JPH01117493A - Luminance signal chrominance signal separation filter corresponding to correlation of picture - Google Patents

Abstract

PURPOSE:To reduce dot disturbance by using a luminance signal chrominance signal separation filter depending on the correlation of horizontal and vertical pictures of a composite color television signal. CONSTITUTION:Delay means 5a, 5b retarding an input sampling signal to separate a luminance signal and a chrominance signal thereby obtaining a noticed sampling point and a sampling point close thereto simultaneously, a picture correlation discrimination means 7 detecting the vertical picture correlation, horizontal picture correlation and oblique picture correlation from the values of the noticed sampling point and the point in vicinity and discriminating the correlation of the picture are provided. Then color signal extraction filters 6a-6c are used depending on the result of discrimination. Thus, the effect of leakage onto the mutual channel of the luminance signal and the chrominance signal at the region where the picture change is rapid is reduced to decrease dot disturbance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image correlation compatible luminance signal and chrominance signal separation filter that separates luminance signals and chrominance signals from, for example, an NTSC composite television signal.

[Prior Art] Fig. 5 is a block IA showing an example of the configuration of a conventional luminance signal chrominance signal separation filter. In the figure, an NTSC composite television signal is input to the input terminal (1). Ru. This composite television signal is processed by an A/D converter (4
) to the vertical filter (6I) and to the l-line delay circuit (5T). The output of the l-line delay circuit (5T) is given as is to the vertical filter (61), and is also fed to the l-line delay circuit (5T).
After being further delayed by one line at step 5u), it is applied to a vertical filter (61). Vertical filter (6I
) is a filter 9 which is usually called a two-line comb filter, and its output is given to a bandpass filter (6m). The output of the bandpass filter (6m) is the color signal (205)
It is derived from the output terminal (2) as a signal and is applied to the first input of the subtraction circuit (9e). Also, the subtraction circuit (
The second input of the above-mentioned l line delay circuit (5T
) is provided via a compensation delay circuit (5V).

This compensation delay circuit (5v) is a circuit for compensating for the delay in the bandpass filter (6m). A luminance signal (207) is output from the subtraction circuit (9e) and applied to the output terminal (3).

Next, the operation of the luminance signal/chrominance signal separation filter for an NTSC composite television signal will be explained.

A composite television signal (201) sampled in synchronization with the color subcarrier at sampling frequency % fs = 4 ・rsc (fsc is the color subcarrier frequency) is displayed on the screen in a two-dimensional grid pattern as shown in Figure 6. It becomes an array. That is, fsc =
(455/2)f)l, the phase of the color signal C is inverted by 180 degrees for each line, and four samples are extracted in one cycle. Here, in the figure, Y is a luminance signal,
C1 and C2 indicate color signals. .

Now, let the symbols represent the delay of l samples and the delay of l lines, and use Z-transform to convert them to z-1 and Z-, respectively.
1 is used. here.

Z-' = cxp(-j2πf/4 fsc)
It is. Also, since fsc - (455/2) ftl, the result is 910. At this time, the delay circuit (5T)
, (50) is used to delay the 1-line delayed signal (20
2), the two-line delay signal (203) and the current input signal (
201) and a line support signal (204) that is supported for each line including color signals by a vertical filter (61).
Extract. Transfer function HV of vertical filter (61)
(Z) is.

Hv(Z)=(-1/4)・(1-Z-')2. That is, the line support signal l1c(s, n) at the coordinates (m, n) on the screen in FIG.
−23(,n)+S(m,n+1)). Since the line support signal also includes the luminance signal Y, the color value No. 1 C, which is a high frequency component, is filtered by a bandpass filter (6m).
Separate (m,n) from Hc(m,n). The color signal (205) obtained thereby is sent to the subtraction circuit (9e).
sent to. The subtraction circuit (9e) receives the l line delay signal (2
02) is further delayed by a compensation delay circuit (5v) according to the bandpass filter (6■).
The color signal C(w, n) (205) is subtracted from 06), and the luminance signal Y(■, n) (207) is separated as shown in the following equation.

Y= (m, n) = S (!l, n) −C(
+a, n) Transfer function oh of h bandpass filter (6m)
(z), for example.

)1h(Z)-(-1/32)(1-Z"2)2(1+
Z-')'(l+z-').

[Problems to be Solved by the Invention] The conventional luminance signal/chrominance signal separation filter is configured by fixing and combining the characteristics of the vertical direction filter and the horizontal direction filter 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, with conventional filters, when the image is in an area where the brightness and color change drastically, the brightness signal and the color signal leak into each other's channels, which causes deterioration in the quality of the reproduced image, especially due to dot interference. There was a hearing.

