JPH0481192A - Luminance signal chrominance signal separation filter - Google Patents

Abstract

PURPOSE:To reduce the effect of leakage of a luminance signal and a chrominance signal to mutual channels by detecting the correlation between pictures in horizontal and vertical directions of a composite color television signal and selecting an output signal of a luminance signal chrominance signal separation filter with a different characteristic based on the result of detection and outputting the signal. CONSTITUTION:A switch circuit 23 selects a color output signal of a vertical direction chrominance signal extraction filter 16, a horizontal chrominance signal extraction filter 19 and horizontal/vertical chrominance signal extraction filter 17. The detection of the correlation of the picture and the control of the switch circuit 23 are implemented by a picture correlation discrimination circuit 18. That is, when the vertical correlation is weak and the horizontal correlation is strong in a sampled value at a noted sampling point, a 1st color signal extracted by the horizontal chrominance signal extraction filter 19, when the vertical correlation is strong and the horizontal correlation is weak in the sampled value at the noted sampling point, a 2nd color signal extracted by the vertical chrominance signal extraction filter 16, and when not in the cases above, a 3rd color signal extracted by the horizontal/vertical chrominance signal extraction filter 17 are selected as the color signal selection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a luminance signal and chrominance signal separation filter for separating luminance signals and chrominance signals from, for example, an NTSC system composite television signal.

[Prior Art] FIG. 10 is a block diagram of a conventional NTSC luminance signal chrominance signal separation filter. In the figure, (1) is NTS
(2) is an A/D converter that converts the analog composite color television signal into a digital signal; (3);
4) is the first. The second 1-line delay circuit, (5) is a compensation delay circuit, (6) is a vertical filter, (7) is a bandpass filter, (8) and (10) are output terminals, and (9) is a subtraction circuit. .

Next, the operation will be explained.

The composite color telephony signal input to the input terminal (1) is converted into a digital signal (201) by the A/D converter (2), and then sent to the vertical filter (6) and the first 1-line delay circuit (3). ) is entered.

The output (202) of the first 1-line delay circuit (3) is input to the second 1-line delay circuit (4), the compensation delay circuit (5), and the vertical filter (6). The output further delayed by l lines in the delay circuit (4) is (
203L vertical filter (6).

The vertical filter (6) is usually composed of a two-line filter (referred to as a rectangular filter), and its output (204
) is input to the bandpass filter (7).

The output (205) of the bandpass filter (7) is derived from the output terminal (8) as a color signal and is also sent to the subtraction circuit (9).
) is input to one input end of the The other input terminal of this subtraction circuit (9) is connected to the output (206) of the compensation delay circuit (5).
) is input. This compensation delay circuit (5) is a circuit for compensating for the delay in the bandpass filter (7). A luminance signal (207) is output from the subtraction circuit (9) and derived from the output terminal (10).

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

In the A/D converter (2), the sampling frequency f,=4·
Composite color television signal (201) sampled synchronously with the color subcarrier at f, c (f, e are color subcarrier frequencies)
becomes a two-dimensional array on the screen as shown in FIG.

That is, f. = (455/2)fH, so
The phase of the color signal C is inverted by 180 degrees for each line, and four samples are extracted in one cycle.

In the figure, Y is a luminance signal, CI, C2 are color signals, white circles are Y + CI, circles with diagonal lines are Y-C1, white circles are Y
10C2, the triangle with diagonal lines is Y-C2.

Now, Z and z-1 are used as symbols to represent the sample delay and the one-line delay, respectively, using Z transformation.

Here, Z −'=exp(−j2πf/4f, j.

Also, since f, e = (455/2)fH, n = 91
It becomes 0.

The vertical filter (6) receives the current input signal (201)
A line support signal (204) that supports each line including the color signal C is extracted from the 1-line delayed signal (202) and the 2-line delayed signal (203). The transfer function HV (Z) of the vertical filter (6) in this case is HV (Z) - (-1/4) - (1-Z -1)
It becomes 2.

