Browse Prior Art Database

Nonlinear Encoding for Image Data Transmission

IP.com Disclosure Number: IPCOM000108832D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 97K

Publishing Venue

IBM

Related People

Feig, E: AUTHOR [+2]

Abstract

Disclosed is a nonlinear encoding method for achieving prescribed uniform reliability for various segments of image data, such as for HDTV and satellite transmission of image data. The scheme can be customized to meet channel constraints.

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This is the abbreviated version, containing approximately 52% of the total text.

Nonlinear Encoding for Image Data Transmission

       Disclosed is a nonlinear encoding method for achieving
prescribed uniform reliability for various segments of image data,
such as for HDTV and satellite transmission of image data.  The
scheme can be customized to meet channel constraints.

      This invention is concerned with image data which is
transmitted over a channel with a priori known signal-to-noise
characteristics, as a function of frequency.  A motivating example is
provided by HDTV (High Definition TV), where the transmission of
image data is over a channel constrained by legal requirements.  The
most common constraint is that the channel reside (in frequency)
between two presently existing channels whose frequency supports are
separated by about 6 MHz, and each of whose signals leak onto this
separation band.  Thus transmission is limited to what we will call a
"fixed constrained channel."

      Fourier transform (FT) coding, as described in (1-5), is ideal
for transmitting over constrained channels.  Here, the FT codes will
be baseband and then modulated by a carrier frequency to their proper
passband.  Here, we call such methods Fourier Transform Coded
Modulation (FTCM) schemes.

      The invension calls for passing the image data (actual image
data for initial image, and difference image for subsequent images
until reinitialization) through a 2-dimensional filter bank of L
filters, yielding L strings of numbers.  By image we mean to include
any portion of the image which is to be transmitted independently.

      Each of the L strings is encoded with some fixed prescribed
reliability, as described in (5-6).  The invention here is concerned
with the generation of constellations specific to the image data at
hand.  In general, strings corresponding to lower frequencies in the
image are encoded with greater reliability.  Several strings may be
encoded simultaneously with possibly different prescribed
reliabilities along corresponding utilized subchannels.

      The various subchannels Cj encoded integers mk with m some
positive integer and -K<k<K.  These are encoded as levels aj,k, and
each level appears with probability Pj(k).  With image data and the
standard subband coding techniques, it is assumed that Pj(-...