This invention was made to solve the above-mentioned problems, and it provides a luminance signal and chrominance signal separation compatible with image correlation that can achieve accurate separation of luminance signals and chrominance signals even in the case of rapid signal changes in television images. The purpose is to provide filters.

[Means for Solving the Problems] The image correlation compatible luminance signal and chrominance signal separation filter according to the present invention is capable of separating a luminance signal and a chrominance signal by delaying an input sampling signal at a sample point of interest and its vicinity. a delay means for simultaneously obtaining sample points to be sampled, and an image for determining image correlation by detecting vertical image correlation, horizontal image correlation, and diagonal image correlation from the values of the sample point of interest and neighboring sample points, respectively. According to the result of the determination, the output of the horizontal filter or the vertical filter is used as the output of the luminance signal/chrominance signal separation filter for images that are particularly resistant to correlation.

[Function] According to the present invention, since the luminance signal and chrominance signal separation filters are used depending on the correlation between vertical, horizontal, and diagonal images of the composite video signal, the luminance signal and chrominance signal of three types are used in areas where the image changes rapidly. The effect of leakage to each other's channels can be reduced, and dot interference can be alleviated.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described based on the drawings.

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

The composite color television signal sampled by the A/D converter (4) is given to an l-line delay circuit (5a), and further passes through an l-line delay circuit (5b) to obtain a certain sample point of interest. The sample value at and the sample value at the sample point on the l line on the screen and below the sample point of interest are simultaneously extracted. This l line delay circuit (5
The sample values extracted by a) and (5b) are passed through a vertical color signal extraction filter (6a), a horizontal color signal extraction filter (6b), and a horizontal/vertical color signal extraction filter (
6C) is given to the image correlation determination circuit (7) as follows.

That is, the output (1) of the A/D converter (4) is input to the vertical color signal extraction filter (6a), the horizontal/vertical color signal extraction filter (6c), and the image correlation determination circuit (7).
01), the output (10) of the l line delay circuit (5a)
2) Output of l line delay circuit (5b) (1G:
l) are given respectively. Further, the horizontal color signal extraction filter (6b) is supplied with the output (102) of the l-line delay circuit (5a). At this time, for example, when the vertical color signal extraction filter (6a) is expressed using a transfer function, Cv(Z) = (-1/4) (1-Z-'
)2, and the horizontal color signal extraction filter (6b) is expressed as Cv(Z)-(-1/4)(1
-Z), and the horizontal/vertical color signal extraction filter (6c) is expressed as (:1lv(Z)=(-1/4)(1-Z-")
' (-1/4) (1-Z-')2.

Output (104) of vertical color signal extraction filter (6a)
is given to the switch circuit (8) via the compensation delay circuit (5c), and the output (106) of the horizontal color signal extraction filter (6b) is given to the switch circuit (8) via the compensation delay circuit (5d). The output (tOa) of the horizontal/vertical color signal extraction filter (6c) is given to the switch circuit (8) via the compensation delay circuit (5C). In addition, the output (110) of the one-image correlation determination circuit (7) is connected to the switch circuit (8).
) as a control signal. The output (til) of the switch circuit (8) is output as a color signal from the output terminal (2). Further, this output is given to one input of the subtraction circuit (9a). The output (102) of the l-line delay circuit (5a) is applied to the other input of the subtraction circuit (9a) via a compensation delay circuit (5f). Subtraction circuit (9a
) is output as a luminance signal from the output terminal (3). In addition, a compensation delay circuit (5c).

(5d), (5e), and (5f) are circuits for compensating for delays in each circuit.

FIG. 2 is a block diagram showing an embodiment of the image correlation determination circuit (7), and shows the output (101) of the A/D converter (4).
), output (102) of l line delay circuit (5a)
, the output (103) of the one-line delay circuit (5b) is given to a vertical low-pass filter (5d), and vertical band-pass filters (6f) and (6j). In addition, the output (101) of the A/D converter (4) and the l line delay circuit (5
The output (103) of b) is passed through the diagonal bandpass filter (6
g), and a diagonal bandpass filter (6h). Also, the output (102) of the l line delay circuit (5a)
) is applied to the horizontal bandpass filter (6k).

The output (114) of the vertical low-pass filter (6d) is connected to the horizontal high-pass filter (6e) and the absolute value circuit (10).
a) to one input of the subtraction circuit (9b). On the other hand, the output of the vertical high-pass filter (6f) (
120) is connected to the absolute value circuit (5g) via the compensation delay circuit (5g).
1, Ob). The compensation delay circuit (5g) is a circuit for compensating for the delay in the horizontal band-pass filter (6C). The output of the absolute value circuit (10b) is the other input of the subtraction circuit (9b) and the comparison circuit (Ilb).
is given to one input of The output of the subtraction circuit (9b) (
117) is applied to one input of the comparison circuit (lla), and the output (118) of the constant generation circuit (12a) is applied to the other input of this comparison circuit (lla).

