JPH0490289A - Luminance signal chrominance signal separation filter - Google Patents

Abstract

PURPOSE:To reduce dot disturbance by comparing non-correlation energy in horizontal and vertical directions as to a noted sampling point, deciding the quantity of the correlation in the horizontal and vertical directions and selecting a chrominance signal having a larger correlation among 1st-3rd chrominance signal based on the result of discrimination. CONSTITUTION:A picture correlation discrimination circuit 18 selects a 1st chrominance signal extracted by a horizontal direction chrominance signal extraction filter 19 when a sampled value of a sampling point of interest has a weak correlation in the vertical direction and has a strong correlation in the horizontal direction. The picture correlation discrimination circuit 18 selects a 2nd chrominance signal extracted by a vertical direction chrominance signal extraction filter 16 when the sampled value of the noted sampling point has a weak correlation in the horizontal direction and has a strong correlation in the vertical direction. In other cases, the picture correlation discrimination circuit 18 selects a 3rd chrominance signal extracted by a horizontal vertical direction chrominance signal extraction filter 17. Thus, the effect of leakage onto mutual channels of the luminance signal and the chrominance signal in a region where a picture change is rapid in the vertical direction is reduced to decrease dot disturbance.

Description

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

[Prior Art] FIG. 9 is a block diagram showing an example of the configuration of a conventional luminance signal/chrominance signal separation filter.
An input terminal into which an SC system composite color television signal is input, (2) 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 television signal input to the input terminal (1) is converted into a digital signal (201) by the A/D converter (2), and is applied to the vertical filter (6). The signal is applied to the delay circuit (3).

The output (202) of the first one-line delay circuit (3) is given as is to the vertical filter (6), and
After being further delayed by one line in the second one-line delay circuit (4), it is applied to the vertical filter (6).

The vertical filter (6) is usually a two-line filter (referred to as a rhombic filter), and its output is given to a bandpass filter (7).

The output of the bandpass filter (7) is derived from the output terminal (8) as a color signal (205), and is also sent to the subtraction circuit (9).
is given to one input of The output of the first one-line delay circuit (3) is applied to the other input of the subtraction circuit (9) via the compensation delay circuit (5). Compensated delay circuit (
5) is a circuit for compensating for the delay in the bandpass filter (7). Then, from the subtraction circuit (9), the luminance signal (
207) is output and applied to the output terminal (10).

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

Sampling frequency f, -4·f,. The input signal (201) of the composite color television signal, which is sampled synchronously with the color subcarrier at f<6 is the color subcarrier frequency, is the 10th
The result will be a two-dimensional array as shown in the figure. That is, fsc =
(455/2) fH, so the color signal C for each line
4 samples are extracted in one cycle, with the phase of 180 degrees reversed. Here, in the figure, Y indicates the luminance signal, CI and C2 indicate the color signal, and the white circles indicate Y+CI,
The hatched circle is Y-C1, the white triangle is Y+C2, and the hatched triangle is Y-C2.

Now, it is assumed that Z and z-1 are used as symbols to represent a delay of one sample and a delay of one line, respectively, using Z transformation. Here, Z −'= exp(−j2
πf/4fsc). Also, f, c= (455/2
) fH, so N=910.

At this time, the first and second one-line delay circuits (3).

1 line delayed signal delayed using (4) <202)
, the 2-line delayed signal (203) and the current input signal (20
1), a vertical direction filter (6) extracts a line support signal (204) that supports each line including the color signal. The transfer function HV (Z) of the vertical filter (6) is: )IV (Z) = (-1/4)-(]-Z-'
)”.

That is, the line support signal HC (m, n) at the coordinates (m, n) on the screen in Fig. 10 is expressed as HC (m, n) = - (1/4) (S (m, n
1) -23 (m, n) + S (m, n+ 1)). Line support signal is brightness signal Y
The color signal C(m, n), which is a high-frequency component, is converted into a line support signal HC(m, n) by a bandpass filter (7).
n). The color signal C (205) thus obtained is sent to the subtraction circuit (9). Subtraction circuit (
9) passes the one-line delayed signal (202) through the bandpass filter (
7), the signal S(
The color signal C(m, n) is subtracted from the color signal C(m, n), and the luminance signal Y(+++, n) is separated as follows.

