JP3003177B2 - Luminance signal color signal separation filter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a luminance signal / color signal separation filter for separating a luminance signal and a chrominance signal from, for example, an NTSC composite television signal.

[Prior Art] FIG. 9 is a block circuit diagram of a conventional NTSC system luminance signal color signal separation filter. In the figure, (1) is an input terminal to which a composite color television signal of the NTSC system is input, (2) is an A / D converter for converting an analog composite color television signal into a digital signal, (3), (4) is a first and second one-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 described.

The composite color television signal input to the input terminal (1) is converted into a digital signal (201) by an A / D converter (2) and input to a vertical filter (6) and a first one-line delay circuit. Is done.

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

The vertical filter (6) is usually composed of a filter called a two-line comb filter, and its output (20
4) 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 input to one input terminal of a subtraction circuit (9). The other input terminal of the subtraction circuit (9) is connected to the output (20) of the compensation circuit (5).
6) is entered. The compensation delay circuit (5) is a circuit for compensating for a delay in the bandpass filter (7).
Then, a luminance signal (207) is output from the subtraction circuit (9) and is derived from the output terminal (10).

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

In the A / D converter (2), the sampling frequency f _S = 4 · f _SC
(F _SC is the chrominance carrier frequency) composite color television signal synchronized sampling to the color subcarrier at (201) is a two-dimensional array as shown in FIG. 10 on the screen. That is, f
_{Since SC} = (455/2) fH, a signal obtained by inverting the phase of the color signal C by 180 ° for each line and extracting four samples in one cycle is obtained. In the figure, Y indicates a luminance signal, C1 and C2 indicate color signals, white circles indicate Y + C1, hatched circles indicate Y-C1, white triangles indicate Y + C2, and hatched triangles indicate Y-C2.

Now, as a symbol that represents a one sample delay and a line delay, and the use of Z ^-1 and Z ^-l using, respectively abacus Z transform. Here, Z ⁻¹ = exp (−j2πf / 4fs). Also, since f _SC = (455/2) fH, 1 = 910.

The vertical filter (6) outputs the current input signal (201).
, One-line delay signal (202) and two-line delay signal (3
03), a line support signal (204) to be supported for each line including the color signal C is extracted.

The transfer function HV is applied to the vertical filter (6) in this case.
(Z) becomes HV (Z) = (− 1/4) · (1−Z− ^l ) ² .

That is, the line support signal HC (m, n) (204) at the coordinates (m, n) is converted to HC (m, n) =-(1/4)） S (m, n-1) on the screen shown in FIG. ) −2S (m, n) + S (m, n + 1).

Since the 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 to the line support signal HC (m, n) (204) by the bandpass filter (7). )
Separate from Then, the obtained color signal C
(205) is sent to the subtraction circuit (9). Subtraction circuit (9)
Is a signal S (m, n) obtained by delaying a one-line delay signal (202) by a compensation delay circuit (5) according to a bandpass filter (7).
The color signal C (m, n) (205) is subtracted from (206), and the luminance signal Y (m, n) (207) is separated as follows.

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

[Problems to be Solved by the Invention] In a conventional luminance signal / color signal separation filter, the characteristics of a vertical filter and a horizontal filter are fixed and combined. That is, the luminance signal Y and the chrominance 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 are largely changed, the luminance signal Y and the color signal C leak to the mutual channel, thereby causing a problem that the image quality of the reproduced image is deteriorated particularly due to dot disturbance. Was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and a luminance signal and a chrominance signal capable of accurately separating a luminance signal and a chrominance signal even when a sudden change occurs in a television signal. It is intended to obtain a separation filter.