Further, the output (123) of the constant generation circuit (12b) is applied to the other input of the comparison circuit (llb).

The output (125) of the diagonal band-pass filter (6g) is applied to one input (126) of the subtraction circuit (9C) via an absolute 11 circuit (1oc). On the other hand, the output (127) of the diagonal band-pass filter (6h) is the absolute value circuit (
10d) to the other input (12) of the subtraction circuit (9C).
8). The output (12
9) is connected to the comparison circuit (llc) via the absolute value circuit (10e).
) is given to one input (1:10) of the comparator circuit (lie), and the other input of this comparator circuit (lie) is given to a constant generator circuit (12c).
The output (1:11) is given.

The output (133) of the vertical band pass filter (61) is passed through the horizontal low pass filter (6j) and the absolute value circuit (
10f) to one input of the subtraction circuit (9d). On the other hand, the output (139) of the horizontal band-pass filter (6k) is given to the absolute value circuit (10g) via the compensation delay circuit (51). The compensation delay circuit (51) is a circuit for compensating for the delay in the horizontal low-pass filter (6j). Absolute value circuit (10g) output (1
41) is applied to the other input of the subtraction circuit (9d) and one input of the comparison circuit (lie). Subtraction circuit (9d
) is applied to one input of the comparison circuit (lld), and the output (137) of the constant generation circuit (12d) is applied to the other input of this comparison circuit (ttti). The output (143) of the constant generation circuit (12e) is given to the other input of the comparison circuit (lie).

The output (119) of the comparison circuit (lla) and the comparison circuit (
The output (124) of the vertical correlation detection circuit (13a
), and the output (138) of the comparator circuit (lid) and the output (14:l) of the comparator circuit (lie) are supplied to the horizontal correlation detection circuit (13b). Vertical correlation detection circuit (
13a) output (144) and the horizontal correlation detection circuit (1
The output (146) of 3b) is given to the determination circuit (14).

Further, the output (132) of the comparison circuit (llc) is given to the determination circuit (14) via the compensation delay circuit (5h).

The compensation delay circuit (5h) is a circuit for compensating for delays that occur during vertical correlation detection and horizontal correlation detection.The output (lty) of the 0 determination circuit (14) is sent as the output of the image correlation determination circuit. .

The filter in FIG. 2 is one example.

The vertical low-pass filter (6d) is F v * (Z)
−1/4 (1+Z), and the horizontal bandpass filter (6e) is.

The vertical bandpass filter (6r) is denoted as FMH(Z)-1-Z-'.

It is expressed as Fov(z)-1-Z.

The diagonal band pass filter (6g) is Fol(z)■
1-Z -Z, and the diagonal bandpass filters (2) and (6h) are expressed as Fo2(z)=1-Z
-2Iz4, the vertical bandpass filter (61) is expressed as FVH(Z)all-Z, and the horizontal lowpass filter (6j) is expressed as FVH(Z)al1-Z.

F? lL, (Z)II 1/4 (1+ Z-')2
The horizontal bandpass filter (6k) is expressed as .

This is a digital filter expressed as "Fp+(z)-1-1-".

FIG. 3 is a block IA showing an embodiment of the determination circuit (14) in the first invention, and is a block IA showing an embodiment of the determination circuit (14) in the first invention.
The output (144) of 3a) is given as the negative input of the AND circuit (15a). The output of the comparison circuit (Ilc) (
132), the output (14
5) is supplied as the other input of the AND circuit (15a), and is also supplied as one input of the AND circuit (15b). The output (1) of the horizontal correlation detection circuit (13b)
46) is given as the other input of the AND circuit (15b).

The output (147) of the AND circuit (15a) is sent to the l sample delay circuit (5k), (
51). The output of the compensation delay circuit (5j) is applied to one input of the OR circuit (16a), and the output of the l sample delay circuit (51) is applied to the other input of the OR circuit (16a).

The AND circuit (15c) is the l sample delay circuit (5k)
) output (149) and the output (16a) of the OR circuit (16a)
151) as an input, and its output (152) is given to one input of a NOR circuit (18). Also, the output (153) of the AND circuit (15b) is the l line delay circuit (5m
).

(5n), and the OR circuit (16b
) is resented by the input from the −・ side. The above OR circuit (16b
) is supplied with the output (+ss) of the l-line delay circuit (5m).

The AND circuit (15d) is the above l line delay circuit (5m)
output (154) and the output (16b) of the OR circuit (16b)
156) as input, and its output (157) is the above NO.
The other input of the R circuit (18) and the N07 circuit (17a
) is given to The above NOR circuit (18) and the above N07
The output of the circuit (17a) is the output of the image correlation determination circuit (11
0).

