JP2596739B2 - Image correlation compatible luminance signal color signal separation filter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image correlation-compatible luminance signal color signal separation filter, and more particularly to a luminance signal for separating a luminance signal and a chrominance signal from, for example, an NTSC composite television signal. The present invention relates to a color signal separation filter.

[Conventional technology]

FIG. 5 is a block diagram showing an example of the configuration of a conventional luminance signal / color signal separation filter. In the figure, input terminal 1
Receives a composite color television signal of the NTSC system. The composite color television signal is supplied to the vertical filter 6j via the A / D converter 4 and to the one-line delay circuit 5s. The output of the one-line delay circuit 5s is supplied to the vertical filter 6j as it is, and further delayed by one line in the one-line delay circuit 5t, and then supplied to the vertical filter 6j. The vertical filter 6j is a filter usually called a two-line comb filter, and its output is given to the bandpass filter 6k.
The output of the bandpass filter 6k is derived from the output terminal 2 as a color signal 205 and is provided to a first input of a subtraction circuit 9d. The output of the one-line delay circuit 5s is given to the second input of the subtraction circuit 9d via the compensation delay circuit 5u.
The compensation delay circuit 5u is a circuit for compensating for a delay in the bandpass filter 6k. The luminance signal is output from the subtraction circuit 9d.
207 is output and given to the output terminal 3.

Next, the operation of the above-described filter for a composite color television signal of the NTSC system will be described.

Sampling frequency fs = 4 · fsc (fsc is the color subcarrier frequency)
The composite color television signal 201 synchronously sampled with the color subcarriers in the above-described manner has a two-dimensional lattice arrangement on the screen as shown in FIG. That is, since it is fsc = (455/2) f _H, the phase of the chrominance signal C for each line is obtained by 4 samples extracted one period obtained by 180 ° inversion. Here, in the figure, Y
Represents a luminance signal, and C ₁ and C ₂ represent chrominance signals. Now, as a symbol that represents a delay of one sample and one line delay, and the use of Z ^-1 and Z ^-l using Z transform, respectively. Here, Z ⁻¹ = exp (−j2πf / 4fsc). Further, the l = 910 since it is fsc = (455/2) f _H. At this time, 1 which is delayed using the delay circuits 5s and 5t
From the line delay signal 202, the two-line delay signal 203, and the current input signal 201, the vertical direction filter 6j extracts a line support signal 204 that supports each line including the color signal.
The transmission circuit Hv (Z) of the vertical filter 6j is Hv (Z) = (− 1/4) · (1−Z− ^l ) ² . That is, the line support signal Hc (m, n) at the coordinates (m, n) on the screen of FIG. 6 is calculated as follows: Hc (m, n) = (− 1/4) ｛S (m, n−1) − 2S (m, n) + S (m, n + 1)}. Since the line assist signal also includes the luminance signal Y, the color signal C (m, n), which is a high-frequency component, is separated from Hc (m, n) by the bandpass filter 6k. Then, the obtained color signal 205 is sent to the subtraction circuit 9d. The subtraction circuit 9d further converts the one-line delay signal 202 into a bandpass filter 6.
Signal S (m, n) 20 delayed by compensation delay circuit 5u according to k
The color signal C (m, n) 205 is subtracted from 6, and the luminance signal Y (m, n) 207 is separated as in the following equation.

Y (m, n) = S (m, n) -C (m, n) The transfer function Hh (Z) of the bandpass filter 6k is, for example, Hh (Z) = (− 1/32) (1-Z ^-2 ) ² (1 + Z ^-4 ) ² (1 + Z ^-8 ).

[Problems to be solved by the invention]

The conventional luminance signal color signal separation filter fixes the characteristics of the vertical filter and the horizontal filter as described above,
It was composed in combination. That is, the luminance signal and the chrominance signal are separated by the bandpass filter in both the vertical and horizontal directions. Therefore, in the conventional method, in a region where the luminance and color of the image change greatly, there is a problem that the luminance signal and the chrominance signal leak to the mutual channel, thereby causing deterioration of the image quality of the reproduced image such as dot interference. Was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a luminance signal color signal separation filter capable of achieving accurate separation of a luminance signal and a chrominance signal even in a sudden signal change in a television image. The purpose is to do.

