JPH01289392A - Filter for separating luminance signal/chrominance signal corresponding to picture correlation - Google Patents

Abstract

PURPOSE:To decrease a dot disturbance by suitably using a luminance signal/ chrominance signal separating filter according to the correlation of a picture in the vertical and horizontal directions of a composite color television signal. CONSTITUTION:A delay means 5, which simultaneously obtains a notable sampled point to delay an input sampling signal and to separate a luminance signal and a chrominance signal and a sampled point to approach the former point, and a picture correlation deciding means 7, which detects the picture correlation in the vertical and horizontal directions from the values of the notable sampled point and the approaching sampled point and decides the correlation of the picture are provided. Based on a decision result, one of the outputs of a horizontal directional filter 6b, a vertical directional filter 6a, or a horizontal/vertical directional filter 6c is made into the chrominance signal output of the luminance signal/chrominance signal separating filter. Thus, by the correlation of the picture in the horizontal and vertical directions of the composite video signal, the luminance signal/chrominance signal separating filter is suitably used according to a case. Thus, the effect of leakage to the mutual channel of the luminance signal and a chrominance signal in an area, where the picture drastically changes, can be reduced, and the dot disturbance can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a luminance signal and chrominance signal separation filter compatible with image correlation, and particularly to a luminance signal and chrominance signal separating filter for separating a luminance signal and a chrominance signal from a composite television signal of the NTSC system, for example. This invention relates to color signal separation filters.

[Conventional technology]

FIG. 4 is a block diagram showing an example of the configuration of a conventional luminance signal/chrominance signal separation filter. In FIG. 0, an NTSC composite color television signal is input to an input terminal 1. The composite color television signal is applied to a vertical filter 6j via an A/D converter 4, and
A line delay circuit 50 is provided. 1 line delay circuit 5
The output 202 of 0 is applied as is to the vertical filter 6j, and after being further delayed by one line in the one line delay circuit 5p, it is applied to the vertical filter 6j. The vertical filter 6j is a filter commonly called a two-line comb filter, and its output 204 is given to the bandpass filter 6k. The output of the bandpass filter 6 is derived from the output terminal 2 as a chrominance signal 205, and is applied to the first input of the subtraction circuit 9b. Further, the output of the one-line delay circuit 50 is applied to the second input of the subtraction circuit 9b via the compensation delay circuit 5q. The compensation delay circuit 5q is a circuit for compensating for the delay in the bandpass filter 6k. Then, a luminance signal 20 is output from the subtraction circuit 9b.
7 is output and applied to output terminal 3.

Next, the operation of the filter for an NTSC composite color television signal will be explained.

The composite color television signal 201 sampled in synchronization with the color subcarrier at the sampling frequency fs=4·fsc (fsc is the color subcarrier frequency) is displayed on the screen as a two-dimensional grid-like array as shown in FIG. Become. That is, fsc” (455
/2) fH, the phase of the color signal C is inverted by 180° for each line, and four samples are extracted in one cycle. Here, in the figure, Y is a luminance signal, C+, Cz
indicates a color signal.

Now, it is assumed that Z-1 and 2-1 are used as symbols representing a delay of one sample and a delay of one line, respectively, using Z transformation. Here, Z-'=e Xp(-j 2 πf/4 fsc). Also, since fsc = (455/2) f s, 1=910. At this time, delay circuits 5o, 5p
A vertical direction filter 6j extracts a line support signal 204 for each line including a color signal from the one-line delayed signal 202, the two-line delayed signal 203, and the current input signal 201, which are delayed by using the chrominance signal.

