Luminance/chrominance separator including cross-talk reducing function

A luminance/chrominance separator comprising:

• a first filter for separating a high-frequency signal from a composite video signal;
• a first delay circuit, receiving said high-frequency signal, for delaying said high-frequency signal by one horizontal period and outputting a delayed high-frequency signal;
• a first adder, receiving said high-frequency signal and said delayed high-frequency signal, for finding a sum signal by summing said high-frequency signal and said delayed high-frequency signal of a current processing scanning line;
• a first subtracter, receiving said high-frequency signal and said delayed high-frequency signal, for finding a difference signal by calculating a difference between said high-frequency signal and said delayed high-frequency signal;
• a first absolute value circuit, receiving said sum signal, for finding an absolute value of said sum signal;
• a second absolute value circuit, receiving said difference signal, for finding an absolute value of said difference signal;
• a correction value calculation circuit for finding a correction signal based on said sum signal and said difference signal on the basis of an absolute value magnitude relationship between the sum and difference signals;
• a first calculation circuit for finding an absolute value of a second difference signal indicative of a difference in absolute value between said sum and difference signals;
• a first amplitude limiting circuit for limiting an amplitude of the correction signal of said correction value calculation circuit based on the absolute value of the second difference signal to obtain a second correction signal;
• a comb filter for separating a luminance signal and a chrominance signal from said high-frequency signal and said delayed high-frequency signal;
• a correction circuit for removing an unnecessary component contained in an output of said comb filter in accordance with said second correction value of said first amplitude limiting circuit;
• a second delay circuit for delaying an output of said correction circuit by one line;
• a correlation detection circuit for detecting a correlation in accordance with said composite video signal;
• and
• a switch circuit for selecting one of (i) the output of the correction circuit and (ii) an output of said second delay circuit and (iii) a predetermined value in accordance with an output of said correlation detection circuit.

A luminance/chrominance separator comprising:

• a first filter for separating a high-frequency signal from a composite video signal;
• a first delay circuit, receiving said high-frequency signal, for delaying said high-frequency signal by one horizontal period and outputting a delayed high-frequency signal;
• a first adder, receiving said high-frequency signal and said delayed high-frequency signal, for finding a sum signal by summing said high-frequency signal and said delayed high-frequency signal of a current processing scanning line;
• a first subtracter, receiving said high-frequency signal and said delayed high-frequency signal, for finding a difference signal by calculating a difference between said high-frequency signal and said delayed high-frequency signal;
• a first absolute value circuit, receiving said sum signal, for finding an absolute value of said sum signal;
• a second absolute value circuit, receiving said difference signal, for finding an absolute value of said difference signal;
• a correction value calculation circuit for finding a correction signal based on said sum signal and said difference signal on the basis of an absolute value magnitude relationship between the sum and difference signals;
• a first calculation circuit for finding an absolute value of a second difference signal indicative of an absolute value difference between said sum and difference signals;
• a first judgement circuit for judging whether said second difference signal is smaller than a predetermined value and for outputting a first judgement signal;
• a second delay circuit for delaying said first judgement signal by one horizontal period to obtain a second judgement signal;
• a comb filter for separating a luminance signal and a chrominance signal from said high-frequency signal and said delayed high-frequency signal delayed by one horizontal period;
• a correction circuit for removing an unnecessary component contained in an output of said comb filter in accordance with said correction value of said correction value calculation circuit;
• a third delay circuit for delaying an output of said correction circuit by one line;
• a second luminance/chrominance separation circuit for separating said luminance signal and said chrominance signal;
• and
• a switch circuit for (i) selecting an output of said second luminance/chrominance separation circuit when said first and second judgement signals each indicate that an absolute value of said second difference signal is smaller than a predetermined value and (ii) selecting an output of said third delay circuit when only said first judgement signal indicates that said second difference signal is smaller than the predetermined value and (iii) selecting an output of said correction value circuit when only said second judgement signal indicates that said second difference signal is smaller than the predetermined value.