That is, on the screen in FIG. 11, line support signal HC(m, n) (204) at coordinates (m, n) is
n)=-(1/4) (S(m, nn-1)-25(,
n)+S(m, n+1)).

Since this line support signal (204) also includes the luminance signal Y, the color signal C(m, n) (205), which is a high-frequency component, is converted into the line support signal 1m by the bandpass filter (7).
n) (204). The color signal (205) thus obtained is sent to the subtraction circuit (9). The subtraction circuit (9) extracts the color signal C (m ,
n) (205), the luminance signal Y is obtained as follows:
Separate (m, n) (207).

Y (m, n) = S (m, n) − C (m, n)
The transfer function Hh(Z) of the bandpass filter (7) in this case is, for example, Hh(Z)=(-1/32)(1-Z-2)2(1
+Z')2(1+Z-8).

[Problems to be Solved by the Invention] Conventional luminance signal/chrominance signal separation filters combine vertical filters and horizontal filters with fixed characteristics. In other words, bandpass filters (
7), the luminance signal Y and color signal C were separated.

Therefore, in areas where the brightness and color of the image change rapidly, the brightness signal Y and the color signal C 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 it provides a luminance signal and chrominance signal that can accurately separate the luminance signal and chrominance signal even if a sudden change occurs in the television signal. The purpose is to obtain a separation filter.

[Means for Solving the Problems] The luminance signal/chrominance signal separation filter according to the present invention is notable for its delay means for delaying the decoded video signal sampled at a frequency synchronized with the horizontal scanning frequency one line at a time or two lines at a time. The sample point, the reference sample point, and each sample value of the reference sample point one or two lines before and after them are extracted, and the horizontal color signal extraction filter is used to extract the horizontal color signal from each sample value of the target sample point and the reference sample point. A first color signal in which color subcarrier components are extracted, and a second color signal in which vertical color subcarrier components are extracted by a vertical color signal extraction filter from each sample value of the sample point of interest and the reference sample point. Image correlation determination means extracts the same color signal from each sample value (a third color signal in which horizontal and vertical color subcarrier components are extracted from each sample value by a horizontal and vertical color signal extraction filter). The color signal is selected based on the correlation in the horizontal direction and the vertical direction detected by the image correlation detection method, and is output as a color signal, and the luminance signal is obtained by subtracting this color signal from the sample value of interest. horizontal direction luminance signal uncorrelated energy detection means for detecting the uncorrelated energy DYH of the horizontal luminance signal from each sample value of the sample point of interest and the reference sample point; horizontal direction color signal decorrelation energy detection means for detecting decorrelation energy DCH of the color signal; and vertical direction color signal decorrelation energy detection means for detecting decorrelation energy DYV of the vertical luminance signal from each sample value of the sample point of interest and the reference sample point. Luminance signal uncorrelated energy detection means;
Vertical direction color signal non-correlation energy detection means for detecting vertical direction color signal non-correlation energy DCV from each sample value of the sample point of interest, and horizontal direction non-correlation energy DHI, DH21, DH22, Detect the vertical uncorrelated energy DV and calculate these uncorrelated energies DCV, DYV, DHI, DH21
. It is characterized by the points made up of.

[Operation] The image correlation determining means in the present invention selects the first color signal extracted by the horizontal color signal extraction filter when the sample values of the sample point of interest have weak vertical correlation and strong horizontal correlation. , when the sample value of the sample point of interest has a weak correlation in the horizontal direction and a strong correlation in the vertical direction, the second color signal extracted by the vertical color signal extraction filter is selected, and when neither is the case, the horizontal and vertical color Color signal selection is performed to select the third color signal extracted by the signal extraction filter. Therefore, the influence of leakage of luminance signals and chrominance signals to each other channel in a region where the image changes drastically in the vertical direction is reduced, and it is possible to reduce disturbance.

[Example] Hereinafter, this invention will be explained based on the drawings.