FIG. 4 is a block diagram showing an embodiment of the determination circuit (14) in the second invention, in which delay circuits (5o) to (5s), AND circuits (15e) to (15
h) The configuration of the portion consisting of the OR circuit (16c) and (llid) is exactly the same as in the case of FIG.

The output (163) of the above AND circuit (15f) is exclusive N
It is given to one input of the OR circuit (19), and
It is supplied to one input of the AND circuit (15i) via the N07 circuit (17b).

In addition, the output (168) of the AND circuit (15h) is connected to the exclusive NOR circuit (19) and the AND circuit (15i).
) is given to the other input of The above exclusive NOR circuit (
19) and the output of the AND circuit (15i) becomes the output (110) of the image correlation determination circuit.

Next, the operation of the above configuration will be explained.

Sampling frequency fs=4 by A/D converter (4)
By passing the sampled series (101) of the NTS, C system composite color television signal sampled by the fsc through the delay circuits (5a) and (5b), the three lines on the vertical line on the screen are The sample values at the sample points will be obtained at the same time. That is, when the composite color television signal at the position of the coordinates (m , n), that is, the coordinate value S (m , n) appears on the signal line (+02), as shown in FIG. ), a signal S(m, n-1) appears on the signal line (101), and a signal S(m, n+1) appears on the signal line (101).
) appears. A luminance signal/chrominance signal separation filter is constructed based on sample values of sample points across three lines on the screen.

This luminance signal color signal separation filter includes a vertical color signal extraction filter (6a), a horizontal color signal extraction filter (6b), and a horizontal/vertical color signal extraction filter (6C).
) extracts the color signal through filter processing with the following transfer function.

Forward color signal extraction filter: Cv (z) = (-1/4) (1-Z-')' Wood direction color signal extraction filter: X Z (:?I (z) = (-1/4) ) (1-2) Horizontal/vertical direction color signal extraction filter: CHv(z) = (-1/4)
(1-Z-”)ζ(-1/4)(1-Z-')2 The vertical color signal extraction filter (6
a) output (104), horizontal color signal extraction filter (
The output (106) of 6b) and the output (108) of the horizontal/vertical color signal extraction filter (6C) are sent to the switch circuit (8) via compensation delay circuits (5c), (5d), and (5e), respectively. be done.

Here, a 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) is selected is selected. The operation will be explained.

Regarding the sample point of interest, the correlation between the images in the diagonally upward-rightward direction, diagonally downward-rightward direction, vertical direction, and horizontal direction is detected, and the absolute value of the output difference in the diagonally upward-rightward direction and the diagonally downward-rightward direction is greater than a certain setting value. When the correlation is small and particularly strong in the horizontal direction, the output of the horizontal color signal extraction filter (6b) is selected, and when the absolute value of the difference is smaller than the set value and the correlation is particularly strong in the vertical direction, The switch circuit (8) is switched to select the output of the vertical color signal extraction filter (6c), and otherwise select the output of the horizontal/vertical color signal extraction filter (6c).

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

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

Dv(z) = 11-Z-"1 DH(Z) = l l-Z l The above two equations have filter characteristics that block the DC component and the color subcarrier frequency component in the vertical and horizontal directions. There is.

Also, the uncorrelated energy in the diagonally upward right direction is DI(2),
The uncorrelated energy in the diagonally downward rightward direction is assumed to be 02(z), and is expressed as follows by introducing absolute value approximation and using a transfer function.

Dp, 1(z) = l 1-Z -Z IDD2CZ
)=l l−Z −21Also. Horizontal high frequency luminance signal energy DY? 1(Z) and the vertical high-frequency luminance signal energy DYv(z), introducing absolute value approximation and using a transfer function, it is expressed as follows.

DYH(z)=1(1/4)・(1+Z-')"
・(1-Z) IDYv(z)=1(1/4)
・(1+Z) ・(1-Z) 1 At this time,
The output (145) via the comparison circuit (lie) D# (compensation delay circuit (5h) is: l Dot (z) - Dp2 (z) I≦Ko CKo:
threshold constant), a signal "l" is sent to the determination circuit (14). Also, I Dol(z)−Dp2(z)I>K
.

At this time, the signal "p" is sent to the determination circuit (14).

The vertical correlation detection circuit (13a) satisfies the following conditions: Dv(z)≦01 (KC)1: correlation threshold constant) and DYM(Z)-DV(Z)≧KOYI (in oil: high-frequency signal energy threshold constant) When , it is determined that there is a correlation in the vertical direction and a signal "l" is sent to the 1 determination circuit (14).

Also.

Dv(z) ) Kol or DY? 1(Z) -Dv(z)(pYI), it is determined that there is no correlation in the vertical direction, and a signal "o" is sent to the determination circuit (14).