Y (m, n) = S (m, n) −C(+++,
n) In this case, the transfer function ah of said bandpass filter (7)
(Z) is, for example, Hh(Z)=(-1/32)(1-Z-")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 in order 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] A luminance signal/chrominance signal separation filter according to the present invention uses a delay means for delaying a visual video signal sampled at a frequency synchronized with a horizontal scanning frequency one line at a time or two lines at a time. The sample values of the target sample point, the reference sample point, and the reference sample points one or two lines before and after them are extracted, and each sample value of the target sample point and the reference sample point is extracted horizontally by a horizontal color signal extraction filter. - a first color signal in which a color subcarrier component in the vertical direction is extracted; and - a first color signal in which a vertical color subcarrier component is extracted by a vertical color signal extraction filter from each sample value of the sample point of interest and the reference sample point; The second color signal and the third color signal, in which horizontal and vertical color subcarrier components are extracted from each sample value using horizontal and vertical color signal extraction filters, are detected by image correlation detection from each sample value. The image correlation means selects and outputs a color signal based on the horizontal and vertical correlations detected by the means, and subtracts this color signal from the sample value of interest to obtain a luminance signal. The detection means includes horizontal luminance signal uncorrelated energy detection means for detecting uncorrelated energy DYH of the horizontal luminance signal from each sample value of the sample point of interest and the reference sample point; Horizontal color signal decorrelation energy detection means for detecting decorrelation energy DCH of the horizontal color signal, and decorrelation energy DYV of the vertical luminance signal from each sample value of the sample point of interest and the reference sample point.
vertical luminance signal non-correlation energy detection means for detecting the non-correlation energy DCV of the vertical color signal from each sample value of the reference sample points; Horizontal uncorrelated energy DH, vertical uncorrelated energy D from correlated energy
V1: D V21, D V22 are detected, and their uncorrelated energies DCHDYV, DH, DV1: D
V21. DV22 is compared at the sample point of interest or sample points before and after it to determine the magnitude of the correlation in the horizontal and vertical directions, and based on this determination result, the color signal with the highest correlation among the first to third color signals is selected. The present invention is characterized by comprising means for transmitting a signal to be selected.

[Operation] The image correlation determination 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. However, 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; Color signal selection is performed to select the third color signal extracted by the color signal extraction filter. Therefore, the influence of leakage of luminance signals and chrominance signals to each other channel in areas where the image changes drastically in the vertical direction is reduced, and dot interference can be reduced.

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

FIG. 1 is a schematic block diagram showing a luminance signal/chrominance signal separation filter according to an embodiment of the present invention, and (11) is an input terminal to which an NTSC composite color television signal is applied. (I2) is an A/D converter, and input terminal (1
1) Converts the analog composite color television signal input from 1) into a dental signal. (13) is the first 1-line delay circuit that inputs the output signal of the A/D converter (12), (14) is the second 1-line delay circuit, (15) is the compensation delay circuit, and (16) is the Vertical color signal extraction filter,
(]7) is a horizontal/vertical color signal extraction filter, (18
) is an image correlation determination circuit, (]9) 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 the output terminal of the switch circuit (23), (
25) is a subtraction circuit, and (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, (29
) is a vertical color signal decorrelation energy extraction circuit, (30
) is a vertical luminance signal decorrelation energy extraction circuit, (3
4), (35), (36) are comparison circuits, (37) are judgment circuits, (71) to (81) are multiplication circuits, (82) to
(85) is a maximum value circuit, (86) to (89) are delay circuits, and (90) is an AND circuit. A/D in Figure 1
The output signal (101) of the converter (12) is transmitted to the horizontal luminance signal decorrelation energy extraction circuit (28) in FIG.
, a vertical color signal uncorrelated energy extraction circuit (29), and a vertical luminance signal uncorrelated energy extraction circuit (30).
) is given to

Output signal (102) of first 1-line delay circuit (13)
are a horizontal color signal uncorrelated energy extraction circuit (27), a horizontal luminance signal uncorrelated energy extraction circuit (28), and a vertical luminance signal uncorrelated energy extraction circuit (30).
) is given to

Output signal (103) of second 1-line delay circuit (14)
is the horizontal luminance signal decorrelation energy extraction circuit (28)
and 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 DC)l of the horizontal color signal uncorrelated energy extraction circuit (27) is divided into three sides, one of which is connected to the comparison circuit (35).
), and the other is multiplied by a constant f by a multiplier (72) and then given to a maximum value circuit (82).