FIG. 1 is a schematic block diagram showing one embodiment of the present invention, in which reference numeral (11) is an input terminal to which an NTSC composite color television signal is applied. (12)
is an A/D converter which converts an analog composite color television signal inputted from an input terminal (11) into a digital signal. (13) is a first one-line delay circuit that inputs the output signal of the A/D converter (12), (14) is a second one-line delay circuit, (15) is a compensation delay circuit, (16)
is a vertical color signal extraction filter, (17) is a horizontal/vertical color signal extraction filter, (18) is an image correlation determination circuit, (19) is a horizontal color signal extraction filter, (20) is a compensation delay circuit, ( 21) is a compensation delay circuit, (22) is a compensation delay circuit, (23) is a switch circuit, (24) is an output terminal of the switch circuit (23), (25) is a subtraction circuit, (
26) is an output terminal of the subtraction circuit (25).

FIG. 2 is a block circuit diagram showing an embodiment of the image correlation determination circuit (18) in FIG.
) is a horizontal color signal decorrelation energy extraction circuit, (28
) is a horizontal luminance signal decorrelation energy extraction circuit, (2
9) is a vertical color signal decorrelation energy extraction circuit, (3
0) is a vertical luminance signal decorrelation energy extraction circuit, (
34), (35), (36) are comparison circuits, (37)
is a judgment circuit, (71) to (8I) are multiplication circuits, (82)
-(85) are maximum value circuits.

The output signal (1,
01) is applied to a horizontal luminance signal uncorrelated energy extraction circuit (28), a vertical chrominance signal uncorrelated energy extraction circuit (29), and a vertical luminance signal uncorrelated energy extraction circuit (30) in FIG. The output signal (102) of the first one-line delay circuit (13) is the horizontal color signal uncorrelated energy extraction circuit (27), the horizontal luminance signal uncorrelated energy extraction circuit (28), and the vertical luminance signal uncorrelated energy. It is applied to an extraction circuit (30).

Output signal (103) of second 1-line delay circuit (14)
is the horizontal luminance signal decorrelation energy extraction circuit (28)
, a vertical color signal uncorrelated energy extraction circuit (29), and a vertical luminance signal uncorrelated energy extraction circuit (30).
) is given to

The output signal DCH of the horizontal color signal uncorrelated energy extraction circuit (27) is divided into three parts, one side is multiplied by a constant by a multiplier (72) and then given to the maximum value circuit (82), and the other side is multiplied by a constant. After being multiplied by a constant f1 by a multiplier (74), the other is given to a maximum value circuit (83), and the other is multiplied by a constant f2 by a multiplier (76) and then given to a maximum value circuit (84).

The output signal DYH of the horizontal luminance signal decorrelation energy extraction circuit (28) is divided into three sides, one of which is a multiplier (71).
The other is multiplied by a constant el by a multiplier (73) and then given to the maximum value circuit (83), and the other is multiplied by a constant el by a multiplier (73) and then given to the maximum value circuit (83). ) is multiplied by a constant 02 and then given to the maximum value circuit (84).

The output signal DCV of the vertical color signal uncorrelated energy extraction circuit (29) is divided into three sides, one of which is connected to the comparison circuit (35).
and the other is multiplied by a constant d by a multiplier (78) and then provided to a maximum value circuit (85).

The output signal DYV of the vertical luminance signal decorrelation energy extraction circuit (30) is divided into three sides, one of which is connected to the comparison circuit (36).
), and the other is multiplied by a constant C by a multiplier (77) and then given to a maximum value circuit (85).

The output signal of the maximum value circuit (82) is given to the comparator circuit (34) as the first horizontally uncorrelated energy DHI.

The output signal of the maximum value circuit (83) is converted to a constant ml by a multiplier (79) as a second horizontally uncorrelated energy DH21.
After being multiplied by , it is applied to a comparison circuit (35). The output signal of the maximum value circuit (84) is multiplied by a constant m2 by a multiplier (80) as the third horizontally uncorrelated energy DH22, and then given to the comparison circuit (36). The output signal of the maximum value circuit (85) is multiplied by a constant n by a multiplier (81) as vertically uncorrelated energy DV, and then given to a comparison circuit (34).

