight, to paper, and finally to a CRT …
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Effects of target size, luminance contrast, and illumination on visual target detection and recognition with AN/AVS-6 goggles
… research examined the effects of target size, luminance contrast, and illumination level on visual target detection and recognition while using AN/AVS-6 night vision goggles. Vehicle silhouette targets were rear-projected on random screen positions under various levels of illumination, …
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Visual performance in the mesopic range
… Chromatic thresholds were obtained using dynamic luminance contrast noise to isolate responses to colour signals. The effects of stimulus size and spatial distribution were examined in normal trichromats, dichromats and subjects with acquired colour vision deficiency. The chromatic sensitivity of …
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Sunlight readability and luminance characteristics of light-emitting diode push button switches.
… for six attributes of lighting quality: average luminance and power consumption at full voltage, sunlight readable contrast, luminance contrast under ambient sunlight, legend uniformity, and dual-color uniformity. Three of the four manufacturers have not developed LED push button switches that …
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The role of pigmentation in face perception
… pigmentation, with female faces having more luminance contrast between the eyes and lips and the rest of the face than do male faces. This sex difference in pigmentation is used as a cue for judgments of facial sex classification and facial attractiveness. Together, these results implicate an …
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The effects of age, illumination, and anti-glare treatments on visual task performance and perceived image quality with VDTs
… treatments which either reduced glare, enhanced contrast, or both; three lighting conditions, dark, diffuse, and specular; and two character resolutions, high and low, subtending visual angles of 16.1 arcmin. and 32.2 arcmin. respectively. Performance was measured using both a speed of reading …
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Colour constancy: human mechanisms and machine algorithms
… of the Plankian locus. The effects of overall illuminance and the luminance contrast between target and surround are investigated. Chapter four considers the spatial structure of the visual scene. Simple uniform surrounds are compared with those which have a more complex spatiochromatic structure …
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Comparing LED Lighting Systems in the Detection and Color Recognition of Roadway Objects
… CCT of each luminaire and their color contrast impact. Mesopic vision, the mode of vision most commonly used for night driving, was considered in this study. Off-axis objects were presented to participants to assess the peripheral abilities of the luminaires. The impacts of luminance …
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A study of pupil response components in human vision
… of several stimulation parameters such as: luminance contrast, stimulus size, spatial and temporal frequency content, and colour. Much larger responses were found for square-wave as compared to sinusoidal luminance modulation. A model with two populations of neurones (sustained and …
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A study of pupil response components in human vision
… of several stimulation parameters such as: luminance contrast, stimulus size, spatial and temporal frequency content, and colour. Much larger responses were found for square-wave as compared to sinusoidal luminance modulation. A model with two populations of neurones (sustained and …
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An electrophysiological study of chromatic processing in the human visual system. Using visual evoked potentials and electroretinograms to study cortical and retinal contributions to human trichromatic vision.
… morphology is dependent upon 1) chromatic and or luminance contrast content of the stimulus, 2) stimulus size, and 3) extent to which the chromatic stimulus activates either the L/M or S/(L+M) opponent mechanism. The experiments indicate that chromatic stimulation is indexed by large N1 component …
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Effects of Intersection Lighting Design on Driver Visual Performance, Perceived Visibility, and Glare
… The second goal was to determine the effect of illuminance on visual performance at intersections. The third goal was to understand the relationships between object luminance, contrast, and visibility. To achieve these goals, three specific configurations were used, that illuminated the …
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Visual System Development in People with One Eye: Behaviour and Structural Neural Correlates
… In Chapter II, I conducted a series of speed and luminance contrast discrimination tasks not yet implemented in this group. Early monocular enucleation results in impaired speed discrimination but intact contrast perception compared to binocular and monocular viewing controls. These findings …
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CRT anti-glare treatments, image quality, and human performance
… wide range of filter transmissions and diffuse illuminance on measured image quality and the same user measures as in Phase I. Phase I showed that while none of the glare filters yielded improved readability or legibility over a baseline condition, the etched and low transmission filters were …
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Functional Dynamics of Primate Retinal Ganglion Cells
<p>Contrast forms the substrate for human pattern vision. The retina is the first stage in the processing of complex spatial and temporal contrast signals. The responses of retinal ganglion cells to such signals provide the means to explore such processing in the retina. Most primate retinal …
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Effects of Font Design on Highway Sign Legibility
… components: retro-reflectivity, irradiation, luminance, contrast, and font design. Understanding these five components, and the benefits of each, can lead to the betterment of the font design on highway signs. This study consisted of two web-based tests. In the first test, the "Letters Test", …
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Scene-Dependency of Spatial Image Quality Metrics
… to the objective and subjective reproduction of luminance contrast signals by the system, respectively; they are critical to overall perceived image quality. The Modulation Transfer Function (MTF) and Noise Power Spectrum (NPS) describe the signal (contrast) transfer and noise characteristics of …
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Variability of chromatic sensitivity: fundamental studies and clinical applications
… procedure that employs spatiotemporal luminance contrast (LC) masking techniques to isolate the use of colour signals. The colour-defined stimuli were buried in dynamic LC noise and moved diagonally across a square. The subject's task is to indicate one of the four possible directions …
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Examining Visual Masking in Target Aquisition Uning Two-dimensional Fourier Analysis Techniques
… simple phenomena, such as the minimum size and luminance contrast needed for visual detection. This dissertation was directed at establishing ways to improve the prediction of target perception performance. Specifically, this research was motivated by the idea that contemporary theories of …
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