Method and apparatus for concealing errors in a transmitted video signal

Claim 1

A method for concealing channel errors in an image signal, wherein the image signal is divided into a multiplicity of blocks of M×N pixels, M and N being positive integers, respectively, the method comprising the steps of: (a) detecting a lost region, wherein the lost region is of a polygonal form having a plurality of sides and includes one or more connected lost blocks, each lost block containing a channel error; (b) finding a reference region of pixels, wherein the reference region includes a plurality of groups of first pixels and a corresponding number of groups of second pixels, each group of first pixels being adjacent to a side of the lost region and each group of second pixels being adjacent to a group of first pixels, each group of first pixels being placed between a group of second pixels and the lost region; (c) determining edge pixels among the pixels within the reference region, each edge pixel having a non-zero valued edge magnitude, the edge magnitude for an edge pixel representing differences between pixels residing adjacent to the edge pixel; (d) detecting edge points, each of the edge points representing an edge pixel having a largest edge magnitude among edge pixels included in a group of first pixels and a group of second pixels for a side of the lost region; and (e) rectifying the channel errors of the lost region by compensating all pixels within the lost region based on the edge points and the pixels of the reference region; wherein said rectifying step includes the steps of: (e1) if two or more edge points are detected, determining two edge points of a first and second largest edge magnitudes as primary edge points and dividing the lost region into two or more subregions by a primary line passing through the primary edge points; (e2) if fewer than two edge points are deleted, setting the lost region itself as a subregion; and (e3) rectifying the channel errors by compensating pixels within each subregion based on the pixels of the reference region.

Claim 2

A method for concealing channel errors in an image signal, wherein the image signal is divided into a multiplicity of blocks of M×N pixels, M and N being positive integers, respectively, the method comprising the steps of: (a) detecting a lost region, wherein the lost region is of a polygonal form having a plurality of sides and includes one or more connected lost blocks, each lost block containing a channel error; (b) finding a reference region of pixels, wherein the reference region includes a plurality of groups of first pixels and a corresponding number of groups of second pixels, each group of first pixels being adjacent to a side of the lost region and each group of second pixels being adjacent to a group of first pixels, each group of first pixels being placed between a group of second pixels and the lost region; (c) determining edge pixels among the pixels within the reference region, each edge pixel having a non-zero valued edge magnitude, the edge magnitude for an edge pixel representing differences between pixels residing adjacent to the edge pixel; (d) detecting edge points, each of the edge points representing an edge pixel having a largest edge magnitude among edge pixels included in a group of first pixels and a group of second pixels for a side of the lost region; and (e) rectifying the channel errors of the lost region by compensating all pixels within the lost region based on the edge points and the pixels of the reference region; wherein said rectifying step includes the steps of: (e1) if two or more edge points are detected, determining two edge points of a first and second largest edge magnitudes as primary edge points and dividing the lost region into two or more subregions by a primary line passing through the primary edge points; (e2) if fewer than two edge points are deleted, setting the lost region itself as a subregion; and (e3) rectifying the channel errors by compensating pixels within each subregion based on the pixels of the reference region.

Claim 8

A method for concealing channel errors in an image signal, wherein the image signal is divided into a multiplicity of blocks of M×N pixels, M and N being positive integers, respectively, the method comprising the steps of: (a) detecting a lost region, wherein the lost region includes one or more lost blocks connected together, each lost block containing a channel error; (b) finding a reference region of pixels, wherein the reference region is a group of pixels residing outside the lost region; (c) obtaining edge lines in the reference region, each edge line being formed by edge pixels connected together; (d) determining primary lines among the edge lines, each primary line being an edge line traversing the lost region; and (e) rectifying channel errors of the lost region by compensating pixels of the lost region based on the primary lines and the pixels of the reference regions; wherein said rectifying step (e) includes the steps of: (e1) finding edge points, an edge point representing an edge pixel having a largest edge magnitude among edge pixels of the primary lines included in a set of first neighboring pixels for a side of the lost region; (e2) if the number of edge points is fewer than two, setting the lost region as a subregion and if the number of edge points is greater than one, dividing the lost region into two or more subregions by a primary line passing through two primary edge points, the primary edge points being edge points of a first and a second largest edge magnitude; and (e3) compensating pixels of each subregion with substitution data obtained based on the pixels of the reference region, thereby rectifying the channel errors of the lost region.