The comparison circuit (34) detects the first horizontally uncorrelated energy DH.
I and n-DVl, which is the vertical uncorrelated energy DVI multiplied by a constant n, are compared, and when DHI ≧n・DV, the output signal (114) is set to high level, otherwise it is set to low level. do.

The comparator circuit (35) generates a second horizontally uncorrelated energy DH.
21 multiplied by a constant ml] is compared with the vertical color signal uncorrelated energy DCV, and the DCV
When ≧m1·DH21, the output signal (+15) is set to high level, and at other times, set to low level. The comparator circuit (36) outputs the third horizontally uncorrelated energy DH22.
Compare the magnitude of m2・DH22, which is obtained by multiplying by the constant m2, with the vertical luminance signal uncorrelated energy DYV, and find that DYV≧m
The output signal (116) is set to high level when 2.DH22 is set, and set to low level at other times.

The output signal (11, 4) of the comparison circuit (34) and the comparison circuit (
The output signal (11, 5) of the comparator circuit (35) and the output signal (116) of the comparator circuit (36) are given to a determination circuit (37). The output signal (110) of this determination circuit (37) is sent out as the output of the image correlation determination circuit (18).

FIG. 3 is a block circuit diagram showing one embodiment of the determination circuit (37) in FIG. 2, including an AND circuit (38).

(39), NOT circuit (40) and NOR circuit (41)
), and the output signal (1
14) is applied to one input terminal of the AND circuit (39) and the input terminal of the NOT circuit (40), and is applied to the comparison circuit (
35) Output signal (115) C, NOR circuit (41'
)+7) is given to one input terminal, and the comparison circuit (36)
The output signal (116) is given to the other input terminal of the NOR circuit (41), and the output of this NOR circuit (41) is
It is applied to the other input terminal of the AND circuit (39) and one input terminal of the AND circuit (38).
The output signal of 0) is given to the other input terminal of the AND circuit (38). The output signal of the AND circuit (38) and the output signal of the AND circuit (39) become the output signal (+10) of the image correlation determination circuit (18).

FIG. 4 is a block circuit diagram showing an embodiment of the horizontal color signal uncorrelated energy extraction circuit (27) in FIG. Delay circuit (44), subtraction circuit (45) and absolute value circuit (46)
), the first 1-line delay circuit (13)
The output signal (102) is given to one input terminal of the delay circuit (44) and the subtraction circuit (45), and the output signal (102) of the delay circuit (
The output signal of 44) is given to the other input terminal of the subtraction circuit (45). The output signal of the subtraction circuit (45) is given to an absolute value circuit (46), and the output of this absolute value circuit (46) becomes the horizontal color signal non-correlation energy DCH.

FIG. 5 is a block circuit diagram of an embodiment of the horizontal luminance signal uncorrelated energy extraction circuit (28) in FIG.
Vertical low pass filter (47), 17 of color subcarriers
Delay circuits (48), (49), subtraction circuits (50), (5
1), absolute value circuits (52), (53) and maximum value circuit (54), output signal (101) of A/D converter (12), first line delay circuit (13) output signal (102) and the second line delay circuit (14)
) output signal (103) is passed through a vertical low-pass filter (
47), and this vertical low-pass filter (4
The output of 7) is sent to a delay circuit (48) and a subtraction circuit (50).
), and the output of the delay circuit (48) is given to the delay circuit (49), the other input terminal of the subtraction circuit (50), and one input terminal of the subtraction circuit (51), The output of the delay circuit (49) is given to the other input terminal of the subtraction circuit (51), and the output of the subtraction circuit (50) is given to the absolute value circuit (52).
The output of 2) is given to the maximum value circuit (54), the output of the subtraction circuit (51) is given to the absolute value circuit (53), and the output of this absolute value circuit (53) is given to the maximum value circuit (54). Given. The output of the maximum value circuit (54) becomes the output DYH of the horizontal luminance signal decorrelation energy extraction circuit (28).