[Means for solving the problem]

The image correlation corresponding luminance signal color signal separation filter according to the present invention includes: a delay unit that delays an input sampling signal to simultaneously obtain a target sample point for separating a luminance signal and a chrominance signal and a sample point close thereto, Image correlation determining means for detecting the image correlation in the vertical direction and the image correlation in the horizontal direction from the values of the sample points of interest and the adjacent sample points, respectively, and determining the correlation of the images. One of the output of the filter, the vertical filter, and the output of the horizontal / vertical filter is used as the color signal output of the luminance signal color signal separation filter.

[Action]

According to the present invention, since the luminance signal and the color signal separation filter are selectively used depending on the correlation between the vertical and horizontal images of the composite video signal, the influence of the leakage of the luminance signal and the chrominance signal to the mutual channel in a region where the image changes drastically. Can be reduced, and dot disturbance can be reduced.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic block diagram showing an embodiment of the present invention. In the figure, reference numeral 1 denotes an input terminal to which a composite color television signal of the NTSC system is supplied, and this composite color television signal is supplied to an A / D converter 4. The A / D converter 4 is configured to sample a composite color television signal at a sampling frequency fs = 4fsc. The composite color television signal sampled by the A / D converter 4 is applied to a one-line delay circuit 5a, and further to a one-line delay circuit 5b.
, A sample value at a given sample point and a sample value at a sample point one line above and one line below the target sample point on the screen are simultaneously extracted. The sample values extracted by the one-line delay circuits 5a and 5b are used as a vertical color signal extraction filter 6a and a horizontal color signal extraction filter 6a.
b, the horizontal / vertical color signal extraction filter 6c and the image correlation determination circuit 7 are given as follows.

That is, the input of the vertical color signal extraction filter 6a, the horizontal / vertical direction color signal extraction filter 6c, and the image correlation determination circuit 7 are input to the output 101 of the A / D converter 4, the output 102 of the one-line delay circuit 5a, And the output 103 of the one-line delay circuit 5b. The output 102 of the one-line delay circuit 5a is provided to the horizontal color signal extraction filter 6b. At this time, for example, the vertical color signal extraction filter 6a is expressed as Cv (Z) = (− 1/4) (1−Z− ^l ) ² by using a transfer function. The filter 6b is expressed as Ch (Z) = (− 1/4) (1-Z− ² ) ^2, and the horizontal / vertical color signal extraction filter 6c
Is, Chv (Z) = (- 1/4) a ^{(1-Z -2) 2 (} -1/4) (1-Z -l) filter, as denoted ^2.

The output 104 of the vertical color signal extraction filter 6a is output from the horizontal color signal extraction filter 6b via the compensation delay circuit 5c.
106 is through a compensation delay circuit 5d, and the output 108 of the horizontal / vertical color signal extraction filter 6c is through a compensation delay circuit 5e.
Each is provided to the switch circuit 8. The output 110 of the image correlation determination circuit 7 is supplied to the switch circuit 8 as a control signal. The output 111 of the switch circuit 8 is the output terminal 2
It is output as a color signal and is also provided to one input of a subtraction circuit 9a. The other input of the subtraction circuit 9a includes:
The output 102 of the one-line delay circuit 5a is provided via a compensation delay circuit 5f. The output 113 of the subtraction circuit 9a is output from the output terminal 3 as a luminance signal. The compensation delay circuits 5c, 5d,
5e and 5f are circuits for compensating the delay in each circuit.

