JP2536675B2 - Luminance signal Color signal separation filter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a luminance signal / color signal separation filter for separating a luminance signal and a color signal from an NTSC composite television signal, for example.

[Prior Art] FIG. 10 is a block diagram showing an example of the configuration of a conventional luminance signal / color signal separation filter. In FIG.
An input terminal for inputting an SC composite color television signal, (2) is an A / D converter that converts an analog composite color television signal into a digital signal, (3), (4)
Is a first and 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 It is a subtraction circuit.

 Next, the operation will be described.

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 given to the vertical direction filter (6), and also the first 1-line delay Given to the circuit (3).

The output (202) of the first 1-line delay circuit (3) is given to the vertical filter (6) as it is, and
The second one-line delay circuit (4) further delays the signal by one line, and then supplies it to the vertical direction filter (6).

The vertical filter (6) is a filter usually called a two-line type comb filter, and its output is given to the bandpass filter (7).

The output of the band-pass filter (7) is derived from the output terminal (8) as a color signal (205) and is also subtracted by the subtraction circuit (9).
Given to one input of. The output of the first one-line delay circuit (3) is given to the other input of the subtraction circuit (9) through the compensation delay circuit (5). The 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 given to the output terminal (10).

Next, the operation of the above filter with respect to the NTSC composite color television signal will be described.

The input signal (201) of the composite color television signal sampled synchronously with the color subcarrier at the sampling frequency fS = 4 · fSC (fSC is the color subcarrier frequency) is displayed on the screen as shown in FIG. It becomes a dimensional array. That is, since fSC = (455/2) fH, four samples are extracted in one cycle in which the phase of the color signal C is inverted by 180 ° for each line.

In the figure, Y indicates a luminance signal and C1 and C2 indicate color signals. The white circles are Y + C1, the shaded circles are Y-C1, the white triangles are Y + C2, and the shaded triangles are Y-C2.

Now, it is assumed that Z ⁻¹ and Z ^−l are used as the symbols representing the delay of one sample and the delay of one line, respectively, by using the Z transform. Here, Z ⁻¹ = exp (−j2πf / 4fSC). Also, since fSC = (455/2) fH, l = 910
Becomes

At this time, the first and second 1-line delay circuits (3),
From the 1-line delay signal (202) and 2-line delay signal (203) delayed by using (4) and the current input signal (201), for each line including the color signal by the vertical direction filter (6) Extract a line support signal (204) to support.

The transfer function HV (Z) of the vertical filter (6) is HV (Z) = (− 1/4) · (1-Z ^−l ) ² .

That is, the line support signal HC (m, n) at the coordinates (m, n) on the screen of FIG. 11 is HC (m, n) =-(1/4) {S (m, n-1) -2S It will be extracted as (m, n) + S (m, n + 1)}. Since the line support signal also includes the luminance signal, the bandpass filter (7) separates the color signal C (m, n), which is a high frequency component, from the line support signal HC (m, n). Then, the color signal (205) thus obtained is sent to the subtraction circuit (9).

The subtraction circuit (9) converts the 1-line delay signal (202) into the color signal C (m, n) from the signal S (m, n) delayed by the compensation delay circuit (5) according to the bandpass filter (7). Then, the luminance signal Y (m, n) is separated as follows.

Y (m, n) = S (m, n) -C (m, n) In this case, the transfer function Hh of the bandpass filter (7)
(Z) can be configured as, for example, Hh (Z) = (-1/32) (1-Z ^-2 ) ² (1 + Z ^-4 ) ² (1 + Z ^-8 ).

[Problems to be Solved by the Invention] In the conventional luminance signal / chrominance signal separation filter, the characteristics of the vertical direction filter and the horizontal direction filter are fixed and combined. That is, the luminance signal Y and the color signal C are separated by the bandpass filter (7) in both the vertical and horizontal directions.

Therefore, in a region where the luminance and color of the image change drastically, the luminance signal Y and the color signal C leak to the mutual channels, which causes a problem that the reproduced image quality is deteriorated due to dot interference in particular. It was

The present invention has been made to solve the above problems, and a luminance signal color signal capable of accurately separating a luminance signal and a color signal even when a television signal changes abruptly. The purpose is to obtain a separation filter.

