JPS61186095A - Adaptive type luminance signal and chrominance signal separation filter - Google Patents

Abstract

PURPOSE:To prevent cross color disturbance and dot disturbance by using a comb-line filter for a region where signal change is slow and using a filter having a slow signal change in horizontal and vertical direction filters where a signal change is steep to separate a luminance signal and a chrominance signal. CONSTITUTION:A composite video signal sampled by a frequency four times that of a chrominance subcarrier is inputted to delay circuits 102-104, four sample serial signals adjacent vertically and horizontally to a sampling point are obtained, and the output of the circuits is fed to a comparator circuit 106, the vertical direction filter 107 and the horizontal direction filter 108. The horizontal and vertical signal change is operated by the circuit 106 and a control signal is fed to a selector 113. When the vertical and horizontal change in the picture are small, the selector 113 outputs an output of a band pass filter 111 to a signal line 116 and when the horizontal or vertical picture change is rapid, an output of the filters 107, 108 is outputted to the signal line 116.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an adaptive luminance signal and chrominance signal separation filter, and in particular, for example, in a television receiver etc., the luminance signal component and the chrominance signal component are digitally separated from a composite video signal. The present invention relates to an adaptive luminance signal and chrominance signal separation filter for extracting luminance and chrominance signals.

[Prior Art] FIG. 6 is a schematic block diagram showing an example of a conventional luminance signal/chrominance signal separation filter. In the figure, this conventional luminance signal color signal separation filter includes variable line delay circuits 701 and 702 whose delay time is variable, and a filter for extracting frequency components corresponding to color subcarrier components from a signal sequence in the vertical direction of the screen. vertical filter 703 and vertical filter 7
03, a compensation delay circuit 705 to compensate for the delay in the bandpass filter 704, and a luminance signal by subtracting the output of the bandpass filter 704 from the output of the delay circuit 705. and a subtractor 706 for extraction. In addition, the signal 510
1 is supplied with a composite video signal sampled in synchronization with the horizontal scanning frequency. The separated luminance signal components are output to the signal line 115. The separated color signal components are output to the signal line 116.

Next, the operation of the conventional circuit shown in FIG. 6 will be explained. The digital video signal supplied as signal 11101 is input to the variable line delay circuit 701 and to the vertical filter 7.
03, respectively. The output signal of the variable line delay circuit 701 is supplied to the second input of the vertical filter 703 and
02 further delays the vertical filter 703.
is supplied to the third input of the . Now, the signal value series of the video signal supplied to the signal 1a101 is expressed as f(nT) (n-0, 1,
2,...). If L is one horizontal scanning period and the delay time of the variable line delay circuits 701 and 702 is ml, then the signal value series supplied to the second and third inputs of the vertical filter 703 are respectively f (nT -n+L),
f (nT-2m L). Vertical filter 7
03 performs the operation shown by the following equation on the above input.

m l-) + f (nT-211>) The variable line delay circuits 701 and 702 switch the delay time depending on whether the video signal is the NTSC system or the PAL system, and are m-1 in the case of the NTSC system and m-2 in the case of the PAL system. shall be. Therefore, the operation performed by the vertical filter 703 is
SC system% formula%)) In the case of PAL system, it becomes 2L)+f (n T-41)). In the NTSC system, the phase of the color subcarrier is reversed every scanning line, so in the above equation, f(nT) and f(
nT-21) are in phase, and f(nT> and f(nT-L) are in opposite phase (equal magnitude and opposite sign). Therefore, if there is no color change in the vertical direction, the color subcarrier is It passes through the vertical filter 703 as it is.On the other hand, the luminance signal is sent as is without modulating the carrier wave, so
If there is no change in brightness in the vertical direction, f(nT) + f(nT
-21> and -2f(nT-L) cancel each other out, and the luminance signal does not pass through the vertical filter 703. That is, the vertical filter 703 is a bandpass filter that extracts vertical high frequency components including color signal components. In the case of the PAL system, a similar argument can be made if it is noted that the phase of the color subcarrier is inverted every two scanning lines.