On the other hand, the horizontal correlation detection circuit (13b) detects DH(z)≦K
D2 (nio2: correlation threshold constant) and DYv(z)-DH(z)≧KoY2 (Koy2:
(high frequency signal energy threshold constant), it is determined that there is a correlation in the horizontal direction, and a signal "1" is sent to the determination circuit (14).

When DH(Z) > KO2 or DYv(z) - DH(Z) (KoY2, it is determined that there is no correlation in the horizontal direction, and the signal "
Send 0”.

The determination circuit (14) controls the switch circuit (8) as follows according to the above correlation detection result.

In the embodiment shown in FIG. 3, when the output (145) of the comparator circuit (llc) via the compensation delay circuit (5h) is 0,
Which output (1) of the AND circuit (15a) or (15b)
47) and (153) also become 0. Also, output (145)
When is 1, the output (147) of the AND circuit (15a)
The output (144) of the vertical correlation detection circuit (13a) appears at the output (153) of the AND circuit (15b), and the output (146) of the horizontal correlation detection circuit (t:+b) appears at the output (153) of the AND circuit (15b).

From the above, each output of the delay circuits (5j) to (51) provides detection results of horizontal correlation at 34v4 sample points arranged horizontally on one screen. If the horizontal correlation detection result for either of the two reference sample points located on the left and right of the center sample point of interest is "correlation", then OR
The output of the circuit (16a) becomes l, and the detection result of the horizontal correlation at the sample point of interest appears as it is at the output of the AND circuit (15c). If there is "no correlation" at any of the reference sample points, the output of the OR circuit (16a) becomes 0, and regardless of the horizontal correlation detection result at the sample point of interest, the AN
The output of the D circuit (15c) is 0 (no correlation).

Therefore, the output of the AND circuit (15c) provides the detection result of the horizontal correlation of the sample point of interest from which isolated points have been removed in the horizontal direction.

In addition, since the vertical correlation detection results at three sample points arranged vertically on the screen are obtained at the input/output of the l-line delay circuits (5■) and (5n), the AN
The output of the D circuit (15d) is the detection result of the vertical correlation of the sample point of interest from which isolated points have been removed in the vertical direction. AN
The D circuit (18) receives the horizontal and vertical correlation detection results from which isolated points have been removed, and outputs 1 only when there is no horizontal or vertical correlation. The output of the AND circuit (18) controls the switch circuit (8), and when the output is 1, the horizontal/vertical color signal extraction filter (6C), that is, the signal line (10
9), and when it is 0, the switch is switched to the horizontal color signal extraction filter (6b), that is, the signal line (107), or the vertical color signal extraction filter (6C), that is, the signal line (tOS). In the latter case, whether to select the horizontal or vertical filter is determined by the N07 circuit (1
When this output is 0, the horizontal color signal extraction filter (6b) is selected, and when it is 1, the vertical color signal extraction filter (6a) is selected.

Since the input of the N07 circuit (17a) is given the detection result of vertical correlation from which isolated points have been removed, the switch is changed depending on the presence or absence of vertical correlation.

From the above, in the first invention using the determination circuit shown in FIG. 3, the characteristic C(z) of the color signal extraction filter changes as follows depending on the presence or absence of correlation.

If the difference between the diagonal upward-sloping correlation and the diagonally downward-sloping correlation is less than a certain value, and there is horizontal correlation, C(z) = Cs(z), and if there is vertical correlation when there is no horizontal correlation, C(z) = Cv(z). If there is no vertical correlation, C(z)-CHv(z) When the difference between the diagonally upward-sloping correlation and the diagonally downwards-sloping correlation is greater than a certain value
C(z)=C+v(z) The operation of removing isolated points in the determination circuit of FIG. 4 is exactly the same as that of FIG. 3, so
Only the control operation of the switch circuit (8) based on the detection result of the horizontal/vertical correlation after removal of isolated points will be described.

The exclusive NOR circuit (19) receives the detection results of the horizontal and vertical correlations from which isolated points have been removed, and its output becomes 1 when there is "correlation" in both the horizontal and vertical directions, or when there is "no correlation" in both directions. The output of this exclusive NOR circuit (■9) controls the switch circuit (8), and when the output is 1, the horizontal/vertical color signal extraction filter (6c) is controlled, and when it is not, the horizontal color signal is controlled. Select the extraction filter (6b) or the vertical color signal extraction filter (6a).

The AND circuit (51) outputs the vertical correlation detection result and N07.
In response to the horizontal correlation detection result via the circuit (17b),
When there is vertical correlation and no horizontal correlation, the output is l; otherwise, the output is 0.

When the output of the exclusive NOR circuit (19) is 0, the switch circuit (8) switches the filters in the horizontal and vertical directions according to the output of the AND circuit (51), and when the output is 1, the filters in the vertical direction are switched. When the signal extraction filter is 0, the horizontal color signal extraction filter is selected.

