Browse Prior Art Database

Window of Focus for Variable Resolution Display of Video

IP.com Disclosure Number: IPCOM000105822D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 6 page(s) / 253K

Publishing Venue

IBM

Related People

Singh, A: AUTHOR

Abstract

Digital video is a well-established component of multimedia system; this is primarily a result of the nature of visual information, which cannot easily be conveyed in text or sound alone. However, the added information conveyed by images comes at a price; images require vast amounts of data for digital representation. The problem of transmitting and displaying the large amount of data associated with images mandates the development of more efficient methods for coding and display. In addition to compressing this data, greater flexibility is necessary in coding schemes to allow receivers to most efficiently allocate resources.

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Window of Focus for Variable Resolution Display of Video

      Digital video is a well-established component of multimedia
system; this is primarily a result of the nature of visual
information, which cannot easily be conveyed in text or sound alone.
However, the added information conveyed by images comes at a price;
images require vast amounts of data for digital representation.  The
problem of transmitting and displaying the large amount of data
associated with images mandates the development of more efficient
methods for coding and display.  In addition to compressing this
data, greater flexibility is necessary in coding schemes to allow
receivers to most efficiently allocate resources.

      The concept of scalability in image representation [1] recently
in an attempt to instill greater granularity in resolution.
Scalability centers on the notion that the decoder should dynamically
allocate processing resources, image size, and bandwidth without
prior knowledge at the encoder.  When parameters of the system change
as the demands on the system change,  scalability becomes a necessary
attribute.  For example, if one system allows decoding and
presentation of a 160x120 image in a second and another possess
enough processing power to allow decoding of a 640x480 image in a
second, a scalable coding scheme would produce a single data stream
that may be decoded by either system by selecting an appropriate
subset of the data stream.  For a more technical definition,
scalability in an algorithm may be interpreted as a combination of
allowing the receiver to select a subset of transmitted bits to
reconstruct an image, allowing the receiver to employ a set of
decoding schemes that have varying degrees of complexity, and causing
image quality to vary with the complexity of the decoder.  The
approach discussed here will add another degree of freedom at the
receiver, whereby scalability will be extended to allow variable rate
decoding within an image.  This "window of focus" algorithm presents
a novel means for image delivery within a multimedia environment by
allowing the user to specify regions of greater importance.  In
contrast, current systems only allow resolutions to vary from lower
to higher for an entire image.

      One consequence of scalability is the need for a hierarchical
scheme for image coding.  By introducing an ordering of the coded
information, it facilitates variable rate decoding at the receiver.
One is subband coding.  Subband coding creates a pyramid structure in
frequency (Figs. 1 and 2) by recursively filtering an image sequence
to separate it into its vertical and horizontal components [4].  The
pyramid refers to the levels of separation created by filtering.
Lower levels in the pyramid contain more information, while higher
levels contain successively less information.  In employing this
scheme for data reduction, subbands are normally discarded or
retained in their entirety (subject to redundancy...