JPH07336722A - Luminance signal chrominance signal separation - Google Patents

Abstract

PURPOSE:To reduce dot disturbance caused in the vertical direction with A small scale configuration by comparing image correlation energy sets based on a required sampling value so as to select a 1st or 2nd color signal filter. CONSTITUTION:A 1-line digital composite color image signal 20a and a delay digital composite signal 19a of one preceding line are inputted to an image correlation decision circuit 23, a horizontal luminance signal non-correlation energy extract circuit 32 extracts a signal DYH from a noted sampling point of one line and a sampling value of a reference sample point and a prescribed coefficient is multiplied with the signal DYH to calculate a horizontal direction non-correlation energy DH. Similarly a vertical non-correlation energy DV is calculated from a reference point sampling value in the signals 19a, 20b and color filters in horizontal and in horizontal/vertical direction are selected depending on the comparison result of both the energy sets DH, DV. Thus, the effect of leakage of a luminance and a chrominance signal onto mutual channels in an area where an image change is rapid in the vertical direction is reduced and dot disturbance is reduced.

Description

Detailed Description of the Invention

[0001]

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 color signal from a composite color television signal of, for example, NTSC system or PAL system.

[0002]

2. Description of the Related Art FIG. 14 is a block diagram of a conventional NTSC system luminance signal / color signal separation filter disclosed in, for example, Japanese Patent Laid-Open No. 4-81191. In the figure, 1 is NTS
An input terminal for inputting a C type composite color television signal, 2 is an A / D converter for converting an analog composite color television signal into a digital signal, 3 and 4 are first,
Second 1-line delay circuit, 5 vertical color signal extraction filter, 6 horizontal color signal extraction filter, 7 horizontal / vertical color signal extraction filter, 8 image correlation determination circuit,
Reference numerals 9, 10, 11, 12, and 13 are compensation delay circuits, 14 is a switch circuit, 15 is a subtraction circuit, 16 is a color signal output terminal, and 17 is a luminance signal output terminal.

Next, the operation will be described. The NTSC color television signal applied to the input terminal 1 is A
A sample value at a sample point of interest sampled by the / D converter 2 and passing through the first and second one-line delay circuits 3 and 4, and one line above and one line below the sample point of interest. And the sample values of the two reference sample points of are simultaneously extracted. When the sample value of the sample point of interest has a weak vertical correlation and a strong horizontal correlation, the first color signal extracted by the horizontal color signal extraction filter 6 is selected, and the sample value of the sample point of interest shows the horizontal direction. When the correlation is weak and the correlation in the vertical direction is strong, the second color signal extracted by the vertical color signal extraction filter 5 is selected, and when neither is the third color signal extracted by the horizontal / vertical color signal extraction filter 7. The image correlation determination circuit 8 controls the switch circuit 14 so as to select the color signal, and the color signal 14a and the luminance signal 1
5a is separated.

[0004]

Although the above-mentioned conventional luminance signal / color signal separation filter is completely effective for dot interference, it requires two one-line delay circuits, and the circuit scale inside the image correlation determination circuit is further increased. However, there is a problem that a large increase in cost is inevitable compared to the two-line comb filter that has been known for a long time.

The present invention has been made in order to solve the above problems, and reduces dot interference as compared with a two-line comb filter even when a rapid change occurs in the vertical direction of a television signal. It is an object of the present invention to obtain a luminance signal / color signal separation filter which can be realized and which does not increase the circuit scale as in the conventional example.

[0006]