FIG. 2 shows an embodiment of the image correlation judging circuit 7, in which the vertical low-pass filter 6d, the horizontal band-pass 6e, and the absolute value circuit 10a have a low frequency in the vertical direction at the sample point of interest, and In the horizontal direction, means for extracting a frequency component corresponding to a half of the color subcarrier frequency, calculating the absolute value of the frequency component, and detecting the horizontal high-band luminance signal energy is constituted. By the delay circuit 5g and the absolute value circuit 10b, a DC component in the vertical direction at the sample point of interest and a frequency component corresponding to the color subcarrier component are removed,
Means for obtaining the absolute value and detecting the decorrelation energy in the vertical direction is constituted. Also, a vertical band-pass filter 6g, a horizontal low-pass filter 6h, and an absolute value circuit 10c
By extracting the frequency component corresponding to half of the color subcarrier frequency in the horizontal direction in the horizontal direction and the vertical direction in the sample point of interest, the absolute value of the frequency component is obtained, and the vertical high-range luminance signal energy is calculated. A detecting means is configured, and a horizontal band-pass filter 6i, a compensation delay circuit 5h, and an absolute value circuit 10d remove a horizontal DC component and a frequency component corresponding to a color subcarrier component at a sample point of interest. , Means for calculating the absolute value of the horizontal direction decorrelation energy.

The output 101 of the A / D converter 4, the output 102 of the one-line delay circuit 5a,
The output 103 of the one-line delay circuit 5b is given to the vertical low-pass filter 6d, the vertical band-pass filters 6f and 6g,
The output 102 of the one-line delay circuit 5a is provided to the horizontal bandpass filter 6i.

The output 114 of the vertical low-pass filter 6d
Is supplied to one input of a subtraction circuit 9b via a horizontal bandpass filter 6e and an absolute value circuit 10a. On the other hand, the output 120 of the vertical bandpass filter 6f is provided to the absolute value circuit 10b via the compensation delay circuit 5g. The compensation delay circuit 5g is a circuit for compensating for a delay in the horizontal bandpass filter 6e. The output of the absolute value circuit 10b is provided to the other input of the subtraction circuit 9b and one input of the comparison circuit 11b. An output 117 of the subtraction circuit 9b is provided to one input of a comparison circuit 11a, and an output 118 (Kdy ₁ described later) of the constant generation circuit 12a is provided to the other input of the comparison circuit 11a. The other input of the comparison circuit 11b is connected to an output 123 of the constant generation circuit 12b (K
d ₁ ) is given.

The output 125 of the vertical band-pass filter 6g is provided to one input of the subtraction circuit 9c via the horizontal low-pass filter 6h and the absolute value circuit 10c. On the other hand, the output 131 of the horizontal bandpass filter 6i is provided to the absolute value circuit 10d via the compensation delay circuit 5h. The compensation delay circuit 5h is a circuit for compensating for a delay in the horizontal low-pass filter 6h. The output of the absolute value circuit 10d is provided to the other input of the subtraction circuit 9c and one input of the comparison circuit 11d. The output 128 of the subtraction circuit 9c is given to one input of the comparison circuit 11c,
An output 129 (Kdy ₂ described later) of the constant generation circuit 12c is provided to the other input of c. The other input of the comparison circuit 11d includes:
An output 134 (Kd ₂ described later) of the constant generation circuit 12d is provided.

In this case, for example, the vertical low-pass filter 6d, expressed as Fv l (Z) = (1/4 ) (1 + Z -l) 2, the horizontal band-pass filter 6e, Fhh (Z) = 1- Z ^-4, that is, a frequency component corresponding to half of the color subcarrier frequency in the horizontal direction is extracted, and the horizontal band-pass filter 6i calculates Fdh (Z) = 1−Z ^-4, and the vertical band-pass filter 6g is expressed as Fvh (Z) = 1-Z- ^2l , ie, extracts a frequency component corresponding to 1/2 of the color ^subcarrier frequency in the vertical direction. And the horizontal low-pass filter 6h is expressed as Fhl (Z) = (1/4) (1 + Z− ² ) ^2, and the vertical bandpass filter 6f is expressed as Fdv (Z) = 1− It is a digital filter as represented by Z- ^2l .