In the output of the vertical filter 703, a luminance signal component is slightly added to the color signal component. This luminance signal component is
The vertical frequency is high, but the horizontal frequency is generally low. The bandpass filter 704 is for removing this luminance signal component, and can be configured as a filter having the following transfer function, for example.

H(Z)-Ikko (1-Z-2>2 (1+Z-仝)2z (1+Z-9) However, Z-1 represents a delay of one sampling period.

The bandpass filter 704 can completely block the luminance signal component if there is no change in luminance or color in the horizontal direction. The output of bandpass filter 704 is taken from signal l1116 as the color signal component and is also provided to a first input of subtractor 706. The second . For input,
A video signal compensated for the delay time in the process of extracting the color signal component is provided, and a subtracter 706 subtracts the color signal component from this video signal and provides the result as signal [115]. Therefore, the nth signal component is extracted from the signal 11115. A luminance signal/chrominance signal separation filter having such a configuration is usually called a comb filter.

[Problems to be solved by the invention] As described above, the conventional luminance signal color signal separation filter has the following problems:
Fix the characteristics of the vertical filter and horizontal filter,
It is based on the assumption that pixels that are a sample value sequence of a video signal that are adjacent on the screen are similar. Therefore, in areas where the brightness and color of the image change rapidly, the brightness signal and color signal leak into each other's channels, resulting in color turbidity due to cross color, dot interference, and deterioration of the image quality during playback. There was a problem.

This invention was made to solve the above-mentioned problems, and provides a luminance signal and chrominance signal separation filter that can achieve accurate separation of luminance signals and chrominance signals even in the case of rapid signal changes in television images. The purpose is to

[Means for solving the problem] The adaptive luminance signal/chrominance signal separation filter according to the present invention has the following features:
It is equipped with a plurality of filters having different characteristics, detects waveform attributes of a composite video signal in a small area, and selects an optimal filter according to the detection result.

[Effect]

In this invention, in areas where signal changes are gradual, a conventional comb filter is used to separate luminance signals and color signals,
In a region where the signal changes rapidly, a filter in which the signal changes are relatively similar is selected from among the horizontal filter and the vertical filter to separate the signals by fT.

[Practical example] FIG. 1 is a schematic block diagram showing an adaptive luminance signal/chrominance signal separation filter according to an embodiment of the present invention.

As shown in the figure, this adaptive luminance signal/chrominance signal separation filter includes delay circuits 102 to 105, 109, 110 and 1.
12, a comparison circuit 106, a vertical filter 107, a horizontal filter 108, a bandpass filter 111,
It includes a selector 113, a subtracter 114, and a plurality of signal lines connecting these elements. Here, the signal line 101
is supplied with a digital composite video signal sampled at a frequency four times that of the color printing WJ transmission wave. Delay circuit 10
2 and 105 are delay circuits that can manually change the delay time, for example, and when the video signal is in the NTSC format, 908 sampling periods 11t (1 horizontal scanning period - 2 sampling periods), and in the case of PAL format, 2268 sampling periods ( A delay time of 2 horizontal scanning periods - 2 sampling periods) is provided. Delay circuits 103 and 104 have a delay time of two sampling periods. Based on the digital composite video signal supplied from the signal 11101, the output of the delay circuit 102, the output of the delay circuit 104, and the output of the delay circuit 105, the comparison circuit 1o6
This circuit calculates horizontal signal changes and vertical signal changes and generates control signals. The vertical filter 107 is a circuit for extracting high frequency components from signal values of sample points arranged in the vertical direction of the screen. The horizontal filter 108 is a circuit for extracting high frequency components from signal values of sample points arranged in the horizontal direction of the screen. The bandpass filter 111 is a circuit for further extracting horizontal high frequency components from the output of the vertical filter 107. Delay circuits 110 and 112 are circuits for compensating for delay time caused by bandpass filter 111. The selector 113 connects the outputs of the delay circuits 110 and 112 and the bandpass filter 11.
This circuit takes the output of the comparator circuit 106 as an input and switches the output according to a control signal from the comparator circuit 106. Delay circuit 1
09 is a circuit for compensating for signal propagation delay caused by the color signal extraction filter made up of the above elements. The subtracter 114 is a circuit for calculating a luminance signal component by inputting the digital value of the composite video signal output from the delay circuit 109 and the digital value of the color signal component output from the selector 113. A signal line 115 is a signal line for outputting separated luminance signal components. The signal line 116 is a signal line for outputting separated color signal components.