The transmission circuit Hv (Z) of the vertical filter 6j is )1
v (Z)=(-1/4)-(1-Z-L)". That is, on the screen in FIG. 6, the line support signal Hc (m, n) at the coordinates (m, n> HC(m,n)-(1/4)
(S(m, nn-1)-2S(,n)+S(o+,
n+1)). Since the line support signal also includes the luminance signal Y, the bandpass filter 6k converts the color signal C(m, n), which is a high frequency component, into the line support signal Hc.
Separate from (m, n). The color signal 205 obtained thereby is sent to the subtraction circuit 9b. Subtraction circuit 9b
is a signal S (m, n
) 206 to separate the color signal C (m, n) 205 from the following equation and (luminance signal Y (m, n) 207.

Y (m, n) = S (m, n) - C (m, n) The transfer function Hh (Z) to the bandpass filter 6 is, for example, Hh (Z)□ (-1/32) (1- Z-”)t(1+
Z-')"(1+Z-').

[Problem to be solved by the invention]

The conventional luminance signal/chrominance signal separation filter is configured by fixing the characteristics of the vertical filter and the horizontal filter and combining them as described above. That is, the luminance signal and the color signal are separated by bandpass filters in both the vertical and horizontal directions. Therefore, in the conventional method, in areas where the brightness and color of the image change rapidly, the brightness signal and the color signal leak into each other's channels, which causes problems such as deterioration of the quality of the reproduced image, especially due to dot interference. Ta.

This invention was made to solve the above-mentioned problems, and provides a luminance signal and chrominance signal separation filter that can accurately separate luminance signals and chrominance signals even in television images where the signal changes rapidly. The purpose is to provide

[Means to solve the problem]

The image correlation compatible luminance signal/chrominance signal separation filter according to the present invention includes a delay means for simultaneously obtaining a sample point of interest and a sample point close to the sample point from which one luminance signal and one color signal are to be separated by delaying an input sampling signal; Image correlation determination means is provided for detecting vertical image correlation and horizontal image correlation from the values of the sample point of interest and neighboring sample points, respectively, and determining the image correlation. filter,
The chrominance signal output of the luminance signal chrominance signal separation filter is the output of the vertical direction filter or the horizontal/vertical direction filter.

[Effect]

In this invention, since the luminance signal and chrominance signal separation filters are used depending on the correlation between the vertical and horizontal images of the composite video signal, the influence of leakage of the luminance signal and chrominance signal to each channel in areas where the image changes rapidly can be reduced, and dot interference can be reduced.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic block diagram showing a luminance signal/chrominance signal separation filter compatible with image correlation according to an embodiment of the present invention. In FIG. The composite color television signal is applied to an A/D converter 4. This A/D
The converter 4 is configured to sample the composite color television signal at a sampling frequency fs=4f3c.

The composite color television signal sampled by the A/D converter 4 is given to a 1-line delay circuit 5a, and further passes through a 1-line delay circuit 5b to determine the sample value at a certain sample point of interest and the sample of interest. Point 1 on the screen
Sample values at sample points on the line and one line below are extracted simultaneously. The sample values extracted by the delay means 5 consisting of the l-line delay circuits 5a and 5b are processed by the vertical color signal extraction filter 5a and the horizontal color signal extraction filter 6.
b, horizontal/vertical color signal extraction filter 6c, and image correlation determination circuit 7 as follows.

That is, the vertical color signal extraction filter 5a, the horizontal/vertical color signal extraction filter 6c, and the image correlation determination circuit 70.
The inputs include the output 101.1 of the A/D converter 4 and the output 102.1 of the line delay circuit 5a. and the output 103 of the one-line delay circuit 5b. Further, the output 102 of the one-line delay circuit 5a is applied to the horizontal color signal extraction filter 6b.

At this time, for example, when the vertical color signal extraction filter 6a is expressed using a transfer function, it is expressed as "Cv(Z)=(-1/4)(1-Z-L)",
The horizontal color signal extraction filter 6b is expressed as Ch(Z)=(-1/4)(1-Z-2)'', and the horizontal/vertical color signal extraction filter 6C is expressed as Chv(Z)= (-1/4) (1-Z-”)2・(
-1/4) (1-Z-')''.