A luminance signal / chrominance signal separation filter according to the present invention refers to a sampling point of interest by a delay means for delaying a composite video signal sampled at a frequency synchronized with a horizontal scanning frequency by one line. Each sample value of the sample point and the reference sample point one line before is extracted, and the horizontal color subcarrier component is extracted from the sample value of the sample point of interest and the sample value of the reference sample point by the horizontal color signal extraction filter. Similarly, the extracted first color signal and the second color signal obtained by extracting the components of the color subcarriers in the horizontal and vertical directions from the respective sample values by the horizontal and vertical direction color signal extraction filters A color signal is selected and output based on the horizontal and vertical correlations detected by the correlation detecting means, and the color signal is subtracted from the sample point of interest to obtain a luminance signal. Thus, the image correlation detecting means includes a horizontal luminance signal 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, and the sample point of interest and the reference sample. Vertical direction luminance signal decorrelation energy detecting means for detecting the decorrelation energy DYV of the luminance signal in the vertical direction from each sample value of the point, and decorrelation of the color signal in the vertical direction from each sample value of the sample point of interest and the reference sample point Vertical color signal decorrelation energy detection means for detecting energy DCV is compared with these decorrelation energies DYH, DYV and DCV to determine the magnitude of the correlation in the horizontal direction and the vertical direction, and based on this determination result, And a means for transmitting a signal for selecting the one having the larger correlation between the first and second color signals.

Further, the decorrelation energy DYH of the luminance signal in the horizontal direction in the image correlation determining means is extracted by the first luminance signal decorrelation energy extracting means in the horizontal direction from each sample value of the sample point of interest and the reference sample point. The second horizontal direction luminance signal non-correlation energy extraction means from the first horizontal direction luminance signal non-correlation energy DYH1 and the sample values of the sample point of interest and the reference sample point. Energy DYH of the luminance signal of
2 is multiplied by b and the larger one is used.

Further, the image correlation determining means outputs an output of a comparison circuit for comparing the vertical decorrelation energy DV and the horizontal decorrelation energy DH with an inequality of DV> DH, and a plurality of references around the sample point of interest. A continuous determination circuit is provided so as to select the first color signal when the sampling point (R pixel) holds, and to select the second color signal when the inequality does not hold.

Further, the image correlation determining means detects horizontal luminance signal decorrelation energy extracting means for detecting the decorrelation energy DYH1 of the first horizontal luminance signal from each sample value of the target sampling point and the reference sampling point, Horizontal luminance signal decorrelation energy extracting means for detecting the second decorrelation energy DYH2 of the luminance signal in the horizontal direction from the respective sample values of the sample point of interest and the reference sample point, and sample values of the sample point of interest and the reference sample point Energy DY of the luminance signal in the vertical direction from
Vertical luminance signal decorrelation energy detecting means for detecting V, and vertical color signal decorrelation energy extracting means for detecting decorrelation energy DCV of the color signal in the vertical direction from each sample value of the sample point of interest and the reference sample point. , A first maximum value circuit that takes the larger one of the first horizontal luminance signal decorrelation energy DYH1 and the second horizontal luminance signal decorrelation energy DYH2 multiplied by a, and the first horizontal luminance A second maximum value circuit that takes the larger of the signal decorrelation energy DYH1 and the second horizontal direction luminance signal decorrelation energy DYH2 multiplied by b, and the output of the first maximum value circuit multiplied by α And a first comparison circuit for comparing the vertical direction color signal decorrelation energy DCV with the output of the second maximum value circuit multiplied by β, and the vertical direction luminance signal decorrelation energy DYV. And a second comparison circuit for comparing the above, and the result of the first comparison circuit is DCV> αmax (D
YH1, aDYH2), which satisfies the first inequality
Alternatively, the result of the second comparison circuit is DYV> βmax
A configuration in which the first color signal is selected when the second inequality (DYH1, bDYH2) is satisfied, and the second color signal is selected when neither of the first and second inequalities holds. Is.

In the image correlation judging means, the result of the first comparing circuit is DCV> αmax (DYH1, aDYH
2) or the result of the second comparison circuit shows that the second inequality DYV> βmax (DYH1, bDYH2) is obtained at the sample point of interest and a plurality of reference sample points (R pixels) around it. It has a continuity determination circuit that selects the first color signal when the condition is satisfied, and selects the second color signal when the condition is not satisfied.