FIG. 2 is a block diagram showing details of comparison circuit 106 shown in FIG. 1. As shown in the figure (this comparison circuit 106 is
Subtractors 301 to 305 and absolute value circuits 306 and 30
7, a NOR circuit 308, and signal lines for connecting these elements.

The signal line 201 is a signal line for inputting the video signal supplied as the signal F1101 shown in FIG. 1 as it is. Signal lines 202, 204 and 205 are signal lines for supplying the outputs of delay circuits 102, 104 and 105 shown in FIG. 1, respectively. Subtraction! 1301 is signal 11
This is a circuit for calculating the difference between the signal values on 201 and 205. Subtractor 302 is a circuit for taking the difference between the signal values on signals 11202 and 204. Absolute value circuit 306
and 307 are subtracters 301 and 302, respectively.
This is a circuit that is connected to the circuit and takes the absolute value of the signal. The subtracter 304 is a circuit for taking the difference between the outputs of the absolute value circuits 306t3 and 307 and outputting only the sign bit.

The subtracters 303 and 305 are respectively connected to the absolute value circuit 3.
This circuit takes the difference between 06 and 307 and a constant given from the outside and outputs only the sign bit. N
The OR circuit 308 is a circuit that receives the signals output from the subtracters 303 and 305 and performs a predetermined logical judgment. A signal 11209 is a signal line for outputting a control signal.

FIG. 3 is a block diagram showing details of the vertical filter 107 shown in FIG. 1. As shown in the figure, this vertical filter 107 includes coefficient circuits 401 to 403 and an adder 4.
04 and signal lines for connecting these elements. Signal line 203 is a signal line for supplying the output of delay circuit 103 shown in FIG. Coefficient circuits 401 and 4
02 are circuits for multiplying the signal values on the signals WA201 and WA205 by 11/4. Coefficient circuit 40
3 is a circuit for multiplying the signal value on the signal line 203 by 1/2. Addition circuit 404 is a circuit for calculating the sum of outputs of coefficient circuits 401 to 403.

A signal 1206 is a signal line for outputting the calculation result of the adder 404.

FIG. 4 is a block diagram showing details of the horizontal filter 108 shown in FIG. 1. As illustrated, the horizontal filter 108 includes coefficient circuits 501 to 503, an adder circuit 504, and a signal line for connecting these elements. Coefficient circuits 501 and 502 each receive signal 6
This is a circuit for multiplying the signal values on 202 and 204 by 1/4. The coefficient circuit 503 is a circuit for multiplying the signal value on the signal $11203 by 1/2. Addition circuit 504
is a circuit for calculating the sum of the outputs of coefficient circuits 501 to 503. A signal [1207 is a signal line for outputting the calculation result of the adder 504.

FIG. 5 is a block diagram showing details of the bandpass filter 111 shown in FIG. 1. As shown, this bandpass filter 1
11 are delay circuits 601 and 602 and a coefficient circuit 60
3 to 605, an adder circuit 606, and signal lines for connecting these elements. Delay circuits 601 and 60
2 is a delay circuit whose delay time is selected to be two sampling periods. 603 and 604 respectively represent the signal 52
06 and the signal value at the output of the delay circuit 602 to 1
This is a circuit for multiplying by /4. A coefficient circuit 605 is a circuit for multiplying the output of the delay circuit 601 by 1/plan. Addition circuit 606 is a circuit for calculating the sum of the outputs of coefficient circuits 603-605.

A signal line 208 is a signal line for outputting the addition result of the addition circuit 606.