[Means for Solving the Problems] The luminance signal and chrominance signal separation filter according to the present invention employs delay means for delaying a decoded video signal sampled at a frequency synchronized with a horizontal scanning frequency line by line or line by line. Sample point and reference sample point, and their 1
The sample values of the reference sample points before and after the line or two lines are extracted, and a horizontal color subcarrier component is extracted from the sample values of the target sample point and the reference sample points by a horizontal color signal extraction filter. 1 color signal, a second color signal obtained by extracting a component of a color subcarrier in the vertical direction from each sample value of the target sample point and the reference sample point by a vertical color signal extraction filter, and a horizontal signal from each sample value. A third color signal from which the components of the color subcarriers in the horizontal and vertical directions are extracted by the vertical color signal extraction filter is used for the correlation in the horizontal direction and the vertical direction detected by the image correlation determination means from each sample value; And outputting the selected color signal as a color signal, and subtracting the color signal from the target sample point to obtain a luminance signal. Horizontal luminance signal decorrelation energy detecting means for detecting decorrelation energy DYH of the luminance signal in the horizontal direction from each sample value of the target main point and the reference sample point; Horizontal color signal decorrelation energy detection means for detecting decorrelation energy DCH, and vertical luminance signal decorrelation for detecting decorrelation energy DYV of a luminance signal in the vertical direction from each sample value of the noted sample point and reference sample point Energy detection means, vertical color signal decorrelation energy detection means for detecting decorrelation energy DCV of a color signal in the vertical direction from each sample value of the reference sample point, and horizontal decorrelation energy DH from these decorrelation energies. , Vertical uncorrelated energy DV1, DV21, D
V22 is detected and these uncorrelated energies DCH, DYH, DH, DV
1, DV21 and DV22 are compared to determine the magnitude of the correlation between the horizontal direction and the vertical direction.
And means for transmitting a signal for selecting a color signal having a large correlation among the color signals.

[Operation] The image correlation determining means according to the present invention selects the first color signal extracted by the horizontal color signal extraction filter when the sample value of the target sample point has a weak vertical correlation and a strong horizontal correlation. If the sample value of the target sample point has a weak horizontal correlation and a strong vertical correlation, the second color signal extracted by the vertical color signal extraction filter is selected. A color signal selection for selecting the third color signal extracted by the signal extraction filter is performed. 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.

[Example] Hereinafter, the present invention will be described 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 for receiving a composite color television signal of the NTSC system. (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) is a first one-line delay circuit for inputting 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, and (18) is image correlation. Judgment circuit, (19) 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, (29) is a vertical color signal decorrelation energy extraction circuit, and (30) is a vertical direction luminance signal decorrelation energy. Extraction circuit, (34),
(35) and (36) are comparison circuits, (37) is a judgment circuit, and (71)
(81) is a multiplication circuit, and (82) to (85) are maximum value circuits.

Output signal (101) of the A / D converter (12) in FIG.
Are supplied to a horizontal luminance signal decorrelation energy extraction circuit (28), a vertical color signal decorrelation energy extraction circuit (29) and a vertical luminance signal decorrelation energy extraction circuit (30) in FIG. The output signal (102) of the first one-line delay circuit (13) is a horizontal color signal decorrelation energy extraction circuit (27), a horizontal luminance signal decorrelation energy extraction circuit (28), and a vertical luminance signal decorrelation energy. It is provided to an extraction circuit (30).

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

The output signal DCH of the horizontal color signal uncorrelated energy extraction circuit (27) is divided into two parts, one of which is supplied to a comparison circuit (35), and the other of which is multiplied by a constant f by a multiplier (72) and then has a maximum value. Circuit (82). The output signal DYH of the horizontal luminance signal decorrelation energy extraction circuit (28) is divided into two parts, one of which is supplied to a comparison circuit (36), and the other of which is multiplied by a constant e by a multiplier (71) and then the maximum value Circuit (82).

The output signal DCV of the vertical color signal decorrelation energy extraction circuit (29) is divided into three parts, one of which is multiplied by a constant d1 by a multiplier (74) and then given to a maximum value circuit (83).
The other is given to the maximum value circuit (84) after being multiplied by the constant d2 by the multiplier (76), and the other is given to the maximum value circuit (85) after being multiplied by the constant b by the multiplier (78). . Vertical luminance signal decorrelation energy extraction circuit (30)
The output signal DYV is divided into three parts. One is multiplied by a constant c1 by a multiplier (73) and then given to a maximum value circuit (83), and the other is multiplied by a constant c2 by a multiplier (75). The maximum value circuit (84) is provided, and the other is a multiplier (77)
Is given to the maximum value circuit (85) after being multiplied by the constant a.

