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Method and apparatus for correcting errors in a transmitted video signal

  • US 5,751,361 A
  • Filed: 12/20/1996
  • Issued: 05/12/1998
  • Est. Priority Date: 12/23/1995
  • Status: Expired due to Term
First Claim
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1. A method, for use in a video signal decoding system, for concealing errors in a video signal transmitted in a compressed form, wherein the video signal is divided into a plurality of blocks each of which has N×

  • M pixel values with N and M being positive integers, the method comprising the steps of;

    (a) detecting a lost block containing errors;

    (b) providing pixel values of blocks neighboring the lost block in the video signal;

    (c) calculating an edge gradient at each of neighboring pixels included in a predetermined range of pixels surrounding the lost block based on the pixel values of the neighboring blocks and computing a magnitude and an angle of each of the edge gradients;

    (d) generating a spatially interpolated block based on the edge gradients and the pixel values of the neighboring blocks; and

    (e) providing the spatially interpolated block as a substitution block for compensating the lost block,wherein the step (d) includes the steps of;

    (d1) classifying the angle of the edge gradient at each of the neighboring pixels along with one of predetermined directional indicators with which the angle of the edge gradient is most closely aligned;

    (d2) if a line drawn through a neighboring pixel location along the direction determined by the angle of the gradient at the neighboring pixel passes through the lost block, determining that particular pixel as a voting pixel;

    (d3) summing up the magnitudes of the gradients aligned with each directional indicator in order to mutually exclusively accumulate the directional indicators of the voting pixels;

    (d4) selecting the directional indicator exhibiting a largest accumulated sum as a pixel interpolation direction by comparing the sum of the magnitudes for each of the directional indicators with one another;

    (d5) comparing the largest accumulated sum with a predetermined threshold value; and

    (d6) if the largest accumulated sum is larger than or equal to the predetermined threshold value, producing the spatially interpolated block through the use of a directional interpolation based on pixel values of the neighboring blocks along the pixel interpolation direction.

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