Outputs of the comparison circuits 11a and 11b are supplied to a vertical correlation detection circuit 13a, and outputs of the comparison circuits 11c and 11d are supplied to a horizontal correlation detection circuit 13b. The output 136 of the vertical correlation detection circuit 13a and the output 137 of the horizontal correlation detection circuit 13b are provided to the determination circuit 14. The output 110 of the judgment circuit 14 is sent out as the output of the image correlation judgment circuit 7.

FIG. 3 shows an example of the configuration of the determination circuit 14 shown in FIG.
The output 136 of the vertical correlation detection circuit 13a is one-line delay circuits 5i and 5
j are sequentially added, whereby the detection results of the vertical correlation at the sample points arranged in the vertical direction on the screen are simultaneously obtained. The output 136 of the vertical correlation detection circuit 13a is
The output 139 of the one-line delay circuit 5j is provided to one input of the D circuit 18a and the OR circuit 19a.
To the other input. The AND circuit 18b receives the outputs 138 and 141 of the one-line delay circuit 5i and the OR circuit 19a as inputs, and
The OR circuit 19b receives the outputs 140 and 142 of the AND circuits 18a and 18b as inputs. An output 143 of the OR circuit 19b is provided to one input of the NOR circuit 15.

The output 137 of the horizontal correlation detection circuit 13b is sequentially added to the one-sample delay circuits 51 and 5m via the compensation delay circuit 5k, thereby simultaneously obtaining the horizontal correlation detection results at the sample points arranged in the horizontal direction on the screen. Will be done. The output 144 of the compensation delay circuit 5k is also connected to the AND circuit 18c and the OR circuit 1
Input to one input of 9c, output of 1m delay circuit 5m
146 is given to the other input of the AND circuit 18c and the OR circuit 19c. The AND circuit 18d includes the one-sample delay circuit 51 and the OR circuit.
The outputs 145 and 148 of the circuit 19c are input, and the OR circuit 19d is
The outputs 147 and 149 of the circuits 18c and 18d are input. An output 150 of the OR circuit 19d is provided to the other input of the NOR circuit 15 and a NOT circuit 16a. The outputs of the NOR circuit 15 and the NOT circuit 16a become the output 110 of the image correlation determination circuit.

FIG. 4 shows another example of the configuration of the determination circuit 14. In the figure, delay circuits 5n to 5r, OR circuits 19e to 19h, AND
The configuration of the portion composed of the circuits 18e to 18h is exactly the same as in the case of FIG. Output 163 of OR circuit 19h is exclusive NOR circuit 17.
One input and a NOT circuit 16b, and an OR circuit 19
The output 156 of f is given to the other input of the exclusive NOR circuit 17. The outputs of the exclusive NOR circuit 17 and the NOT circuit 16b become the output 110 of the image correlation determination circuit.

 Next, the operation will be described.

The sampled sequence 101 of the NTSC composite color television signal sampled at the sampling frequency fs = 4fsc by the A / D converter 4 passes through delay circuits 5a and 5b, and thereby, is vertically aligned on the screen. Sample values at three sample points are obtained at the same time. That is, the composite color television signal (sample value) S (m, n) at the position of coordinates (m, n) is
02, the signal S (m, n-1)
Appears, and the signal S (m, n + 1) appears on the signal line 101 (see FIG. 6). A luminance signal color signal filter is constructed based on the sample values of the sample points over three lines on the screen.

In this method, color signals are extracted by the filter processing having the following transfer functions as the vertical color signal extraction filter 6a, the horizontal color signal extraction filter 6b, and the horizontal / vertical color signal extraction filter 6c.

Vertical color signal extraction filter Cv (Z) = (− 1/4) (1-Z− ^l ) ² Horizontal color signal extraction filter Ch (Z) = (− 1/4) (1-Z− ² ) ² Horizontal / vertical color signal extraction filter Chv (Z) = (− 1/4) (1-Z− ² ) ² (−1/4) (1-Z− ^l ) ² Vertical direction thus obtained The filter output 104, the horizontal filter output 106, and the horizontal / vertical color signal extraction filter output 108 are sent to the switch circuit 8 via the compensation delay circuit.