The output signal of the maximum value circuit (82) is given to the comparison circuit (34) after being multiplied by a constant m by the multiplier (79) as horizontal decorrelation energy DH. The output signal of the maximum value circuit (83) is given to the comparison circuit (35) as the second vertical decorrelation energy DV21 after being multiplied by the constant n1 by the multiplier (80).

The output signal of the maximum value circuit (84) is provided as a third vertical decorrelation energy DV22 to the comparison circuit (36) after being multiplied by a constant n2 by the multiplier (81). The output signal of the maximum value circuit (85) is the first vertical decorrelation energy DV1
Is given to the comparison circuit (34). The comparison circuit (34) calculates m · DH obtained by multiplying the horizontal uncorrelated energy DH by a constant m.
And the magnitude of the first vertical non-correlation energy DV1 is compared. When DV1 ≧ m · DH, the output signal (114) is set to a high level, otherwise, the output signal (114) is set to a low level.

The comparison circuit (35) includes a second vertical decorrelation energy DV2
The magnitude of n1 · DV21 obtained by multiplying 1 by a constant n1 is compared with the horizontal color signal decorrelation energy DCH. If DCH ≧ n1 · DV21, the output signal (115) is set to a high level; Level. The comparison circuit (36) calculates n2 · DV22 obtained by multiplying the third vertical decorrelation energy DV22 by a constant n2;
The magnitude of the horizontal luminance signal non-correlation energy DYH is compared, and when DYH ≧ n2 · DV22, the output signal (116) is set to a high level; otherwise, the output signal (116) is set to a low level.

Output signal (114) of comparison circuit (34) and comparison circuit (35)
Output signal (115) and output signal (116) of the comparison circuit (36)
Is supplied to the judgment circuit (37). An output signal (110) of the determination circuit (37) is sent out as an output of the image correlation determination circuit (18).

FIG. 3 is a block circuit diagram showing an embodiment of the judgment circuit (37) in FIG. 2, and is composed of AND circuits (38) and (39), a NOT circuit (40), and a NOR circuit (41). The output signal (114) of the comparison circuit (34) is supplied to one input terminal of the AND circuit (39) and the input terminal of the NOT circuit (40), and the output signal (115) of the comparison circuit (35) is output. Is the NOR circuit (4
1), the output signal (116) of the comparison circuit (36) is provided to the other input terminal of the NOR circuit (41), and the output of the NOR circuit (41) is supplied to the AND circuit (41). 39), and the output signal of the NOT circuit (40) is supplied to the AND circuit (38).
To the other input terminal. The output signal of the AND circuit (38) and the output signal of the AND circuit (39) become the output signal (110) of the image correlation determination circuit (18).

FIG. 4 is a block circuit diagram showing an embodiment of the horizontal chrominance signal decorrelation energy extracting circuit (27) in FIG. 2, and has a delay amount of one cycle (1 / f _SC ) of the color subcarrier. Circuit (4
4) a subtraction circuit (45) and an absolute value circuit (46). The output signal (102) of the first one-line delay circuit (13) is a delay circuit (44) and a subtraction circuit (45). And the output signal of the delay circuit (44) is applied 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 the absolute value circuit (46) becomes the horizontal color signal decorrelation energy DCH.

FIG. 5 is a block circuit diagram of one embodiment of the horizontal luminance signal decorrelation energy extraction circuit (28) in FIG. 2; a vertical low-pass filter (47); Delay circuits (48) with delay amount of (1 / (2f _SC )), (4
9), subtraction circuit (50), (51), absolute value circuit (52), (5
3) and a maximum value circuit (54). The output signal (101) of the A / D converter (12), the output signal (102) of the first one-line delay circuit (13), and the second The output signal (103) of the line delay circuit (14) is applied to a vertical low-pass filter (47), and the vertical low-pass filter (4
The output of 7) 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
The output of the delay circuit (49) is supplied to the other input terminal of the subtraction circuit (51) and the other input terminal of the subtraction circuit (51). And the output of the subtraction circuit (50) is given by the absolute value circuit (52)
The output of the absolute value circuit (52) is applied to the maximum value circuit (54), the output of the subtraction circuit (51) is applied to the absolute value circuit (53), The output is provided to a maximum value circuit (54). The output of the maximum value circuit (54) is the output D of the horizontal luminance signal decorrelation energy extraction circuit (28).
YH.