[Means for Solving the Problem] The luminance signal / chrominance signal separation filter according to the present invention is noticed by a delay unit that delays the composite video signal sampled at a frequency synchronized with the horizontal scanning frequency by one line or two lines. The sample values of the sample points and the reference sample points and the reference sample points one line or two lines before and after the sample points are extracted, and the sampled values of the sample points of interest and the reference sample points are horizontally extracted by the horizontal color signal extraction filter. Of the first color signal from which the component of the color sub-carrier is extracted, and from the sample values of the sample point of interest and the reference sample point described above, the second component obtained by extracting the component of the color sub-carrier in the vertical direction by the vertical color signal extraction filter. Similarly, the color signal and the third color signal obtained by extracting the components of the color subcarriers in the horizontal and vertical directions from each sample value by the horizontal / vertical color signal extraction filter Similarly, a configuration is adopted in which each sample value is selected based on the correlation in the horizontal direction and the vertical direction detected by the image correlation determining means and output as a color signal, and the color signal is subtracted from the sample value of interest to obtain a luminance signal. The image correlation detecting means is a horizontal luminance signal non-correlation energy detecting means for detecting the non-correlation 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 detecting means for detecting the decorrelation energy DCH of the color signal in the horizontal direction from each sample value of the sample point of interest, and luminance signal in the vertical direction from each sample value of the sample point of interest and the reference point. Vertical luminance signal non-correlation energy detecting means for detecting the non-correlation energy DYV of the above, and the non-correlation energy DCV of the color signal in the vertical direction from each sample value of the sample point of interest. And a vertical color signal uncorrelated energy detection means for detecting, these horizontal non-correlation energy than non-correlation energy DH1, DH21, DH22, vertical non-correlation energy DV
Is detected, and these decorrelation energies DCV, DYV, DH1, DH21,
DH22, DV are compared at the sample point of interest or at sample points before and after it, and the magnitude of the correlation in the horizontal direction and the vertical direction is determined. Based on this determination result, the color having the highest correlation among the first to third color signals And a means for transmitting a signal for selecting a signal.

[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 value of the sample point of interest has a weak vertical correlation and a strong horizontal correlation. , The second color signal extracted by the vertical color signal extraction filter is selected when the sample value of the target sample point has a weak horizontal correlation and a strong vertical correlation, and when neither of them is selected, the horizontal vertical color is selected. Color signal selection is performed to select the third color signal extracted by the signal extraction filter. For this reason, the influence of the leakage of the luminance signal and the chrominance signal to the mutual channel in the region where the image changes greatly in the vertical direction is reduced, and the dot disturbance can be reduced.

[Examples] The present invention will be described below with reference to the drawings.

FIG. 1 is a schematic block diagram showing a luminance signal / color signal separation filter according to an embodiment of the present invention.
(11) is an input terminal to which an NTSC composite color television signal is given. (12) is an A / D converter, which converts an analog composite color television signal input from the input terminal (11) into a digital signal. (13) receives the output signal of the A / D converter (12). A first 1-line delay circuit, (14) a second 1-line delay circuit, (15) a compensation delay circuit, (16) 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. 1, in which (27) is a horizontal color signal decorrelation energy extraction circuit and (28) is a horizontal direction. Directional luminance signal decorrelation energy extraction circuit, (29) vertical direction color signal decorrelation energy extraction circuit, (30) vertical direction luminance signal decorrelation energy extraction circuit, (34), (3
5) and (36) are comparison circuits, (37) is a judgment circuit, and (71) ~
(81) is a multiplication circuit, (82) to (85) is a maximum value circuit, (8
6) to (89) are delay circuits, and (90) is an AND circuit. First
The output signal (101) of the A / D converter (12) in the figure is the second
In the figure, the horizontal luminance signal decorrelation energy extraction circuit (28) and the vertical color signal decorrelation energy extraction circuit (2
9) and the vertical luminance signal decorrelation energy extraction circuit (30).

