Browse Prior Art Database

Randomized Data Ordering for Transform Encoded Data

IP.com Disclosure Number: IPCOM000108190D
Original Publication Date: 1992-Apr-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 51K

Publishing Venue

IBM

Related People

Feig, E: AUTHOR [+2]

Abstract

A scheme is disclosed for the ordering of image transform data. When the scheme is used, the effects of channel errors are less severe than when standard techniques are used.

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Randomized Data Ordering for Transform Encoded Data

      A scheme is disclosed for the ordering of image transform data.
When the scheme is used, the effects of channel errors are less
severe than when standard techniques are used.

      Instead of organizing the blocks in the usual way, the blocks
are first permuted according to a psudo-random permutation known to
both encoder and decoder.  The invention disclosed here is used for
fixed-rate compression. Let the desired average number of compressed
bits per block be b.  Segment the image into groups of n blocks and
adjust the quantization for each group so that each group uses bn
bits.  If block error control is used, then the size of (uncoded)
data blocks should be factors of bn bits.  Each group of n blocks
will likely contain blocks from smooth and rough parts of the image,
so that enforcing an average bit rate over the group will not be much
worse than enforcing an average rate over the whole image.
Uncorrected errors will not propagate beyond a group, so an
uncorrected error will only cause errors in a small part of the
image.

      Disclosed anonymously.