FIG. 6 is a block circuit diagram of one embodiment of the vertical color signal decorrelation energy extraction circuit (29) in FIG. 2, and includes horizontal band pass filters (55) and (56) and a subtraction circuit (5).
7) An absolute value circuit (58), an output signal (101) of the A / D converter (12) is given to a horizontal band pass filter (55), and a second one-line delay circuit (14) Is output to a horizontal band-pass filter (56), and the output of the horizontal band-pass filter (55) is applied to one terminal of a subtraction circuit (57). ) Is applied to the other input terminal of the subtraction circuit (57). The output of the subtraction circuit (57) is supplied to an absolute value circuit (58), and the output of the absolute value circuit (58) is the output D of the vertical color signal decorrelation energy extraction circuit (29).
It becomes CV.

FIG. 7 is a block circuit diagram of an embodiment of a vertical luminance signal decorrelation energy extraction circuit (30) in FIG. 2, a horizontal low-pass filter (59), (60), (61), and a subtraction circuit. (62), (63), an absolute value circuit (64), (65) and a maximum value circuit (66). The output signal (101) of the A / D converter (12) The output signal (10) of the first one-line delay circuit (13) is supplied to a pass filter (59).
2) is applied to a horizontal low-pass filter (60), and the output signal (103) of the second one-line delay circuit (14) is applied to a horizontal low-pass filter (61).

The output of the horizontal low-pass filter (59) is supplied to one input terminal of a subtraction circuit (62), and the output of the horizontal low-pass filter (60) is supplied to the other input terminal of the subtraction circuit (62). To one input terminal of the circuit (63),
The output of the horizontal low-pass filter (61) is applied to the subtraction circuit (6
3) is applied to the other input terminal, 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), (64),
The output of (65) is 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 described.

When a composite color television signal of the NTSC system is supplied via the input terminal (11), the A / D converter (12) samples the composite color television signal at a sampling frequency f _S = 4f _SC .

The sampled composite color television signal passes through a first one-line delay circuit (13) and a second one-line delay circuit (14) to obtain a sample value at a certain sample point of interest and the sample point of interest. At the same time, the sample values of the two reference sample points on one line 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 one-line delay circuit (13), the second The signal (m, n-1) is output to the output (103) of the one-line delay circuit (14).
Appears on the output (101) of the A / D converter (12).
(M, n + 1) appears. (See Figure 10).

The signal (102) is supplied to the horizontal color signal extraction filter (19). This signal (102) and the other two signals (101), (10)
3) The vertical color signal extraction filter (16),
It is supplied to the inputs of the horizontal / vertical 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) (1-
Z ^-l ) ² .

The output signal of the vertical color signal extraction filter (16) (10
4) As 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 (108) of the horizontal / vertical color signal extraction filter (17). ) Is the output signal (10) of the compensation delay circuit (21).
9) is given to the switch circuit (23).

Next, a vertical color signal extraction filter (16) and a horizontal color signal extraction filter (1
9), and horizontal and vertical color signal extraction filters (17)
Will be described.

The correlation between the vertical and horizontal images with respect to the target sample point is detected, and when the vertical correlation is particularly strong, a compensation delay circuit (20) to which the output signal (104) of the vertical color signal extraction filter (16) is input. ), The output signal (107) of the compensation delay circuit (22) to which the output signal (106) of the horizontal color signal extraction filter (19) is input when the correlation in the horizontal direction is particularly strong. Select the horizontal and vertical color signal extraction filter (1
Compensation delay circuit (21) to which the output signal (108) of 7) is input
Switch circuit (2) to select the output signal (109) of
Switch 3).