The output signal (102) of the first 1-line delay circuit (13) is the horizontal color signal non-correlation energy extraction circuit (27), the horizontal luminance signal non-correlation energy extraction circuit (28), and the vertical luminance signal non-correlation energy. It is given to the extraction circuit (30).

The output signal (103) of the second one-line delay circuit (14) is a horizontal direction luminance signal decorrelation energy extraction circuit (28), a vertical direction color signal decorrelation energy extraction circuit (29), and a vertical direction luminance signal decorrelation energy. It is given to the extraction circuit (30).

The output signal DCH of the horizontal color signal decorrelation energy extraction circuit (27) is divided into three directions, one of which is multiplied by the constant b by the multiplier (72) and then given to the maximum value circuit (82),
The other is multiplied by a constant f1 by a multiplier (74) and then 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 directions, one is multiplied by the constant a by the multiplier (71) and then given to the maximum value circuit (82), and the other is multiplied. The constant (e1) is multiplied by the multiplier (73) and then applied to the maximum value circuit (83), and the other is multiplied by the multiplier (75).
Is applied to the maximum value circuit (84) after being multiplied by the constant e2.

The output signal DCV of the vertical color signal decorrelation energy extraction circuit (29) is divided into two directions, one is given to the comparison circuit (35), and the other is multiplied by the constant b by the multiplier (78), and then the maximum value is obtained. Given to the circuit (85). The output signal DYV of the vertical direction luminance signal decorrelation energy extraction circuit (30) is divided into two directions, one is given to the comparison circuit (36), and the other is multiplied by the constant c by the multiplier (77) and then the maximum value. Given to the circuit (85).

The output signal of the maximum value circuit (82) is supplied to the comparison circuit (34) as the first horizontal decorrelation energy DH1. The output signal of the maximum value circuit (83) is multiplied by the constant m1 by the multiplier (79) as the second horizontal decorrelation energy DH21 and then given to the comparison circuit (35). The output signal of the maximum value circuit (84) is multiplied by the constant m2 by the multiplier (80) as the third horizontal uncorrelated energy DH22, and then the comparison circuit (36).
Given to. The output signal of the maximum value circuit (85) is multiplied by a constant n by a multiplier (81) as vertical direction uncorrelated energy DV, and then applied to a comparison circuit (34).

The comparison circuit (34) has a first horizontal decorrelation energy DH1.
And n × D obtained by multiplying the vertical uncorrelated energy DV1 by a constant n
The magnitude of V1 is compared, and the output signal (114) is set to a high level when DH1 ≧ n · DV, and is set to a low level otherwise.

The comparison circuit (35) has a second horizontal decorrelation energy DH21.
M1 · DH21 obtained by multiplying by with a constant m1 and the magnitude of the vertical direction color signal decorrelation energy DCV are compared. When DCV ≧ m1 · DH21, the output signal (115) is set to the high level, otherwise it is set to the low level. And The comparator circuit (36) compares the magnitude of m2 · DH22 obtained by multiplying the third horizontal decorrelation energy DH22 by a constant m2 with the vertical luminance signal decorrelation energy DYV, and D
When YV ≧ m2 · DH22, the output signal (116) is set to high level, and otherwise it is set to low level.

The output signal (114) of the comparison circuit (34) is the delay circuit (86).
The output signal (115) of the comparison circuit (35) is delayed by the delay circuit (8
The output signal (116) of the comparison circuit (36) is sent to the delay circuit (88) and the AND circuit (90), and the output signal (119) of the delay circuit (88) is sent to the delay circuit (89) and the AND circuit (7). 90, the output signal (120) of the delay circuit (89) is given to the AND circuit (90). The output signal (117) of the delay circuit (86) and the delay circuit (8
7) output signal (118) and AND circuit (90) output signal (12
1) is given to the decision circuit (37).

The output signal (110) of the determination circuit (37) is sent as the output of the image correlation determination circuit (18).

