René Rosenbaum

Rate-distortion optimized interactive browsing of JPEG2000 images

This paper is concerned with remote browsing of JPEG2000 compressed imagery. A potentially interactive client identifies a region and maximum resolution of interest. The server responds by sending information from the JPEG2000 code-stream which is relevant to this region and resolution. We propose an algorithm for sequencing data from the original code-stream in such a way as to maximize the received image quality within the region of interest, at each point in the transmission. The proposed R-D optimal sequencing algorithm is demonstrated in the context of two quite different client-server paradigms, one of which is consistent with the evolving JPIP (JPEG2000 Internet protocols) standard. Performance improvements as large as 8 dB are achieved with respect to a layer progressive sequencing strategy.

Flexible, dynamic and compliant region of interest coding in JPEG2000

Image transmission with JPEG2000 can be speeded up by using regions of interest (RoIs). By such a mechanism, parts of an image not belonging to RoIs can be transmitted later or encoded at a lower bit rate. This paper describes a flexible dynamic RoI-scheme which supports the definition and handling of arbitrarily-shaped RoIs in JPEG2000. The scheme supports the dynamic definition and prioritization of new and existing RoIs at any time during image transmission. This can be done without having to decode and re-encode the JPEG2000 datastream. To reach this, we use the flexible precinct/layer-mechanism of the standard. The proposed scheme is fully compliant with the JPEG2000-baseline-codec.

Grid-based interaction for effective image browsing on mobile devices

Compared with stationary environments, mobile devices suffer from a number of limitations like small screen space, limited processing power and bandwidth. Thus, it is very difficult and expensive to browse large images by using current mobile hardware. In this publication a new image browsing technique especially designed for mobile devices with limited screen space is introduced, and a completely new concept to communicate important image properties based on a well-defined grid structure is proposed. As every browsing technique needs reasonable concepts for user interaction, this publication introduces intuitive ways for image exploration, which need only little action of the user during browsing and processing power to calculate an appropriate image representation. To decrease the need for expensive bandwidth in remote environments, it will also be shown how to combine this browsing technique with image compression and transmission. Thus,a whole system for image communication is presented. Due to its excellent compression performance and flexibility, the modern JPEG2000 image coding standard is adopted as a foundation of the proposed system regarding a compliant compression and efficient transmission of the image. Concrete performance measures show the applicability of the introduced system.

Progressive refinement: more than a means to overcome limited bandwidth

Progressive refinement is commonly understood as a means to solve problems imposed by limited system resources. In this publication, we apply this technology as a novel approach for information presentation and device adaptation. The progressive refinement is able to handle different kinds of data and consists of innovative ideas to overcome the multiple issues imposed by large data volumes. The key feature is the mature use of multiple incremental previews to the data. This leads to a temporal deskew of the information to be presented and provides a causal flow in terms of a tour-through-the-data. Such a presentation is scalable leading to a significantly simplified adaptation to the available resources, short response times, and reduced visual clutter. Due to its rather beneficial properties and feedback we received from first implementations, we state that there is high potential of progressive refinement far beyond its currently addressed application context.

Progressive parallel coordinates

Progressive refinement is a methodology that makes it possible to elegantly integrate scalable data compression, access, and presentation into one approach. Specifically, this paper concerns the effective use of progressive parallel coordinates (PPCs), utilized routinely for high-dimensional data visualization. It discusses how the power of the typical stages of progressive data visualization can also be utilized fully for PPCs. Further, different implementations of the underlying methods and potential application domains are described. The paper also presents empirical results concerning the benefits of PPC with regard to efficient data management and improved presentation, indicating that the proposed approach is able to close the gap between data handling and visualization.

JPEG2000-based image communication for modern browsing techniques

The size of large images often exceeds the display area of the users output device. To present such images appropriately sophisticated image browsing techniques have been developed. To achieve a better image comprehension, these techniques combine detailed and distorted image regions in a variety of ways. However, much of the commonly transmitted image data is discarded during the creation of the representation. Our proposal for remote image browsing is to limit the image transmission to data mandatory to represent the image within a certain browsing technique without loss of information. In this publication a systematic view on image communication for different browsing techniques is presented. It can be shown that an appropriate linkage and combination of all communication steps can significantly improve the performance of the whole system. Based on Regions of Interest and Levels of Detail, a classification of current image browsing approaches is presented, in order to characterize these techniques regarding their representation of the image. Based on this, appropriate strategies for image compression and transfer are derived and guidelines for the design of remote image browsing systems are given. Due to its excellent compression performance and numerous features, the JPEG2000 standard is adopted as a foundation of the proposed scheme regarding compression and efficient transmission of the image.

A flexible low-complexity device adaptation approach for data presentation

Visual data presentations require adaptation for appropriate display on a viewing device that is limited in re- sources such as computing power, screen estate, and/or bandwidth. Due to the complexity of suitable adaptation, the few proposed solutions available are either too resource-intensive or in exible to be applied broadly. Eective use and acceptance of data visualization on constrained viewing devices require adaptation approaches that are tailored to the requirements of the user and the capabilities of the viewing device. We propose a predictive device adaptation approach that takes advantage of progressive data renement. The approach relies on hierarchical data structures that are created once and used multiple times. By incrementally reconstructing the visual presentation on the client with increasing levels of detail and resource utilization, we can determine when to truncate the renement of detail so as to use the resources of the device to their full capacities. To determine when to nish the renement for a particular device, we introduce a prole-based strategy which also considers user preferences. We discuss the whole adaptation process from the storage of the data into a scalable structure to the presentation on the respective viewing device. This particular implementation is shown for two common data visualization methods, and empirical results we obtained from our experiments are presented and discussed.

Structural decomposition trees

Researchers and analysts in modern industrial and academic environments are faced with a daunting amount of multi‐dimensional data. While there has been significant development in the areas of data mining and knowledge discovery, there is still the need for improved visualizations and generic solutions. The state‐of‐the‐art in visual analytics and exploratory data visualization is to incorporate more profound analysis methods while focusing on fast interactive abilities. The common trend in these scenarios is to either visualize an abstraction of the data set or to better utilize screen‐space.

Progressive Presentation of Large Hierarchies Using Treemaps

The presentation of large hierarchies is still an open research question. Especially, the time-consuming calculation of the visualization and the cluttered display lead to serious usability issues on the viewer side. Existing solutions mainly address appropriate visual representation and usually neglect considering system resources. We propose a holistic approach for the presentation of large hierarchies using treemaps and progressive refinement . The key feature of the approach is the mature use of multiple incremental previews of the data. These previews are well-designed and lead to reduced visual clutter and a causal flow in terms of a tour-through-the-hierarchy . The inherent scalability of the data thereby allows for a reduction in the consumed resources and short response times . These characteristics are substantiated by the results we achieved from a first implementation. Due to its many beneficial properties, we conclude that there is much potential for the use of progressive refinement in visualization.

Remote raster image browsing based on fast content reduction for mobile environments

Enhanced browsing techniques for digital imagery and small displays facilitate the exploration process of large images often by using new ways to represent the image. Reduction of image content is such an approach mostly linked with need for strong processing power. To overcome this, we propose the use of the Discrete Wavelet Transform (DWT), which inherently separates detail and approximation of the image. By enhancing the detail and removing the approximation directly in wavelet domain, a very fast content reduction can be achieved. Due to its flexibility, JPEG2000 is used as basis for an efficient system for remote image browsing. To satisfy demands which are imposed by the use of current mobile hardware, every stage of the image communication pipeline is adapted and tightly coupled to the used browsing technique to reduce the need for processing power and bandwidth.