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Methods and apparatus for preventing rounding errors when transform coefficients representing a motion picture signal are inversely transformed

DC
  • US 5,481,553 A
  • Filed: 02/28/1994
  • Issued: 01/02/1996
  • Est. Priority Date: 03/01/1993
  • Status: Expired due to Term
First Claim
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1. A method of processing a set of transform coefficients, each of the transform coefficients having parity, to provide an error-immune set of transform coefficients for processing by an inverse orthogonal transform, the error-immune set of transform coefficients being immune to rounding errors when subject to the inverse orthogonal transform, the method comprising the steps of:

  • summing the transform coefficients in the set to provide a sum, the sum having parity;

    judging the parity of the sum;

    when the parity of the sum is even, inverting the parity of one of the transform coefficients in the set to provide a parity-inverted transform coefficient, the parity-inverted transform coefficient making the parity of the sum odd; and

    providing the transform coefficients including the parity-inverted transform coefficient as the error-immune set.

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