Here, the operation of the circuit for determining which of the color output signals of the vertical color signal extraction filter 6a, the horizontal color signal extraction filter 6b, and the horizontal / vertical color signal extraction filter 6c to select will be described.

For the target sample point, the correlation between the images in the vertical and horizontal directions is detected, and when the correlation is particularly strong in the vertical direction, the output 105 of the vertical color signal extraction filter 6a is selected.When the correlation is particularly strong in the horizontal direction, The switch circuit 8 is switched so that the output 107 of the horizontal color signal extraction filter 6b is selected, and in other cases, the output 109 of the horizontal / vertical color signal extraction filter 6c is selected.

The detection of the image correlation and the control of the switch circuit 8 are performed by the image correlation determination circuit 7. Image correlation determination circuit 7
Then, the switch circuit 8 is controlled by the following operation.

The vertical decorrelation energy is Dv (Z), the horizontal decorrelation energy is Dh (Z), an absolute value approximation is introduced, and a transfer function is used to represent the following.

Dv (Z) = | 1−Z ^−2l | Dh (Z) = | 1−Z ⁻⁴ | The above two equations are filter characteristics for blocking a DC component and a color subcarrier frequency component in the vertical and horizontal directions. Dv (Z) is obtained by the vertical bandpass filter 6f, the compensation delay circuit 5g, and the absolute value circuit 10b, and Dh (Z) is obtained by the horizontal direction bandpass filter 6i, the compensation delay circuit 5h, and the absolute value circuit. Obtained by 10d. The horizontal high-band luminance signal energy is DYh (Z), and the vertical high-band luminance signal energy is D
Let Yv (Z) be an absolute value approximation, and express it as follows using a transfer function. Here, Dyh (Z) is a vertical low-pass filter 6d, a horizontal band-pass filter 6e,
DYv (Z) is obtained by the vertical band pass filter 6g, the horizontal low pass filter 6h, and the absolute value circuit 10c.

DYh (Z) = | (1/4) (1 + Z- ^l ) ² (1-Z- ⁴ ) | DYv (Z) = | (1/4) (1 + Z- ² ) ² (1-Z- ^2l ) | At this time, the vertical correlation detection circuit 13a calculates Dv (Z) ≦ Kd ₁ (Kd ₁ : correlation threshold constant) and DYh (Z) −Dv (Z) ≧ Kdy ₁ (Kdy ₁ : high-band signal energy threshold constant) ), It is determined that there is a correlation in the vertical direction, and a signal “1” is sent to the determination circuit 14. Further, when the Dv (Z)> Kd ₁ or DYh (Z) -Dv (Z) <Kdy 1, determines that there is no correlation in the vertical direction, and sends a signal "0" to the determination circuit 14.

On the other hand, the horizontal correlation detection circuit 13b calculates Dh (Z) ≦ Kd ₂ (Kd ₂ : correlation threshold constant) and DYv (Z) −Dh (Z) ≧ Kdy ₂ (Kdy ₂ : high-band signal energy threshold constant) In the case of, it is determined that there is a correlation in the horizontal direction, and a signal “1” is sent to the determination circuit 14. If Dh (Z)> Kd ₂ or DYv (Z) −Dh (Z) <Kdy ₂ , It is determined that there is no correlation, and a signal “0” is sent to the determination circuit 14.

The determination circuit 14 controls the switch circuit 8 as follows according to the result of the above-described correlation detection.