FIG. 3 is a block diagram showing an embodiment of the decision circuit (37) in FIG. 2, which is composed of AND circuits (38), (39), NOT circuit (40) and NOR circuit (41). The output signal (117) of the delay circuit (86) is given to one input terminal of the AND circuit (39) and the input terminal of the NOT circuit (40),
The output signal (118) of the delay circuit (87) is given to one input terminal of the NOR circuit (41), and the output signal (121) of the AND circuit (90) is given to the other input terminal of the NOR circuit (41). Given,
The output of the NOR circuit (41) is given to the other input terminal of the AND circuit (39) and one input terminal of the AND circuit (38), and the output signal of the NOT circuit (40) is the AND circuit (38). Applied to the other input terminal of.

The output signal of the AND circuit (38) and the output signal of the AND circuit (39) are the output signal (110) of the image correlation determination circuit (18).
Becomes

FIG. 4 is a block circuit diagram showing an embodiment of the horizontal color signal decorrelation energy extraction circuit (27) in FIG. 2, which has a delay amount of one cycle (1 / f _sc ) of the color subcarrier. Circuit (4
4), the subtraction circuit (45) and the absolute value circuit (46), and the output signal (102) of the first one-line delay circuit (13) is the delay circuit (44) and the subtraction circuit (45). The output signal of the delay circuit (44) is applied to one of the input terminals, and is applied to the other input terminal of the subtraction circuit (45). The output signal of the subtraction circuit (45) is given to the absolute value circuit (46), and the output of this absolute value circuit (46) becomes the horizontal color signal decorrelation energy DCH.

FIG. 5 is a block circuit diagram of an embodiment of the horizontal luminance signal decorrelation energy extraction circuit (28) in FIG. 2, which shows a vertical low pass filter (47) and a half cycle of the color subcarrier. Delay circuit (48), (4 with delay amount of (1 / (2f _sc ))
9), subtraction circuits (50), (51), absolute value circuits (52), (5
3) and the maximum value circuit (54), the output signal (101) of the A / D converter (12) and the first line delay circuit (1
3) output signal (102) and the second line delay circuit (1
The output signal (103) of 4) is the vertical low pass filter (4
Given to 7) this vertical low pass filter (47)
The output of is given to one input terminal of the delay circuit (48) and the subtraction circuit (50), and the output of the delay circuit (48) is given to the other input terminal of the delay circuit (49) and the subtraction circuit (50). The output of the delay circuit (49) is given to the subtraction circuit (51), and the output of the subtraction circuit (50) is given to the absolute value circuit (52). , The output of this absolute value circuit (52) is given to the maximum value circuit (54),
The output of the subtraction circuit (51) is given to the absolute value circuit (53),
The output of the absolute value circuit (53) is given to the 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 decorrelation energy extraction circuit (29) in FIG. 2, which shows horizontal bandpass filters (55) and (56) and a subtraction circuit (5
7), composed of an absolute value circuit (58), the output signal (101) of the A / D converter (12) is given to the horizontal band pass filter (55), and the second 1-line delay circuit (14) Output signal (103) is given to the horizontal band pass filter (56), the output of the horizontal band pass filter (55) is given to one input terminal of the subtraction circuit (57), and the horizontal band pass filter is output. The output of (56) is given to the other input terminal of the subtraction circuit (57). The output of the subtraction circuit (57) is given to the absolute value circuit (58), and the output of the absolute value circuit (58) becomes the output DCV of the vertical color signal decorrelation energy extraction circuit (29).

FIG. 7 is a block circuit diagram of an embodiment of the vertical direction luminance signal decorrelation energy extraction circuit (30) in FIG. 2, in which horizontal direction low pass filters (59), (60), (61) and subtraction are performed. It is composed of circuits (62), (63), absolute value circuits (64), (65) and maximum value circuit (66). The output signal (101) of the A / D converter (12) is low in the horizontal direction. The output signal (10) of the first line delay circuit (13) is given to the band pass filter (59).
2) 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 (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 applied to the other input terminal of the subtraction circuit (62). Given to one input terminal of the subtraction circuit (63),
The output of the horizontal 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 subtraction circuit (63). The output of is given to the absolute value circuit (65), and the absolute value circuit (6
The outputs of 4) 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 direction luminance signal decorrelation energy extraction circuit (30).