FIG. 6 is a block circuit diagram of an embodiment of the vertical color signal uncorrelated energy extraction circuit (29) in FIG. Consists of an absolute value circuit (58), A, /
The output signal (1,01) of the D converter (12) is given to the horizontal band-pass filter (55), and the output signal (+03) of the second l-line delay circuit (14) is given to the horizontal band-pass filter (55). 56), the output of the horizontal bandpass filter (55) is fed to one input terminal of the subtraction circuit (57), and the output of the horizontal bandpass filter (56) is fed to the subtraction circuit (57). given to the other input terminal. The output of this subtraction circuit (57) is the absolute value circuit (58).
), and the output of this absolute value circuit (58) becomes the output DCV of the vertical color signal non-correlation energy extraction circuit (29).

FIG. 7 is a block circuit diagram of an embodiment of the vertical luminance signal decorrelation energy extraction circuit (30) in FIG.
Horizontal low-pass filters (59), (60).

(61), subtraction circuit (62), (63L absolute value circuit (
64), (65) and a maximum value circuit (66), the output signal (101) of the A/D converter (12)
is given to the horizontal low-pass filter (59), and the first
The output signal (102) of the second line delay circuit (13) is given to the horizontal low-pass filter (60), and the output signal (103) of the second line delay circuit (14) is given to the horizontal low-pass filter (60). 61).

The output of the horizontal low-pass filter (59) is given to one input terminal of the subtraction circuit (62), and the output of the horizontal low-pass filter (60) is given to the other input terminal of the subtraction circuit (62) and The output of the horizontal low-pass filter (61) is given to one input terminal of the subtraction circuit (63).
is applied to the other input terminal of the subtraction circuit (63), the output of the subtraction circuit (62) is applied to the absolute value circuit (64), the output of the subtraction circuit (63) is applied to the absolute value circuit (65), The outputs of the absolute value circuits (64) and (65) are given to the maximum value circuit (66), and the output of this maximum value circuit (66) becomes the output DYV of the vertical luminance signal decorrelation energy extraction circuit (30). .

Next, the operation of the embodiment shown in FIGS. 1 to 7 will be explained.

When an NTSC composite color television signal is applied through the input terminal (11), the A/D converter (12)
is the sampling frequency f of this composite color television signal,
=4f, sample at e.

This sampled composite color television signal is
By passing through the 1-line delay circuit (13) and the second 1-line delay circuit (14), the sample value at a certain sample point of interest and the two lines one line above and one line below the sample point of interest are The sample values of the reference sample points are extracted at the same time.

That is, when the composite color television signal (sample value) S(m, n) at the position of coordinates (m, n) appears at the output (102) of the first one-line delay circuit (13), the second A signal (m, n-1) appears at the output (+03) of the 1-line delay circuit (14), and a signal S (m, n+1) appears at the output (101) of the A/D converter (12). . (
(See Figure 11).

The signal (1,02) is passed through the horizontal color signal extraction filter (19
), this signal (102) and the other two signals (101
) (103) are a vertical color signal extraction filter (16) and a horizontal/vertical color signal extraction filter (17), respectively.
and is given to the input of the image correlation determination circuit (18).

For example, the vertical color signal extraction filter (16
) is CV (Z) −(−1/4)(1−Z −′)2
It is also expressed as a horizontal color signal extraction filter (19
) is expressed as Ch(Z)=(-1/4)(1-Z-2)2, and the horizontal/vertical color signal extraction filter (17)
The transfer function of is Chv(Z)・(−1/4)(1−Z−”)2・(
-1/4) (1-Z -L)2.

The output signal (10) of the vertical color signal extraction filter (16)
4) as the output signal (105) of the compensation delay circuit (20), and the output signal (106) of the horizontal color signal extraction filter (19) as the output signal (107) of the compensation delay circuit (22). , and output signals (108) of the horizontal/vertical color signal extraction filter (17) are respectively given to the switch circuit (23) as the output signal (109) of the compensation delay circuit (21).