A luminance/chrominance separator comprising:

• a first filter for separating a high-frequency signal from a composite video signal and outputting said high-frequency signal;
• a first delay circuit, receiving said high-frequency signal, for delaying said high-frequency signal by one horizontal period and outputting a delayed high-frequency signal;
• a first adder, receiving said high-frequency signal and said delayed high-frequency signal, for finding a sum signal by summing said high frequency signal and said delayed high-frequency signal of a current processing scanning line;
• a first subtracter, receiving said high-frequency signal and said delayed high-frequency signal, for finding a difference signal by calculating a difference between said high-frequency signal and said delayed high-frequency signal;
• a first absolute value circuit, receiving said sum signal, for finding an absolute value of said sum signal;
• a second absolute value circuit, receiving said difference signal, for finding an absolute value of said difference signal;
• a correction value calculation circuit for finding a correction signal based on said sum signal and said difference signal on the basis of an absolute value magnitude relationship between the sum and difference signals;
• a first calculation circuit for finding an absolute value of a second difference signal indicative of an absolute value difference between said sum and difference signals;
• a first judgement circuit for judging whether said second difference signal is smaller than a predetermined value and for outputting a first judgement signal;
• a second delay circuit for delaying said first judgement signal by one horizontal period to obtain a second judgement signal;
• an amplitude limiting circuit for limiting an amplitude of the correction value of said correction value calculation circuit based on said first and second judgement signals so as to output a second correction value;
• a comb filter for separating a luminance signal and a chrominance signal from the high-frequency signal and said delayed high-frequency signal;
• a correction circuit for removing an unnecessary component contained in an output of said comb filter in accordance with said second correction value of said second amplitude limiting circuit;
• a third delay circuit for delaying an output of said correction circuit by one line;
• a switch circuit for selecting (i) an output of said third delay circuit when said first judgement signal indicates that said second difference signal is smaller than a predetermined value and (ii) selecting an output of said correction circuit when said second judgement signal indicates that said second difference signal is smaller than the predetermined value and (iii) selecting a predetermined one of the outputs of said correction value circuit and second delay circuit when said first and second judgement signals each indicate that an absolute value of said second difference signal is smaller than the predetermined value;
• and
• a third amplitude limiting circuit for limiting an output of said switch circuit based on said first and second judgement signals.

A luminance/chrominance separator comprising:

• first filter for separating a high-frequency signal from a composite video signal and outputting said high-frequency signal;
• a first delay circuit, receiving said high-frequency signal, for delaying said high-frequency signal by one horizontal period and outputting a delayed high-frequency signal;
• a first adder, receiving said high-frequency signal and said delayed high-frequency signal, for finding a sum signal by summing said and said delayed high-frequency signal of a current processing scanning line;
• a first subtracter, receiving said high-frequency signal and said delayed high-frequency signal, for finding a difference signal by calculating a difference between said high-frequency signal and said delayed high-frequency signal;
• a first absolute value circuit, receiving said sum signal, for finding an absolute value of said sum signal;
• a second absolute value circuit, receiving said difference signal, for finding an absolute value of said difference signal;
• a correction value calculation circuit for finding a correction signal based on said sum signal and said difference signal on the basis of an absolute value magnitude relationship between the sum and difference signals;
• a first calculation circuit for finding an absolute value of a second difference signal indicative of an absolute value difference between said sum and difference signals;
• a first judgement circuit for judging whether said second difference signal is smaller than a predetermined value and for outputting a first judgement signal;
• a second delay circuit for delaying said first judgement signal by one horizontal period to obtain a second judgement signal;
• an amplitude limiting circuit for limiting an amplitude of the correction value of said correction value calculation circuit based on said first judgement signal so as to obtain a second correction value;
• a comb filter for separating a luminance signal and a chrominance signal from said high-frequency signal and said delayed high-frequency signal;
• a correction circuit for removing an unnecessary component contained in an output of said comb filter in accordance with said second correction value of said amplitude limiting circuit;
• a third delay circuit for delaying an output of said correction circuit by one line;
• and
• a switch circuit for (i) selecting an output of said third delay circuit when said first judgement signal indicates that said second difference signal is smaller than a predetermined value and (ii) selecting an output of said correction circuit when said second judgement signal indicates that said second difference signal is smaller than the predetermined value and (iii) selecting a zero signal when said first and second judgement signals each indicate that an absolute value of said second difference signal is smaller than the predetermined value.

A luminance/chrominance separator comprising:

• a filter means for separating particular frequency components, including a chrominance subcarrier frequency component, from a composite video signal and outputting a particular frequency components signal;
• a first delay circuit, receiving said particular frequency components signal, for delaying said particular frequency components signal by one horizontal scanning period and outputting a delayed signal;
• an adder, receiving said particular frequency components signal and said delayed signal, for finding a sum signal by summing said particular frequency components signal and said delayed signal;
• a subtracter, receiving said particular frequency components signal and said delayed signal, for finding a difference signal by calculating a difference between said particular frequency components signal and said delayed signal;
• a first absolute value circuit, receiving said sum signal, for finding an absolute value of said sum signal;
• a second absolute value circuit, receiving said difference signal, for finding an absolute value of said difference signal;
• a correction signal calculation circuit for finding a correction signal based on said sum signal and said difference signal in accordance with a magnitude relationship between the absolute value of the sum signal and the absolute value of the difference signal;
• a comb filter for separating at least one of (i) a luminance signal and (ii) a chrominance signal from said particular frequency components signal and said delayed particular frequency components signal in accordance with one of (a) said sum signal and (b) said difference signal;
• and
• a correction circuit for reducing unnecessary components contained in an output of said comb filter in accordance with said correction signal.