The detection of the correlation of the image 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 operation.

The horizontal color signal decorrelation energy is DCH (Z), the horizontal luminance signal decorrelation energy is DYH (Z), the vertical color signal decorrelation energy is DCV (Z), and the vertical luminance signal decorrelation energy is DYV (Z) and will 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 ^-l -Z ^-2l ) |) The energy is DH, the first vertical decorrelation energy is DV1, the second vertical decorrelation energy is DV21, and the third vertical decorrelation energy is DV22.

DH = max (e-DYH, f-DCH) DV1 = max (a-DYV, b-DCV) DV21 = max (c1-DYV, d1-DCV) DV22 = max (c2-DYV, d2-DCV) Comparison circuit In (34), DV1 is compared with m · DH1, and when DV1 ≧ m · DH, it is determined that there is a correlation in the horizontal direction and there is no correlation in the vertical direction, and the signal of “1” is sent to the determination circuit (37). (114), and when DV1 <m.DH, 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 DCH with n1 · DV21. When DCH ≧ n1 · DV21, it is determined that the correlation in the vertical direction is strong and the correlation in the horizontal direction is weak. When DCH <n1.DV21, it is determined that the correlation is weak in the vertical direction, and a "0" signal (115) is sent to the determination circuit (37).

On the other hand, the comparison circuit (36) compares DYH with n · 2DV22, and when DYH ≧ n · DV22, determines that the correlation in the vertical direction is strong and the correlation in the horizontal direction is weak. The signal (116) of "1" is transmitted, and when DYH <n2.DV22, it is determined that the correlation is weak in the horizontal direction, and the signal "0" is transmitted to the determination circuit (37).

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

That is, the input signals (114), (1
15) (116), the output signal (110) and the color output signals (105), (10) selected by the switch circuit (23).
The functions of 7) and (109) are as shown in Table 1.

That is, when the output signal (110a) of the AND circuit (38) and the output signal (110b) of the AND circuit (39) are both "0", the output signal (105) of the compensation delay circuit (20) is switched. 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) When the output signal (110a) of the AND circuit (38) is “0” and the output signal of the AND circuit (39) is “1”, the compensation delay circuit (2
2) Select the output signal (107).

Therefore, in the embodiment shown in FIG. 1, the filter characteristic C (Z) of the color signal extraction is determined according to the presence or absence of the correlation, when there is a horizontal correlation, C (Z) = Ch (Z) No horizontal correlation, vertical correlation When there is, C (Z) = CV (Z) When there is no horizontal correlation and when there is no vertical correlation, switching is made as follows: C (Z) = ChV (Z).

In the above embodiment, the composite color television signal is sampled at four times the frequency of the color subcarrier synchronized with the horizontal scanning frequency. However, any method may be used in which the sampling points are arranged 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 order of the filter may be increased.

In the above embodiment, the NTSC-system luminance signal / chrominance signal separation filters are arranged. However, the one-line delay circuits (13) and (14) in FIG. 1 are replaced by two-line delay circuits (13a) and (13a) as shown in FIG. If (14a) is set, the filter can be applied as a luminance signal / color signal separation filter of a PAL composite color television signal.