The output 104 of the vertical color signal extraction filter 6a is passed through the compensation delay circuit 5c to the horizontal color signal extraction filter 6b.
The output 106 of the horizontal/vertical color signal extraction filter 6C is provided to the switch circuit 8 via the compensation delay circuit 5d, and the output 108 of the horizontal/vertical color signal extraction filter 6C is provided to the switch circuit 8 via the compensation delay circuit 5e. Further, the output 110 of the image correlation determination circuit 7 is connected to the switch 8
is given as a control signal. Output 1 of switch circuit 8
11 is output as a color signal from the output terminal 2 and is also applied to one input of the subtraction circuit 9a.

The output 102 of the 1-line delay circuit 5a is applied to the other input of the subtraction circuit 9a via the compensation delay circuit 5f. The output 113 of the subtraction circuit 9a is outputted from the output terminal 3 as a luminance signal. Note that the compensation delay circuits 5c, 5d,
5e and 5f are circuits for compensating for delays in each circuit.

FIG. 2 shows an example of the configuration of the image correlation determination circuit 7.

In the image correlation determination circuit 7, the output 101 of the A/D converter 4, the output 102 of the line delay circuit 5a, the output 103 of the line delay circuit 5b, bandpass filter 6d,
The signal is applied to the vertical bandpass filters 6f and 6g of the vertical uncorrelation energy detection means 21 and the vertical band luminance signal energy detection means 24. Further, the output 102 of the one-line delay circuit 5a is given to the horizontal band-pass filter 61 of the horizontal non-correlation energy detection means 23.

The horizontal band luminance signal energy detection means 22 includes a vertical low-pass filter 5d and a horizontal band-pass filter 6e.
and an absolute value circuit 10a, and the output 114 of the vertical low-pass filter 6d is a horizontal band-pass filter 6 that extracts a frequency component corresponding to one half of the color subcarrier.
e and is applied to one input of the comparison circuit 11a via the absolute value circuit 10a. The output (third set value) 117 of the constant generation circuit 12a is applied to the other input of the comparison circuit 11a.

The vertical non-correlation energy detection means 21 includes a vertical band pass filter 6f, a compensation delay circuit 5g, and an absolute value circuit 10.
b, and the output 11 of the vertical bandpass filter 6f
9 is applied to one input of the comparison circuit 11b via the compensation delay port 85g and the absolute value circuit 10b. The other input of the comparison circuit 11b is connected to the output (
The first set value) 122 is given.

The vertical band luminance signal energy detection means 24 includes a vertical band pass filter 6g and a horizontal low pass filter 6h.
and an absolute value circuit 10C, which corresponds to one half of the color subcarrier.
The output 125 of the vertical band-pass filter 6g that extracts the frequency component corresponding to
h and the absolute value circuit 10c to one input of the comparison circuit 10c. The output (fourth set value) 128 of the constant generation circuit 12C is applied to the other input of the comparison circuit 10c.

The horizontal non-correlation energy detection means 23 includes a horizontal band pass filter 6i, a compensation delay circuit 5h, and an absolute value circuit 10.
d, the output 13 of the horizontal bandpass filter 61
0 is applied to one input of the comparison circuit lid via the compensation delay circuit 5h and the absolute value circuit 10d. The output (second set value) I33 of the constant generation circuit 12d is applied to the other input of the comparison circuit 11d.

Note that the compensation delay circuit 5g is a horizontal band pass filter 6.
The compensation delay circuit 5h is a circuit for compensating for the delay in the horizontal low-pass filter 6h.

At this time, for example, the vertical low-pass filter 6d is expressed as FVL(Z)=(1/4)(1+Z −' ), and the horizontal band-pass filter 6e is expressed as FHh(Z)・
1-Z-', that is, the frequency component corresponding to 172 of the color subcarrier in the horizontal direction is extracted, and the vertical band-pass filter 6f is Fuh(z)-1-Z-
"L", that is, the vertical band-pass filter 6g extracts a frequency component corresponding to 1/2 of the color subcarrier in the vertical direction.
−”, and the horizontal low-pass filter 6h is FH, (
The horizontal band-pass filter 61 is a digital filter expressed as FHb(Z)·1-Z-'.