Next, a vertical color signal extraction filter (16) and a horizontal color signal extraction filter (1
9), and horizontal/vertical color signal extraction filter (17)
) color output signal selection operation will be explained.

The vertical and horizontal image correlations with respect to the sample point of interest are detected, and when the vertical correlation is particularly strong, the output signal (104) of the vertical color signal extraction filter (16) is detected.
The output signal (105) of the compensation delay circuit (20) into which
), and when the horizontal correlation is particularly strong, the output signal (107) of the compensation delay circuit (22) is inputted with the output signal (106) of the horizontal color signal extraction filter (19).
otherwise, the switch circuit selects the output signal (109) of the compensation delay circuit (21) to which the output signal (108) of the horizontal/vertical color signal extraction filter (17) is input. Switch (23).

Detection of this image correlation and control of the switch circuit (23) are performed by an image correlation determination circuit (18), and this image correlation determination circuit (18) controls the switch circuit by the following operations.

Let the horizontal direction color signal uncorrelated energy be DCH (Z),
The horizontal luminance signal decorrelation energy is DYI((Z), the vertical color signal decorrelation energy is DCV(Z), the vertical luminance signal decorrelation energy is DYV(Z), and it is expressed as follows. do.

DCH(Z)= ]-Z-' DY)I(Z)=max(1(1/4)(]+Z-
')"(1,-Z -2)1(1/4)・(1+Z
)2・(Z −Z−′)l) DCV(Z )・l
(1-Z-2)2・(l+Z-21)DYV(Z
)−max(l (1/4) ・(1+Z −2)2
・(1-Z-')(1/4)・(1+Z-2)2・
(Z-moxibustion-Z-”)l) At this time, the first horizontal uncorrelated energy DHL and the second horizontal uncorrelated energy D
H21, third horizontal uncorrelated energy DH22, and vertical uncorrelated energy DV are expressed as D
H1=max(a-DYH,b-DCH)DH21
=max(elJYH,fl・DcH)D H22=
max(e2・DYH,fl-DCH)DV-ma
In the x (c-DYV, d-DCV) comparison circuit (34),
Comparing DVI and m-'D H1, DHI≧n-DV
When , it is determined that there is a correlation in the vertical direction and no correlation in the horizontal direction, and a signal of "1" (114) is sent to the determination circuit (37).
), and when DHI<n-DV, it is determined that there is no correlation in the horizontal direction and a signal (114) of "0" is sent to the determination circuit (37).

The comparison circuit (35) compares DCV and ml・DH21, and when DCV≧m1−DH21, it is determined that the correlation is strong in the horizontal direction and weak in the vertical direction, and the judgment circuit (35)
37), and sends the “l” signal (115) to the DC
When V< ml ・DH21, it is judged that the correlation is weak in the horizontal direction, and the judgment circuit (
37) and sends a "0" signal (115).

The comparison circuit 36) compares DYV and m2-DH22, and when DYV≧m2・DH22, it is determined that the correlation is strong in the horizontal direction and the correlation is weak in the horizontal direction, and the judgment circuit (37) is ” (116)
), and when DYv×m2·DH22, it is determined that the correlation in the horizontal direction is weak and a signal "0" is sent to the determination circuit (37).

The determination circuit (37) controls the switch circuit (23) as follows according to the above correlation detection result. That is,
Input signals (114), (115) to the determination circuit (37)
) (116) and a color output signal (105) selected in the output signal (110) and the switch circuit (23);
(107).

The relationship (109) is shown in Table 1.

In other words, the switch circuit (23) is an AND circuit (38)
When the output signal (110a) of the AND circuit (39) and the output signal (110b) of the AND circuit (39) are both "0", the output signal (107) of the compensation delay circuit (22) is selected, and A, N D
The output signal (110a) of the circuit (38) is “O” and the AN
When the output signal (110b) of the D circuit (39) is "L", the output signal (1, 05) of the compensation delay circuit (20) is selected, and the output signal (], 10a) of the AND circuit (38) is "1". 1”, the output signal (110b) of the AND circuit (39)
When is “0”, the output signal of the compensation delay circuit (21) (
109).