That is, in the embodiment shown in FIG. 3, a detection result of the vertical correlation at three sample points arranged in the vertical direction on the screen is obtained at each input / output of the delay circuits 5i and 5j. The center sample point is a target sample point, and two sample points located above and below the target sample point are reference sample points. If the detection results of the vertical correlation at the reference sample point are both “no correlation”, the outputs 140 and 141 of the AND circuit 18a and the OR circuit 19a are both “0”, and the output 14 of the OR circuit 19b is “0”.
3 is "0 (no correlation)" regardless of the detection result of the vertical correlation at the target sample point. Conversely, when the detection results of the vertical correlation at the reference sample point are all “correlated”, the output 140 of the AND circuit 18a becomes “1”, and regardless of the detection result of the vertical correlation at the target sample point, The output 143 of the OR circuit 19b becomes "1 (correlated)". If the detection result of the vertical correlation at the reference sample point is “correlation” on the one hand and “no correlation” on the other hand, the outputs of the AND circuit 18a and the OR circuit 19a
140 and 141 become “0” and “1”, respectively, and the detection result of the vertical correlation at the sample point of interest appears as it is on the output 143 of the OR circuit 19b. Therefore, the output of the OR circuit 19b is a detection result of the vertical correlation of the target sample point from which isolated points have been removed in the vertical direction.

In addition, the input / output of the one-sample delay circuits 5l and 5m can obtain the detection result of the horizontal correlation at three sample points arranged in the horizontal direction on the screen.
In the output of d, the detection result of the horizontal correlation of the target sample point from which the isolated points have been removed in the horizontal direction is obtained.

The NOR circuit 15 receives the detection result of the horizontal and vertical correlations from which the isolated points have been removed, and outputs “1” only when there is no horizontal or vertical correlation. The output of the NOR circuit 15 controls the switch circuit 8. When the output is "1", the switch is switched to the horizontal / vertical color signal extraction filter 6c (signal line 105), and "0"
At this time, the switch is switched to the horizontal color signal extraction filter 6b (signal line 107) or the vertical color signal extraction filter 6c (signal line 109). In the latter case, the choice of horizontal or vertical filter is controlled by the output of the NOT circuit 16a,
When this output is “0”, the horizontal color signal extraction filter 6b
When "1", the vertical color signal extraction filter 6c is selected.
Since the detection result of the horizontal correlation from which the isolated point is removed is given to the input of the NOT circuit 16a, the switch is switched according to the presence or absence of the horizontal correlation.

From the above, in the embodiment using the determination circuit 14 shown in FIG. 3, the filter characteristic C (Z) of the color signal extraction is
It changes as follows according to the presence or absence of the correlation.

With horizontal correlation C (Z) = Ch (Z) Without horizontal correlation C (Z) = Cv (Z) if there is vertical correlation C (Z) = Chv (Z) if there is no vertical correlation Since the operation of removing the isolated points in the determination circuit shown in the figure is completely the same as that in the case of FIG. 3, only the control operation of the switch circuit 8 based on the detection result of the horizontal and vertical correlations after the removal of the isolated points will be described.

The exclusive NOR circuit 17 receives the detection result of the horizontal and vertical correlations from which the isolated points have been removed, and “correlation exists” in both the horizontal and vertical directions.
, Or in the case of “no correlation” in both directions, the output is “1”. The output of the exclusive NOR circuit 17 controls the switch circuit 8. When the output is "1", the horizontal / vertical color signal extraction filter 6c is used. Otherwise, the horizontal color signal extraction filter 6b or the vertical color signal is used. The signal extraction filter 6a is selected. The switch circuit 8 includes an exclusive NOR circuit 17
When the output of “0” is “0”, the horizontal and vertical filters are switched by the output of the NOT circuit 16b. When this output is “0”, the horizontal color signal extraction filter 6b is switched. The vertical color signal extraction filter 6a is selected. Therefore, in the embodiment using the determination circuit shown in FIG.
The filter characteristics C (Z) for color signal extraction are switched as follows.

With horizontal correlation and without vertical correlation C (Z) = Ch (Z) With vertical correlation and without horizontal correlation C (Z) = Cv (Z) With both horizontal and vertical correlation or without C (Z) = Chv (Z) The color signal output of the switch circuit 8 is subtracted from the composite video signal of the output 112 of the compensation delay circuit 5f to obtain a luminance signal 113.