Next, the operation of the embodiment shown in FIGS. 1 to 5 will be explained. The composite video signal sampled at four times the frequency of the color II carrier wave is successively delayed by delay circuits 102 to 105, and these delay circuits change the sample value of the video signal at a certain sampling point and the corresponding value on the screen. The sample values of the video signal at a total of four adjacent sample points adjacent to the top, bottom, left, and right of the sample point are extracted. That is, one sampling period is T, one horizontal scanning period is L, and the sample value series supplied to the signal line 101 is t(n T).
(n -0,1,2,・'), and the delay time in delay circuits 102 and 105 is l@L-2T (NTS
If it is wh-1 in the C system and -2 in the PAL system, then the sample value series output from the delay circuit 102 and supplied to the signal line 202 is f (nT-m L+2T), which is output from the i-delay circuit 103. The sample value series outputted from the delay circuit 104 and supplied to the signal line 203 is f(nT-1m), and the sample value series outputted from the delay circuit 104 and supplied to the signal line 204 is f (T-L-27). The sample value series output from the circuit 105 and supplied to the signal line 205 is f (nT-211L). f (
If nT-+gL) is the sample value at a central sample point, then f (n T), f (n T-
211) are the sample a(D+j combination values adjacent to the bottom and top of the screen, respectively, and f (n T −r
a L+2T) and f (n T-t L-2T) are the sample values of the sample points adjacent to the left and on the left, respectively. These sample value series are passed through a comparator circuit 106 and a vertical filter 107 . A horizontal filter 108 is provided.

Next, the operation of comparison circuit 106 will be described.

The signal value series f(nT) and f(nT-2mL) supplied to the signals [201 and 205 are supplied to two inputs of the subtracter 301, and after subtracting one from the other, the absolute value circuit 306 calculates the Absolute value is taken. Therefore, the signal value at the output of the absolute value circuit 306 is as follows.

Dv-If (nT)-f (nT-2m L)l
In the case of the NTSC system, Dv -l is ta-1.
f (n T) - f (n T-21) 1PA
In the case of the L method, as ra −2, Dv −l f
(nT)-f(nT-4L)1. N.T.
In the SC method, the phase of the color subcarrier is inverted for each scanning line, so if there is no change in color or brightness in the vertical direction, f(nT) and f (nT-21) in the above equation are equal. That is, Dv -0.

Furthermore, in the PAL system, the phase of the color subcarrier is inverted every two scanning lines, so similarly, when there is no change in color or brightness in the vertical direction, Dv-0 occurs. That is, in both the NTSC system and the PAL system, [)v is an index representing a change in the image in the vertical direction. On the other hand, signal 1120
2 and 204, the signal value series f (n T
-i L+27) and f (n T -g+ L-
2T) C is input to the subtracter 302, and a difference signal is output. Since the absolute value circuit 307 calculates the absolute value of this difference signal, its output is expressed by the following formula. Since the sampling frequency is four times that of the color subcarrier, the phases of the color subcarriers are equal to each other. Therefore, if there is no change in brightness and color in the horizontal direction, f (n T-m L4-2
T) -f (n T-m L-27), [)
h becomes O. That is, oh is one index representing a change in the image in the horizontal direction. The signal value sequences appearing at DV and Qh are then passed through subtractors 303 and 304 and 30, respectively.
5 and 304, and the other input of subtracters 303 and 305 is given a constant K from the outside. The subtracter 303 calculates KV-K and outputs only its code pit, so when KV≧, 1. When KV<K, 0 is output. Similarly, the subtracter 305 performs 1 when Kh≧. Kh<
Outputs O when K. These outputs are sent to the NOR circuit 30
8, its output becomes 1 when KV<K and Kh<H, and becomes O otherwise. That is, it is 1 if there is no large signal change in either the horizontal or vertical direction of the image, and O if there is a large signal change in at least one direction. This signal is supplied to signal 111209 as one of the control signals. On the other hand, the subtractor 304
calculates Kv-Kh, outputs 1 if the result is 0 or more, and outputs O if the result is negative. That is, the output of the subtractor 304 is 1 when the signal difference in the vertical direction of the image is greater than or equal to the signal difference in the horizontal direction, and is 0 otherwise. This signal is supplied to signal 11!209 as another one of the control signals.