The output signal DY)l of the horizontal luminance signal uncorrelated energy extraction circuit (28) is divided into three sides, one of which is connected to the comparison circuit (3).
6), and the other is multiplied by a constant e by a multiplier (71) and then given to a maximum value circuit (82).

The output signal DCV of the vertical color signal non-correlation energy extraction circuit (29) is divided into three parts, one is multiplied by a constant dl by a multiplier (74) and then given to the maximum value circuit (83), and the other is multiplied by a constant dl. After being multiplied by a constant d2 by a multiplier (76), it is applied to a maximum value circuit (84), and the other is multiplied by a constant d2 by a multiplier (78), and then applied 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 a multiplier (73).
The other is multiplied by a constant 01 by a multiplier (75) and then given to the maximum value circuit (83), the other is multiplied by a constant 02 by a multiplier (75) and then given to the maximum value circuit (84), and the other is multiplied by a constant 02 by a multiplier (75). ) is multiplied by a constant a and then given to the maximum value circuit (85).

The output signal of the maximum value circuit (82) is multiplied by a constant m by a multiplier (79) as the horizontally uncorrelated energy DI() and then given to the comparison circuit (34).The maximum value circuit (
83) is the second vertically uncorrelated energy DV
21, the signal is multiplied by a constant n1 by a multiplier (80) and then provided to a comparison circuit (35). Maximum value circuit (8
The output signal of 4) is the third vertically uncorrelated energy D V
22, it is multiplied by a constant n2 by a multiplier (81) and then provided to a comparison circuit (36).

The output signal of the maximum value circuit (85) is given to the comparator circuit (34) as the first vertically uncorrelated energy DVI.

The comparison circuit (34) compares the magnitude of m-DH, which is obtained by multiplying the horizontal direction uncorrelated energy DB by a constant m, and the first vertical direction uncorrelated energy DVI, and when DVI≧1・DB, outputs an output signal (114 ) is set to high level, and otherwise set to low level.

The comparator circuit (35) outputs the second horizontally uncorrelated energy DV.
21 multiplied by a constant nl and the horizontal color signal non-correlation energy DCH, DCH≧
When n1/DV21, the output signal (115) is set to high level, and at other times, set to low level. The comparator circuit (36) outputs the third vertically uncorrelated energy D V22
Compare n2・D■22, which is obtained by multiplying by
2-DV22, the output signal (116) is set to high level, and at other times, set to low level.

The output signal (114) of the comparator circuit (34) is sent to the delay circuit (8
6), the output signal (115) of the comparison circuit (35) is sent to the delay circuit (87), and the output signal (116) of the comparison circuit (36) is sent to the delay circuit (87).
) is sent to the delay circuit (88) and the AND circuit (90), the output signal (119) of the delay circuit (88) is sent to the delay circuit (89) and the AND circuit (90), and the output signal (
120) is applied to an AND circuit (90). The output signal (117) of the delay circuit (86), the output signal (118) of the delay circuit (87), and the output signal (1) of the AND circuit (90)
21) is given to the 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 diagram showing an embodiment of the determination circuit (37) in FIG. 2, and includes AND circuits (38), (39),
It is composed of an N07 circuit (40) and a NOR circuit (41), and the output signal 4j (11?) of the delay circuit (86)
is one input terminal of the AND circuit (39) and N07
Provided to the input terminal of the circuit (40) and connected to the delay circuit (87)
The output signal (118) is given to one input terminal of the NOR circuit 41), and the output signal (118) of the AND circuit (90) is given to one input terminal of the NOR circuit 41).
12]) is given to the other input terminal of the NOR circuit (41), and the output of this NOR circuit (41) is applied to the AND circuit (
The output signal of the N07 circuit (40) is applied to the other input terminal of the AND circuit (38). The output signal of this AND circuit (38) and the AND circuit (
The output signal of 39) becomes the output signal (110) 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. (44), subtraction circuit (45) and absolute value circuit (46)
The output signal (102) of the first one-line delay circuit (13) is given to one input terminal of the delay circuit (44) and the subtraction circuit (45), and
The output signal of 4) is given to the other input terminal of the subtraction circuit (45), and the output signal of the subtraction circuit (45) is given to the absolute value circuit (46). The output becomes horizontal color signal uncorrelated energy DCH.