The vertical correlation detection means 25 includes the comparison circuit 11a and the comparison circuit 11.
b, consisting of a comparison circuit lid and a vertical correlation detection circuit 13a, an output 118 of the comparison circuit 11a, one output 123 of the comparison circuit 11b, and one output 135 of the comparison circuit lid
is given to the vertical correlation detection circuit 13a. Further, the horizontal correlation detection means 26 includes a comparison circuit 11c, a comparison circuit 11d, a comparison circuit 11b, and a horizontal correlation detection circuit 13b, and the output 129. of the comparison circuit 11C. One output 134 of the comparison circuit 11d and one output 124 of the comparison circuit 11b are given to the horizontal correlation detection circuit 13b. Vertical correlation detection circuit 1
3a output 136 and horizontal correlation detection circuit 13b output 1
37 is applied to the determination circuit (determination means) 14. The output 110 of the determination circuit 14 is sent as the output of the image correlation determination 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 input to one sample delay circuit 51 and one of the AND circuits 15a and NOT
The output 147 of the NOT circuit 16b is applied to one input of an AND circuit 15d.

Further, the output 137 of the horizontal correlation detection circuit 13b is connected to one input of the 1-sample delay circuit 5j and the AND circuit 15d and N
The output 140 of the NOT circuit 16a is applied to one input of the AND circuit 15a. The output 141 of the AND circuit 15a is applied to a one-sample delay circuit 5k, and also to one input of an AND circuit 15C. Output 1 to 1 sample delay circuit 5
42 is a 1 sample delay circuit 5I! It is also applied to one input of the AND circuit 15b and one input of the AND circuit 15c. The output 143 of the one-sample delay circuit 5β is applied to one input of the AND circuit 15b. The output 144 of the AND circuit 15b and the output 145 of the AND circuit 15c are given to the OR circuit 17a,
The output 146 of the R circuit 17a is given to one input of the OR circuit 17c.

The output 148 of the AND circuit 15d is the 1-sample delay circuit 5.
m, and also to one input of the AND circuit 15f. 1 sample delay circuit 5m output 149
is given to the 1-sample delay circuit 5n, and AN
These signals are applied to one input of the D circuit 15e and one input of the AND circuit 15f, respectively. The output 150 of the 1-sample delay circuit 5n is given to one input of the AND circuit 15e, and the output 151 of the AND circuit 15e and the AND circuit 15
The output 152 of f is given to the OR circuit 17b, and the output 153 of the OR circuit 17b is given to one input of the OR circuit 17C.

The output 154 of the OR circuit 17c is applied to one input of an AND circuit 15g and one input of an AND circuit 15h, respectively. The output 138 of the 1-sample delay circuit 51 is applied to the other input of the AND circuit 15g, and the output 139 of the 1-sample delay circuit 5j is applied to the other input of the AND circuit 15h. Output of AND circuit 15g and AN
The output of the D circuit 15h becomes the output 110 of the determination circuit 14.

Next, the operation will be explained.

The sampling sequence 101 of the NTSC system color television signal sampled by the A/D converter 4 at the sampling frequency fs=4fsc is transmitted through delay circuits 5a and 5b, so that the line on the screen - the line on the straight line Sample values at three sample points are obtained simultaneously. That is, the coordinates (m,
Composite color television signal (sample value) at position n)
When S (m, n) appears on the signal line 102, the signal S (m, n-1) appears on the signal line 103, and the signal S (m, n+1) appears on the signal line 101 (
(See Figure 5). A luminance signal and chrominance signal filter is constructed based on the sample values of sample points over three lines on the screen.

In this method, the vertical color signal extraction filter 6a.