A luminance/chrominance separator comprising:

• a filter means for separating particular frequency components, including a chrominance subcarrier frequency component, from a composite video signal and outputting a particular frequency components signal;
• a first delay circuit, receiving said particular frequency components signal, for delaying said particular frequency components signal by one horizontal scanning period and outputting a delayed signal;
• an adder, receiving said particular frequency components signal and said delayed signal, for finding a sum signal by summing said particular frequency components signal and said delayed signal;
• a subtracter, receiving said particular frequency components signal and said delayed signal, for finding a difference signal by calculating a difference between said particular frequency components signal and said delayed signal;
• a first absolute value circuit, receiving said sum signal, for finding an absolute value of said sum signal;
• a second absolute value circuit, receiving said difference signal, for finding an absolute value of said difference signal;
• a correction signal calculation circuit for finding a correction signal based on said sum signal and said difference signal in accordance with a magnitude relationship between said absolute value of the sum signal and the absolute value of the difference signal;
• a calculation circuit for finding an absolute value of a comparison signal by calculating a difference between the absolute value of said sum signal and the absolute value of said difference signal;
• an amplitude limiting circuit for limiting an amplitude of said correction signal based on the absolute value of the comparison signal so as to obtain a second correction signal;
• a comb filter for separating a selected one of (i) a luminance signal and (ii) a chrominance signal from said particular frequency components signal and the delay signal by using a selected one of (a) the sum signal and (b) the difference signal;
• a correction circuit for reducing unnecessary components contained in an output of said comb filter in accordance with said second correction signal;
• a second delay circuit for delaying an output of said correction circuit by one horizontal scanning period;
• a correlation detection circuit for detecting a correlation in accordance with said particular frequency components signal;
• and
• a selector for selecting one of (i) the output of said correction circuit and (ii) an output of said second delay circuit and a predetermined one of (a) a predetermined value and (b) said delayed signal in accordance with an output of said correlation detection circuit.

A luminance/chrominance separator comprising:

• a filter means for separating particular frequency components, including a chrominance subcarrier frequency component, from a composite video signal and outputting a particular frequency components signal;
• a first delay circuit, receiving said particular frequency components signal, for delaying said particular frequency components signal by one horizontal scanning period and outputting a delayed signal;
• an adder, receiving said particular frequency components signal and said delayed signal, for finding a sum signal by summing said particular frequency components signal and said delayed signal;
• a subtracter, receiving said particular frequency components signal and said delayed signal, for finding a difference signal by calculating a difference between said particular frequency components signal and said delayed signal;
• a first absolute value circuit, receiving said sum signal, for finding an absolute value of said sum signal;
• a second absolute value circuit, receiving said difference signal, for finding an absolute value of said difference signal;
• a correction signal calculation circuit for finding a correction signal based on said sum signal and said difference signal in accordance with a magnitude relationship between the absolute value of the sum signal and the absolute value of the difference signal;
• a comb filter for separating a selected one of (i) a luminance signal and (ii) a chrominance signal from said particular frequency components signal and said delayed signal in accordance with one of (a) said sum signal and (b) said difference signal;
• a correction circuit for reducing unnecessary components contained in an output of said comb filter in accordance with said correction signal;
• a second delay circuit for delaying an output of said correction circuit by one horizontal scanning period;
• a calculation circuit for finding an absolute value of a comparison signal indicative of a difference between the absolute value of said sum signal and the absolute value of said difference signal;
• a judgement circuit for outputting a first judgement signal when said judgement circuit judges that the absolute value of said comparison signal is smaller than a predetermined value;
• a third delay circuit for delaying said first judgement signal by one horizontal scanning period so as to obtain a second judgement signal;
• a luminance/chrominance separation circuit for separating a selected one of (i) a luminance signal and (ii) a chrominance signal from said particular frequency components signal and said delayed signal;
• and
• a selector for (i) selecting an output of said correction signal calculation circuit in the presence of only said second judgement signal and (ii) selecting an output of said second delay circuit in the presence of only said first judgement signal and (ii) selecting an output of said luminance/chrominance separation circuit in the presence of both of said first and second judgement signals.