FIG. 5 is a block circuit diagram of an embodiment of the horizontal luminance signal decorrelation energy extraction circuit (28) in FIG.
Delay circuits (48), (49), subtraction circuits (50), (51L) having a delay amount of period (1/(2fsc))
Absolute value circuit (52), (53) and maximum value circuit (5
4), the output signal of the A/D converter (12) (the output signal (102) of the IOIL first 1-line delay circuit (13) and the output of the second 1-line delay circuit (14)) The signal (103) is passed through a vertical low pass filter (4
7), and this vertical low-pass filter (47
) is output from the delay circuit (48) and the subtraction circuit (50).
The output of the delay circuit (48) is given to one input terminal of 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 circuit (49) is given to the other input terminal of the subtraction circuit (51), and the output of the subtraction circuit (50) is
The absolute value circuit (52) is given to the absolute value circuit (52).
) is given to the maximum value circuit (54), and the output of the subtraction circuit (
The output of 51) is given to an absolute value circuit (53), and the output of this absolute value circuit (53) is directed to a maximum value circuit (54). 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. 2, which includes the horizontal band-pass filter (55), (5
6), a subtraction circuit (57), and an absolute value circuit (58), the output signal (101) of the A/D converter (12) is given to a horizontal band-pass filter (55), and a second The output signal (103) of the line delay circuit (14) is applied to a horizontal band-pass filter (56), and the output of the horizontal band-pass filter (55) is applied to one input terminal of a subtraction circuit (57). , the output of the horizontal bandpass filter (56) is given to the other input terminal of the subtraction circuit (57). The output of this subtraction circuit (57) is given to an absolute value circuit (58), and the output of this absolute value circuit (5B) is sent to a vertical color signal uncorrelated energy extraction circuit (29).
The output DCV becomes.

FIG. 7 is a block circuit diagram of an embodiment of the vertical luminance signal uncorrelated energy extraction circuit (30) in FIG. 2, including horizontal low-pass filters (59), (60) (6]),
Subtraction circuit (62), (63), absolute value circuit (64),
(65) and a maximum value circuit (66), the output signal (101) of the A/D converter (12) is given to a horizontal low-pass filter (59), and the first one-line delay The output signal (102) of the circuit (13) is fed to a horizontal low-pass filter (60), and the output signal (103) of the second line delay circuit (14) is fed to a horizontal low-pass filter (61). Given.

The output of the horizontal low-pass filter (59) is sent to the subtraction circuit (
62), and the output of the horizontal low-pass filter (60) is fed to the other input terminal of the subtraction circuit (62) and one input terminal of the subtraction circuit (63). The output of the low-pass filter (61) is given to the other input terminal of the subtraction circuit (63), the output of the subtraction circuit (62) is given to the absolute value circuit (64), and the output of the subtraction circuit (63) is given to the other input terminal of the subtraction circuit (63). is given to the absolute value circuit (65),
The output of the absolute value circuits (64) and (65) is 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 fs of this composite color television signal
“Sampling at 4 fs.

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

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 (103) 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 10). The signal (102) is passed through the horizontal color signal extraction filter (19), and this signal (102) and other signals (1,01) and (103) are passed through the vertical color signal extraction filter (16) and the horizontal color signal extraction filter (16), respectively.・Vertical direction color signal extraction filter (17) and image correlation determination circuit (18)
) is given to the input. For example, the transfer function of the vertical color signal extraction filter (16) at this time is expressed as CV (Z) - (-1/4) (1-Z -')2, and the transfer function of the vertical color signal extraction filter (16) is The transfer function of the filter (19) is expressed as CH(Z) = (-1/4)(1-Z-2)', and the horizontal/vertical color signal extraction filter (
The transfer function of 17) is CFIV(Z)=(-1/4)(1-Z-2)"-
It is expressed as (-1/4)(1-Z-')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 (] using a switch circuit (23) are used.
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 (106) of the horizontal color signal extraction filter (19) is selected.
The output signal (107) of the compensation delay circuit (22) into which
), otherwise switch to select 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 the circuit (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.