The horizontal color signal extraction filter 6b and the horizontal/vertical color signal extraction filter 6c extract color signals through filter processing having the following transfer function.

Vertical color signal extraction filter Cv (Z) = (-1/4) (1-Z-')"Horizontal color signal extraction filter Ch (Z) = (-1/4) (1-Z-")" Horizontal/
Vertical direction color signal extraction filter Chv (Z)□ (-1/4) (1-Z-")" ・(
-1/4) (1-Z-1)" Vertical filter output 104 and horizontal filter output 10 obtained in this way
6. The horizontal and vertical color signal extraction filter outputs 108 are sent to the switch circuit 8 via compensation delay circuits 5c, 5d, and 5e, respectively.

Here, the operation of the circuit that determines which color output signal to select from the vertical color signal extraction filter 6a + horizontal color signal extraction filter 6b, and the horizontal/vertical color signal extraction filter 6C will be explained. do.

Regarding the sample point of interest, the correlation between 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, and when the correlation is particularly strong in the horizontal direction, The switch circuit 8 is switched so that the output of the horizontal color signal extraction filter 6b is selected, and in other cases, the output of the horizontal and vertical color signal extraction filters is selected.

Detection of image correlation and control of the switch circuit 8 are performed by the image correlation determination circuit 7. The image correlation determination circuit 7 controls the switch circuit 8 through the following operations.

Let the vertical direction uncorrelated energy be Dv (Z) and the horizontal direction uncorrelated energy be Dh (Z), introduce absolute value approximation, and express using a transfer function as follows.

pv (Z) = 11-Z-”, IDh (Z)
= + 1-Z-' 1 The above two equations have filter characteristics that block DC components and color subcarrier frequency components in the vertical and horizontal directions. Further, let the horizontal high-frequency luminance signal energy be DYh (Z), and the vertical high-frequency luminance signal energy be DYv (Z), introduce absolute value approximation, and express using a transfer function as follows.

DYh (Z) = l (1/4) (1+Z-')
”・(1-Z-') IDYv (Z) = I
(1/4) (1+Z-”)z-(1-Z-”) 1
At this time, the vertical correlation detection circuit 13a detects that DV (Z)≦
Ka+ (Ka+: correlation threshold constant) and DYh (Z)≧K 4 y 1 (Ka□: high frequency signal energy threshold constant) and Dh (Z)>Kaz (Kdz: correlation threshold constant)
When this is satisfied, it is determined that there is a correlation in the vertical direction, and a signal "1" is sent to the determination circuit 14. If the above conditions are not satisfied, it is determined that there is no correlation in the vertical direction, and a signal "0°" is sent to the determination circuit 14.

On the other hand, the horizontal correlation detection circuit 13b satisfies the following conditions: Dh (Z)≦Kdz (Kaz: correlation threshold constant) and DYV (Z)≧K dyz (Kdy2: high frequency signal energy threshold constant) and Dv (Z) > When Kat (Kat: correlation threshold constant) is satisfied, it is determined that there is a correlation in the horizontal direction, and a signal "1" is sent to the determination circuit 14. When the above condition is not satisfied, it is determined that there is no correlation in the horizontal direction. Judgment and judgment circuit 1
Send a signal “0” to 4.

The determination circuit 14 sends out a control signal 110 in accordance with the above correlation detection result, and controls the switch circuit 8 as follows.

If there is a correlation in the vertical direction and no correlation in the horizontal direction, the output of the switch circuit 8 is the output of the vertical color signal extraction filter. Further, if there is no correlation in the vertical direction but there is correlation in the horizontal direction, the output of the switch circuit 8 is set as the horizontal color signal extraction filter output. Furthermore, if there is no correlation in both the vertical and horizontal directions, the output of the switch circuit 8 is taken as the output of the horizontal and vertical color signal extraction filters.

Note that, due to the correlation detection algorithm, there is in principle no case where there is a correlation in both the vertical and horizontal directions.

