Liquid crystal displays (LCDs) have been widely used in the information technology such as LCD-TV, LCD monitor, laptop computer and mobile phones. Because liquid crystal does not emit lights by itself, a backlight source should be needed in order to produce viewable images on a LCD. The module which provides the light source is usually called ¡¥¡¥backlight module (BLM)¡¦¡¦ and a cold cathode fluorescent lamp (CCFL) is used as the light source, which is placed behind the panel of the LCD. Due to the temperature increase of the CCFL in a BLM of a LCD subjected to lighting state, micro-deformation will occur in the BLM and result uneven luminance phenomena. The purpose of this research is to study the effects of heat source from CCFL on luminance in the BLM of a 7-inch LCD. The temperature distributions are measured by using thermal couple and the luminance variations of the BLM are measured by using luminance meters and CCD camera. The results show that the luminance distribution is more even because of the heat source from CCFL in BLM.

The need to see traffic signs at night has led to the development of increasingly brighter retroreflective sign sheeting. The impact of this increased brightness has been shown to increase the legibility distance of the sign, but at what cost? With brighter signs being visible from farther away, there is an increased opportunity for the driver to look at the sign. This thesis assesses the impact of sign brightness on the nighttime driver’s sign viewing behavior; such as the number of glances and the total glance duration directed at the sign. Eye-tracking technology has been used to follow the nighttime driver’s eye movements through tasks based on sign usage. The six signs used for the analysis are classified in three relative brightness categories of bright, medium, and dim on a closed course and on a public road. Data relating to the beginning and end of each glance were recorded as well as the distance at which the sign became legible to the driver. Comparisons were made between the three brightness levels for the number of glances, total glance duration, and legibility distance of the sign. Further analysis was conducted to determine the effect of the testing environment on a driver’s sign viewing behavior by comparing the results from the closed course with those from the open road. The data for this thesis show varying results between the two courses with more defined differences based on luminance for the open road. The results of this thesis indicate that drivers do not consistently change the number of times they look at a sign or the amount of time dedicated to a sign based on its brightness. During real world driving scenarios, the brightest sign resulted in the longest legibility distance and the lowest total glance duration, indicating an increased efficiency reading the sign by the driver. Typically, a sign with a longer total glance duration had a shorter legibility distance. Comparisons between the closed and open courses revealed that open road driving resulted in a longer total glance duration and a shorter legibility distance.

No / Natural visual scenes are a rich source of information. Objects often carry luminance, colour, motion, depth and textural cues, each of which can serve to aid detection and localization of the object within a scene. Contemporary neuroscience presumes a modular approach to visual analysis in which each of these attributes are processed within ostensibly independent visual streams and are transmitted to geographically distinct and functionally dedicated centres in visual cortex (van Essen & Maunsell, 1983; Zihl, von Cramon & Mai, 1983; Maunsell & Newsome, 1987; Tootell, Hadjikhani, Mendola, Marrett & Dale, 1998). In the present study we ask how the visual system localizes objects within this framework. Specifically, we investigate how the visual system assigns a unitary location to objects defined by multiple stimulus attributes, where such attributes provide conflicting positional cues. The results show that conflicting sources of visual information can be effortlessly combined to form a global estimate of spatial position, yet, this conflation of visual attributes is achieved at a cost to localization accuracy. Furthermore, our results suggest that the visual system assigns more perceptual weight (Landy, 1993; Landy & Kojima, 2001) to visual attributes which are reliably related to object contours.