[0011]

The image correlation determining means in the present invention determines the image correlation from the sample point of interest, the reference sample point in the horizontal direction and the reference sample value one line before them. You can do it. Further, when the sample value of the sample point of interest has a weak vertical correlation and a strong horizontal correlation, the first color signal extracted by the horizontal color signal extraction filter is selected. Since the second color signal extracted by the color signal extraction filter is selected, the influence of the leakage of the luminance signal and the color signal on the mutual channel in the region where the image changes significantly in the vertical direction is reduced, and the dot interference is reduced. You can

[0012]

【Example】

Example 1. 1 is a block diagram showing an embodiment of the present invention according to claim 1, in which 18 is an input terminal to which an NTSC composite color television signal is applied,
Reference numeral 19 denotes an A / A that converts an analog composite color television vision signal input from the input terminal 18 into a digital signal.
D converter, 20 is a one-line delay circuit for inputting the output signal of the A / D converter 19, 21 is a horizontal color signal extraction filter, 22 is a horizontal / vertical color signal extraction filter, 23 is an image correlation determination circuit, Reference numerals 24, 25, 26 and 27 are compensation delay circuits, 28 is a switch circuit, 29 is a subtraction circuit, 30 is an output terminal of the switch circuit 28, and 31 is an output terminal of the subtraction circuit 29.

FIG. 2 is a block diagram showing an example of the image correlation determination circuit 23 in FIG. 1, in which 32 is a horizontal luminance signal non-correlation energy extraction circuit and 33 is a vertical luminance signal non-correlation energy extraction circuit. , 34 are vertical color signal decorrelation energy extraction circuits, 35 and 37 are multiplication circuits, 36 is a maximum value circuit, and 38 is a comparison circuit.

The output signal 19a of the A / D converter 19 in FIG. 1 is the horizontal direction luminance signal decorrelation energy extraction circuit 32, the vertical direction luminance signal decorrelation energy extraction circuit 33, and the vertical direction color signal decorrelation energy in FIG. It is given to the extraction circuit 34. On the other hand, the output signal 20a of the 1-line delay circuit 20 is given to the horizontal direction luminance signal decorrelation energy extraction circuit 32, the vertical direction luminance signal decorrelation energy extraction circuit 33, and the vertical direction color signal decorrelation energy extraction circuit 34.

The output signal DYH of the horizontal luminance signal decorrelation energy extraction circuit 32 is multiplied by the constant α by the multiplier 37 and is given to the comparison circuit 38 as a DH signal.
The output signal DYV of the vertical luminance signal decorrelation energy extraction circuit 33 is multiplied by the constant a by the multiplier 35,
It is given to the maximum value circuit 36. The output signal DCV of the vertical color signal decorrelation energy extraction circuit 34 is the maximum value circuit 3
Given to 6. The output signal DV of the maximum value circuit 36 is given to the comparison circuit 38.

The maximum value circuit 36 outputs the output signal 3 of the multiplier 35.
5a and the maximum value of the output signal DCV of the vertical color signal decorrelation energy extraction circuit 34 are output. The comparison circuit 38 compares the output signal DH of the multiplier 37 with the output signal DV of the maximum value circuit 36, and outputs a high level when the inequality of DV> DH holds, and outputs a low level when the inequality does not hold. The DH is αDYH, and the DV is the maximum value of aDYV and DCV.

FIG. 3 is a block diagram showing an example of the horizontal luminance signal decorrelation energy extraction circuit 32 in FIG.
A vertical low-pass filter (hereinafter referred to as LPF) 39,
The delay circuits 40 and 41, the subtraction circuits 42 and 43, and the absolute value circuit 4 having the delay amount of 1/2 the cycle fsc / 2 of the color subcarrier.
4, 45 and maximum value circuit 46, and A / D
The output signal 19a of the converter 19 and the output signal 20a of the one-line delay circuit 20 are given to the vertical LPF 39.

The output signal 39a of this vertical direction LPF 39
Is applied to one input terminal of the delay circuit 40 and the subtraction circuit 42, and the output signal 40a of the delay circuit 40 is
1, the other input terminal of the subtraction circuit 42 and one input terminal of the subtraction circuit 43, the output signal 4 of the delay circuit 41
1a is applied to the other input terminal of the subtraction circuit 43. The output signal of the subtraction circuit 42 is given to the absolute value circuit 44, the output signal 44a of this absolute value circuit 44 is given to one input terminal of the maximum value circuit 46, and the output signal of the subtraction circuit 43 is given to the absolute value circuit 45. The output signal 45a of the absolute value circuit 45 is given to the other input terminal of the maximum value circuit 46. The output signal of the maximum value circuit 46 becomes the output signal DYH of the horizontal luminance signal decorrelation energy extraction circuit 32.

