JP3230902B2 - Luminance signal / color signal separation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a luminance / chrominance signal separating apparatus for separating a luminance signal and a carrier chrominance signal from a composite television signal of the NTSC system, for example.

[0002]

2. Description of the Related Art In recent years, with the development of digital signal processing technology, a luminance signal / chrominance signal separation device for separating a composite color television signal into a luminance signal and a carrier chrominance signal has been developed.
An adaptive luminance signal / chrominance signal separation device that selects a plurality of filters in accordance with the presence or absence of a correlation between a signal of interest and a horizontal or vertical neighboring point is used.

Hereinafter, a conventional luminance signal / chrominance signal separation device will be described with reference to the drawings. FIG. 5 is a block diagram of a configuration example of a conventional luminance signal / color signal separation device.
In FIG. 5, reference numeral 44 denotes a bandpass filter (BP) for extracting a color signal component of the input composite color television signal (VBS).
F), 45 and 46 are 1H line memories for delaying the output of the BPF 44 for one horizontal period, 47 is a comb filter for separating a color signal from a signal obtained by delaying the output of the BPF 44 and the output of the BPF 44 for one horizontal period, and 48 is a comb filter for the BPF 44. A comb filter for separating a color signal from a signal whose output is delayed by one horizontal period and a signal whose delay is two horizontal periods. 49 adds a signal obtained by delaying the output of the BPF 44 by one horizontal period and a signal delayed by two horizontal periods. An adder 50 for adding the output of the BPF 44 and a signal obtained by delaying the output of the BPF 44 by one horizontal period; and 51 and 52, absolute value circuits (AB) for obtaining the absolute values of the outputs of the adders 49 and 50
S), 53 and 54 are low-pass filters (LPFs) for smoothing the outputs of the absolute value circuits 51 and 52, 55 is a comparator for comparing the outputs of the LPFs 53 and 54, and 56 is the output of the comparator 55. Selector for selecting the output of the comb filters 47 and 48, 57 is a 1H line memory for delaying the VBS signal for one horizontal period, and 58 is for delaying the color signal (VBS) output from the selector 56 for one horizontal period. This is a filter circuit for obtaining a luminance signal by subtracting the luminance signal.

[0004] The operation of the luminance signal / chrominance signal separation device configured as described above will be described.

First, the input composite color television signal (VBS) is input to a BPF 44, and a color signal component is extracted. The extracted color signal components are stored in 1H line memory 4.
The signals are sequentially input to 5, 46 to obtain signals for a total of three lines.
The signals of the three lines are respectively added to the signals of one line by adders 49 and 50.
The correlation value can be obtained by adding That is, since the phase of a color signal is inverted between one line, if the sum of the color signal components between one line is 0, the color signals can be regarded as having a correlation. Actually, the absolute value of the sum between one line is obtained by absolute value circuits (ABS) 51, 52, and the absolute value is smoothed by LPFs 53, 54, and the smoothed becomes a correlation value.

Here, the comparator 55 compares the correlation value between the signal one line before and the signal one line after the signal of interest, and outputs which one has a correlation. According to the output of the comparator 55, the output of the comb filter 47 or 48 formed between the signals determined to have a correlation by the selector 56 is selected.
The luminance signal can be obtained by subtracting the color signal obtained by the selector 56 from the signal obtained by delaying the VBS signal in the 1H line memory 57 by the filter circuit 58.

[0007]

However, in the above configuration, since the high-frequency component of the luminance signal cannot be distinguished from the chrominance signal component, for example, an erroneous determination occurs in the correlation determination near the vertical edge of the multiburst signal. However, there has been a deterioration of a cross color in which a luminance signal is mixed with a color signal. That is, the phase of the chrominance signal is inverted every line, but the high-frequency component of the luminance signal has the same phase. Therefore, 1
When the signal of the line sum is obtained, if the component has a color signal correlation, it becomes 0. However, when there is a correlation between the luminance signals, the component is not 0 and becomes twice the original component. Therefore, the correlation differs depending on whether there is a color signal correlation or a luminance signal correlation.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a luminance signal / color signal separating apparatus in which even when there is a high frequency component of the luminance signal, a cross color in which the luminance signal is mixed with the color signal is less likely to occur. It is assumed that.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a delay device which receives a composite color television signal as an input and delays the signal of interest in the vertical direction, and a point adjacent to the signal of interest in the vertical direction. A vertical filter that separates a luminance signal and a carrier chrominance signal using and a phase detection circuit that calculates a phase difference between colors of the signal of interest and a point near the vertical direction ,
Leaving the luminance signal correlation value and the color signal correlation value the correlation of the correlation and the luminance signal before Symbol focused signal and a color signal of the vertical direction near the point
A correlation detection circuit you force output of the phase detector circuit Iroshin
In the case of indicating the presence of a signal, the ratio using the color signal correlation value is
More often, the output of the phase detection circuit indicates the presence of a luminance signal.
If it is increasing the share of this use of the luminance signal correlation value
Characterized by comprising a mixing circuit urchin said mixing said color signal correlation value and the luminance signal correlation value obtaining the correlation values.

