Adaptive comb filter for artifact-free decoding

Claim 2

An adaptive comb filter comprising: a) a filter input for receiving a composite video signal; b) vertical high pass filtering means coupled to said filter input, for filtering said composite video signal and providing therefrom a first filtered signal; c) switching means having a first input coupled to said filter input and a second input coupled to said ver­tical high pass filtering means, for connecting either said first filtered signal or said composite video signal to a horizontal band-pass filtering means in response to a control signal, said horizontal band-pass filtering means providing a chrominance signal; d) vertical edge detection means coupled to said filter input, for detecting the presence of vertical edges in said composite video signal and for providing said control signal in response thereto, said control signal causing said switching means to connect said filter input to said horizontal band-pass filtering means during the occurrence of said vertical edges and to connect said ver­tical high pass filtering means to said horizontal band-­pass filtering means at all other times; and e) subtracter means coupled to said horizontal band-­pass filtering means and said filter input, for subtracting said chrominance signal from said composite video signal so as to provide a luminance signal.

Claim 3

An adaptive comb filter comprising: a) a filter input for receiving a composite video signal; b) vertical high pass filtering means coupled to said filter input, for filtering said composite video signal and providing therefrom a first filtered signal; c) horizontal band-pass filtering means coupled to said vertical high pass filtering means, for providing from said first filtered signal, a chrominance signal; d) a switching means having a first input coupled to said horizontal band-pass filtering means and a second input coupled to said vertical high pass filtering means, for providing either said first filtered signal or said chrominance signal at a chrominance output in response to a control signal; e) horizontal edge detection means coupled to said filter input for detecting the presence of horizontal edges in said composite video signal and providing said control signal in response thereto, said control signal causing said switching means to connect said vertical high pass filtering means to said chrominance output during the occurrence of said horizontal edges and said horizontal band-pass filtering means to said chrominance output at all other times; and f) subtracter means coupled to said switching means and said filter input, for subtracting the signal provided at said chrominance output from said composite video signal so as to provide a luminance signal.

Claim 4

An adaptive comb filter comprising: a) a filter input for receiving a composite video signal; b) vertical high pass filtering means coupled to said filter input, for filtering said composite video signal and providing therefrom a first filtered signal; c) horizontal band-pass filtering means coupled to said vertical high pass filtering means, for providing from said first filtered signal, a chrominance signal; d) a switching means having a first input coupled to said horizontal band-pass filtering means and a second input coupled to said vertical high pass filtering means, for providing either said first filtered signal or said chrominance signal at a chrominance output in response to a control signal; e) horizontal edge detection means coupled to said filter input for detecting the presence of horizontal edges in said composite video signal and providing said control signal in response thereto, said control signal causing said switching means to connect said vertical high pass filtering means to said chrominance output during the occurrence of said horizontal edges and said horizontal band-pass filtering means to said chrominance output at all other times; and f) subtracter means coupled to said switching means and said filter input, for subtracting the signal provided at said chrominance output from said composite video signal so as to provide a luminance signal.

Claim 5

An adaptive comb filter comprising: a filter input for receiving a composite video sig­nal; a first switching path coupled at its input to said filter input having a vertical high-pass filtering means for vertically filtering said composite video signal; a second switching path coupled at its input to said filter input; a first switching means coupled at a first input to the output of the first switching path, coupled at a se­cond input to the output of said second switching path, and having a control input; a third switching path coupled at its input to the output of said first switching means having a horizontal band-pass filtering means for horizontally filtering the signal received at its input; a fourth switching path coupled to the output of said first switching means; a second switching means having a first input coupled to said third switching path, a second input coupled to said fourth switching path, and a control input; a subtracter means coupled to the output of said second switching means and to said second switching path, for subtracting the output of said second switching means representing a chrominance signal from the composite video signal received from the output of said second switching path, and producing a luminance signal at its output; a vertical edge detection means coupled at its input to said filter input, for outputting a vertical control signal via an output coupled to the control input of said first switching means, wherein said vertical edge detection means determines the presence of vertical edges in said composite video signal, and said vertical control signal causes said first switching means to switch to said second switching path during the occurrence of vertical edges and said vertical control signal causes said first switching means to switch to said first switching path at all other times; a horizontal edge detection means coupled at its input to said filter input, for outputting a horizontal control signal via an output coupled to the control input of said second switching means, wherein said horizontal edge detection means determines the presence of horizontal edges in said composite video signal; and a logic switching control means coupled at its inputs to the outputs of said vertical and horizontal edge de­tectors for outputting a switching control signal to the control input of said second switching means, wherein said switching control signal causes said second switching means to switch to said fourth switching path during the occurrence of horizontal edges, except that said second switching means switches to said third switching path during the presence of both vertical and horizontal edges, and said switching control signal causes said second switching means to switch to said third switching path at all other times.