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

When an NTSC composite color television signal is given through the input terminal (11), the A / D converter (12) samples the composite color television signal at a sampling frequency fS = 4fSC.

The sampled composite color television signal passes through the first 1-line delay circuit (13) and the second 1-line delay circuit (14) to obtain a sample value at a certain sample point of interest and the sample point of interest. Sample values of two reference sample points one line above and one line below the screen are simultaneously extracted.

That is, when the composite color television signal (sample value) S (m, n) at the position of the coordinates (m, n) appears at the output (102) of the first 1-line delay circuit (13), the second The signal (m, n-1) is output to the output (103) of the 1-line delay circuit (14).
Appears, and the signal S appears at the output (101) of the A / D converter (12).
(M, n + 1) appears. (See Figure 11).

Signal (102) is horizontal color signal extraction filter (19)
And this signal (102) and the other two signals (101),
(103) are vertical color signal extraction filters (1
6), to the inputs of the horizontal / vertical direction color signal extraction filter (17) and the image correlation determination circuit (18).

For example, the vertical color signal extraction filter (1
The transfer function of 6) is expressed as CV (Z) = (-1/4) (1-Z ^-l ) ² and the transfer function of the horizontal color signal extraction filter (19) is Ch (Z). = (-1/4) (1-Z- ² ) ^2, and the transfer function of the horizontal / vertical color signal extraction filter (17) is ChV (Z) = (-1/4) (1 −Z ⁻² ) ² · (−1/4) (−1Z
^-l ) ^{Expressed as 2} .

Output signal of vertical color signal extraction filter (16) (10
4) is the output signal (105) of the compensation delay circuit (20),
The output signal (106) of the horizontal color signal extraction filter (19) is used as the output signal (107) of the compensation delay circuit (22), and the output signal of the horizontal / vertical color signal extraction filter (17) ( 108) is the output signal (1) of the compensation delay circuit (21).
09) is given to each switch circuit (23).

Next, a vertical color signal extraction filter (16) and a horizontal color signal extraction filter (1
9), and horizontal / vertical color signal extraction filters (17)
The operation of selecting the color output signal of will be described.

A correlation delay circuit (20) that detects the correlation between the vertical and horizontal images with respect to the sample point of interest and receives the output signal (104) of the vertical color signal extraction filter (16) when the vertical correlation is particularly strong. ) Output signal (105) is selected, and the output signal (106) of the horizontal color signal extraction filter (19) is input when the horizontal correlation is particularly strong, the output signal (107) of the compensation delay circuit (22). Select, otherwise, select the horizontal / vertical color signal extraction filter (1
Compensation delay circuit (21) to which the output signal (108) of 7) is input
Switch circuit to select the output signal of (109) (2
3) Switch.

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

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

DCH (Z) = | 1−Z ⁻⁴ | DYH (Z) = max (| (1/4) ・ (1 + Z ^−l ) ²・ (1-Z ⁻² ) |, | (1/4) ・ ( 1 + Z ^-l ) ²・ (Z ^-2 -Z ^-4 ) |) DCV (Z) = | (1-Z ^-2 ) ²・ (1-Z ^-2l ) | DYV (Z) = max (| (1 / 4) ・ (1 + Z ^-2 ) ²・ (1-Z ^-l ) |, | (1/4) ・ (1 + Z ^-2 ) ²・ (Z ^-- Z ^-2l ) |) The horizontal decorrelation energy DH1, the second horizontal decorrelation energy DH21, the third horizontal decorrelation energy DH22, and the vertical decorrelation energy DV are expressed as follows.

DH1 = max (a ・ DYH, b ・ DCH) DH21 = max (e1 ・ DYH, f1 ・ DCH) DH22 = max (e2 ・ DYH ・ f2 ・ DCH) DV = max (c ・ DYV, d ・ DCV) Comparison circuit In (34), DV1 and m · DH1 are compared and DH1
When ≧ n · DV, there is a correlation in the vertical direction, and it is judged that there is no correlation in the horizontal direction and a “1” signal is sent to the delay circuit (86). When DH1 <n · DV, the correlation is in the horizontal direction. When it is determined that there is no correlation, a "0" signal (114) is sent to the delay circuit (86).