Therefore, in the second invention using the determination circuit shown in FIG. 4, the color signal extraction filter characteristic C(z) is switched as follows.

When the difference between the diagonally upward-sloping correlation and the diagonally downward-sloping correlation is less than a certain value, and there is horizontal correlation and no vertical correlation, C(z) is CH(Z). When there is vertical correlation and no horizontal correlation, C(z) = Cv. (z) When horizontal and vertical correlations are both present or absent, C(z) = Csv(z) Also, the color signal output of the switch circuit (8) is the composite of the output (112) of the compensation delay circuit (5V). A tR degree signal (113) is obtained by subtracting from the video signal.

In the above embodiment, the composite color television signal is sampled at a frequency four times as high as the color subcarrier synchronized with the horizontal scanning frequency. Sampling is not limited to four times the color subcarrier, but 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.

[Effects of the Invention] As described above, according to the present invention, brightness signal and color signal separation filters are used depending on the correlation between vertical and horizontal images of a composite color television signal, so that drastic image changes can be avoided. It is possible to reduce the influence of leakage of luminance signals and chrominance signals into each other's channels in the area, and has the effect of reducing dot interference.

[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 circuit diagram showing details of the determination portion in the first invention and the second invention, Fig. 5 is a schematic block diagram showing an example of a conventional luminance signal/chrominance signal separation filter, and Fig. 6 is a composite of the NTSC system. FIG. 3 is a diagram showing an arrangement on a screen of a signal sequence obtained by synchronously sampling a color television signal with four times the color image carrier wave; (1) - Input terminal, (2), (3) - Output terminal, (4) A/D converter, (5a) - (Sv)...
Delay circuit, (6a) to (6m)...Digital filter, (7)...Image correlation detection circuit, (8)...Switch circuit, (9a) to (9e)...Subtraction circuit, (
10a) to (10g) = absolute value circuit. (Ila) ~ (lie) ... Comparison circuit, (12
a) ~(12e) -=constant generation circuit, (13a)
. . . Vertical correlation detection circuit, (13b) - . . Horizontal correlation detection circuit, (14) . . . Determination circuit, (15a) to (15
h) ...A N D circuit, (16a) ~ (16
d) =OR circuit, (17a), (17b)...N
O7 circuit, (18)--NOR circuit, (19)--
・Exclusive NOR circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (6)