A luminance/chrominance separator comprising:

• a filter means for separating particular frequency components, including a chrominance subcarrier frequency component, from a composite video signal and outputting a particular frequency components signal;
• a first delay circuit, receiving said particular frequency components signal, for delaying said particular frequency components signal by one horizontal scanning period and outputting a delayed signal;
• an adder, receiving said particular frequency components signal and said delayed signal, for finding a sum signal by summing said particular frequency components signal and said delayed signal;
• a subtracter, receiving said particular frequency components signal and said delayed signal, for finding a difference signal by calculating a difference between said particular frequency components signal and said delayed signal;
• a first absolute value circuit, receiving said sum signal, for finding an absolute value of said sum signal;
• a second absolute value circuit, receiving said difference signal, for finding an absolute value of said difference signal;
• a correction signal calculation circuit for finding a correction signal based on said sum signal and said difference signal in accordance with a magnitude relationship between the absolute value of the sum signal and the absolute value of the difference signal;
• a calculation circuit for finding an absolute value of a comparison signal indicative of a difference between the absolute value of the sum signal and the absolute value of the difference signal;
• a judgement circuit for outputting a first judgement signal when said judgement circuit judges that an absolute value of said comparison signal is smaller than a predetermined value;
• a second delay circuit for delaying said first judgement signal by one horizontal scanning period so as to obtain a second judgement signal;
• a first amplitude limiting circuit for limiting an amplitude of said correction signal based on said first and second judgement signals so as to obtain a second correction signal;
• a comb filter for separating a selected one of (i) a luminance signal and (ii) a chrominance signal from said particular frequency components signal and said delayed signal by using a selected one of said sum signal and said difference signal;
• a correction circuit for reducing unnecessary components contained in an output of said comb filter by using said second correction signal;
• a third delay circuit for delaying an output of said correction circuit by one horizontal scanning period;
• a selector for (i) selecting an output of said correction circuit in the presence of only said second judgement signal and (ii) selecting an output of said third delay circuit in the presence of only said first judgement signal and (iii) selecting a predetermined one of (a) the output of said correction circuit and (b) the output of said second delay circuit in the presence of both of said first and second judgement signals;
• and
• a second amplitude limiting circuit for limiting an output of said selector based on said first and second judgement signals.

A luminance/chrominance separator comprising:

• a filter means for separating particular frequency components, including a chrominance subcarrier frequency component, from a composite video signal and outputting a particular frequency components signal;
• a first delay circuit, receiving said particular frequency components signal, for delaying said particular frequency components signal by one horizontal scanning period and outputting a delayed signal;
• an adder, receiving said particular frequency components signal and said delayed signal, for finding a sum signal by summing said particular frequency components signal and said delayed signal;
• a subtracter, receiving said particular frequency components signal and said delayed signal, for finding a difference signal by calculating a difference between said particular frequency components signal and said delayed signal;
• a first absolute value circuit, receiving said sum signal, for finding an absolute value of said sum signal;
• a second absolute value circuit, receiving said difference signal, for finding an absolute value of said difference signal;
• a correction signal calculation circuit for finding a correction signal based on said sum signal and said difference signal in accordance with a magnitude relationship between the absolute value of the sum signal and the absolute value of the difference signal;
• a calculation circuit for finding an absolute value of a comparison signal indicative of a difference between the absolute value of the sum signal and the absolute value of the difference signal;
• a judgement circuit for outputting a first judgement signal when said judgement circuit judges that an absolute value of said comparison signal is smaller than a predetermined value;
• a third delay circuit for delaying said first judgement signal by one horizontal scanning period so as to obtain a second judgement signal;
• an amplitude limiting circuit for limiting an amplitude of said correction signal based on said first judgement signal so as to obtain a second correction signal;
• a comb filter for separating a selected one of (i) a luminance signal and (ii) a chrominance signal from said particular frequency components signal and said delayed signal by using a selected one of said sum signal and said difference signal;
• a correction circuit for reducing unnecessary components contained in an output of said comb filter by using said second correction signal;
• a second delay circuit for delaying an output of said correction circuit by one horizontal scanning period;
• a selector for (i) selecting an output of said correction circuit in the presence of only said second judgement signal and (ii) selecting an output of said second delay circuit in the presence of only said first judgement signal and (iii) selecting a predetermined one of (a) a value zero and (b) said delayed signal in the presence of both of said first and second judgement signals.