YC separation circuit

• US 6,288,754 B1
• Filed: 02/19/1998
• Issued: 09/11/2001
• Est. Priority Date: 05/21/1997
• Status: Expired due to Term

• Current Assignee: JVC Kenwood Corporation
• Original Assignee: Victor Company of Japan Limited (JVC Kenwood Corporation)
• Inventors: Ito, Kazuki
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Tran, Trang U.
• Application Number:
  US09/025,867
• Time in Patent Office: 1,300 Days
• Field of Search: H04/N.977, 348/663, 348/664, 348/665, 348/666, 348/667, 348/668, 348/669, 348/670
• US Class Current: 348/663
• CPC Class Codes: H04N 9/78 for separating the brightness signal or the chrominance signal from the colour television signal, e.g. using comb filter

Abstract

A video composite signal is thinned by sub-Nyquist sampling signal to reduce a capacity of a memory, a carrier chrominance signal is separated from the thinned video composite signal by an inter-frame YC separation circuit 13, the first separated carrier chrominance signal is interpolated by horizontal interpolation circuit 25 to reproduce the lost data due to thinning, the interpolation data is compensated by an adding circuit 29 in accordance with a high frequency component in a second separated carrier chrominance signal separated without thinning detected by an intra-field YC separation circuit 16 and high frequency component extraction circuit 28 when an edge is present in the separated carrier chrominance signal from the inter-frame YC separation circuit 13, which is detected by an edge detection circuit 26, the first separated carrier chrominance signal is outputted at the timing corresponding to the sub-Nyquist sampling signal, the interpolation data is outputted at an interpolation timing when the edge is not present, and the compensated interpolation data outputted at the interpolation timing when the edge is-not present by a selection circuit 30, and the luminance signal is separated from the composite video signal with the outputted carrier chrominance signal by a subtractor 18.

Claims

1. A YC separator comprising:

thinning means for thinning a composite video signal including a luminance signal and a carrier chrominance signal multiplexed in a common band in response to a sub-Nyquist sampling signal to output a thinned composite video signal;

first separation means for separating said carrier chrominance signal from said thinned composite video signal through inter-frame operation;

second-separation means for separating said carrier chrominance signal from said composite video signal through intra-field operation;

first high frequency component detecting means for detecting a first high frequency component in the separated carrier chrominance signal from said first separation means;

second high frequency component detection means for detecting a second high frequency component in said carrier chrominance signal from said second separation means;

first interpolation means for generating a first interpolated carrier chrominance signal from the separated carrier chrominance signal from said first separation means at an interpolation timing defined by said sub-Nyquist sampling signal through linear-interpolating;

second interpolation means for selectively adding said detected second high frequency component to said first interpolated carrier chrominance signal in accordance with the detected first high frequency component to generate a second interpolated carrier chrominance signal;

outputting means for outputting the separated carrier chrominance signal from said first separation circuit at the timing corresponding to said sub-Nyquist sampling signal and said second interpolated carrier chrominance signal at said interpolation timing; and

luminance signal generation means for effecting subtraction between said composite video signal and an output of said outputting means to generate and output a separated luminance signal.

2. The YC separator as claimed in claim 1, wherein said first interpolation means comprises a horizontal interpolating circuit for averaging consecutive data of the separated carrier chrominance signal from said first separation means derived from consecutive two sampling timings of said sub-Nyquist sampling signal in said thinning means to generate said first interpolated carrier chrominance signal.

3. The YC separator as claimed in claim 1, wherein said second interpolation means further includes median means for detecting consecutive data of the separated carrier chrominance signal from said first separation means derived from consecutive two sampling timings of said sub-Nyquist sampling signal in said thinning means and limiting a value of said second interpolated carrier chrominance signal with the detected consecutive data.

4. The YC separator as claimed in claim 1, wherein said second separation circuit comprises a first three-line-logical comb filter with band pass limitation in the horizontal direction for separating said carrier chrominance signal from said composite video signal, a first high frequency component extracting filter for extracting a third high frequency component in the separated carrier chrominance signal from said first three-line-logical comb filter, a second three-line-logical comb filter without band pass limitation in the horizontal direction for separating said carrier chrominance signal from said composite video signal, a second high frequency component extracting filter for extracting a fourth high frequency component in the separated carrier chrominance signal from said second three-line-logical comb filter, a correlation detection circuit for detecting vertical correlation in said composite video signal, and a switch for outputting said third high frequency component as said second high frequency component when said vertical correlation is less than a reference and outputting said fourth high frequency component as said second high frequency component when said vertical correlation is not less than said reference.

5. A YC separator comprising:

thinning means for thinning a composite video signal including a luminance signal and a carrier chrominance signal multiplexed in a common band in response to a sub-Nyquist sampling signal to output a thinned composite video signal;

first separation means for separating said carrier chrominance signal from said thinned composite video signal through inter-frame operation;

second separation means for separating said carrier chrominance signal from said composite video signal through intra-field operation;

edge detection means for detecting an edge image portion in the separated carrier chrominance signal from said first separation means;

high frequency component detection means for detecting a second high frequency component in said carrier chrominance signal from said second separation means;

first interpolation means for generating a first interpolated carrier chrominance signal from said thinned carrier chrominance signal at an interpolation timing defined by said sub-Nyquist sampling signal through linear-interpolating;

second interpolation means for adding said high frequency component to said first interpolated carrier chrominance signal to generate a second interpolated carrier-chrominance signal;

outputting means for outputting the separated carrier chrominance signal from said first separation circuit at the timing corresponding to said sub-Nyquist sampling signal, said first interpolated carrier chrominance signal at said interpolation timing when said edge detecting means does not detect said edge image portion, and said second interpolated carrier chrominance signal at said interpolation timing when said edge detecting means detects said edge image portion; and

luminance signal generation means for effecting subtraction between said composite video signal and an output of said outputting means to generate and output a separated luminance signal.

6. The YC separator as claimed in claim 5, wherein said first interpolation means comprises a horizontal interpolating circuit for averaging consecutive data of the separated carrier chrominance signal from said first separation means derived from consecutive two sampling timings of said sub-Nyquist sampling signal in said thinning means to generate said first interpolated carrier chrominance signal.

7. The YC separator as claimed in claim 5, wherein said second interpolation means further includes median means for detecting consecutive data of the separated carrier chrominance signal from said first separation means derived from consecutive two sampling timings of said sub-Nyquist sampling signal in said thinning means and limiting a value of said second interpolated carrier chrominance signal with the detected consecutive data.

8. The YC separator as claimed in claim 5, wherein said second separation circuit comprises a first three-line-logical comb filter with band pass limitation in the horizontal direction for separating said carrier chrominance signal from said composite video signal, a first high frequency component extracting filter for extracting a third high frequency component in the separated carrier chrominance signal from said first three-line-logical comb filter, a second three-line-logical comb filter without band pass limitation in the horizontal direction for separating said carrier chrominance signal from said composite video signal, a second high frequency component extracting filter for extracting a fourth high frequency component in the separated carrier chrominance signal from said second three-line-logical comb filter, a correlation detection circuit for detecting vertical correlation in said composite video signal, and a switch for outputting said third high frequency component as said second high frequency component when said vertical correlation is less than a reference and outputting said fourth high frequency component as said second high frequency component when said vertical correlation is not less than said reference.