[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 convert the luminance signal and color signal from this composite video signal. An image correlation-compatible luminance signal and chrominance signal separation filter that delays the composite video signal to separate the luminance signal and chrominance signal at a sample point of interest and a sample point perpendicular to the sample point of interest on the screen. a 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 the horizontal color subcarrier component; A horizontal color signal extraction filter, and a horizontal/vertical filter that receives the sample values of the sample point of interest and a predetermined reference sample point as input, and extracts and outputs frequency components corresponding to color subcarrier components in both the vertical and horizontal directions. A directional color signal extraction filter, inputting the sample values of the sample point of interest and a predetermined reference sample point, extracts frequency components corresponding to the DC component in the vertical direction and the color subcarrier component from among the frequency components at the sample point of interest. a vertically uncorrelated energy detecting means for detecting the vertically uncorrelated energy by excluding the absolute value of the vertically uncorrelated energy; Among the frequency components, a frequency component that is a low frequency component in the vertical direction and one half of the color subcarrier frequency in the horizontal direction is extracted, and its absolute value is determined to generate a horizontal high frequency luminance signal. horizontal high-frequency luminance signal energy detection means for detecting energy;
The above vertically uncorrelated energy and the externally applied first
The vertical non-correlation energy is smaller than the first setting value, and the vertical non-correlation energy is equal to the value obtained by subtracting the vertical non-correlation energy from the horizontal high-frequency luminance signal energy. When the value obtained by subtracting the vertical non-correlation energy from the horizontal high-frequency luminance signal energy is larger than the second setting value, the correlation is determined in the vertical direction. a vertical correlation detection means that determines that there is a vertical correlation; and inputs the sample values of the sample point of interest and a predetermined reference sample point, and extracts the DC component in the horizontal direction and the color subcarrier component from among the frequency components at the sample point of interest. a horizontally uncorrelated energy detection means for detecting horizontally uncorrelated energy by excluding corresponding frequency components and finding its absolute value; Among the frequency components at the sample point of interest, extract the frequency component that is a low frequency component in the horizontal direction and corresponds to half the color subcarrier frequency in the vertical direction, calculate its absolute value, and extract the frequency component in the vertical direction. vertical high-frequency luminance signal energy detection means for detecting high-frequency luminance signal energy;
The above horizontal uncorrelated energy and the externally applied third
The horizontal non-correlation energy is smaller than the third setting value, and the value obtained by subtracting the horizontal non-correlation energy from the vertical high-frequency luminance signal energy is compared with the external Comparing the magnitude with the given fourth setting value, if the value obtained by subtracting the horizontal non-correlation energy from the vertical high frequency luminance signal energy is larger than the fourth setting value, the horizontal direction A horizontal correlation detection means that determines that there is a correlation, inputs the sample values of the sample point of interest and a predetermined reference sample point, and detects the DC component and color of the frequency component at the sample point of interest diagonally upward to the right on the screen. Exclude frequency components corresponding to subcarrier components,
a diagonally upward-rightward uncorrelated energy detecting means for detecting the obliquely upward-rightward uncorrelated energy by determining the absolute value; Components, frequency components corresponding to the DC component and color subcarrier component in the diagonally downward direction on the screen are excluded, and their absolute values are determined to detect the diagonally downward downward direction decorrelation energy. energy detection means, a determination result of the vertical correlation detection means, a determination result of the horizontal correlation detection means, a diagonally upward-to-the-right direction uncorrelated energy detection result, and a diagonally right-downward direction uncorrelated energy detection result; If the absolute difference between the diagonally upward-right direction uncorrelated energy detection result and the diagonally right-downward direction uncorrelated energy detection result is smaller than the fifth setting value given from the outside, and there is a correlation in the horizontal direction, A control signal for selecting the color signal extraction filter output is sent, and the absolute value of the difference between the diagonally upward-right direction uncorrelated energy detection result and the diagonally right-downward direction uncorrelated energy detection result is smaller than the fifth setting value. , and when there is no correlation in the horizontal direction and there is correlation in the vertical direction, a control signal is sent to select the vertical color signal extraction filter output, and the detection result of the uncorrelated energy in the diagonally upward right direction and the diagonally downward direction If the absolute value of the difference with the uncorrelated energy detection result is smaller than the fifth setting value and there is no correlation in either the horizontal or vertical directions, or if the absolute value of the difference is larger than the fifth setting value, a determining means for transmitting a control signal for selecting the output of the horizontal/vertical color signal extraction filter; a switch circuit for outputting a color signal component in accordance with the signal sent from the determining means; and a combination of the outputs of the switch circuit as described above. 1. An image correlation compatible luminance signal/chrominance signal separation filter comprising: a subtraction circuit that subtracts a luminance signal from a video signal and outputs a luminance signal. (2) The determination means includes a delay means for delaying the output of the vertical correlation detection means to simultaneously obtain the detection results of the vertical correlation at a plurality of sample points arranged in a straight line in the vertical direction on the screen; If the detection result of vertical correlation at the sample point of interest is "correlated" and all the detection results of vertical correlation at predetermined reference sample points located above and below the sample point of interest are "no correlation", then The image correlation compatible luminance signal/chrominance signal separation filter according to claim 1, which has a vertical isolated point removal function that corrects a vertical correlation detection result to "no correlation". (3) The determination means includes a delay means for delaying the output of the horizontal correlation detection means to simultaneously obtain horizontal correlation detection results at a plurality of sample points arranged in a straight line in the horizontal direction on the screen; If the detection result of horizontal correlation at the sample point of interest is "correlation", and the detection results of horizontal correlation at predetermined reference sample points located on the left and right of the sample point of interest are all "no correlation", then the detection result of horizontal correlation at the sample point of interest is "no correlation". 