[Effects of the Invention] As described above, according to the present invention, a correlation between vertical and horizontal images of a composite color television signal is detected,
Since the output signals of the luminance signal and color signal separation filters having different characteristics are selected and output based on the detection result, the influence of the leakage of the luminance signal and the color signal to the mutual channel can be reduced. Thus, there is an effect that a luminance signal / color signal separation filter capable of reducing dot disturbance can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic block circuit diagram showing a luminance signal / color signal separation filter according to an embodiment of the present invention, 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 judgment 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.
FIG. 6 is a block diagram showing an embodiment of a horizontal luminance signal decorrelation energy extraction circuit in the figure, FIG. 6 is a block diagram showing an embodiment of a vertical color signal decorrelation energy extraction circuit in FIG. 2, and FIG. FIG. 2 is a block diagram showing an embodiment of a vertical luminance signal decorrelation energy extraction circuit in FIG. 2, and FIG. 8 is a block circuit diagram of an embodiment of a PAL type luminance signal color signal separation filter according to the present invention. FIG. 9 is a block diagram of a conventional luminance signal / chrominance signal separation filter, and FIG.
FIG. 3 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 at four times the color subcarrier. In the figure, (12) is an A / D converter, (13) and (14) are 1
Line delay circuit, (16) is a vertical color signal extraction filter, (17) is a horizontal / vertical color signal extraction filter, (1
8) 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, ( 30) is a vertical luminance signal decorrelation energy extraction circuit, (71) to (81) are multipliers, and (34) to (36)
Is a comparison circuit, (37) is a judgment circuit, and (82) to (85) are maximum value circuits. In the drawings, the same reference numerals indicate the same or corresponding parts.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-289392 (JP, A) JP-A-1-78593 (JP, A) JP-A-2-141193 (JP, A) JP-A-1- 98385 (JP, A) JP-A-1-137786 (JP, A) JP-A-63-30085 (JP, A) JP-A-63-141490 (JP, A) JP-A-4-81911 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H04N 9/78

Claims (1)

(57) [Claims] 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 sample values of a target sample point and a plurality of reference sample points around the target sample point. A horizontal color signal extraction filter for extracting a frequency component corresponding to a horizontal color subcarrier component from each sample value of the noted sample point and the reference sample point to obtain a first color signal; A vertical color signal extraction filter for extracting a frequency component corresponding to a vertical color subcarrier component from each sample value of the target sample point and the reference sample point to obtain a second color signal; A horizontal / vertical color signal extraction filter for extracting a frequency component corresponding to a vertical and horizontal color subcarrier component from each sample value of a point to obtain a third color signal; A switch circuit for selecting a signal and outputting the selected signal as a color signal; and image correlation determining means for detecting a horizontal and vertical correlation from each sample value of the target sample point 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 target sample point and outputting a luminance signal, wherein the image correlation determining means is configured to output each of the target sample point and the reference sample point. Horizontal luminance signal decorrelation energy detecting means for detecting at least one decorrelation energy DYH of the luminance signal in the horizontal direction from the sample values, and at least one horizontal correlation signal from each sample value of the noted sample point and the reference sample point. Horizontal color signal decorrelation energy detecting means for detecting decorrelation energy DCH of mainly color signals; At least one of
Vertical luminance signal decorrelation energy detecting means for detecting decorrelation energy DYV of mainly luminance signals; and at least one decorrelation of mainly color signals in the vertical direction from each sample value of the noted sample point and the reference sample point. A vertical color signal decorrelation energy detecting means for detecting energy DCV; a horizontal color signal decorrelation energy DYH multiplied by e (e: an integer);
A horizontal non-correlation energy detecting means for detecting the larger one of CH times f (f: integer) as horizontal non-correlation energy DH, and a-times the vertical luminance signal non-correlation energy DYV (a: integer) Vertical direction decorrelation energy detecting means for detecting the larger one of the calculated value and the value obtained by multiplying the vertical color signal decorrelation energy DCV by b (b: an integer) as the vertical direction decorrelation energy DV1; The luminance signal decorrelation energy DYV is multiplied by c1 (c1:
An integer) and a vertical color signal non-correlation energy DCV multiplied by d1 (d1: an integer), a larger one of which is detected as a vertical non-correlation energy DV21; A third method detects, as the vertical non-correlation energy DV22, a larger one of the vertical luminance signal non-correlation energy DYVc2 times (c2: integer) and the vertical color signal non-correlation energy DCV d2 (d2: integer). The vertical non-correlation energy detecting means, and the case where the correlation is strong in the vertical direction,
When the inequality of CH ≧ n1 · DV21 or DYH ≧ n2 · DV22 (n1, n2: an integer) is satisfied, the second color signal is selected. In other cases, the correlation is strong in the horizontal direction. When the inequality DV1 ≧ m · DH (m: an integer) holds, the first color signal is selected, and the correlation is not strong in both the horizontal direction and the vertical direction. And a color signal extracting means for controlling a switch circuit to select the third color signal when none of the above is satisfied.