Coherent optical data processing is recognised, for many applications, as a viable alternative to digital electronic signal processing; the case for using coherent optics is particularly strong when the data to be processed is two dimensional in nature. It has long been accpeted that, in order for coherent optical processing to achieve its full performance potential, two dimensional spatial light modulators - capable of operating in real time - are essential at both the object plane (where the data is input to the system) and the Fourier plane (where the operation carried out on the data is determined). Most previous research in the field of spatial modulators has concentrated on optically addressed devices for use in the object plane. This thesis describes a prototype liquid crystal over silicon spatial light modulator built to test the feasibility of using such devices in a coherent optical processor. Optically, the device operates as a binary amplitude modulator, consisting of a square array of 16x16 pixels, each of size 100x100 m^2 and located at 200m centres. The integrated circuit is designed for a 6m wafer fabrication process. Each pixel of the IC contains a static memory element (which stores a digital logic voltage corresponding to the optical state of that pixel) and provides a stable square wave voltage signal to drive the liquid crystal layer. The component parts of the spatial light modulator are tested individually: the liquid crystal, in test cells, for contrast and switching speed; the IC for electrical performance and optical (flatness) characteristics. The effect of pixellation on optical performance is investigated. The performance of live devices is demonstrated. The results indicate the feasibility of using such a device as a binary amplitude spatial light modulator.

Although motion processing in insects has been extensively studied for over almost 40 years, velocity detection in insects and how the insect brain computes the velocity of a moving feature, independent of its size or contrast, is a major enigma that remains unsolved. This study examines the accuracy of velocity estimation using two biologi-cally inspired models of motion detection, (i) the Horridge template model and (ii) the Reichardt correlator model. Various extensions and enhancements of these models are implemented with the goal of achieving robust velocity measurements. The template model is one of the prominant models of motion detection, which was proposed by Horridge in 1990. This Thesis further extends this model with the aim of improving accuracy in velocity detection using chrominance as well as luminance channels with various error checking mechanisms using different stimuli. Then the template model response is compared with Dror's elaborated Reichardt model and electro-physiological experimental results obtained from the fly visual system using similar stimuli in each case. A modified Reichardt model is shown to give a more similar response to that of fly neurons. In order to improve velocity performance of the Reichardt model, it is necessary to reduce contrast dependance of the correlator response as well as to make it independent of the structure of the visual stimuli. With this aim, the Reichardt model is then further elaborated to include contrast adaptation by a feedback adaptive mechanism and a clear reduction in contrast dependency is demonstrated. The deviation of the correlator response depending on the stimulus is termed as pattern noise. To reduce this pattern noise, the Reichardt correlator model is further extended to implement compressive non-linearity or saturation. It is seen that saturation has a profound effect on the shape of the pattern noise. Further studies on pattern noise is then performed in this Thesis using different stimuli at different speeds and contrasts. Work carried out in this Thesis on the affect of various receptive field shapes on the pattern noise reveals circular sampled arrays reduce pattern noise and hence, based on this result, a small 16 pixel yaw sensor using our elaborated model is built that shows promising performance with various potential applications. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1337180 / Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2008

Thesis (Ph.D.)--Rochester Institute of Technology, 2007. / Typescript. Includes bibliographical references (p. 180-185).

Thesis (M.S.)--Rochester Institute of Technology, 1989. / Spine title: Correcting geometric distortion in holographic stereograms. Includes bibliographical references (leaves 37-39).

Thesis (M. S.)--Aerospace Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Eric Feron; Committee Member: Eric Johnson; Committee Member: Jerry Seitzman.

Thesis (Ph. D.)--UCLA, 2009. / Vita. Description based on print version record. Includes bibliographical references (leaves 300-309).

Thesis (Ph. D.)--University of Lund. / Includes bibliographical references (p. 234-238).

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 111-120). Also available in electronic version.

Visual attention is an important characteristic in the human vision system, which is capable of allocating the cognitive resources to the selected information. Many researchers are attracted to the study of this mechanism in the human vision system and have achieved a wide range of successful applications. Generally, there are two tasks encountered in the visual attention research including visual saliency detection and gaze estimation. The former is normally described as distinctiveness or prominence as a result of a visual stimulus. Given images or videos as input, saliency detection methods try to simulate the mechanism of human vision system, predicting and locating the salient parts in them. While the later involves physical device to track the eye movement and estimate the gaze points. As for saliency detection, it is an effective technique for studying and mimicking the mechanism of the human vision system. Most of saliency models can predict the visual saliency with the boundary or the rough location of the true salient object, but miss the appearance or shape information. Besides, they pay little attention to the image quality problem such as low-resolution or noises. To handle these problems, in this thesis, we propose to model the visual saliency from local and global perspectives for better detection of the visual saliency. The combination of the local and global saliency scheme employing different visual cues can make fully use of their respective advantages to compute the saliency. Compared with existing models, the proposed method can provide better saliency with more appearance and shape information, and can work well even in the low-resolution or noisy images. The experimental results demonstrate the superiority of the proposed algorithm. Next, video saliency detection is another issue for the visual saliency computation. Numerous works have been proposed to extract the video saliency for the tasks of object detection. However, one might not be able to obtain desirable saliency for inferring the region of foreground objects when the video presents low contrast or complicated background. Thus, this thesis develops a salient object detection approach with less demanding assumption, which gives higher detection performance. The method computes the visual saliency in each frame using a weighted multiple manifold ranking algorithm. It then computes motion cues to estimate the motion saliency and localization prior. By adopting a new energy function, the data term depends on the visual saliency and localization prior; and the smoothness term depends on the constraint in time and space. Compared to existing methods, our approach automatically segments the persistent foreground object while preserving the potential shape. We apply our method to challenging benchmark videos, and show competitive or better results than the existing counterparts. Additionally, to address the problem of gaze estimation, we present a low cost and efficient approach to obtain the gaze point. As opposed to eye gaze estimation techniques requiring specific hardware, e.g. infrared high-resolution camera and infrared light sources, as well as a cumbersome calibration process. We concentrate on visible-imaging and present an approach for gaze estimation using a web camera in a desktop environment. We combine intensity energy and edge strength to locate the iris center and utilize the piecewise eye corner detector to detect the eye corner. To compensate for head movement causing gaze error, we adopt a sinusoidal head model (SHM) to simulate the 3D head shape, and propose an adaptive weighted facial features embedded in the pose from the orthography and scaling with iterations algorithm (AWPOSIT), whereby the head pose can be estimated. Consequently, the gaze estimation is obtained by the integration of the eye vector and head movement information. The proposed method is not sensitive to the light conditions, and the experimental results show the efficacy of the proposed approach

Colour images can be formed by the combination of stimuli in three primary colours. As a result, digital colour images are typically represented as a triplet of values, each value corresponding to the stimulus of a primary colour. The precise stimulus that the eye receives as a result of any particular triplet of values depends on the display device or medium used. Photographic film is one such medium for the display of colour images. This work implements a software system to calibrate the response given to a triplet of values by an arbitrary combination of film recorder and film, in terms of a measurable film property. The implemented system determines the inverse of the film process numerically. It is applied to calibrate the Optronics C-4500 colour film writer of the UBC Laboratory for Computational Vision. Experimental results are described and compared in order to estimate the expected accuracy that can be obtained with this device using commercially available film processing. / Science, Faculty of / Computer Science, Department of / Graduate