FIG. 4 is a block diagram showing an example of the vertical direction luminance signal decorrelation energy extraction circuit 33 in FIG.
It is composed of horizontal LPFs 47, 48, a subtraction circuit 49, and an absolute value circuit 50. The output signal 19a of the A / D converter 19 is given to the horizontal LPF 47, and the output signal 20a of the 1-line delay circuit 20 is horizontal. Given to direction LPF 48. The output signal 47a of the horizontal LPF 47 is applied to one input terminal of the subtraction circuit 49, and the horizontal LPF 47 is supplied.
The output signal 48a of 48 is given to the other input terminal of the subtraction circuit 49, the output signal 49a of the subtraction circuit 49 is given to the absolute value circuit 50, and the output signal of the absolute value circuit 50 is the vertical direction luminance signal decorrelation energy extraction. Output signal D of circuit 33
It will be YV.

FIG. 5 is a block circuit diagram showing an example of the vertical color signal decorrelation energy extraction circuit 34 in FIG. 2, and a horizontal bandpass filter (hereinafter referred to as BPF) 5
1, 52, subtraction circuit 53, addition circuit 54, absolute value circuit 5
The output signal 19a of the A / D converter 19 is applied to the horizontal direction BPF 51, and the output signal 20a of the 1-line delay circuit 20 is applied to the horizontal direction BPF 52. These horizontal BPF51,
The output signals 51a and 52a of 52 are given to the subtraction circuit 53 and the addition circuit 54, the output signal 53a of the subtraction circuit 53 is given to the absolute value circuit 55, and the output signal 5 of the addition circuit 54 is given.
4a is given to the absolute value circuit 56, and the output signal 56a of the absolute value circuit 56 is given to the other input terminal of the minimum value circuit 57. The output signal of the minimum value circuit 57 becomes the output signal DCV of the vertical color signal decorrelation energy extraction circuit 34.

Next, the operation of the circuit shown in FIGS. 1 to 5 will be described. When an NTSC composite color television signal is given through the input terminal 18, the A / D converter 19 samples the composite color television signal at the sampling frequency fs = 4fsc. The sampled composite color television signal passes through the one-line delay circuit 20 to simultaneously extract the sample value at a certain sample point of interest and the reference sample point on one line on the screen of the sample point of interest. . That is, the sample value S (m, n) of the composite color television signal at the position of coordinates (m, n) is the A / D converter 1.
The signal S (m, n-1) appears in the output signal 20a of the 1-line delay circuit 20 when it appears in the output signal 19a of 9 (see FIG. 6). The signals 19a and 20a are supplied to the horizontal color signal extraction filter 21, the horizontal / vertical color signal extraction filter 22, and the image correlation determination circuit 23, respectively.

Now, it is assumed that z ⁻¹ and z ^−L are used as the symbols representing the delay of 1 sample and the delay of 1 line, respectively, by using z transform. Here, z ⁻¹ = exp (−
j2πf / 4f _sc ). Also, f _sc = (445 /
2) Since f _H , L = 910. Therefore, the transfer function C _h (z) of the horizontal color signal extraction filter 21 is
Is represented by, for example, _Ch (z) = (-1/4) (1-z- ² ) ^2, and the horizontal / vertical direction color signal extraction filter 22
The transfer function C _hv (z) of is, for example, C _hv (z) = (− 1 /
4) It is represented as (1-z- ² ) ² (-1/4) (1-z- ^L ) ² .