Glare is an important, but often overlooked parameter in lighting systems design. This parameter can significantly affect human biorhythm, causing a discomfort or in the worst cases it can dazzle drivers, which can lead to car accidents. Therefore, it´s necessary for lighting designers to consider glare in their designs, specifically threshold increment value. This thesis focuses on glare measurement caused by exterior lighting systems and comparison of usage different types of camera lens for threshold increment measurements with luminance analyser. For a better understanding of the whole issue, there is a part describing how human eye perceives light, which is followed by definition and division of the glare. Afterwards, there is part describing calculation procedure of the threshold increment, which serves as a basis for the practical part of the thesis. Practical part of the thesis is dedicated to experimental measurement of glare from exterior lighting system on Technická street, right behind VUT FEKT T12 building. The measurement is done using luminance analyser and the LumiDISP program, while 3 lenses are used for the measurements. The output of this thesis are values of threshold increment obtained by using 4 different methods (3 lenses) and subsequent comparison of the suitability of the lenses for the glare measurements. To supplement, a simulation of the measured lighting system in the Relux program and a subsequent comparison of the results with the measured values are performed.

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In this thesis, I investigated how human vision processes colour and luminance information to enable perception of our environment. I first tested how colour can alter the perception of depth from shading. A luminance variation can be interpreted as either variation of reflectance (patterning) or variation of shape. The process of shape-from-shading interprets luminance variation as changes in the shape of the object (e.g. the shading on an object might elicit the perception of curvature). The addition of colour variation is known to modify this shape-from-shading processing. In the experiments presented here I tested how luminance driven percepts can be modified by colour. My first series of experiments confirmed that depth is modulated by colour. I explored a larger number of participants than previously tested. Contrary to previous studies, a wide repertoire of behaviour was found; participants experienced variously more depth, or less depth, or no difference. I hypothesised that the colour modulation effect might be due to a low-level contrast modulation of luminance by colour, rather than a higher-level depth effect. In a second series of experiments, I therefore tested how the perceived contrast of a luminance target can be affected by the presence of an orthogonal mask. I found that colour had a range of effects on the perception of luminance, again dependant on the participants. Luminance also had a similar wide range of effects on the perceived contrast of luminance targets. This showed that, at supra-threshold levels, a luminance target's contrast can be modulated by a component of another orientation (colour or luminance defined). The effects of luminance and colour were not following a particular rule. In a third series of experiments, I explored this interaction at detection levels of contrast. I showed cross-interaction between luminance target and mask but no effects of a colour mask.

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Recent research suggests that by 4 months of age infants are able to individuate objects using form features, such as shape and size, but surface features, such as pattern and color, are not used until later in the first year (Wilcox, 1999). The current study sought to investigate two possible explanations for this developmental hierarchy. The visual maturation hypothesis suggests that the order in which infants use features to individuate objects corresponds to the order in which they are most readily processed by the developing visual system. A second hypothesis, the information processing biases hypothesis, suggests that infants are biased to attend to form features because form features provide information that is relevant to reasoning about object interactions. One way to test these hypotheses is to investigate infants' ability to individuate objects based on luminance. Luminance is detected at birth, so, according to the visual maturation hypothesis, luminance, like shape and size, will be used to individuate objects early in the first year. However, luminance is a surface property, so according to the information processing biases hypothesis, luminance, like pattern and color, will be used to individuate objects late in the first year. In the current study, 7-month-old (Experiment 1) and 11-month-old (Experiment 2) infants' use of luminance information in an object individuation task was investigated. The narrow-screen event-monitoring paradigm developed by Wilcox and Baillargeon (1998a) was used. Infants saw an event in which a ball moved behind a screen and a second ball emerged from behind the opposite edge of the screen. In one condition, the balls were identical, suggesting the presence of one object (same-luminance condition), and in another condition, the balls differed in luminance, suggesting the presence of two objects (different-luminance condition). The screen was either too narrow (narrow-screen event) or sufficiently wide (wide-screen event) to occlude two objects simultaneously. Seven-month-olds looked equally at each event, whereas 11.5-month-old's looked longer at the narrow-screen event in the different-luminance condition. These results suggest that 11.5-month-olds, but not 7.5-month-olds used luminance information to conclude that two distinct objects were involved in the event, thus supporting the information processing biases hypothesis.