3. The image correlation compatible luminance signal/chrominance signal separation filter according to claim 2, which has a horizontal direction isolated point removal function that corrects the horizontal correlation detection result to "no correlation". (4) 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 convert the luminance signal and color signal from this composite video signal. An image correlation-compatible luminance signal and chrominance signal separation filter that delays the composite video signal to separate the luminance signal and chrominance signal at a sample point of interest and a sample point perpendicular to the sample point of interest on the screen. a 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 the horizontal color subcarrier component; A horizontal color signal extraction filter, and a horizontal/vertical filter that receives the sample values of the sample point of interest and a predetermined reference sample point as input, and extracts and outputs frequency components corresponding to color subcarrier components in both the vertical and horizontal directions. A directional color signal extraction filter, inputting the sample values of the sample point of interest and a predetermined reference sample point, extracts frequency components corresponding to the DC component in the vertical direction and the color subcarrier component from among the frequency components at the sample point of interest. a vertically uncorrelated energy detecting means for detecting the vertically uncorrelated energy by excluding the absolute value of the vertically uncorrelated energy; Among the frequency components, a frequency component that is a low frequency component in the vertical direction and one half of the color subcarrier frequency in the horizontal direction is extracted, and its absolute value is determined to generate a horizontal high frequency luminance signal. horizontal high-frequency luminance signal energy detection means for detecting energy;
The above vertically uncorrelated energy and the externally applied first
The vertical non-correlation energy is smaller than the first setting value, and the vertical non-correlation energy is equal to the value obtained by subtracting the vertical non-correlation energy from the horizontal high-frequency luminance signal energy. When the value obtained by subtracting the vertical non-correlation energy from the horizontal high-frequency luminance signal energy is larger than the second setting value, the correlation is determined in the vertical direction. a vertical correlation detection means that determines that there is a vertical correlation; and inputs the sample values of the sample point of interest and a predetermined reference sample point, and extracts the DC component in the horizontal direction and the color subcarrier component from among the frequency components at the sample point of interest. a horizontally uncorrelated energy detection means for detecting horizontally uncorrelated energy by excluding corresponding frequency components and finding its absolute value; Among the frequency components at the sample point of interest, extract the frequency component that is a low frequency component in the horizontal direction and corresponds to half the color subcarrier frequency in the vertical direction, calculate its absolute value, and extract the frequency component in the vertical direction. vertical high-frequency luminance signal energy detection means for detecting high-frequency luminance signal energy;
The above horizontal uncorrelated energy and the externally applied third
The horizontal non-correlation energy is smaller than the third setting value, and the value obtained by subtracting the horizontal non-correlation energy from the vertical high-frequency luminance signal energy is compared with the external Comparing the magnitude with the given fourth setting value, if the value obtained by subtracting the horizontal non-correlation energy from the vertical high frequency luminance signal energy is larger than the fourth setting value, the horizontal direction A horizontal correlation detection means that determines that there is a correlation, and the sample values of the sample point of interest and a predetermined reference sample point are input, and in the frequency component at the sample point of interest, the DC component and the color in the diagonally upward right direction of the screen are detected. Exclude frequency components corresponding to subcarrier components,
a diagonally upward-rightward uncorrelated energy detecting means for detecting the obliquely upward-rightward uncorrelated energy by determining the absolute value; Components, frequency components corresponding to the DC component and color subcarrier component in the diagonally downward direction on the screen are excluded, and their absolute values are determined to detect the diagonally downward downward direction decorrelation energy. energy detection means, a determination result of the vertical correlation detection means, a determination result of the horizontal correlation detection means, a diagonally upward-to-the-right direction uncorrelated energy detection result, and a diagonally right-downward direction uncorrelated energy detection result; The absolute difference between the diagonally upward-right direction uncorrelated energy detection result and the diagonally right-downward direction uncorrelated energy detection result is smaller than the fifth setting value given from the outside, and there is correlation in the horizontal direction, and there is a correlation in the vertical direction. If there is no correlation, a control signal is sent to select the output of the horizontal color signal extraction filter, and the absolute value of the difference between the diagonally upward-right direction uncorrelated energy detection result and the diagonally right-downward direction uncorrelated energy detection result is If the value is smaller than the fifth set value, and there is no correlation in the horizontal direction, but there is correlation in the vertical direction, a control signal for selecting the vertical color signal extraction filter output is sent, and the correlation is diagonally upward to the right. The absolute value of the difference between the energy detection result and the uncorrelated energy detection result in the diagonally downward downward direction is smaller than the fifth setting value above, and there is a correlation in both the horizontal and vertical directions, or there is no correlation, or the absolute value of the above difference If the value is greater than the fifth setting value above, the horizontal
a determining means for transmitting a control signal for selecting the output of the vertical color signal extraction filter; a switch circuit for outputting a color signal component in accordance with the output signal of the determining means; 1. A luminance signal/chrominance signal separation filter for image correlation, comprising: a subtraction circuit that outputs a luminance signal by subtracting the resultant signal from the luminance signal. (5) The determination means includes a delay means for delaying the output of the vertical correlation detection means to simultaneously obtain the detection results of the vertical correlation at a plurality of sample points aligned in a vertical direction on the screen; If the detection result of vertical correlation at the sample point of interest is "correlated" and all the detection results of vertical correlation at predetermined reference sample points located above and below the sample point of interest are "no correlation", then 5. The image correlation compatible luminance signal/chrominance signal separation filter according to claim 4, which has a vertical isolated point removal function that corrects a vertical correlation detection result to "no correlation". (6) The determination means includes a delay means for delaying the output of the horizontal correlation detection means to simultaneously obtain horizontal correlation detection results at a plurality of sample points arranged in a straight line in the horizontal direction on the screen; If the detection result of horizontal correlation at the sample point of interest is "correlation", and the detection results of horizontal correlation at predetermined reference sample points located on the left and right of the sample point of interest are all "no correlation", then the detection result of horizontal correlation at the sample point of interest is "no correlation". 6. The image correlation compatible luminance signal/chrominance signal separation filter according to claim 5, which has a horizontal direction isolated point removal function that corrects a detection result of horizontal correlation to "no correlation".