The output signal 21a of the horizontal color signal extraction filter 21 is the output signal 24a of the compensation delay circuit 24, and the output signal 22a of the horizontal / vertical color signal extraction filter 22 is the output signal 25a of the compensation delay circuit 25. , To the switch circuit 28, respectively. The correlation between the vertical and horizontal images with respect to the sample point of interest is detected. When the vertical correlation is particularly weak, the output signal 24a of the compensation delay circuit 24 to which the output signal 21a of the horizontal color signal extraction filter 21 is input is detected. In the other cases, the output signal 25a of the compensation delay circuit 25 to which the output signal 22a of the horizontal / vertical color signal extraction filter 22 is input is selected.
The switch circuit 28 is switched so as to select. The image correlation detection and the control of the switch circuit 28 are performed by the image correlation determination circuit 23, and the image correlation determination circuit 23 controls the switch circuit 28 by the following operations. Horizontal direction luminance signal decorrelation energy DYH
(Z), the vertical direction luminance signal decorrelation energy is DYV
(Z), DCV of the vertical direction color signal decorrelation energy
(Z), and is expressed as follows.

DHY (z) = max (| (1/2) .multidot.
(1 + z ^-L ) ・ (1-z ^-2 ) |, | (1/2) ・ (1+
z ^-L ) ・ (z ^-2 -z ^-4 ) |) DYV = (1/4) ・ (1 + z ^-2 ) ²・ (1-z ^-L ) DCV = min (| (1/4) ・ ( 1-z ^-2 ) ² · (1
−z ^−L ) |, | (1/4) · (1-z ⁻² ) ² · (1 + z
^-L ) |)

At this time, the vertical decorrelation energy D
V and horizontal decorrelation energy DH are expressed as follows. DV = max (aDYV, DCV) DH = αDYH In the comparison circuit 38, DV is compared with DH, and DV> D
When H, it is determined that the correlation is weak in the vertical direction and the signal 23a of "1" is transmitted. When DV≤DH, it is determined that the correlation is weak in the horizontal direction and the signal 23a of "0" is transmitted.

That is, the switch circuit 28 selects the output signal 24a of the compensation delay circuit 24 when the output signal 26a of the compensation delay circuit 26 is "1", and the output signal 26a of the compensation delay circuit 26 is "0". Sometimes, the output signal 25a of the compensation delay circuit 25 is selected. Therefore, in the embodiment of FIG. 1, the color signal extraction filter characteristic C (z) is C (z) = C when the vertical correlation is weak depending on the presence or absence of the correlation.
_h (z), C (z) = C when horizontal correlation is weak
It 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, but the sample points are arranged in a grid on the screen. If it is a method, it is not limited to four times the color subcarrier, and it may be sampled at another frequency. Also,
The digital filter used in the above embodiment is an example,
For example, the filter order may be increased. Further, although each digital filter is an FIR filter in the above embodiment, it may be configured as an IIR filter.

Example 2. FIG. 7 is a block circuit diagram showing the configuration of the image correlation judging circuit 23 in the embodiment of the invention according to claim 2. In the figure, 59 is a second horizontal direction luminance signal decorrelation energy extraction circuit, 62 is a multiplier that multiplies a constant b, 64 is a maximum value circuit, and 66 is a multiplier that multiplies a constant α.

FIG. 8 is a block diagram showing an example of the second horizontal luminance signal decorrelation energy extraction circuit 59 in FIG. 7, in which 67 is a delay having the same amount of delay as the color subcarrier. A circuit, 68 is a subtraction circuit, and 69 is an absolute value circuit. The output signal DYH2 of the second horizontal luminance signal decorrelation energy extraction circuit 59 is, for example, DYH.
It is represented as 2 (z) = | 1-z ^-4 |.

At this time, the vertical decorrelation energy DV and the horizontal decorrelation energy DH in the image correlation determination circuit 23 are expressed as follows. DV = max (aDYV, DCV) DH = αmax (bDYH2, DYH1) The comparison circuit 38 compares DH with DV, and DV> DH
In the case of, it is judged that the correlation is weak in the vertical direction and the signal 23a of "1" is transmitted, and when DV≤DH, it is judged that the correlation is weak in the horizontal direction and the signal 23a of "0" is transmitted. Here, DYH1 is an output signal of the first horizontal luminance signal decorrelation energy extraction circuit 32.

Since the other operations are exactly the same as those in the first embodiment, the description thereof will be omitted. Although the circuit scale of the second embodiment is slightly larger than that of the first embodiment, a more accurate image determination result can be obtained.