Therefore, in the embodiment shown in FIG. 1, the filter characteristic C(Z) for color signal extraction is as follows depending on the presence or absence of correlation: When there is horizontal correlation, C(Z)=CH(Z) No horizontal correlation, vertical correlation When yes, C(Z)=C
V (Z) When there is no horizontal correlation and no vertical correlation, C (Z) = C
Switches like HV (Z).

The embodiment shown in FIG. 8 is a modification of the embodiment shown in FIG. 1st
horizontal color signal decorrelation energy extraction circuit (27a)
b-, which is obtained by multiplying the output DCI11 by b in the multiplier (72).
DCIII and a-DYH are input to the maximum value circuit (82) to detect DHI. One of the outputs DCH2 of the second horizontal direction color signal uncorrelated energy extraction circuit (27b) is multiplied by f] by the multiplier (74), fl-DC+(2 and ei
DYH is input to the maximum value circuit (83) to detect DH21, and the other side of D CH2 is multiplied by f2 by the multiplier (76), f2・DCI+2 and e2・DYH are input to the maximum value circuit (84).
) to detect DH22, and output DCV2 of the second vertical color signal decorrelation energy extraction circuit (29b).
d-D multiplied by d in the multiplier (78) CV2 and C-
Manually input DYV to the maximum value circuit (85) to detect DV,
The comparison circuit (34) compares DHI and n-DV, the comparison circuit (35) compares DCVl and ml・DH2], and the comparison circuit (36) compares DYV and m2・DH22. It is.

The selection control operation of the switch circuit (23) based on the output (110) of the determination circuit (37) in the embodiment shown in FIG. 8 is the same as in Table 1.

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. For example, 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 larger number of orders, for example.

Further, in the above embodiment, the NTSC luminance signal/chrominance signal separation filter was described, but the 1-line delay circuits (13) and (14) in FIG.
If the line delay circuits (13a) and (14a) are PA
It can be applied as a luminance signal/chrominance signal separation filter for an L-scheme composite color television signal.

[Effects of the Invention] As described above, according to the present invention, the correlation between vertical and horizontal images of a composite color television signal is detected, and based on this detection result, a luminance signal/chrominance signal separation filter with different characteristics is created. Since the configuration is configured to select and output the output signals of the luminance signal and the chrominance signal, it is possible to reduce the influence of leakage of the luminance signal and chrominance signal to each other channel, thereby providing a luminance signal/chrominance signal separation filter that can reduce dot interference. effective.

[Brief explanation of drawings]

