Method and apparatus for correcting errors in a transmitted video signal

Claim 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.

Claim 2

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.

Claim 12

An apparatus, 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, which comprises: means for detecting a lost block containing errors; means for providing pixel values of blocks neighboring the lost block in the video signal; a gradient calculation means for computing 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 calculating a magnitude and an angle of each of the edge gradients; a direction determination means for determining a pixel interpolation direction based on the edge gradients of neighboring pixels; a block generation means for producing a spatially interpolated block based on the pixel values of the neighboring blocks and the pixel interpolation direction; and a contribution means for providing the spatially interpolated block as a substitution block for compensating the lost block, wherein the gradients are computed through the use of a Sobel operator.

Claim 13

An apparatus, 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, which comprises: means for detecting a lost block containing errors; means for providing pixel values of blocks neighboring the lost block in the video signal; a gradient calculation means for computing 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 calculating a magnitude and an angle of each of the edge gradients; a direction determination means for determining a pixel interpolation direction based on the edge gradients of neighboring pixels; a block generation means for producing a spatially interpolated block based on the pixel values of the neighboring blocks and the pixel interpolation direction; and a contribution means for providing the spatially interpolated block as a substitution block for compensating the lost block, wherein the gradients are computed through the use of a Sobel operator.

Claim 15

An apparatus, 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, which comprises: means for detecting a lost block containing errors; means for providing pixel values of blocks neighboring the lost block in the video signal; a gradient calculation means for computing 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 calculating a magnitude and an angle of each of the edge gradients; a direction determination means for determining a pixel interpolation direction based on the edge gradients of neighboring pixels; a block generation means for producing a spatially interpolated block based on the pixel values of the neighboring blocks and the pixel interpolation direction; and a contribution means for providing the spatially interpolated block as a substitution block for compensating the lost block, wherein the direction determination means includes: means for 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; means for determining, 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, that particular pixel as a voting pixel; means for 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; and means for selecting the directional indicator exhibiting a largest accumulated sum as the pixel interpolation direction by comparing the sum of the magnitudes for each of the directional indicators with one another.

Claim 16

An apparatus, 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, which comprises: means for detecting a lost block containing errors; means for providing pixel values of blocks neighboring the lost block in the video signal; a gradient calculation means for computing 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 calculating a magnitude and an angle of each of the edge gradients; a direction determination means for determining a pixel interpolation direction based on the edge gradients of neighboring pixels; a block generation means for producing a spatially interpolated block based on the pixel values of the neighboring blocks and the pixel interpolation direction; and a contribution means for providing the spatially interpolated block as a substitution block for compensating the lost block, wherein the direction determination means includes: means for 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; means for determining, 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, that particular pixel as a voting pixel; means for 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; and means for selecting the directional indicator exhibiting a largest accumulated sum as the pixel interpolation direction by comparing the sum of the magnitudes for each of the directional indicators with one another.