Clustered-dot periodic halftone screen design and ICC profile color table compression

This dissertation studies image quality problems associated with rendering images in devices like printing or displaying. It mainly includes two parts: clustered-dot periodic halftone screen design, and color table compression. Screening is a widely used halftoning method. As a consequence of the lower resolution of digital presses and printers, the number of printer-addressable dots or holes in each microcell may be too few to provide the requisite number of tone lev- els between paper white and full colorant coverage. To address this limitation, the microcells can be grouped into supercells. The challenge is then to determine the desired supercell shape and the order in which dots are added to the microcell. Using DBS to determine this order results in a very homogeneous halftone pattern. To simplify the design and implementation of supercell halftone screens, it is common to repeat the supercell to yield a periodically repeating rectangular block called the basic screen block (BSB). While applying DBS to design a dot-cluster growth order- ing for the entire BSB is simpler to implement than is the application of DBS to the single non-rectangular supercell, it is computationally very inefficient. To achieve a more efficient way to apply DBS to determine the microcell sequence, we describe a procedure for design of high-quality regular screens using the non-rectangular super- cell. A novel concept the Elementary Periodicity Set is proposed to characterize how a supercell is developed. After a supercell is set, we use DBS to determine the micro-cell sequence within the supercell. We derive the DBS equations for this situation, and show that it is more efficient to implement. Then, we mainly focus on the regular and irregular screen design. With digital printing systems, the achievable screen angles and frequencies are limited by the finite addressability of the marking engine. In order for such screens to generate dot clusters in which each cluster is identical, the elements of the periodicity matrix must be integer-valued, when expressed in units of printer-addressable pixels. Good approximation of the screen sets result in better printing quality. So to achieve a better approximation to the screen sets used for commercial offset printing, irregular screens can be used. With an irregular screen, the elements of the periodicity matrix are rational numbers. In this section, first we propose a procedure to generate regular screens starting from midtone level. And then we describe a procedure for design of high-quality irregular screens based on the regular screen design method. We then propose an algorithm to determine how to add dots from midtone to shadow and how to remove dots from midtone to highlight. We present experimental results illustrating the quality of the halftones resulting from our design procedure by comparing images halftoned with irregular screens using our approach and a template-based approach. We also present the evaluation of the smoothness and improvement of the proposed methods. In the next part, we study another quality problem: ICC profile color table compression. ICC profiles are widely used to provide transformations between different color spaces in different devices. The color look-up tables (CLUTs) in the profiles will increase the file sizes when embedded in color documents. In this chapter, we discuss compression methods that decrease the storage cost of the CLUTs. For DCT compression method, a compressed color table includes quantized DCT coefficients for the color table, the additional nodes with large color difference, and the coefficients bit assignment table. For wavelet-based compression method, a compressed color table includes output of the wavelet encoding method, and the additional nodes with large color difference. These methods support lossy table compression to minimize the network traffic and delay, and also achieves relatively small maximum color difference

Large-Scale Patterning and Dynamics of Topological Solitons In Chiral Nematic Liquid Crystals

The coexistence of order and fluidity in soft condensed matter often mimics that found in biological cells, which allows for complex collective dynamics and for highly technological applications, like displays and sensors. In active soft matter, different forms of emergent order can even arise because of this out-of-equilibrium dynamic behavior, powered by local energy conversion. We show that this emergent ordering can mimic behavior of familiar living systems with coherent motion, like crowds of people and schools of fish. Most active matter systems are biological in origin, although the discovery of inanimate, purely synthetic particles capable of such emergent behavior would enable new breeds of materials and nanomachines. Such examples are limited, typically with chemical or mechanical agitation sources of energy. We show that thousands of particle-like topological solitons can exhibit collective dynamics while either (1) each converting macroscopically-supplied electric energy into motion along spontaneously-selected directions uncorrelated with the direction of electric field, (2) responding to photo-manipulation of the material&rsquo;s elastic free energy landscape by changing shape or moving away from the light, or (3) a combination of the two. We demonstrate that these soliton dynamics occur in the absence of backflows, have the ability to carry cargo, display tunable dynamic self-assembly with their neighbors, possess long-range repulsive interactions, and exhibit emergent order and giant-number fluctuation scaling consistent with active systems such as schooling fish. We uncover how these topological solitons react to changes in the local and global elastic free energy, both in samples with flat geometries and spherical liquid crystal shells. We further show that skyrmions in motion can pack together as dense quasi-hexagonal crystallites and exhibit crowding and jamming behavior similar to crowds of people moving around obstacles. Uniquely to our system, this plethora of emergent active behavior occurs in the absence of physical or biological particles and material flows, revealing the defining characteristics of the new field of solitonic active matter and promising many technological uses.</p

