Focusing on digital imagery, this paper introduces a strategy to handle heterogeneous hardware in mobile environments.
Constrained system resources of most mobile viewing devices require contents that are tailored to the
requirements of the user and the capabilities of the device. Appropriate image adaptation is still an unsolved
research question. Due to the complexity of the problem, available solutions are either too resource-intensive or
inflexible to be more generally applicable.
The proposed approach is based on scalable image compression and progressive refinement as well as data
and user profiles. A scalable image is created once and used multiple times for different kinds of devices and
user requirements. Profiles available on the server side allow for an image representation that is adapted to
the most important resources in mobile computing: screen space, computing power, and the volume of the
transmitted data. Options for progressively refining content thereby allow for a fluent viewing experience during
adaptation. Due to its flexibility and low complexity, the proposed solution is much more general compared
to related approaches. To document the advantages of our approach we provide empirical results obtained in
experiments with an implementation of the method.
A widely applicable approach to visualizing properties of high-dimensional data is to view the data as a linear
projection into two- or three-dimensional space. However, developing an appropriate linear projection is often
difficult. Information can be lost during the projection process, and many linear projection methods only apply
to a narrow range of qualities the data may exhibit. We propose a general-purpose genetic algorithm to develop
linear projections of high-dimensional data sets which preserve a specified quality of the data set as much as
possible. The obtained results show that the algorithm converges quickly and reliably for a variety of different
data sets.
KEYWORDS: Thulium, Visualization, Small screens, Visual analytics, Data communications, Data modeling, Data visualization, Data analysis, Hardware testing, Statistical analysis
In this paper, we evaluate progressive treemaps (PTMs). Progressive refinement has a long tradition in image
communication, but is a novel approach for information presentation. Besides technical benefits it also promises
to provide advantages important for the conveyance of data properties. In this first user study in this domain, we
focus on the additional value of progressive refinement for traditional treemaps to convey the topology of a given
hierarchical data set and properties of its nodes. To achieve this, we compare the results gained for common
squarified treemap displays with and without progression for various related tasks and set-ups. The results we
obtained indicate that PTMs allow for a better conveyance of topological features and node properties in most
set-ups. We also assessed the opinions of our study participants and found that PTMs also lead to a better
confidence about the given answers and provide more assistance and user friendliness.
KEYWORDS: Visualization, Raster graphics, Image quality, Mobile communications, Image transmission, Logic, Image compression, Computer programming, Data communications, Chemical elements
Vector graphics can be scaled without loss of quality, making them suitable for mobile image communication
where a given graphics must be typically represented in high quality for a wide range of screen resolutions. One
problem is that file size increases rapidly as content becomes more detailed, which can reduce response times
and efficiency in mobile settings. Analog issues for large raster imagery have been overcome using progressive
refinement schemes. Similar ideas have already been applied to vector graphics, but an implementation that is
compliant to a major and widely adopted standard is still missing. In this publication we show how to provide
progressive refinement schemes based on the extendable Scalable Vector Graphics (SVG) standard. We propose
two strategies: decomposition of the original SVG and incremental transmission using (1) several linked files and
(2) element-wise streaming of a single file. The publication discusses how both strategies are employed in mobile
image communication scenarios where the user can interactively define RoIs for prioritized image communication,
and reports initial results we obtained from a prototypically implemented client/server setup.
KEYWORDS: Visualization, Data storage, Data visualization, Data storage servers, Mobile devices, Spatial resolution, Visual analytics, Electroluminescence, Image resolution, Data analysis
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.
Progressive refinement is a well-established approach to overcome bandwidth limitations in mobile environments. One outstanding benefit compared to relates approaches is the provision of meaningful content previews during data transfer or processing. Although highly relevant and useful, however, related literature only addresses the
support of this functionality by certain communication stages or proposes systems for specific use cases. No publication is concerned with an abstraction or formalization of progression or takes advantage of its beneficial properties in other application fields.
In this publication we want to give a general view to progression, its key concepts, attributes, and common data processing pipeline. Thereby, we abstract from specifics and usage scenarios in order to simplify the development of new algorithms and schemes and to derive guidelines for its general application. To show that progression is also able to solve problems beyond limited bandwidth, this contribution is also concerned with the introduction of new application areas. The novel idea of content-oriented refinement allows emphasizing important image regions by an animated tour-through-the-data. It will also be shown that progressive representations are a very effective means for device adaptation. Both applications are motivated, discussed, and illustrated by
different examples.
Due to resource limitations, the handling of large imagery in mobile environments is still problematic. This
applies especially for browsing and navigation tasks. As existing technology fails to adapt to restrictions, new
ideas for appropriate image handling are required.
This publication proposes a new approach for image browsing based on JPEG2000, blurring, and progressive
refinement. Blurring is an effective means for user guidance and thus is selected and combined with progression to
increase usability aspects during browsing. The resource-saving implementation of the user interface is founded
on the image compression standard JPEG2000. The DiscreteWavelet Transform and options for Random Spatial
Access are the main features we take advantage of in order to extract the user interface directly from the encoded
image data. A discussion of the results shows that this approach saves valuable computing power and bandwidth
compared to traditional technology, and is an appropriate means to support browsing of large imagery on mobile
devices.
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.
This contribution motivates and proposes the new idea of embedding and hiding a highlighting of particular
regions within a raster image. Existing approaches tightly combine content and means for highlighting, and
thus, do not allow access control to the emphasized contents or a removal of the accentuation. This is overcome
by the introduced approach taking advantage of the Depth of Field effect of the Human Visual System for
highlighting and features of the JPEG2000 image coding standard for its fast implementation. The proposed
method can be applied to already encoded or plain imagery. The achieved results show that hidden context
highlighting is rather appropriate for emphasizing pre-defined image regions and able to control the access to
the respective contents.
The available screen space of common mobile hardware is little compared to stationary devices. This leads to
significant usability problems if large imagery is to be displayed. This can be overcome by an appropriate user
interface in terms of an image browsing technique. Such an interface consists of the two main parts content
representation and means for interaction. However, many existing techniques do not consider the limitations of
mobile environments. To overcome them, this publication proposes 3 new interactive image browsing techniques
based on approaches from general content browsing. To consider remote environments, it is also shown how to
combine each technique with a dynamic image streaming strategy significantly decreasing the transmitted data
volume. Overall, a significant enhancement regarding representation, interaction and use of bandwidth compared
to traditional strategies could be achieved by the introduced image browsing techniques.
Due to limitations of mobile environments, the handling of imagery is still problematic. This becomes especially
apparent if two images are to be blended in order to create a smooth transition. As existing techniques fail to
adapt to the restrictions of mobile environments, new ideas for the appropriate implementation of the blending
are required. This publication proposes a new approach for the creation of transitions for mobile hardware. The
foundation are the different features of the new image compression standard JPEG2000. The main properties
used within the proposed strategy are the Discrete Wavelet Transform as integral part of the codec and the
options for Random Spatial Access within the data-stream. Based on this, different options to blend contents
of two images in JPEG2000-domain either in stationary as well as remote environments are introduced. A
discussion of the results shows that this saves valuable computing power, is able to be applied to partial image
data and achieves better visual results than traditional approaches. Thus, it is appropriate to apply the proposed
approach to support the browsing of image sequences within mobile devices.
The size of large images often exceeds the display area of the user's 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.
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.
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