Example 3. FIG. 9 is a block circuit diagram showing the configuration of the image correlation determination circuit 23 in the embodiment of the invention according to claim 3. In the figure, reference numeral 70 is a continuous determination circuit.

FIG. 10 is a block circuit diagram showing an example of the continuity determination circuit 70 in FIG. In the figure, reference numeral 71 is a serial connection of R D flip-flops (registers), and 72 is an AND circuit having R input terminals.

In this embodiment, the output signal 38a of the comparison circuit 38 in the first and second embodiments is applied to the continuity determination circuit 70 so that DV> DH at the sample point of interest and a plurality of sample points around it. It is determined whether or not the following inequality holds. As a result, although the circuit scale is slightly larger than that of the first and second embodiments, erroneous determination can be prevented and unnecessary cross color interference can be eliminated.

Example 4. FIG. 11 is a block diagram showing the configuration of the image correlation determination circuit 23 in the embodiment of the invention according to claim 4. In the figure, 73 is a multiplier for multiplying a coefficient a, 74 is a multiplier for multiplying a coefficient b, 75 and 76 are maximum value circuits, 77 is a multiplier for multiplying a coefficient α, 78 is a multiplier for multiplying a coefficient β, 79 and 80. Is a comparison circuit, 81 is a 2-input O
It is an R circuit. The first horizontal decorrelation energy DH1 and the second horizontal decorrelation energy DH2 in the image correlation determination circuit shown in FIG. 11 are expressed as follows. DH1 = αmax (aDYH2, DYH1) DH2 = βmax (bDYH2, DYH1)

The comparison circuit 79 determines whether the inequality of DCV> DH1 holds, and the comparison circuit 80 determines whether the inequality of DYV> DH2 holds. The two-input OR circuit 81 outputs "1" if either one of the above two inequalities holds, and outputs "0" if neither holds.

In this embodiment, although the circuit scale is slightly larger than that of the first, second and third embodiments, the color signal of the input composite color television signal is changed line by line. It is possible to reduce dot interference even if it is small.

Example 5. FIG. 12 is a block circuit diagram showing an image determination circuit in an embodiment of the invention according to claim 5. In the figure, reference numeral 70 is the same as the continuity determination circuit shown in the third embodiment.

In this embodiment, the output of the 2-input OR circuit 81 shown in the fourth embodiment is applied to the continuity judging circuit 70, and the fourth embodiment is applied to the sample point of interest and a plurality of reference sample points around it. It is determined whether or not the two inequalities shown in are satisfied and the result is output. In this embodiment, although the circuit scale is slightly larger than that in the fourth embodiment, it is possible to more accurately determine the image correlation and remove unnecessary cross color interference.

Example 6. FIG. 13 is a schematic block diagram showing an embodiment of the invention according to claim 6. In the figure, 82
Is a two-line delay circuit. In this embodiment, the one-line delay circuit 20 in the schematic block diagrams of the first to fifth embodiments is replaced with a two-line delay circuit.
According to this embodiment, not only the composite color television signal of the NTSC system but also the composite color television signal of the PAL system exhibits the same effects as those of the first to fifth embodiments.

[0041]

As described above, according to the present invention, the NT
The correlation between the vertical direction image and the horizontal direction image of the composite color television signal of the SC system or the PAL system is detected by the calculation from the line where the sample point of interest exists and the sample values written by a plurality of reference sample points one line before, Since the output signals of the color signal extraction filters with different characteristics are selected and output based on this detection result, the dots that were generated in the vertically uncorrelated area can be generated by a circuit smaller than the conventional one. There is an effect that a luminance signal / color signal separation filter capable of reducing interference can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an NTSC system luminance signal / color signal separation filter according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an example of an image correlation determination circuit in FIG.

FIG. 3 is a block diagram showing an example of a horizontal direction luminance signal decorrelation energy extraction circuit in FIG.

4 is a block diagram showing an example of a vertical direction luminance signal decorrelation energy extraction circuit in FIG.

5 is a block diagram showing an example of a vertical color signal decorrelation energy extraction circuit in FIG.