In the above embodiment, the composite color television signal is sampled at four times the frequency of the color subcarrier synchronized with the horizontal scanning frequency. However, any method may be used in which the sampling points are arranged in a grid on the screen. For example, the sampling is not limited to four times the color subcarrier and may be performed at another frequency.

Further, the digital filter used in the above embodiment is an example, and for example, the digital filter may be configured to have a higher order.

〔The invention's effect〕

As described above, according to the present invention, by the correlation between the vertical and horizontal images of a composite color television signal,
Since the luminance signal and color signal separation filters are selectively used, it is possible to reduce the influence of the leakage of the luminance signal and the chrominance signal to the mutual channel in an area where the image changes drastically, and to reduce the dot disturbance.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a luminance signal color signal separation filter corresponding to an NTSC image correlation according to an embodiment of the present invention;
FIG. 2 is a block diagram showing an embodiment of the image correlation judging circuit. FIGS. 3 and 4 are diagrams showing first and second embodiments of the judging portion of the image correlation judging circuit, respectively. FIG. 6 is a schematic block diagram showing an example of a conventional luminance signal / color signal separation filter. FIG. 6 is an arrangement on a screen of a signal sequence obtained by synchronously sampling an NTSC composite color television signal at four times the color subcarrier. FIG. 1 ... input terminal, 2, 3 ... output terminal, 4 ... A / D converter,
5a-5u ... delay circuit, 6a-6k ... digital filter,
7 image correlation determining circuit, 8 switch circuit, 9a to 9d
…… Subtraction circuit, 10a to 10d …… Absolute value circuit, 11a to 11d…
Comparison circuit, 12a to 12d: constant generation circuit, 13a: vertical correlation detection circuit, 13b: horizontal correlation detection circuit, 14: determination circuit, 15: NOR circuit, 16a, 16b ... NOT circuit, 17 ... ... Exclusive NOR circuit, 18a-18h ... AND circuit, 19a-19h ... OR circuit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (3)