FIG. 1 is a schematic block circuit diagram of an embodiment of an NTSC luminance signal/color signal separation filter according to the present invention, and FIG. 2 is a block circuit diagram showing an embodiment of the image correlation determination circuit in FIG. 3 is a circuit diagram showing an embodiment of the determination circuit in FIG. 2, FIG. 4 is a block circuit diagram showing an embodiment of the horizontal color signal decorrelation energy extraction circuit in FIG. 2, and FIG.
The figure is a block diagram showing an embodiment of the horizontal direction luminance signal non-correlation energy extraction circuit in FIG. 2, and FIG. 6 is a block diagram showing an embodiment of the vertical direction chrominance signal non-correlation energy extraction circuit in FIG. 7 is a block diagram showing an embodiment of the vertical luminance signal decorrelation energy extraction circuit in FIG. 2, and FIG. 8 is a block circuit diagram showing an embodiment that is a modification of FIG. 9 is a block circuit diagram of an embodiment of the PAL luminance signal chrominance signal separation filter according to the present invention;
The figure shows a block circuit diagram of a conventional luminance signal chrominance signal separation filter, and Fig. 11 shows a signal sequence on the screen obtained by synchronously sampling an NTS C composite color television signal at four times the color subcarrier. It is an explanatory diagram showing an array. In the figure, (12) is the A/D converter, (13), (+4)
is a 1-line delay circuit, (16) is a vertical color signal extraction filter, (17) is a horizontal/vertical color signal extraction filter, (18) is an image correlation determination circuit, (19) is a horizontal color signal extraction filter, (23) is a switch circuit (color signal extraction means), (25) is a subtracter, (27) is a horizontal color signal uncorrelated energy extraction circuit, (28) is a horizontal luminance signal uncorrelated energy extraction circuit, (29) ) is a vertical color signal uncorrelated energy extraction circuit, (30) is a vertical luminance signal uncorrelated energy extraction circuit, (71) to (8])
is a multiplier, (34) to (36) are comparison circuits, (37) is a determination circuit, and (82) to (85) are maximum value circuits. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] means for simultaneously extracting each sample value of a sample point of interest and a plurality of reference sample points around it by delaying the decoded video signal sampled at a frequency synchronized with the horizontal scanning frequency one line at a time or two lines at a time; a horizontal color signal extraction filter for obtaining a first color signal by extracting a frequency component corresponding to a horizontal color subcarrier component from each sample value of the sample point of interest and the reference sample point; a vertical color signal extraction filter for obtaining a second color signal by extracting a frequency component corresponding to a vertical color subcarrier component from each sample value of the sample point; and each sample value of the sample point and reference sample point. a horizontal/vertical color signal extraction filter for extracting frequency components corresponding to the vertical and horizontal color subcarrier components from the filter to obtain a third color signal, and selecting the first to third color signals. a switch circuit for outputting a color signal as a color signal; and a subtracter that subtracts the color signal selected by the switch circuit from the sample value of the point and outputs a luminance signal, and the image correlation determining means is configured to calculate horizontally from each sample value of the sample point of interest and reference sample point. horizontal direction luminance signal uncorrelated energy detection means for detecting at least one primarily uncorrelated energy DYH of the luminance signal in the horizontal direction; Horizontal color signal uncorrelated energy detection means for detecting uncorrelated energy DCH of the signal, and detecting at least one uncorrelated energy DYV mainly of the luminance signal in the vertical direction from each sample value of the sample point of interest and the reference sample point. vertical luminance signal decorrelation energy detecting means for detecting at least one mainly color signal decorrelation energy DCV in the vertical direction from each sample value of the sample point of interest and the reference sample point; a detection means, the horizontal direction luminance signal non-correlation energy DYH multiplied by a (a: integer) and the horizontal direction color signal non-correlation energy DCH multiplied by b (
b: an integer), the first horizontally uncorrelated energy detection means detects the larger one as horizontal uncorrelated energy DH1, and the vertical luminance signal uncorrelated energy DYV is multiplied by e1 (e: integer). and the horizontal color signal decorrelation energy DCH multiplied by f1 (f1: integer), the larger of which is the vertical color signal decorrelation energy DH.
21, and a second horizontal direction uncorrelated energy detection means for detecting the horizontal direction brightness signal uncorrelated energy DYH.
A third horizontal non-correlation that detects the larger of the above horizontal color signal non-correlation energy DCV multiplied by e2 (e2: an integer) and the above horizontal color signal non-correlation energy DCV multiplied by f2 (f2: an integer) as the horizontal non-correlation energy DH22. an energy detection means, and detects the larger of the vertical luminance signal non-correlation energy DYV multiplied by c (c: integer) and the vertical color signal non-correlation energy DCV multiplied by d (d: integer) in the vertical direction. Vertical direction uncorrelated energy detection means for detecting uncorrelated energy DV, and DCV≧m1・DH2
1 or DYV≧m2・DH22 (m1, m2: integer)
When the inequality holds, the first color signal is selected; when the inequality DH1≧n・DV (n: integer) holds, the second color signal is selected; when neither of the two inequalities holds true, the second color signal is selected. A luminance signal/chrominance signal separation filter comprising color signal extraction means for controlling a switch circuit to select the third color signal.