[0010]

According to the present invention, the phase difference between the color signals is detected by the phase detection circuit, and the correlation between the color signal and the luminance signal between the signal of interest and the neighboring point in the vertical direction is obtained by the correlation detection circuit. Then, the mixing circuit obtains a correlation value by mixing the luminance signal correlation value and the chrominance signal correlation value, which are the outputs of the correlation detection circuit, using the output of the phase detection circuit.
Even when there is a high frequency component of the luminance signal, it is possible to reduce the cross color in which the luminance signal is mixed with the color signal.

[0011]

FIG. 1 is a block diagram showing a luminance signal according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration of a color signal separation device. In FIG. 1, reference numerals 1, 2, 3, and 4 denote a 1H line memory for delaying the input composite color television signal (VBS) by one horizontal period, and 5 denotes a signal obtained by delaying VBS by one horizontal period.
A comb filter 6 for separating a color signal from a signal delayed for a horizontal period, a comb filter 6 for separating a color signal from a signal delayed for two horizontal periods of VBS and a signal delayed for three horizontal periods, and 7 for VBS and VBS A first correlation detection circuit for calculating a correlation value of a color signal and a correlation value of a luminance signal from a signal delayed by two horizontal periods and a signal delayed by two horizontal periods. Reference numeral 8 denotes a signal obtained by delaying VBS by one horizontal period and two horizontal periods. A first phase detection circuit 9 for obtaining a phase difference between a delayed signal and a color, 9 is VB
S is a second correlation detection circuit that obtains a correlation value of a color signal and a correlation value of a luminance signal from a signal delayed by two horizontal periods, a signal delayed by three horizontal periods, and a signal delayed by four horizontal periods.
A second phase detection circuit for calculating a color phase difference between a signal delayed by two horizontal periods and a signal delayed by three horizontal periods of the BS, 11
Is a first mixing circuit that mixes the correlation value of luminance and the correlation value of color output from the first correlation detection circuit 7 according to the phase difference output from the first phase detection circuit 8 to obtain a correlation value; Reference numeral 12 denotes a second mixing circuit for mixing the correlation value of luminance and the correlation value of color output from the second correlation detection circuit 9 in accordance with the phase difference output from the second phase detection circuit 10 to obtain a correlation value. , 13 are the correlation value output from the first mixing circuit 11 and the second mixing circuit.
A correlation determination circuit for determining the weight of the comb filter 5 and the comb filter 6 based on the correlation value output from 12, and 14 mixes the color signal output of the comb filter 5 and the color signal output of the comb filter 6 with the output of the correlation determination circuit 13. A third mixing circuit,
Reference numeral 15 denotes a filter circuit for obtaining a luminance signal by subtracting the color signal output of the third mixing circuit 14 from a signal obtained by delaying VBS by two horizontal periods.

FIG. 2 is a block diagram showing the structure of the comb filter of FIG. 1. In FIG. 2, reference numeral 16 denotes a signal obtained by delaying VBS by two horizontal periods, reference numeral 17 denotes a signal which is separated from the signal 16 by one horizontal period, and reference numeral 18 denotes a signal. A first subtractor for subtracting signal 17 from signal 16;
19 is a 乗 算 multiplier, and 20 is a calculated color signal output.

FIG. 3 is a block diagram showing the configuration of the first and second correlation detection circuits of FIG. 1. In FIG.
S is a signal delayed by two horizontal periods, 22 is a signal separated by two horizontal periods from the signal 21, 23 is a signal separated by one horizontal period from the signal 21, 24
Is a second subtractor for subtracting the signal 22 from the signal 21, and 25 is the signal
A third subtractor for subtracting the signal 23 from 21 is a first LPF for finding the low-frequency component of the one-line difference signal obtained by the subtractor 25, and an absolute value for finding the absolute value of the output of the LPF 26 A circuit (ABS), 28 is a second LPF for smoothing the output of the absolute value circuit 27, and 29 is an absolute value circuit (AB) for obtaining the absolute value of the absolute value signal of the two-line difference signal obtained by the subtractor 24.
S), 30 is a third LPF for smoothing the output of the absolute value circuit 29
It is.

FIG. 4 is a block diagram showing the structure of the first and second phase detection circuits of FIG. 1. In FIG.
S is a signal delayed by two horizontal periods, 34 is a BPF that extracts the color signal component of the signal 33, 35 is a delay unit (D) that delays one sample, and 36 is the phase of the color signal from a signal that is one sample away. The phase calculation circuit to be obtained, 37 is a signal separated from the signal 33 by one horizontal period, 38 is a BPF for extracting a color signal component of the signal 37, 39
Is a delay unit (D) for delaying one sample, 40 is a phase operation circuit for obtaining the phase of the color signal from a signal separated by one sample, 41 is a fourth operation for obtaining the difference between the phases obtained by the phase operation circuits 36 and 40 Is a conversion circuit for converting the output of the subtractor 41 into a coefficient K, and 43 is a phase difference coefficient K output from the phase detection circuit.