Next, the operation of the vertical filter 107 will be explained. In FIG. 3, sample value sequences zn'r>, f(nT-ta>, f(nT-2ml)) supplied to signal lines 201, 203.205 are input to coefficient circuits 401, 403.205, respectively. 402, -1/4 times, 1
The signal is multiplied by /2 and -1/4 and supplied to three inputs of the adder 404. Since the adder 404 adds all these input signals, the signal value series at its output is as follows.

(n T-2+w L) ) As mentioned above, r<nT> and f (+'l T-2
11), the phases of the color subcarriers are equal and f(nT-mL)
It is reversed. Therefore, if there is no change in brightness or color in the vertical direction of the screen, the brightness signal component in the above equation is completely canceled and only the color printing carrier wave remains. When the brightness and color changes in the vertical direction become large, the brightness component leaks into the color components, resulting in loss color.

The output of vertical filter 107 is supplied to delay circuit 110 and comb-band filter 111. bandpass filter 11
5 showing a detailed block diagram of signal line 2
If the signal value series supplied to 06 is set as f = (n T), the signal value series after being delayed by f - (rl T) or two sampling periods by the delay circuit 601 is f = (n
T-2T>.

This signal value series is further delayed by two Zumbling periods by the delay circuit 602, resulting in f=(nT-47). These signal value series are multiplied by -1/4 by coefficient circuits 603, 605, and 604, respectively.

The signal is multiplied by 1/2 and -1/4 and supplied to an adder 606. Adder 606 adds all these inputs and the output is:

+f = <nT-4T)) As mentioned above, r-(n]-) and f-(n-r-4
In T), the color subcarriers are in phase, and in f-(n'-27), the color subcarriers are out of phase. Therefore, the bandpass filter 11
1 allows color subcarrier components to pass and blocks low frequency luminance components. That is, the bandpass filter 111 has f =
It has the effect of reducing the luminance signal component leaking to (nT).

However, if the brightness and color change in the horizontal direction, cross color will occur.

The output of bandpass filter 11'1 is then fed to a first input of selector 113. The delay circuit 110 is for compensating for the delay time of the signal in the bandpass filter 111, and has the function of adjusting the delay times of the signal that has passed through the bandpass filter and the signal that has not passed the bandpass filter so that they match at the input of the selector 113.

The output of this delay circuit is supplied to the second input of selector 113.

Horizontal filter 108 performs the same calculation as bandpass filter 111. In Figure 4, signal lines 202 and 203
, 204, the signal value series f (n T-I
L+2T), f(n T-IL), f(n
T-1111-27) GE, Tsuretsure, coefficient circuit 5
01.503.502 -1/4.1/2゜-1/
The signal line 207 is multiplied by 4 and added by an adder 504.
The signal value series output to is as follows.

m L)+f (n T-m L-27)) Similar to the bandpass filters 1 and 11, this horizontal filter 108 is a filter that passes the color subcarrier component and blocks the i degree component. However, if there is no change in the image in the horizontal direction, these separations can be performed perfectly, but if not, the separation will be incomplete. The output of the horizontal filter 108 is supplied to the third input of the selector 113 via a delay circuit 112 for timing adjustment.

The selector 113 switches the above three inputs according to a control signal from the comparison circuit 106. That is, when the change in the image is small in both the horizontal and vertical directions and KV<K and Kh<K, the output of the bandpass filter 111 is supplied to the signal [1116. This is because when the change in the image is small, the cross color generated by the vertical filter 107 and the bandpass filter 111 is considered to be small. In addition, if there is a sudden change in the image in the horizontal direction (for example, a boundary between colors in a color par) and Kh kK, Kh≧KV, using the horizontal filter 108 and the band filter 111 will increase the cross color. , the output of the vertical filter 107 via the delay circuit 110 is supplied to the signal line 116. In addition, there are abrupt changes in the image in the vertical direction,
When KV≧ and KV >Kh, the cross color in the vertical filter 107 is significant, so the delay circuit 1
12 to the output of the horizontal filter 108 to the signal line 1
16. In this way, color signal components without cross colors are always output to the signal line 116. This color signal component is subtracted from the composite video signal by a subtracter 114 to calculate a luminance signal component. The luminance signal component is taken out from the signal line 115 as a digital signal. The delay circuit 109 is for compensating for a delay in signal propagation that occurs during the process of extracting the color signal component, and serves to match the timing of the composite video signal and the color signal component at the input of the subtracter 114.

