In a seminal work, Ungerleider and Mishkin (1982) offered substantial evidence that two separate visual pathways coding what/where-- exist within the primate brain. Recently, human evidence has resulted in the what/where pathways being reconsidered in terms of ventral stream (vision for perception) and dorsal stream (vision for action; Goodale & Milner, 1992). Consistently, many studies have demonstrated that there is an overrepresentation of magnocellular (luminance) information within the dorsal stream; parvocellular input (colour, shape, consistancy) represents the primary source of information for the ventral stream. Although luminance contrast is important in perceiving moving objects, colour discrepancies help the visual system to identify the detailed characteristics of the environment and, subsequently, to prepare the motor system for action. This thesis endeavors to determine the role played by colour, in contrast with luminance, in influencing the programming and control movement production. Using a grasping paradigm and two different luminance conditions (iso-luminance vs. heteroluminance) within two separate experiments (experiment 1 programming; experiment 2 online control), we show that chromatic information can be successfully be used by motor circuits to complete the grasping task faultlessly. Although significant temporal delays in terms of reaction time and movement time between colour and luminance processing are identified, the human visual system seems able to fully integrate colour features for action with no significant spatial error cost.

In a seminal work, Ungerleider and Mishkin (1982) offered substantial evidence that two separate visual pathways coding what/where-- exist within the primate brain. Recently, human evidence has resulted in the what/where pathways being reconsidered in terms of ventral stream (vision for perception) and dorsal stream (vision for action; Goodale & Milner, 1992). Consistently, many studies have demonstrated that there is an overrepresentation of magnocellular (luminance) information within the dorsal stream; parvocellular input (colour, shape, consistancy) represents the primary source of information for the ventral stream. Although luminance contrast is important in perceiving moving objects, colour discrepancies help the visual system to identify the detailed characteristics of the environment and, subsequently, to prepare the motor system for action. This thesis endeavors to determine the role played by colour, in contrast with luminance, in influencing the programming and control movement production. Using a grasping paradigm and two different luminance conditions (iso-luminance vs. heteroluminance) within two separate experiments (experiment 1 programming; experiment 2 online control), we show that chromatic information can be successfully be used by motor circuits to complete the grasping task faultlessly. Although significant temporal delays in terms of reaction time and movement time between colour and luminance processing are identified, the human visual system seems able to fully integrate colour features for action with no significant spatial error cost.

In this thesis, the author developed a retroreflective sheeting selection technique for traffic signs. Previous research was used to determine the luminance needed by drivers (demand luminance). The author used roadways scenarios to determine the amount of luminance the retroreflective sheeting on a sign would produce (supply luminance). A spreadsheet was developed to determine the performance of different retroreflective sheeting types by comparing the demand and supply luminance for specific roadway scenarios. Using the results of previous studies, three demand luminance levels were created: replacement, adequate, and desirable. The replacement level represents the level of luminance when a sign needs to be replaced and is 2.5 cd/m2. The adequate level is the recommended amount of luminance when installing new traffic signs and is 10 cd/m2. The desirable level is the approximate level when additional luminance has diminishing returns and is 30 cd/m2. Supply luminance on a specific traffic sign was determined by evaluating roadway geometries, sign placement, retroreflective sheeting type and vehicle data. The author reviewed roadway geometries in Texas to estimate typical number of lanes, shoulder widths and horizontal curvature in the US. Sign placement from the MUTCD determined the typical lateral placements, sign heights, and sign twists. Vehicle data included vehicle dimensions and headlamp type. Both the supply and demand luminance were determined for a specific viewing distance for a given scenario. The viewing distance is the distance a driver needs to read or recognize a sign to respond properly. In addition, the type of sign, alphanumeric or symbol, determined how this distance was calculated. The author developed four sign groups to calculate the distance required to read and respond to a traffic sign, including 1) Stop required, 2) Reduction in speed required, 3) Read the message provided, and 4) Change of lane required. For symbol signs, the minimum required visibility distance (MRVD) was determined for the sign group and for text signs, the viewing distance at a legibility index (LI) of 30 ft/in was found. At these distances, the author calculated the supply luminance and then compared it to the demand luminance levels to determine the performance level. The author developed the Retroreflective Sheeting Selection Spreadsheet (RSSS) to allow others to use the methodology presented in this thesis. RSSS allows users to input the roadway data, vehicle data, and sign data. RSSS takes this information and looks up the supply luminance for the scenario. RSSS then compares the supply luminance to the demand luminance levels and outputs the retroreflective sheeting performance level for the scenario.

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.

Because luminance is the only value to which our sight responds, its measurement becomes important in terms of ensuring the proper function of vision. Nowadays luminance measuring can be made by conventional methods, such as direct using of luminance meter. However an entirely new method of measuring luminance levels is coming. This method is based on using luminance analyzers which work using a digital photography for the analysis of luminance. This thesis deals with these issues and is divided into several chapters, which form the two main parts of the thesis, the theoretical and the practical one. The theoretical part of the thesis deals with the basics of lighting technology, as well as the principles of measuring the luminance using conventional methods. New methods of measurement, i.e. using luminance analyzers, are discussed in two chapters which analyse both the principle and characteristics of analyzers available today. In the practical part is a comparative measurement carried out – in the laboratory and in terrain – using both methods.