Claim 6

An adaptive comb filter comprising: a filter input for receiving a composite video sig­nal; a first switching path coupled at its input to said filter input having a vertical high-pass filtering means for vertically filtering said composite video signal; a second switching path coupled at its input to said filter input; a first switching means coupled at a first input to the output of the first switching path, coupled at a se­cond input to the output of said second switching path, and having a control input; a third switching path coupled at its input to the output of said first switching means having a horizontal band-pass filtering means for horizontally filtering the signal received at its input; a fourth switching path coupled to the output of said first switching means; a second switching means having a first input coupled to said third switching path, a second input coupled to said fourth switching path, and a control input; a subtracter means coupled to the output of said second switching means and to said second switching path, for subtracting the output of said second switching means representing a chrominance signal from the composite video signal received from the output of said second switching path, and producing a luminance signal at its output; a vertical edge detection means coupled at its input to said filter input, for outputting a vertical control signal via an output coupled to the control input of said first switching means, wherein said vertical edge detection means determines the presence of vertical edges in said composite video signal, and said vertical control signal causes said first switching means to switch to said second switching path during the occurrence of vertical edges and said vertical control signal causes said first switching means to switch to said first switching path at all other times; a horizontal edge detection means coupled at its input to said filter input, for outputting a horizontal control signal via an output coupled to the control input of said second switching means, wherein said horizontal edge detection means determines the presence of horizontal edges in said composite video signal; and a logic switching control means coupled at its inputs to the outputs of said vertical and horizontal edge de­tectors for outputting a switching control signal to the control input of said second switching means, wherein said switching control signal causes said second switching means to switch to said fourth switching path during the occurrence of horizontal edges, except that said second switching means switches to said third switching path during the presence of both vertical and horizontal edges, and said switching control signal causes said second switching means to switch to said third switching path at all other times.

Claim 7

An adaptive comb filter comprising: a filter input for receiving a composite video signal; a first multiplexing path coupled at its input to said filter input having a vertical high-pass filtering means and a horizontal filtering means for vertically and hori­zontally filtering said composite video signal, respec­tively, and for outputting a chrominance signal; a second multiplexing path coupled at its input to said filter input comprising said vertical high-pass filter; a third multiplexing path coupled at its input to said filter input having a second horizontal filtering means; a multiplexing means having a first input coupled to said first multiplexing path, a second input coupled to said second multiplexing path, a third input coupled to said third multiplexing path, and a control input; a subtracter means coupled to the output of said multiplexing means and to said filter input, for sub­tracting the output of said multiplexing means from the composite video signal, producing a luminance signal at its output; a vertical edge detection means coupled at its input to said filter input, for outputting a vertical control signal, wherein said vertical edge detection means deter­mines the presence of vertical edges in said composite video signal, and said vertical control signal assumes a first state during the occurrence of vertical edges and said vertical control signal assumes a second state at all other times; a horizontal edge detection means coupled at its input to said filter input, for outputting a horizontal control signal, wherein said horizontal edge detection means determines the presence of horizontal edges in said composite video signal, and said horizontal control sig­nal assumes a first state during the occurrence of horizon­tal edges and said horizontal control signal assumes a second state at all other times; and a logic switching control means coupled at its inputs to the outputs of said vertical and horizontal edge de­tectors for outputting a switching control signal to the control input of said multiplexing means, wherein said switching control signal causes said multiplexing means to switch to said second multiplexing path during the occur­rence of horizontal edges, except that said multiplexing means switches to said third multiplexing path during the presence of both vertical and horizontal edges, and said switching control signal causes said multiplexing means to switch to said first multiplexing path at all other times.

Claim 8

An adaptive comb filter comprising: a filter input for receiving a composite video signal; a first multiplexing path coupled at its input to said filter input having a vertical high-pass filtering means and a horizontal filtering means for vertically and hori­zontally filtering said composite video signal, respec­tively, and for outputting a chrominance signal; a second multiplexing path coupled at its input to said filter input comprising said vertical high-pass filter; a third multiplexing path coupled at its input to said filter input having a second horizontal filtering means; a multiplexing means having a first input coupled to said first multiplexing path, a second input coupled to said second multiplexing path, a third input coupled to said third multiplexing path, and a control input; a subtracter means coupled to the output of said multiplexing means and to said filter input, for sub­tracting the output of said multiplexing means from the composite video signal, producing a luminance signal at its output; a vertical edge detection means coupled at its input to said filter input, for outputting a vertical control signal, wherein said vertical edge detection means deter­mines the presence of vertical edges in said composite video signal, and said vertical control signal assumes a first state during the occurrence of vertical edges and said vertical control signal assumes a second state at all other times; a horizontal edge detection means coupled at its input to said filter input, for outputting a horizontal control signal, wherein said horizontal edge detection means determines the presence of horizontal edges in said composite video signal, and said horizontal control sig­nal assumes a first state during the occurrence of horizon­tal edges and said horizontal control signal assumes a second state at all other times; and a logic switching control means coupled at its inputs to the outputs of said vertical and horizontal edge de­tectors for outputting a switching control signal to the control input of said multiplexing means, wherein said switching control signal causes said multiplexing means to switch to said second multiplexing path during the occur­rence of horizontal edges, except that said multiplexing means switches to said third multiplexing path during the presence of both vertical and horizontal edges, and said switching control signal causes said multiplexing means to switch to said first multiplexing path at all other times.