In addition, in the description so far, the change in the image is gradual and the KV
In the region of <K and Kh<K, the vertical filter 107
There are sufficiently few cross colors in both the horizontal filter 108 and the bandpass filter 111, and the reason for the existence of the bandpass filter 111 is ambiguous; A conventional comb filter is required. That is, as an example, consider a case where there is a horizontal striped pattern on the screen in which white and black are reversed for each scanning line. If the central sample point is on the black scanning line, the left and right adjacent sample points are also black, and the upper and lower adjacent sample points are white. In this case KV,
! :Kh are both O. Therefore, if bandpass filter 111 is not present, the output of either vertical filter 107 or horizontal filter 108 must be selected. In this case, it would be correct to select the horizontal filter 108, but it would be a mistake to select the vertical filter 107. Since an actual video signal contains noise components, a horizontal filter or a vertical filter is selected for each pixel. As a result, on the screen, horizontal lines appear broken or dots appear to flicker. This also applies when there is a vertical striped pattern on the screen in which white and black are reversed for each pixel.

Also, consider a case where the horizontal striped pattern is slightly tilted. At this time, it is assumed that the vertical signal value still repeats the same value every two scanning lines, and the horizontal signal value changes gradually from white through gray to black and then through gray back to white. In this case, the vertical signal difference KV is 0, whereas the horizontal signal difference Kh is generally a small positive number that is not O. Therefore, a vertical filter is selected and what is actually a luminance signal component is recognized as a color signal component. A conventional comb filter is installed,
) (v, ) (When h are both small, the above problem can be considerably improved by selecting this comb filter. In other words, in the former case, the luminance signal component is shifted somewhat toward the chrominance signal side. Although the resolution deteriorates due to the leakage, line breaks and flickering are eliminated, and in the latter case, the leakage of the luminance signal to the chrominance signal side can be reduced by almost half.

In the embodiments described above, the vertical filter, the horizontal filter, and the bandpass filter are composed of second-order digital filters, but a steep filter may be constructed by increasing the number of orders.

In addition, in the above embodiment, the composite video signal is sampled at a frequency four times as high as the color subcarrier synchronized with the horizontal frequency, but if the sample points are arranged in a grid on the screen, Sampling is not limited to four times the color subcarrier, but may be performed at other frequencies.

In addition, in the above embodiment, sample points adjacent to the top, bottom, left and right of a certain sample point are used as vertical sample points and horizontal sample points, but the present invention is not limited to this. A sample point at a distance from the sample point may be used as a vertical sample point or a horizontal sample point. In addition, in the above embodiment, one sample point on the top and bottom is used as the vertical sample point, and one sample point on the left and right is used as the horizontal sample point. For example, a plurality of sample points on the top and bottom may be used, and a plurality of sample points on the left and right may be used as horizontal sample points. Note that it is preferable in terms of circuit configuration that the phases of the 11 color carrier waves of the upper and lower sample points are in the same phase, and it is also preferable in terms of the circuit structure that the phases of the color subcarriers of the left and right sample points are similarly in phase.

[Effects of the Invention] As described above, according to the present invention, in a region where an image changes sharply, the vertical and horizontal waveforms of the composite video signal are changed using a signal value series in a direction in which they change more gradually. Since the luminance signal and the chrominance signal are separated, an accurate luminance signal/chrominance signal separation filter without cross color interference or dot interference can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing an adaptive luminance signal/chrominance signal separation filter according to an embodiment of the present invention. FIG. 2 is a block diagram showing details of comparison circuit 106 shown in FIG. 1. FIG. 3 is a block diagram showing details of the vertical filter 107 shown in FIG. 1. FIG. 4 is a detailed diagram of the horizontal filter 108 shown in FIG. 1. FIG. 5 is a block diagram showing details of the bandpass filter 111 shown in FIG. 1. FIG. 6 is a block diagram showing a conventional luminance signal chrominance signal separation filter. In the figure, 101, 105, 116.201-209
are signal lines, 102-105, 109.110, 112
, 601, 602, 701, 702° 705 is a delay circuit, 106 is a comparison circuit, 107° 103 is a vertical filter, 108 is a horizontal filter, 111.704 is a bandpass filter, 113 is a selector, 114, 301-305
, 706 is a subtracter, 306.307 is an absolute value circuit, 30
8 is a NOR circuit, 401~403.501~503°6
03 to 605 are coefficient circuits, and 404, 504, and 606 are adders. Agent Masuo Oiwa Figure 3 Figure 4 Figure 5 Figure 6 Procedural amendment (voluntary) Date of May 1982