By the way, correlation is generally a property common to several consecutive sample points, and it is impossible for one sample point to have a different correlation from surrounding sample points.

Therefore, perform the following operations for each sample point.

If the correlation at a sample point of interest is different from the correlation at the sample points on the left and right of it on the screen, it is determined that there is an error in image correlation detection, and both horizontal and vertical correlations at that sample point are absent. shall be.

This operation will be explained below using FIG.

The AND circuit 15a receives the output 1 of the vertical correlation detection circuit 13a.
36 and the output 137 of the horizontal correlation detection circuit 13b to N07.
An inverted signal 140 is provided in the circuit. At this time A
The output of the ND circuit 15a is "1" when the output of the vertical correlation detection circuit is "1".
”, when the output of the horizontal correlation detection circuit is “O”, that is, when the output of the vertical color signal extraction filter is selected, “1” is output, and when the output of the horizontal color signal extraction filter, which is another filter, is selected, “1” is output. When selecting the output of the filter or the horizontal/vertical color signal extraction filter, "0" is output.The output 141 of the AND circuit 15a is sent to the 1-sample delay circuit 5 via 51, so that the same scanning Information on whether the vertical color signal extraction filter output is selected or not can be obtained simultaneously at three consecutive sample points on the line.

That is, when information about the sample point of interest appears on the signal line 142, the signal line 141 contains information about the sample point one spot to the right on the screen, and the signal line 143 contains information about the sample point one sample point to the left on the screen. appear.

At this time, when the value at the sample point of interest is "1",
That is, when the vertical color signal extraction filter output is selected, the vertical color signal extraction filter output must be selected at least for either the left or right sample point.

If the vertical color signal extraction filter output is not selected for either the left or right sample point, the correlation detection result at the sample point of interest is assumed to be a misjudgment, and the horizontal and vertical color signal extraction filter outputs are forcibly output. I'll leave it to you to choose. When the value at the sample point of interest is "1" and the value at at least one of the left and right sample points is "1", the OR circuit 17a finally extracts the vertical color signal at the sample point of interest. Outputs "l" only when selecting filter output.

Further, the same operation is performed when selecting the output of the horizontal color signal extraction filter as in the case of selecting the output of the vertical color signal extraction filter. The operation is the same as in the vertical direction, and the NOR circuit 17b outputs "1" only when selecting the horizontal color signal extraction filter output at the sample point of interest. OR circuit 17a and OR
The output of the circuit 17b is further connected to AN via an OR circuit 17c.
It is given to one input of D circuits 15g and 15h, respectively.

In this way, the AND circuit 15 is finally used in the determination circuit.
The output signals of g and 15h are sent out as a control signal 110, and the switch circuit 8 is controlled as follows.

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 and summed at a frequency four times as high as the color subcarrier synchronized with the horizontal scanning frequency. If so, it is not limited to four times the color subcarrier,
Sampling may be performed at other frequencies.

