for being scalable and interoperable in network and
mobile environments (Sarraf and Wakim, 2007;
Rosenbaum and H. Schumann, 2006). Levels of
detail, regions of interest and progressive
transmission are popular concepts for handling
graphical data in resource-limited environments
(Rauschenbach and Schumann, 1999). Thererfore,
the J2K standard is presented as a suitable tool to
address a proper streaming and visualization on
mobile devices.
Several works have explored the possibilities to
access to J2K content by optimizing the interactive
navigation, by proposing distribution protocols,
management of client/server platforms, cache and
prefetching strategies, among others (Taubman and
Rosenbaum, 2003; Descampe, et al., 2007); (Iregui
et al., 2007); (Deshpande and Zeng, 2001); (Iregui et
al., 2002); (Iregui et al., 2002); (Meessen et al.,
2003); (Moshfeghi and Ta, 2004). However these
works do not consider the problem of minimal
available capabilities of mobile devices.
In the mobile field, some works have focused on
areas such as reliability and error resilience over
noisy channels (Ho and Kahn, 1997) and content
delivery security (Díaz et al., 2006). Liu et al (2003)
presented a model for browsing of images on small
displays, however they work with images of range of
1600x1200 pixels; this model is not applicable to
very large images, as satellite imaging, which may
have sizes of more than 15000x15000 pixels.
Rosenbaum and Schumann (2006) proposed a model
for viewer guidance for mobile devices by exploiting
the J2K features; their solution requires to filling the
omitted code-stream positions with predefined data
to keep it compliant and can be decoded, however,
this solution is not applicable to very large images
because if the area to be processed and decoded is
very large, the required processing time and memory
may exceed the capacities of the device. Otherwise,
Google Earth is a well-known application for
accessing to large satellite images that runs on
desktop computers and mobile devices. It uses a
very large set of hierarchy prerendered tiles of
different spatial resolutions, then, each time a user
increases the level detail of the image, a new set of
images is loaded (MicroImages, Inc., 2010). In this
way, the application requires a complex organization
and hierarchy of files and directories and a big
amount of space to store the whole image.
Furthermore, this application only works with the
provided images and does not allow using different
ones.
The present investigation introduces
anarchitectural model to allow optimal interaction
with very large images of general purpose from
mobile devices. The proposed model facilitates a
mobile client to browse very large remote images by
displaying regions in a flexible and scalable way,
offering a nearly seamless navigation, adapted to the
restricted capabilities of the devices and the channel
bandwidth. This represents an advantage over
available applications that do not allow accessing
and navigation in very large images or regions in full
quality and resolution. Moreover, the proposed
architecture is modular and decoder independent,
permitting thereby easy adaptation to new models
and specialized applications.
This paper is organized as follows. In section 2, a
brief overview of JPEG2000 standard is presented.
Section 3 introduces the proposed model for
streaming and visualization of high definition
images on mobile devices. In Section 4, an
implementation of the proposed model is presented.
In section 5, experimental results are reported,
providing evidence of the performance and efficacy
of the model. Finally, section 6 presents brief
conclusions.
2 JPEG2000 OVERVIEW
JPEG2000 is an image compression standard
designed by the Joint Photographic Expert Group,
based on the Discrete Wavelet Transform and the
EBCOT encoder (ISO/IEC 15444-1, 2000). This
standard provides several advantages such as
improved compression efficiency, lossy and lossless
compression, multiple resolution representation,
random code-stream access and processing and
quality refinement (Rabbani and Rajan, 2002).
A single J2K data stream typically contains
numerous embedded subsets, which may be
extracted to recover a portion of the original image
at any of a large number of different spatial
resolutions, image quality layers, or in selected
spatial regions. A J2K image is split into rectangular
regions that are encoded independently, called tiles,
but also defines collections of spatially adjacent
code-blocks, known as precincts. Each precinct is
represented as a collection of packets, with one
packet for each quality layer, resolution level and
component. These embedded compressed data
subsets allow a low quality or low resolution image,
or one whose details cover only a small spatial
region, to be incrementally improved by adding the
missing elements from the compressed data stream
(Taubman, 2002).
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