Claim 9

A method for concealing channel errors in an image signal, wherein the image signal is divided into a multiplicity of blocks of M×N pixels, M and N being positive integers, respectively, the method comprising the steps of: (a) detecting a lost region, wherein the lost region includes one or more lost blocks connected together, each lost block containing a channel error; (b) finding a reference region of pixels, wherein the reference region is a group of pixels residing outside the lost region; (c) obtaining edge lines in the reference region, each edge line being formed by edge pixels connected together; (d) determining primary lines among the edge lines, each primary line being an edge line traversing the lost region; and (e) rectifying channel errors of the lost region by compensating pixels of the lost region based on the primary lines and the pixels of the reference regions; wherein said rectifying step (e) includes the steps of: (e1) finding edge points, an edge point representing an edge pixel having a largest edge magnitude among edge pixels of the primary lines included in a set of first neighboring pixels for a side of the lost region; (e2) if the number of edge points is fewer than two, setting the lost region as a subregion and if the number of edge points is greater than one, dividing the lost region into two or more subregions by a primary line passing through two primary edge points, the primary edge points being edge points of a first and a second largest edge magnitude; and (e3) compensating pixels of each subregion with substitution data obtained based on the pixels of the reference region, thereby rectifying the channel errors of the lost region.

Claim 14

An apparatus for decoding a transmitted video signal containing channel errors, comprising: means for decoding the transmitted video signal to provide an image signal, the image signal being divided into a multiplicity of block of M×N pixels with M and N being positive integers, respectively; means for storing the image signal; means for detecting a reference region and retrieving reference region data from the storing means for a lost region, wherein the lost region represents a group of channel error containing blocks connected together and the reference region data denote pixel values of the reference region, the lost region being a polygon having a plurality of sides; means for finding in the reference region edge lines traversing the lost region; and means for determining pixel data of the lost region based on the reference region data and the traversing edge lines to thereby store the determined pixel data in the storing means; wherein determining means includes: means for obtaining an edge point for each side of the lost region, the edge point representing an edge pixel having a largest edge magnitude among edge pixels of traversing edge lines residing within a predetermined range from said each side; means for setting the lost region as a subregion if fewer than two edge points is obtained; means for setting two edge points of a first and a second largest edge magnitudes as primary edge points if two or more edge points are obtained, and dividing the lost region into two or more subregions by a primary line passing through the primary edge points; and means for estimating pixel data of each subregion based on adjacent pixels of the reference region to sides of said each subregion and determining pixel data for the subregions as the pixel data of the lost region to be stored in the storing means.

Claim 15

An apparatus for decoding a transmitted video signal containing channel errors, comprising: means for decoding the transmitted video signal to provide an image signal, the image signal being divided into a multiplicity of block of M×N pixels with M and N being positive integers, respectively; means for storing the image signal; means for detecting a reference region and retrieving reference region data from the storing means for a lost region, wherein the lost region represents a group of channel error containing blocks connected together and the reference region data denote pixel values of the reference region, the lost region being a polygon having a plurality of sides; means for finding in the reference region edge lines traversing the lost region; and means for determining pixel data of the lost region based on the reference region data and the traversing edge lines to thereby store the determined pixel data in the storing means; wherein determining means includes: means for obtaining an edge point for each side of the lost region, the edge point representing an edge pixel having a largest edge magnitude among edge pixels of traversing edge lines residing within a predetermined range from said each side; means for setting the lost region as a subregion if fewer than two edge points is obtained; means for setting two edge points of a first and a second largest edge magnitudes as primary edge points if two or more edge points are obtained, and dividing the lost region into two or more subregions by a primary line passing through the primary edge points; and means for estimating pixel data of each subregion based on adjacent pixels of the reference region to sides of said each subregion and determining pixel data for the subregions as the pixel data of the lost region to be stored in the storing means.