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

C. Effects of the Invention] As described above, according to the image correlation compatible luminance signal chrominance signal separation filter according to the present invention, the luminance signal chrominance signal separation is performed by the correlation between vertical and horizontal images of a composite color television signal. Since different filters are used, it is possible to reduce the influence of leakage of luminance signals and chrominance signals into mutual channels, and there is an effect that dot interference can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing an NTSC system image correlation compatible luminance signal/chrominance signal separation filter according to an embodiment of the present invention, FIG. 2 is a block diagram showing an embodiment of the image correlation determination circuit, and FIG. FIG. 4 is a block diagram showing an example of a conventional luminance signal/color signal separation filter. FIG. 5 is a block diagram showing an example of a conventional luminance signal/color signal separation filter. FIG. 4 is an explanatory diagram showing an arrangement on a screen of a signal sequence synchronously sampled at a four-fold magnification. In the figure, 1 is the input terminal, 2.3 is the output terminal, and 4 is the A
/D converter, 5a to 5n are delay circuits, 6a to 6 are digital filters, 7 is an image correlation determination circuit, 8 is a switch circuit, 9a and 9b are subtraction circuits, 10a to 10d are absolute value circuits, 11a to 11d 12a to 12d are constant generation circuits, 13a is a vertical correlation detection circuit, 13b is a horizontal correlation detection circuit, 14 is a determination circuit, 153 to 15h are A
ND circuit, 16a, 16b are NOT circuits, 17a-17
0 is an OR circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) Input a composite video signal sampled at a predetermined frequency synchronized with the horizontal scanning frequency so that each sampling point is arranged in a grid on the screen, and digitally calculate the luminance signal component and color from the composite video signal. An image correlation compatible luminance signal/chrominance signal separation filter for separating signal components, the composite video signal being delayed, and a sample point of interest at which the luminance signal and the color signal should be separated, and a sample point perpendicular to the sample point of interest on the screen. delay means for simultaneously obtaining sample values of a plurality of reference sample points arranged in a straight line in the direction; a vertical color signal extraction filter that extracts and outputs a frequency component corresponding to a horizontal color subcarrier component; a horizontal color signal extraction filter; and a horizontal/vertical color signal extraction filter that receives sample values of the sample point of interest and a predetermined reference sample point as input, extracts and outputs frequency components corresponding to color subcarrier components in both the vertical and horizontal directions. a directional color signal extraction filter, which inputs sample values of the sample point of interest and a predetermined reference sample point, and extracts frequency components corresponding to a vertical direct current component and a color subcarrier component from frequency components at the sample point of interest; and a vertical direction uncorrelated energy detection means for detecting vertical direction uncorrelated energy by excluding the absolute value of the vertical direction uncorrelated energy; extracting a frequency component that is a low frequency component in the vertical direction and corresponds to one half of the color subcarrier frequency in the horizontal direction;
horizontal band luminance signal energy detecting means for detecting the horizontal band luminance signal energy by determining its absolute value; horizontal direction uncorrelated energy detection means for detecting horizontal direction uncorrelated energy by excluding a horizontal direct current component and a frequency component corresponding to a color subcarrier component from among them, and determining the absolute value thereof, and detecting horizontal direction uncorrelated energy; and a sample value of a predetermined reference sample point as input, and among the frequency components at the sample point of interest, a frequency that is a low frequency component in the horizontal direction and corresponds to one half of the color subcarrier frequency in the vertical direction. extract the ingredients,
vertical band luminance signal energy detection means for detecting the vertical band luminance signal energy by determining its absolute value;
The vertical uncorrelated energy is smaller than the first set value, and the horizontal uncorrelated energy is compared with a second set value given from the outside. , the horizontal direction uncorrelation energy is larger than the second set value, and the horizontal band brightness signal energy is compared with a third set value given from the outside, and the horizontal band brightness signal energy is is larger than the third set value, vertical correlation detection means determines that there is a correlation in the vertical direction;
The vertical uncorrelated energy is larger than the first set value, and the horizontal uncorrelated energy is compared with a second set value given from the outside. , the horizontal direction uncorrelation energy is smaller than the second set value, and the vertical direction band luminance signal energy is compared with a fourth set value given from the outside, and the vertical direction band luminance signal energy is is larger than the fourth set value, horizontal correlation detection means determines that there is a correlation in the horizontal direction; and inputs the determination result of the vertical correlation detection means and the determination result of the horizontal correlation detection means, Sending out a control signal for selecting the output of the horizontal color signal extraction filter, the vertical color signal extraction filter, or the horizontal/vertical color signal extraction filter according to the determination result of the presence or absence of vertical correlation. a switch circuit that outputs a color signal component in response to a control signal of the decision means; and a subtraction circuit that subtracts the output of the switch circuit from the composite video signal and outputs a luminance signal component. An image correlation compatible luminance signal chrominance signal separation filter.