(57) [Claims] 1. A composite video signal sampled at a predetermined frequency synchronized with a horizontal scanning frequency so that each sample point is arranged on a grid on a screen, and a luminance signal component is digitally converted from the composite video signal. A color signal separation filter for separating an image correlation corresponding luminance signal and a color signal component, wherein the composite image signal is delayed so as to separate a luminance signal and a color signal from each other, and the target sample point on the screen. And delay means for simultaneously obtaining sample values of a plurality of reference sample points that are aligned on a straight line in the vertical direction, and a sample value of the target sample point and a predetermined reference sample point as inputs, and a vertical color subcarrier. A vertical color signal extraction filter that extracts and outputs a frequency component corresponding to the component of at least the sample value of the sample point of interest, and extracts a frequency component corresponding to a component of a horizontal color subcarrier. A horizontal color signal extraction filter to be applied, and a sample value of the target sample point and a predetermined reference sample point as inputs, and a horizontal component for extracting and outputting a frequency component corresponding to a color subcarrier component in both the vertical and horizontal directions. A vertical direction color signal extraction filter, and inputting sample values of the sample point of interest and a predetermined reference sample point, corresponding to a DC component in the vertical direction and a color subcarrier component among frequency components at the sample point of interest. A vertical non-correlation energy detecting means for removing a frequency component and detecting an absolute value of the frequency component to detect a vertical non-correlation energy; inputting the sample value of the target sample point and a sample value of a predetermined reference sample point; In the frequency component at the point, a frequency component which is a low frequency component in the vertical direction and which corresponds to a half of the color subcarrier frequency in the horizontal direction is extracted,
Horizontal high band luminance signal energy detection means for detecting the absolute value of the signal to detect horizontal high band luminance signal energy;
The magnitude of the vertical direction decorrelation energy is smaller than the first preset value, and a value obtained by subtracting the vertical direction decorrelation energy from the horizontal high band luminance signal energy is given to the outside. If the value obtained by subtracting the vertical non-correlation energy from the horizontal high band luminance signal energy is larger than the second set value, there is a vertical correlation. Vertical correlation detecting means for determining that the sample values of the target sample point and the predetermined reference sample point are input, and correspond to a horizontal DC component and a color subcarrier component among frequency components at the target sample point. Excluding the frequency component, horizontal direction decorrelation energy detecting means for detecting the absolute value of the horizontal direction decorrelation energy by calculating its absolute value, and inputting the sample value of the noted sample point and a predetermined reference sample point, Serial a low frequency components in the horizontal direction in the frequency component of interest sample point, and in the vertical direction to extract a frequency component corresponding to half the color subcarrier frequency,
A vertical high-frequency luminance signal energy detecting means for detecting the absolute value thereof to detect a vertical high-frequency luminance signal energy;
The horizontal direction decorrelation energy is smaller than the third set value, and a value obtained by subtracting the horizontal direction decorrelation energy from the vertical direction high band luminance signal energy is given from the outside. If the value obtained by subtracting the horizontal non-correlation energy from the vertical high band luminance signal energy is larger than the fourth set value, there is a correlation in the horizontal direction. Horizontal correlation detecting means for determining that the output of the vertical correlation detecting means is delayed for a predetermined period to simultaneously obtain vertical correlation detection results at a plurality of sample points aligned in a straight line in the vertical direction on the screen, In the case where the detection result of the vertical correlation is “correlation” and the detection results of the vertical correlation at predetermined reference sample points above and below the sample point of interest are all “no correlation”, Correcting the detection result of the direct correlation to “no correlation”, and if the detection result of the vertical correlation at the sample point of interest is “no correlation” and the detection results of the vertical correlation at the reference sample point are all “correlation”, The detection result of the vertical correlation at the target sample point is corrected to "correlated" to remove the isolated points in the vertical direction, and the output of the horizontal correlation detecting means is delayed for a predetermined period to be aligned in a horizontal line on the screen. The detection results of the horizontal correlation at a plurality of sample points are obtained at the same time, and the detection result of the horizontal correlation at the target sample point is “correlated”, and the detection result of the horizontal correlation at predetermined reference sample points located on the left and right of the target sample point Are all “no correlation”, the detection result of the horizontal correlation at the sample point of interest is corrected to “no correlation”,
When the detection result of the horizontal correlation at the target sample point is “no correlation” and the detection results of the horizontal correlation at the reference sample point are all “correlation”, the detection result of the horizontal correlation at the target sample point is “correlation”. To remove horizontal isolated points, and select one of the horizontal color signal extraction filter, the vertical direction color signal extraction filter, or the horizontal / vertical direction color signal extraction filter according to the correction result. Determining means for transmitting a control signal for performing the control, a switch circuit for outputting a color signal component in accordance with the control signal of the determining means, and outputting a luminance signal component by subtracting the output of the switch circuit from the composite video signal. An image correlation correspondence luminance signal color signal separation filter comprising a subtraction circuit. 2. The method according to claim 1, wherein the determining means sends a control signal for selecting a horizontal color signal extraction filter output when there is a correlation in the horizontal direction, and when there is no correlation in the horizontal direction and there is a correlation in the vertical direction, A control signal for selecting the output of the vertical color signal extraction filter is sent. If there is no correlation in the horizontal and vertical directions, a control signal for selecting the output of the horizontal / vertical color signal extraction filter is sent. 2. The color signal separation filter according to claim 1, wherein the color signal is a luminance signal corresponding to an image correlation. And a control signal for selecting a vertical color signal extraction filter output when there is a correlation in the vertical direction and no correlation in the horizontal direction, wherein the correlation means has a correlation in the horizontal direction. If there is no correlation in the vertical direction, a control signal for selecting the output of the horizontal color signal extraction filter is sent. If there is no correlation in the horizontal and vertical directions, or if there is no correlation, the horizontal and vertical color signals 2. A color signal separation filter according to claim 1, wherein the filter transmits a control signal for selecting an extraction filter output.