Most shading device systems installed in windows or glass walls are used only for protection from overheating and glare, neglecting other possible functions, such as increasing the daylight level in the space or collecting solar energy. The blinds are usually made of opaque or translucent materials, and if they are partially open/closed or completely closed, a direct view to the outside is blocked. A balance between a sufficient amount of daylight and protection from overheating of the space in summer is not often achieved due to inappropriate control of the blinds’ tilt angle. There is also a need for specific guidance for the selection and design of shading device systems in the windows. This research develops a general decision-making framework (DMF) that can be used by architects and manufacturers of shading devices. The general DMF is a guide for the user in analyzing shading device performance in the process of selection/design of the shading device. This research also develops a specific DMF to better understand and validate the general DMF. The specific DMF, based on illuminance and luminance, is used for an analysis of daylighting performance of shading devices to select the best possible existing system or new system among several alternatives. Architects or manufacturers of shading devices, as the users of the DMF, analyze various systems of blinds applied on a particular building and at a given location. The users of the DMF can apply either an experimental procedure or computer simulation that provides information about illuminance and luminance levels in the space. Based on the analysis of the results of the experiments or simulations, the user of the DMF decides which blinds to select. The specific DMF proposes a methodology for both the analysis of the daylighting performance and for the process for making a decision based on the results of the analysis. A case study is conducted in order to validate the DMF. Three types of shading devices are tested: an existing system, a patented system, and a new system, proposed by this research. The shading devices are installed in an office space located in Roanoke, Virginia. The software Autodesk VIZ 4 is used to simulate daylighting performance. The output information, such as illuminance and luminance levels in the space, is used as a basis for making the decision about which type of blinds to apply. A new system of shading device, which has a triangular cross section and is made of clear plastic with a silver coating on one side, shows better performance than the existing shading device and the patented shading device, given the research limitations. By using the specific decision-making framework, a shading device manufacturer/designer is able to understand the shading device daylighting performance from his design-imposed criteria. Selection of the shading device, given the designer's daylighting objectives, is better achieved. Existing shading devices are also able to be analyzed from a building designer's perspective. This analysis is based on the designer-imposed daylighting criteria. The specific decision-making framework helps the designers of the buildings, together with the clients, select the most appropriate shading device based on daylighting performance. The decision-making framework is a model for development of decision-making software that will help designers of buildings, facades, and shading device systems in the selection/design of shading device systems in all phases of the design. / Ph. D.

Contrast sensitivities to one- and two-dimensional luminance patterns were compared in a two-alternative forced choice (2AFC) experiment. Space-averaged luminance was also manipulated. Statistical analyses revealed a main effect of stimulus dimension (p < .05) and no effect of space-averaged luminance. The main effect of stimulus dimension was explained in terms of an on-center, off-center receptive field model combined with watershed spatial vision behavior at spatial frequencies below 1 cycle-per-degree (cpd). The non-significant result for space-averaged luminance was explained by the limited range of manipulation of the variable. Two-dimensional luminance patterns were suggested as ideal patterns for reconciling grating-based spatial vision research with spatial vision behavior in an ecological context. Future research directions are suggested. / Master of Science

This thesis deals with an unconventional possibility of measuring photometric values and the work is based on analysis of luminance made by commercially available digital photo camera. In the first part is represent an overview of current methods for measuring the photometry. You also can see the basic photometric values and required instrumentation needed to measure them. The focus of the work is concentrated on the description of the problems associated with setting the correct luminance of digital photography. It describes the dependency and correction procedures for calculating fixed luminance ratios of the individual images. The last part of this thesis is devoted to the possible use in practice, especially in the analysis of luminance of objects, luminaires and light sources. It also deals with an alternative description of luminaire and light sources to replace the luminous intensity curve etc.

Práce se zabývá měřením křivek svítivosti světelných zdrojů a svítidel konvenčními a nekonvenčními metodami. Úvodní část práce je věnována popisu zrakového systému a základních fotometrických veličin. Hlavní teoretická část je zaměřena na popis současných metod měření křivek svítivosti a nových metod měření pomocí jasového analyzátoru. Současně jsou pro jednotlivé metody uvedeny zdroje nejistot, které ovlivňují výsledky měření. Těžiště práce spočívá v návrhu metodiky měření křivek svítivosti z jasových skenů svítidla a následném ověření tohoto postupu vlastním měřením. Dále bylo provedeno srovnání naměřených výsledků navrženým postupem, s výsledky konvenčního měření na goniofotometru s luxmetrem.

The purpose of this dissertation is to advance the understanding of SrS-based a. c. thin film electroluminescent (ACTFEL) devices. The role of traps in the bulk phosphor layer in the light emission mechanism from ACTFEL devices is studied, characterized and modeled. Experiments were performed to observe the response of the ACTFEL devices to tailored voltage excitations. A physical model was developed to describe the optoelectronic processes taking place in the phosphor; analytical equations were written and numerically simulated to plot the flux and luminance responses of the device to similarly tailored voltage excitations. The voltage excitation parameters such as amplitude, rise times and fall times were varied both experimentally and in simulations and their effect on the opto-electronic response of the device was studied. Thermally stimulated luminance studies were performed to determine critical device parameters. Theoretical predictions matched the experimental data in a qualitative manner. A much improved quantitative accuracy is obtained when the role of dipoles in the EL mechanisms is incorporated into the model.