FIG. 6 is an explanatory diagram showing an array on a screen of a signal sequence in which an NTSC composite color television signal is synchronously sampled at four times the color subcarrier.

FIG. 7 is a block diagram showing an image correlation determination circuit used in the luminance signal / color signal separation filter according to the second embodiment of the present invention.

8 is a block diagram showing an example of a horizontal direction luminance signal decorrelation energy extraction circuit in FIG.

FIG. 9 is a block diagram showing an example of an image correlation determination circuit used in a luminance signal / color signal separation filter according to Embodiment 3 of the present invention.

10 is a block diagram showing an example of a continuity determination circuit in FIG.

FIG. 11 is a block diagram showing an example of an image correlation determination circuit used in a luminance signal / color signal separation filter according to Embodiment 4 of the present invention.

FIG. 12 is a block diagram showing an example of an image correlation determination circuit used in a luminance signal / color signal separation filter according to Embodiment 5 of the present invention.

FIG. 13 is a block diagram showing a PAL system luminance signal / color signal separation filter according to Embodiment 6 of the present invention.

FIG. 14 is a block diagram showing a luminance signal / color signal separation filter in a conventional NTSC system.

[Explanation of symbols]

18 Composite color television signal input terminal, 19 A
/ D converter, 20 1 line delay circuit, 21 horizontal walking color signal extraction filter, 22 horizontal / vertical direction color signal extraction filter, 23 image determination circuit, 24, 25, 26, 2
7 Compensation delay circuit, 28 switch circuit, 29 subtraction circuit, 30 NTSC system color signal output terminal, 31 NTS
C system luminance signal output terminal, 32 horizontal direction luminance signal decorrelation energy extraction circuit, 33 vertical direction luminance signal decorrelation energy extraction circuit, 34 vertical direction color signal decorrelation energy extraction circuit, 35 multiplier for multiplying constant a, 36
Maximum value circuit, 37 Multiplier multiplied by constant α, 38 Comparison circuit, 39 Vertical direction LPF, 40, 41 1 / 2fs
c delay circuit, 42, 43 subtraction circuit, 44, 45 absolute value circuit, 46 maximum value circuit, 47, 48 horizontal direction LP
F, 49 Subtraction circuit, 50 Absolute value circuit, 51, 52
Horizontal BPF, 53 subtraction circuit, 54 addition circuit, 5
5, 56 absolute value circuit, 57 minimum value circuit, 59 horizontal direction luminance signal decorrelation energy extraction circuit, 62 constant b
Multiplier for multiplying 64, maximum value circuit for 66, multiplier for multiplying constant α, 67 1 / fsc delay circuit, 68 subtraction circuit, 69 absolute value circuit, 70 continuous determination circuit, 71 R
Registers, AND circuit with 72 R inputs, 7
3 Multiplier by a constant a, 77 Multiplier by a constant α, 78 Multiplier by a constant β, 79, 80 Comparison circuit, 81 2 input OR circuit, 82 2 line delay circuit.

Claims (6)