In the comparison circuit (35), DCV is compared with m1 · DH21, and D
When CV ≧ m1 · DH21, it is judged that the correlation is strong in the horizontal direction and weak in the vertical direction, and a “1” signal (115) is sent to the delay circuit (87), and when DCV <m1 · DH21 Sometimes it is judged that the correlation is weak in the horizontal direction, and the delay circuit (87) outputs a "0" signal (115).
Is sent.

In the comparison circuit (36), DYV is compared with m2 · DH22, and D
When YV ≧ m2 · DH22, it is determined that the correlation is strong in the horizontal direction and weak in the horizontal direction, and a “1” signal (116) is sent to the delay circuit (88), and when DYV <m2 · DH22 Sometimes, it is judged that the correlation is weak in the horizontal direction, and a "0" signal is sent to the delay circuit (88).

By the delay circuit (88), signal (116) is delayed by 1/2 fsc, it is sent to the delay circuit (89) as a signal (119), where it is further 1 / 2f _sc delay signal to the AND circuit (90) (120) is transmitted. Signals (116), (1
19) is also entered. The delay circuits (86) and (87) and the AND circuit (90) respectively send signals (117) and (11) to the determination circuit (37).
8) and (121) are transmitted.

The determination circuit (37) controls the switch circuit (23) as follows according to the above correlation detection result. That is, the input signals (117), (118), (121) to the determination circuit (37).
Table 1 shows the relationship between the output signal (110) and the color output signals (105), (107) and (109) selected in the switch circuit (23).

That is, the switch circuit (23) outputs the output signal (107) of the compensation delay circuit (22) when the output signal (110a) of the AND circuit (38) and the output signal (110b) of the AND circuit (39) are both "0". When the output signal (110a) of the AND circuit (38) is "0" and the output signal (110b) of the AND circuit (39) is "1", the output signal (105) of the compensation delay circuit (20) is selected. 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. Select.

Therefore, in the embodiment of FIG. 1, the filter characteristic C (Z) for color signal extraction is C (Z) = Ch (Z) without horizontal correlation and with vertical correlation depending on the presence or absence of correlation. If yes, C (Z) = Cv (Z). If there is no horizontal correlation, and if no vertical correlation, C (Z) = Chv (Z).

The embodiment shown in FIG. 8 is a modification of the embodiment shown in FIG. First horizontal color signal decorrelation energy extraction circuit (27a)
The output DCH1 of the above is multiplied by b in the multiplier (72), and b · DCH1 and a · DYH are input to the maximum value circuit (82) to detect DH1. One of the outputs DCH2 of the second horizontal color signal decorrelation energy extraction circuit (27b) is multiplied by f1 in the multiplier (74) to input f1 · DCH2 and e1 · DYH to the maximum value circuit (83) and D
H21 is detected, and the other of DCH2 is multiplied by f2 in the multiplier (76), and f2 · DCH2 and e2 · DYH are input to the maximum value circuit (84) and D
H22 is detected, and the output DCV2 of the second vertical color signal decorrelation energy extraction circuit (29b) is multiplied by d in the multiplier (78) and d · DCV2 and C · DYV are input to the maximum value circuit (85). Then, DV is detected, the comparison circuit (34) compares DH1 and n · DV, the comparison circuit (35) compares DCV1 and m1 · DH21, and the comparison circuit (36) compares DYV and m2 · DH22. This is a configuration for comparison.

The selection control operation of the switch circuit (23) by the output (110) of the judgment 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. However, it is possible to arrange the sample points in a grid on the screen. For example, the sampling is not limited to four times the color subcarrier and may be performed at another frequency.

Further, the digital filter used in the above embodiment is an example, and for example, the filter order may be increased.

Further, although the NTSC system luminance signal / color signal separation filter is described in the above embodiment, the 1-line delay circuits (13) and (14) in FIG. 1 are replaced by the 2-line delay circuit (13a) as shown in FIG. ), (14a) can be applied as a luminance signal / color signal separation filter for a PAL system composite color television signal.