The horizontal color signal uncorrelated energy is DCf((Z)), the horizontal luminance signal uncorrelated energy is DYH(Z), the vertical color signal uncorrelated energy is DCV(Z),
The vertical luminance signal uncorrelated energy is DYV(Z) and is expressed as follows.

DCH(Z)=1l-Z-' DYH(Z)=max(1(1/4)・(1+Z-
')''(1-Z-2)l.

(1/4)・(1+24)2・(Z−2−Z−“ )l
)DCV(Z)・1−Z−”)2・(1+Z−21)
DYV(Z)=max(l(1/4)(1+Z-2
)2・(1−Z −′)(1/4)・(1+Z −2
)2・(Z −1−Z 2o)1) At this time, the horizontal uncorrelated energy is DH1, the first vertical uncorrelated energy is DVI, the second vertical uncorrelated energy is DV21, and the third vertical uncorrelated energy is D V the direction uncorrelated energy
22, it is expressed as follows.

D H= vaax (eJYH, f-DCH) D V!
= wax (a-DYV, b-DcV) DV21 = m
ax (cl-DYV, di-DCV) D v22 =
wax (c2-DYV, d2-DCV) comparison circuit (34
), compare DVl and m-DHl and find that DVI≧m-
In the case of DH, it is determined that there is a correlation in the horizontal direction and no correlation in the vertical direction, and the delay circuit (86) l:: "1"
(7) Send the signal (114) and also send the DVI
When it is DH, it is determined that there is no correlation in the horizontal direction and an "O" signal (114) is sent to the delay circuit (86).

The comparison circuit (35) compares DCH and nl/Dv21, and when DCH≧n1/DV21, it is determined that the correlation is strong in the vertical direction and weak in the horizontal direction, and the delay circuit (35) is
87) and sends a “1” signal (115) to D.
When CH< n 1・DV21, it is determined that the correlation in the vertical direction is weak, and the “O” signal (11) is sent to the delay circuit (87).
5) is sent.

On the other hand, in the comparison circuit (36), DYH and n 2 ·D V
22, when DYH≧n2・D V22, it is judged that the correlation is strong in the vertical direction (and the correlation is weak in the horizontal direction), and the "l" signal (116) is sent to the delay circuit (88). , When D YH < n2・D V22, it is determined that the correlation is weak in the vertical direction, and the delay circuit (88) is
” signal is sent.

Due to the delay circuit (88), the signal (116) is 1/2f,
c is delayed by the delay circuit (89) as a signal (119).
), where it is further delayed by 1/2 fsc, and the signal (120) is sent to the AND circuit (90). Signals (116) and (119) are also input to the AND circuit. The delay circuits (86), (87) and the AND circuit (90) each send a signal (117) to the determination circuit (37).
), (118), and (121) are sent.

The determination circuit (37) controls the switch circuit (23) as follows according to the above correlation detection result.

That is, the input signal (117) to the determination circuit (37).

(118), (121) and the output signal (110) and the color output signal (105) selected in the switch circuit (23).

The relationship between (107) and (109) is shown in Table 1.

[Blank below] 4;2 Table 1 That is, 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 "O", the output signal (105) of the compensation delay circuit (20) is selected, and the AND circuit (
When the output signal (110a) of the AND circuit (38) is "1" and the output signal (110b) of the AND circuit (39) is "0", the output signal (109) of the compensation delay circuit (21) is selected, and the AN
The output signal (110a) of the D circuit (38) is “0”, and the A
When the output signal of the ND circuit (39) is "1", the output signal (107) of the compensation delay circuit (22) is selected.

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)'=
CV (Z) When there is no horizontal correlation and no vertical correlation, C (Z) = C
Switches like HV(Z).

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 large 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.

Further, in the above embodiment, the signal (116) is passed through two delay circuits, but the number is not limited to this as long as the number of delay circuits is even so that non-correlation can be detected over samples (k, an integer) before and after. In that case, the signals (114) and (115) naturally do not necessarily pass through the number of delay circuits as in the above embodiment.