Claims (7)

[Claims] (1) Input a composite video signal sampled at a predetermined frequency synchronized with the horizontal scanning frequency so that each sample point is arranged in a grid on the screen, and digitally extract the luminance signal component from the composite video signal. An adaptive luminance signal separation filter that separates a color signal component from a color signal component, and by delaying the composite video signal, a sample value at a certain sample point and a horizontal line on the screen centered on the sample point are separated. The sample values at the first and second sample points located on the left and right sides of the direction and the sample values at the third and fourth sample points located vertically above and below the certain sample point on the screen are simultaneously calculated. the first and second sample points are on the same scanning line as the certain sample point, and the phases of their color subcarriers are selected to be in phase; The third and fourth sample points are selected so that the phases of their color subcarriers are in phase with each other, and the sample value at the certain sample point and the first and second sample points are selected to be in phase with each other.
a horizontal direction filter that receives as input a sample value at a certain sample point and extracts and outputs a frequency component corresponding to a color subcarrier component from a signal sequence in the horizontal direction of the screen; 3rd and 4th
A vertical filter that takes as input the sample value at the sampling point of and extracts and outputs a frequency component corresponding to a color subcarrier component from a signal sequence in the vertical direction of the screen; a bandpass filter for extracting a frequency component corresponding to a horizontal component of the first and second sampling points; horizontal difference absolute value detection means for determining the absolute value of the difference between the sample values at the first and second sample points, that is, the horizontal difference absolute value; and vertical difference absolute value detection means for determining the absolute value of the difference between the sample values at a fourth sampling point, that is, the vertical difference absolute value, the horizontal difference absolute value and the vertical difference absolute value are set in advance. control signal generating means for generating a control signal based on a constant K, the output of the vertical filter, the output of the horizontal filter, and the output of the bandpass filter being input; A selector that switches input and output connections in response to control signals and outputs them as color signal components;
and a subtraction circuit that subtracts the output of the selector from the composite video signal to output a luminance signal component, the selector comprising:
Upon receiving a control signal from the control signal generating means, when the horizontal difference absolute value is smaller than the vertical difference absolute value and the vertical difference absolute value is larger than the constant K, the output of the horizontal filter is colored. output as a signal component, and output the output of the vertical filter as a color signal component when the absolute value of the vertical difference is less than the absolute value of the horizontal difference and the absolute value of the horizontal difference is greater than the constant K;
An adaptive luminance signal/chrominance signal separation filter, characterized in that when both the horizontal direction absolute difference value and the vertical direction difference absolute value are within the constant K, the output of the bandpass filter is output as a color signal component. (2) The adaptive luminance signal/chrominance signal separation filter according to claim 1, wherein one each of the first and second sample points is selected. (3) The first and second sample points are selected as sample points adjacent to the certain sample point.
Adaptive luminance signal chrominance signal separation filter described in . (4) The adaptive luminance signal/chrominance signal separation filter according to claim 1, wherein a plurality of each of the first and second sample points are selected. (5) The adaptive luminance signal/color signal separation filter according to claim 1, wherein one each of the third and fourth sample points is selected. (6) The adaptive luminance signal/chrominance signal separation filter according to claim 5, wherein the third and fourth sample points are sample points adjacent to the certain sample point. (7) The adaptive luminance signal/chrominance signal separation filter according to claim 1, wherein a plurality of the third and fourth sample points are each selected.