[Claims] 1. A means for simultaneously extracting each sampled 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 by one line, The frequency component corresponding to the component of the color subcarrier in the horizontal direction is extracted from the sample value of the sample point of interest and
Horizontal color signal extraction filter for obtaining the color signal of the second color signal, and a second color signal by extracting frequency components corresponding to the components of the color subcarriers in the vertical direction and the horizontal direction from each sample value of the sampling point and the reference sampling point. A horizontal / vertical color signal extraction filter, a switch circuit for selecting the first and second color signals and outputting them as color signals, and a horizontal and vertical direction from each sample value of the sample point of interest and the reference sample point. An image correlation determining unit that detects a directional correlation and outputs a color signal selection signal, and a subtracter that subtracts the color signal selected by the switch circuit from the sample value of the sample point of interest and outputs a luminance signal. The image correlation determining means includes the decorrelation energy DY of the luminance signal in the horizontal direction from the sample values of the target sample point and the reference sample point.
Horizontal direction luminance signal non-correlation energy detecting means for detecting H, and vertical direction luminance non-correlation energy detecting means for detecting non-correlation energy DYV of the vertical direction luminance signal from each sample value of the sample point of interest and the reference sample point. , Vertical direction color signal decorrelation energy detection means for detecting the decorrelation energy DCV of the color signal in the vertical direction from each sample value of the sample point of interest and the reference sample point, and the vertical direction luminance signal decorrelation energy DYV is multiplied by a times. And a maximum value circuit for outputting the larger one of the vertical direction color signal decorrelation energy DCV as the vertical direction decorrelation energy DV, and a value obtained by multiplying the horizontal direction luminance signal decorrelation energy DYH by α. When the inequality of DV> DH is satisfied, the first color Select No., luminance-chrominance signal separation filter, characterized by being configured to select the second color signal when the inequality is not satisfied. 2. The non-correlation energy DYH of the horizontal luminance signal in the image correlation determining means is extracted by the first horizontal luminance signal non-correlation energy extracting means from each sample value of the sample point of interest and the reference sample point. The second horizontal direction luminance signal non-correlation energy extraction means from the first horizontal direction luminance signal non-correlation energy DYH1 and the sample values of the sample point of interest and the reference sample point. 2. The luminance signal chrominance signal separation filter according to claim 1, wherein the larger one of the luminance signal decorrelation energy DYH2 multiplied by b and the larger one is used. 3. The image correlation determining means outputs an output of a comparison circuit for comparing the vertical decorrelation energy DV and the horizontal decorrelation energy DH, and the inequality of DV> DH is a plurality of the target sample point and its surroundings. When the reference sample point (R pixel) is satisfied, the first color signal is selected,
A continuity determining circuit is provided so as to select the second color signal when the inequality is not satisfied.
Alternatively, the luminance signal / color signal separation filter according to claim 2. 4. A horizontal luminance signal non-correlation energy extraction means for detecting the first correlation signal non-correlation energy DYH1 of the horizontal luminance signal from each sample value of the sample point of interest and the reference sample point, Horizontal luminance signal decorrelation energy extraction means for detecting the decorrelation energy DYH2 of the second horizontal luminance signal from each sampled value of the sample point of interest and reference sample point, and each of the sample point of interest and the reference sample point Vertical luminance signal non-correlation energy detecting means for detecting the non-correlation energy DYV of the luminance signal in the vertical direction from the sample value, and non-correlation energy DCV of the color signal in the vertical direction from each sample value of the sample point of interest and the reference sample point. For detecting the vertical color signal decorrelation energy, the first horizontal luminance signal decorrelation energy DYH1, and the second horizontal brightness. A first maximum value circuit that takes a larger one of the frequency signal decorrelation energy DYH2 multiplied by a, and
The first horizontal luminance signal decorrelation energy DYH1
And the second horizontal luminance signal decorrelation energy DY
A second maximum value circuit that takes the larger of H2 and b, and a value obtained by multiplying the output of the first maximum value circuit by α.
The output of the first comparison circuit for comparing the vertical color signal decorrelation energy DCV and the output of the second maximum value circuit is β
And a second comparison circuit for comparing the vertical direction luminance signal decorrelation energy DYV with each other. The result of the first comparison circuit is DCV> αmax (DYH
1, aDYH2), or the result of the second comparison circuit is DYV> βmax.
The first color signal is selected when the second inequality (DYH1, bDYH2) is satisfied, and the second color signal is selected when neither of the first and second inequalities holds. The luminance signal / color signal separation filter according to claim 1, wherein 5. The image correlation determining means determines whether the result of the first comparison circuit is the first inequality of DCV> αmax (DYH1, aDYH2) or the result of the second comparison circuit is
Second DYV> βmax (DYH1, bDYH2)
The following inequality is satisfied at the sample point of interest and a plurality of reference sample points (R pixels) around the sample point of interest, and a continuous determination circuit that selects the first color signal, and otherwise selects the second color signal is provided. 5. The luminance signal / color signal separation filter according to claim 4. 6. The means for simultaneously extracting the sampled values of the sample point of interest and a plurality of reference sample points around the sampled sample point delays the composite video signal sampled at a frequency synchronized with the horizontal scanning frequency by two lines. The luminance signal / color signal separation filter according to any one of claims 1 to 5, which is configured.