[Effect of the Invention J As described above, according to the present invention, the correlation between vertical and horizontal images of a composite color television signal can be detected, and in the vertical luminance component, not only the pixel of interest but also the pixel of interest can be detected.
Correlation is also detected in the samples before and after that, and based on this detection result, the output signal of the luminance signal/chrominance signal separation filter with different characteristics is selected and output.
It is possible to reduce the influence of leakage of luminance signals and chrominance signals into mutual channels, reduce dot interference, and obtain a luminance signal/chrominance signal separation filter with high resolution in the vertical direction.

[Brief explanation of drawings]

FIG. 1 is a schematic block circuit diagram showing a luminance signal/chrominance signal separation filter according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing an embodiment of the image correlation determination circuit in FIG. 1, and FIG. FIG. 4 is a block 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. 6 is a block diagram showing an embodiment of the horizontal direction luminance signal non-correlation energy extraction circuit in FIG. 2; FIG. 6 is a block diagram showing an embodiment of the vertical color signal non-correlation energy extraction circuit in FIG. 2;
FIG. 7 is a block diagram showing an embodiment of the vertical luminance signal non-correlation energy extraction circuit in FIG. 2, and FIG. 8 is a block diagram of an embodiment of the PAL luminance signal chrominance signal separation filter according to the present invention. Circuit diagram, Figure 9 is a block circuit diagram of a conventional luminance signal chrominance signal separation filter, Figure 10 is an NTSC
FIG. 2 is an explanatory diagram showing an arrangement on a screen of a signal sequence obtained by synchronously sampling a composite color television signal of the system using four times the color subcarrier. In the figure, (12) is an A/D converter, (13), (
14) 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, and (19) is a horizontal color signal extraction filter. 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
(81) is a multiplier, (34) to (36) are comparison circuits, (
37) is a judgment circuit, (82) to (85) are maximum value circuits,
(86) to (89) are delay circuits, and (90) is an AND circuit. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] means for simultaneously extracting each sample value of a sample point of interest and a plurality of reference sample points surrounding 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 reference sample point; and each sample of the sample point and the reference sample point. A horizontal/vertical color signal extraction filter for extracting frequency components corresponding to vertical and horizontal color subcarrier components from the values 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; a subtracter that subtracts the color signal selected by the switch circuit from the sample value of the sample point and outputs a luminance signal, and the image correlation determining means is configured to calculate the correlation value from each sample value of the sample point of interest and the reference sample point. horizontal direction luminance signal uncorrelated energy detection means for detecting at least one mainly 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 color signal; and 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 direction luminance signal decorrelation energy detecting means for detecting, and vertical direction color signal decorrelation device 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. The energy detecting means detects the larger of the horizontal luminance signal non-correlation energy DYH multiplied by e (e: integer) and the horizontal color signal non-correlation energy DCH multiplied by f (f: integer). horizontal direction uncorrelated energy detection means for detecting direction uncorrelated energy DH; and vertical direction brightness signal uncorrelated energy DY.
A first vertical non-correlation unit detects the larger of V multiplied by a (a: integer) and the vertical color signal non-correlation energy DCV multiplied by b (b: integer) as vertical non-correlation energy DV1. Correlation energy detection means and the vertical luminance signal non-correlation energy DYV multiplied by c1 (c1:
integer) and the above vertical color signal decorrelation energy D
The second step detects the larger one of CV multiplied by d1 (d1: integer) as vertical uncorrelation energy DV21.
vertical direction uncorrelated energy detection means and the vertical direction brightness signal uncorrelated energy DYV multiplied by c2 (c2: integer)
and the vertical color signal non-correlation energy DCV multiplied by d2 (d2: integer), the larger of which is detected as the vertical non-correlation energy DV22; and DV1≧m.・DH(
When the inequality (m: integer) holds, the first color signal is selected, and DCH≧n1・DV21 (n1: integer) or DYV≧m2・DH22 (m2: color signal extracting means for controlling a switch circuit so as to select the second color signal when the inequality (integer) holds, and select the third color signal when neither of the two inequalities holds true; A luminance signal and chrominance signal separation filter.