Further, although the signal (116) is passed through the two delay circuits in the above-mentioned embodiment, the number is not limited to this as long as it is an even number so that the decorrelation can be detected over κ samples (κ: integer) before and after. In that case, the number of delay circuits through which the signals (114) and (115) pass is not limited to one according to the number.

As described above, according to the present invention, the correlation between the vertical and horizontal images of the composite color television signal is detected,
In the horizontal direction luminance component, not only the pixel of interest,
Since the correlation is detected also in the samples before and after that, the output signals of the luminance signal color signal separation filters having different characteristics are selected and output based on the detection result.
It is possible to reduce the influence of leakage of the luminance signal and the chrominance signal on the mutual channels, reduce the dot interference, and obtain the luminance signal and chrominance signal separation filter of high resolution in the horizontal direction.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of an NTSC type luminance signal color signal separation filter according to an embodiment of the present invention, and FIG. 2 is a block circuit diagram showing an embodiment of an image correlation determination circuit in FIG.
FIG. 3 is a circuit diagram showing an embodiment of the decision circuit in FIG.
4 is a block diagram showing an embodiment of the horizontal color signal decorrelation energy extraction circuit in FIG. 2, and FIG. 5 is an embodiment of the horizontal luminance signal decorrelation energy extraction circuit in FIG. FIG. 6 is a block diagram showing an embodiment of the vertical color signal decorrelation energy extraction circuit in FIG. 2, and FIG. 7 is a vertical luminance signal decorrelation energy extraction circuit in FIG. FIG. 8 is a block diagram showing an embodiment, FIG. 8 is a block circuit diagram showing an embodiment which is a modification of FIG. 2, and FIG.
FIG. 10 is a block circuit diagram of an embodiment of a PAL type luminance signal color signal separation filter according to the present invention, FIG. 10 is a block circuit diagram of a conventional luminance signal color signal separation filter, and FIG. 11 is NT.
An SC-type composite color television signal is converted into a color subcarrier with 4
It is explanatory drawing which shows the arrangement | sequence on the screen of the signal series which carried out the synchronous sampling with the double. In the figure, (12) is an A / D converter, (13) and (14) are 1-line delay circuits, (16) is a vertical color signal extraction filter, and (1
7) 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 subtractor, (27) 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, and (30) is Vertical luminance signal uncorrelated energy extraction circuit, (71) to (81) multipliers, (34) to (36) comparison circuits, (37) determination circuit, (82) to (85) maximum value circuit , (86) to (89) are delay circuits, and (90) is an AND circuit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