The operation of the luminance / chrominance signal separating device thus constructed will be described.

First, in FIG. 1, when a composite color television signal (VBS) is input as an input signal, VB
S is sequentially input to the line memories 1, 2, 3, and 4, and a signal of a total of 5 lines is obtained. The signals are S1 to S5, respectively. First correlation detection circuit 7 and second correlation detection circuit 9
Then, the correlation value of the luminance signal and the correlation value of the chrominance signal with respect to the signal S1 are obtained. The correlation value of the first correlation detection circuit 7 is a correlation value corresponding to the comb filter 5, and the correlation value of the second correlation detection circuit 9 is a correlation value corresponding to the comb filter 6. Since the phase of the color signal is inverted every other line, the correlation between the color signals can be obtained by taking the difference between the signals two lines apart. Further, if only the low-frequency component of one line difference is extracted, the correlation of the luminance signal can be obtained. Further, the first phase detection circuit 8 and the second phase detection circuit 10 determine the phase difference of the color signal with respect to S1.

Here, in order to determine the phase of the color from two adjacent samples of the color signal, if the VBS is sampling at 4 fsc (fsc: color subcarrier frequency), the amplitude of the adjacent signal is determined by When A1 and A2 are used, the following
It can be obtained by (Equation 1).

[0018]

## EQU1 ## Therefore, in the configuration of FIG. 4 which is the first and second phase detection circuits 8 and 10 of FIG. 1, the color phase of the signal 33 is BPF
The color signal component is obtained by 34, and the expression (1) is calculated by the phase calculation circuit 36 using the amplitude data between two adjacent samples. Further, a signal which is one horizontal period apart from the signal 33 is input to the signal 37, and is similarly operated by the phase operation circuit 40, and the difference in the color phase of each line is obtained by the fourth subtractor 41. The phase difference obtained here is converted into a mixing coefficient K and output by the conversion circuit 42 in order to mix the correlation value of the color and the correlation value of the luminance.

In the first and second mixing circuits 11 and 12,
The color signal correlation value and the luminance signal correlation value are mixed according to the coefficients obtained by the first and second phase detection circuits 8 and 11 to obtain a correlation value. Correlation determination circuit that determines the ratio of presence or absence of filter correlation
The third color mixing circuit 14 mixes the color signal outputs of the comb filters 5 and 6 in accordance with the output of 13 to obtain a color signal.
At 15, a luminance signal is output by subtracting from the original composite color television signal.

[0020]

As described above, the luminance signal / chrominance signal separation apparatus of the present invention comprises a phase detection circuit for detecting a phase difference between color signals, and a correlation between a signal of interest and a color signal near a vertical direction. A correlation detection circuit that calculates the correlation between the luminance signal and the luminance signal, and a mixing circuit that calculates the correlation value by mixing the luminance signal correlation value and the color signal correlation value output from the correlation detection circuit using the output of the phase detection circuit. Thereby, even when there is a high-frequency component of the luminance signal, it is possible to reduce the cross color in which the luminance signal is mixed with the color signal.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a luminance signal / color signal separation device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a comb filter shown in FIG.

FIG. 3 is a block diagram illustrating a configuration of first and second correlation detection circuits in FIG. 1;

FIG. 4 is a block diagram illustrating a configuration of first and second phase detection circuits in FIG. 1;

FIG. 5 is a block diagram of a configuration example of a conventional luminance signal / color signal separation device.

[Explanation of symbols]

1,2,3,4 ... 1H line memory, 5,6 ... com filter, 7,9 ... first and second correlation detection circuit,
8, 10: first and second phase detection circuits, 11, 12, 14: first, second, and third mixing circuits, 13: correlation determination circuit, 15
... Filter circuit.

Claims (1)

(57) [Claims] 1. A delay unit that receives a composite color television signal as an input and delays a signal of interest in a vertical direction, and separates the signal into a luminance signal and a carrier chrominance signal using the signal of interest and a point near the vertical direction. and vertical filter, the noted signal and a phase detection circuit for determining the phase difference in the color of the vertical neighborhood points, before Symbol focused signal and luminance signal the correlation of the correlation and the luminance signal of the color signal with the vertical direction near the point Correlation value and color signal correlation
A correlation detection circuit you output value, the output of the phase detector
Indicates the presence of a color signal, the color signal correlation value is used.
The output of the phase detection circuit increases the presence of a luminance signal.
When showing a within-lot a share of this use of the luminance signal correlation value
Luminance signal and color signal separating apparatus, characterized in that the color signal correlation value and the luminance signal correlation value to a mixture comprising a mixing circuit for obtaining a correlation value.