Improving the Performance of K-Means for Color Quantization

Color quantization is an important operation with many applications in graphics and image processing. Most quantization methods are essentially based on data clustering algorithms. However, despite its popularity as a general purpose clustering algorithm, k-means has not received much respect in the color quantization literature because of its high computational requirements and sensitivity to initialization. In this paper, we investigate the performance of k-means as a color quantizer. We implement fast and exact variants of k-means with several initialization schemes and then compare the resulting quantizers to some of the most popular quantizers in the literature. Experiments on a diverse set of images demonstrate that an efficient implementation of k-means with an appropriate initialization strategy can in fact serve as a very effective color quantizer.Comment: 26 pages, 4 figures, 13 table

An Approach for Object-Oriented Animation Design

In this concept we present tools for faster designing of reconfigurable function oriented animation systems. A set of basic animation structures and a set of basic animation techniques are defined. An object-oriented hierarchy can be built on the basis of the relationship between basic animation structures and animation techniques. We propose a corresponding class hierarchy for animation design. The classes of our hierarchy are incrementally developed through inheritance and dynamic binding. Some programming aspects concerning efficient implementation of basic animation structures through container classes are discussed. - 2 - An Approach for Object-Oriented Animation Design Michael Gervautz 1) , Olga Beltcheva 2) Abstract In this concept we present tools for faster designing of reconfigurable function oriented animation systems. A set of basic animation structures and a set of basic animation techniques are defined. An object-oriented hierarchy can be built on the basis of the ..

Ray tracing of nonlinear fractals

We present a new kind of parametric Lindenmayer-systems called nonlinear CSG-pL-systems, which are useful for the modeling of nonlinear fractals and fractal like objects. Nonlinear CSG-pL-systems describe cyclic CSG-Graphs, which can include several nonlinear transformations. To render the given objects a ray tracing algorithm is introduced, that is independent of the transformations and the under laying CSG-primitives. We use tapering, twist and bend as nonlinear transformations for our implementation. The new modeling possibilities and their visualization for abstract fractals and natural phenomena are investigated

Using genetic algorithms to improve the visual quality of fractal plants generated with CSG-PL-Systems

PL-systems are a powerful and flexible technique for plant modeling. Unfortunately it is a hard task to specify a PL-system, that generates a desired plant. Especially the tuning of the parameter values is time consuming and demands a lot of experience from the user. In this paper we describe how to apply genetic algorithms to CSG-PL-systems, which are a special class of PL-systems. A decomposition of CSG-PL-systems is introduced to extract those parts, which can serve as genotype. Mutation and mating, the two major operations of evolution techniques, are applied to this data set. With the described method it is possible to find easily natural looking individuals out of a species that is described in an abstract way by the underlying CSG-PL-system

Implementing Gibsonian Virtual Environments

. We speculate on the possibilities for a realization of the idea of a threedimensional Cyberspace, as sketched in the novels of William Gibson using today's technology. Virtual reality and global networks such as the Internet together can provide the fundamentals for such an effort. From an examination of the technological principles of a Gibsonian virtual environment, we conclude what properties such an implementation must have. An implementation of a system with these properties faces a number of problems in the large and in the small; especially, the semantics of the virtual environment and its inhabitants must be defined. We also report on our ongoing implementation of a prototype software system which was designed to evaluate the feasibility of these ideas. 1. Introduction In his famous novel "Neuromancer" [Gibs84], William Gibson presents the idea of the Cyberspace, a sensual representation of a global, networked database that is presented to the user directly by brain stimula..

Demand-Driven Geometry Transmission for Distributed Virtual Environments

We present a strategy for rendering in distributed virtual environments. A geometry database is maintained by a server, while users invoke individual clients to interact with the environment. Instead of downloading a complete copy of the geometry data, the data is distributed on demand, thus gaining significant savings in network bandwidth. Our strategy combines several techniques, including levels of detail, progressive refinement and graceful degradation to deliver the data "just in time" over the network to the rendering process. The method allows operate on a tight resource budget, which important if attempting to use low cost systems for virtual reality applications