(57) [Claims] 1. A composite video signal sampled at a frequency synchronized with a horizontal scanning frequency is delayed by one line or two lines to simultaneously extract respective sample values of a sample point of interest and a plurality of reference sample points around it. Means for extracting a frequency component corresponding to a component of a color subcarrier in the horizontal direction from each sample value of the sample point of interest and the reference sample point to obtain a first color signal, and A vertical color signal extraction filter for obtaining a second color signal by extracting a frequency component corresponding to a component of a color subcarrier in the vertical direction from each sample value of the sample point of interest and the reference sample point, and the sample point and the reference sample Horizontal / vertical direction color signal extraction filters for extracting frequency components corresponding to components of color subcarriers in the vertical direction and the horizontal direction from each sample value of points to obtain third color signals; A switch circuit for selecting a signal and outputting it as a color signal; and an image correlation determining means for detecting the correlation in the horizontal and vertical directions from the sample values of the sample point of interest and the reference sample point and outputting a color signal selection signal. A subtractor for subtracting the color signal selected by the switch circuit from the sample value of the sample point of interest and outputting a luminance signal, wherein the image correlation determination means is configured to detect each of the sample point of interest and the reference sample point. Horizontal direction luminance signal decorrelation energy detecting means for detecting at least one horizontal direction luminance signal decorrelation energy DYH from the sample value, and at least one horizontal direction from each sample value of the sample point of interest and the reference sample point. The horizontal direction color signal decorrelation energy detecting means for detecting the decorrelation energy DCH of the color signals, and the vertical direction from each sample value of the sample point of interest and the reference sample point. At least one vertical direction luminance signal non-correlation energy detecting means for detecting mainly non-correlation energy DYV of the luminance signal, and at least one mainly color signal in the vertical direction from each sample value of the sample point of interest and the reference sample point. Vertical color signal non-correlation energy detecting means for detecting the non-correlation energy DCV of the horizontal direction, the horizontal luminance signal non-correlation energy DYH multiplied by a (a: integer), and the horizontal color signal non-correlation energy DCH. b times (b:
An integer) which is greater than the horizontal direction uncorrelated energy detecting means for detecting the larger one as the horizontal direction uncorrelated energy DH1, and the horizontal direction luminance signal uncorrelated energy DYH
Is multiplied by e1 (e1: an integer) or the horizontal color signal decorrelation energy DCH is multiplied by f1 (f1: an integer), and the larger one is detected as the horizontal decorrelation energy DH21. The correlation energy detecting means, one obtained by multiplying the horizontal direction luminance signal non-correlation energy DYH by e2 (e2: integer) and one obtained by multiplying the horizontal direction color signal non-correlation energy DCH by f2 (f2: integer) are the larger ones. Third horizontal direction uncorrelated energy detecting means for detecting as direction uncorrelated energy DH22, the vertical direction luminance signal uncorrelated energy DYV multiplied by c (c: integer), and the vertical direction color signal uncorrelated energy DCV. Vertical direction decorrelation energy detection means for detecting the larger one of d times (d: integer) as vertical direction decorrelation energy DV, and DCV ≧ m1 · DH21
(M1: integer) or when the inequality of DYV ≧ m2 · DH22 (m2: integer) is satisfied over k samples (k: integer) before and after the pixel of interest, the first color signal is selected, and DHI ≧ n
Color signal for controlling the switch circuit so that the second color signal is selected when the DV (n: integer) inequality holds, and the third color signal is selected when neither of the two inequalities holds. A luminance signal / color signal separation filter including an extracting unit. 2. A means for simultaneously extracting each sample value of a sample point of interest and a plurality of reference sample points around it by delaying a composite video signal sampled at a frequency synchronized with a horizontal scanning frequency, and each sample point. From the sample value of at least two kinds of frequency components corresponding to the components of the color subcarriers in non-parallel directions to obtain a color signal, and from at least two kinds of color signals in non-parallel directions. A color signal selecting means for selecting and outputting a signal, an image correlation determining means for detecting a correlation in the horizontal and vertical directions from sample values at respective sampling points, and outputting a color signal selecting signal, and the image correlation determining means. A horizontal luminance signal decorrelation energy detecting means for detecting the degree of correlation of the horizontal luminance signal from the sample value of each sample point,
Horizontal color signal non-correlation energy detecting means for detecting the degree of correlation of horizontal color signals, vertical luminance signal non-correlation energy detecting means for detecting the degree of correlation of vertical luminance signals, and vertical color Vertical color signal decorrelation energy detection means for detecting the degree of signal correlation, horizontal luminance signal decorrelation energy, horizontal color signal decorrelation energy, vertical luminance signal decorrelation energy,
At least one quasi-comparison signal that determines from the vertical direction color signal decorrelation energy that the vertical decorrelation has a certain magnitude or more relative to the horizontal decorrelation, and the horizontal decorrelation is greater than or equal to the vertical decorrelation to some extent. Of at least one quasi-comparison signal for making a decorrelation determination and a delay circuit to delay at least one of the quasi-comparison signals by a predetermined number of samples, and the sample point of interest and the predetermined number of samples are regarded as one unit. 1 if not at least 1 unit before the sample point
If the quasi-comparison signals at a plurality of sample points, that is, at least one sample point at least one unit after the sample point of interest with the predetermined number of samples as one unit, match, A means for generating a quasi-comparison signal indicating that the decorrelation is established, and a comparison signal indicating that the vertical decorrelation or the horizontal decorrelation has a certain magnitude or more from the comparison signal, the color signal selecting means. And a color signal extraction for controlling the color signal selection means so as to select a signal from at least two kinds of color signals in non-parallel directions by the comparison signal received from the comparison signal generation means. And a luminance signal / color signal separation filter.