Data and the city – accessibility and openness. a cybersalon paper on open data

This paper showcases examples of bottom–up open data and smart city applications and identifies lessons for future such efforts. Examples include Changify, a neighbourhood-based platform for residents, businesses, and companies; Open Sensors, which provides APIs to help businesses, startups, and individuals develop applications for the Internet of Things; and Cybersalon’s Hackney Treasures. a location-based mobile app that uses Wikipedia entries geolocated in Hackney borough to map notable local residents. Other experiments with sensors and open data by Cybersalon members include Ilze Black and Nanda Khaorapapong's The Breather, a "breathing" balloon that uses high-end, sophisticated sensors to make air quality visible; and James Moulding's AirPublic, which measures pollution levels. Based on Cybersalon's experience to date, getting data to the people is difficult, circuitous, and slow, requiring an intricate process of leadership, public relations, and perseverance. Although there are myriad tools and initiatives, there is no one solution for the actual transfer of that data

Visualisation of Large-Scale Call-Centre Data

The contact centre industry employs 4% of the entire United King-dom and United States’ working population and generates gigabytes of operational data that require analysis, to provide insight and to improve efficiency. This thesis is the result of a collaboration with QPC Limited who provide data collection and analysis products for call centres. They provided a large data-set featuring almost 5 million calls to be analysed. This thesis utilises novel visualisation techniques to create tools for the exploration of the large, complex call centre data-set and to facilitate unique observations into the data.A survey of information visualisation books is presented, provid-ing a thorough background of the field. Following this, a feature-rich application that visualises large call centre data sets using scatterplots that support millions of points is presented. The application utilises both the CPU and GPU acceleration for processing and filtering and is exhibited with millions of call events.This is expanded upon with the use of glyphs to depict agent behaviour in a call centre. A technique is developed to cluster over-lapping glyphs into a single parent glyph dependant on zoom level and a customizable distance metric. This hierarchical glyph repre-sents the mean value of all child agent glyphs, removing overlap and reducing visual clutter. A novel technique for visualising individually tailored glyphs using a Graphics Processing Unit is also presented, and demonstrated rendering over 100,000 glyphs at interactive frame rates. An open-source code example is provided for reproducibility.Finally, a novel interaction and layout method is introduced for improving the scalability of chord diagrams to visualise call transfers. An exploration of sketch-based methods for showing multiple links and direction is made, and a sketch-based brushing technique for filtering is proposed. Feedback from domain experts in the call centre industry is reported for all applications developed

Approaches to decision making

This book is designed as a brief introduction to the understanding of decision making in work settings. It is designed for use in graduate courses and should be supported by a wide range of additional reading materials and practical exercises. The approach is multi-disciplinary and pluralistic: there are many perspectives from which decision making may be viewed. Similarly, there are many differences in decision making between individuals and between contexts. The book is intended to contribute to a raised awareness of the many issues and high complexity attaching to important decisions. It may or may not help the reader to become a better decision maker. That outcome depends on personal desire and availability of resources, including time and pressure, as much as anything else. However it is hoped that those readers who are accustomed to the traditional focus on \u27rational\u27 decision making will quickly learn that decision making is a complex and many faceted activity. The text is divided into six modules or parts, each looking at a specific aspect of decision making in organisations. Module 1 looks at some important philosophical issues, and introduces the \u27convential\u27 theories based in economics and sociology. Theoretical and empirical explanations of the decision process are examined in Module 2. Module 3 explores some of the aids to decision making. The individual as decision maker is the subject of Module 4, and Module 5 examines group decision making behaviours. Module 6 is a review, and suggests some of the implications and consequences of a course of study into decision making..

Pattern Recognition

Pattern recognition is a very wide research field. It involves factors as diverse as sensors, feature extraction, pattern classification, decision fusion, applications and others. The signals processed are commonly one, two or three dimensional, the processing is done in real- time or takes hours and days, some systems look for one narrow object class, others search huge databases for entries with at least a small amount of similarity. No single person can claim expertise across the whole field, which develops rapidly, updates its paradigms and comprehends several philosophical approaches. This book reflects this diversity by presenting a selection of recent developments within the area of pattern recognition and related fields. It covers theoretical advances in classification and feature extraction as well as application-oriented works. Authors of these 25 works present and advocate recent achievements of their research related to the field of pattern recognition