JPS63221793A - Adaptive luminance signal and chrominance signal separation filter - Google Patents

Abstract

PURPOSE:To attain YC separation high in resolution and less in cross color generation by using a horizontal/vertical/time direction selection type filters based on the quantity of correlation in the horizontal/vertical/timewise directions of a picture. CONSTITUTION:When a NTSC signal converted into a digital signal is inputted to a horizontal/vertical/timewise direction selection type filter 23, first horizontal noncorrelation energy, vertical noncorrelation energy and a timewise direction difference absolute value are calculated from a noted sampling point and adjacent sampling points in the horizontal/vertical/timewise direction. Then the figures are compared respectively with a horizontal threshold constant, vertical threshold constant and timewise threshold constant respectively. Thus, one of the horizontal filter, the vertical filter, horizontal/vertical both direction filter and the timewise filter is selected, based on the result of comparison and its output is outputted from the filter 23 as 1st signal component.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an NTSC color television signal (
This relates to a YC separation filter for extracting a luminance signal (hereinafter referred to as "Y signal") or a color signal (hereinafter referred to as "C signal") from an NTSC signal in an analog NTSC signal (hereinafter referred to as "rNTsc signal"). A
After /D conversion, YC separation is performed digitally.

[Prior art] First, when an analog NTSC signal is digitized,
The signal sequence S (i, J) with the screen as a two-dimensional plane
(i = 1, 2.3-・, m, J = 1゜2 + 3+ ”
" + n) is shown in FIG. 12 (however, i.

(j indicates the array numbers of the sampling points in the horizontal direction and vertical direction, respectively), and the sampling frequency fs at this time is usually selected to be four times the color layer lit transmission frequency fsc.

In FIG. 12, Y of the sample point signal S (i, j)
The following relationship exists between the signal and the C signal.

S (i, j) = Y (i, D + C(i
, j) Furthermore, in a normal television signal, there is a strong correlation between adjacent sample points in the horizontal and vertical directions within one field. Furthermore, in the NTSC system, the phase of the C signal is inverted line by line and every two sample points, as shown in FIG. YC separation can be performed digitally by utilizing these characteristics.

Furthermore, as indicated by the corresponding symbols in FIGS. 12 and 13, the sample point C(i,
j), 4 points before and after the 2 sample points and 4 points above and below the 1 line.
Since the color subcarrier phases differ by 180° at two points, YC separation can be performed by adaptively switching digital filters within one field.

FIG. 14 is a block circuit diagram showing the configuration of a conventional adaptive YC separation filter disclosed in, for example, Japanese Unexamined Patent Publication No. 58-242367.
an A/D converter that digitizes the SC signal (101);
(2) is a horizontal/vertical direction selective filter that removes the Y signal component from the output (102) of this A/D converter (1);
(3) is a delay element for compensating the delay in this horizontal/vertical direction selective filter (2), (0 is the output C signal (104) of the horizontal/vertical direction selective filter (2) and the delay element (3) ) and the output (105) of Y signal (
10B).

In Figure 15, which shows the configuration of the horizontal/vertical direction selective filter (2), (5) is the input signal (102).
An IHN delayer that delays by one line.

(8) delays the input signal (102) by two sample points.
D delay device (7) is the output (103) of IH delay device (5)
(8) is an IH that delays the output (111) of the 2D delay device (7) by one line.
7 delayer, (9) is a 2D delayer that delays the output (111) of 2D delayer (7) by 2 sample points, (lO) is the output (110) of 2D delayer (6) and IH delayer ( 8) Output (
112), and (11) is a 2D delay device (
8) output (110) to the IH delay device (8) output (1
(12) is a 2D delay device (9)
from the output (113) of the IH delay device (5) to the output (103) of the IH delay device (5).
), (13) is an adder that adds the output (113) of the 2D delay device (8) and the output (103) of the IH delay device (5), (14) is the adder (10) The output (1
Multiplier that multiplies 15) by %, (15) is a subtractor (11)
Absolute value circuit that takes the absolute value of the output (121) of (16)
is a multiplier that multiplies the output (111) of the 2D delay device (7), (17) is an absolute value circuit that takes the absolute value of the output (122) of the subtracter (12), and (18) is an adder (13). ) is a multiplier that multiplies the output (tie) by the station, (18) is a multiplier (1
B) output (114) to the output (11) of the multiplier (14)
7), (20) is a subtracter that subtracts the output (118) of the multiplier (18) from the output (114) of the multiplier (18), (21) is the absolute value circuit (15), (
A judgment circuit compares the outputs (123) and (124) of the judgment circuit (17), and the judgment circuit (22) determines whether the output (119) of the subtracter (18) or the subtracter (20) depends on the output (125) of the judgment circuit (21).
) output (120).

Next, the operation will be explained.

The digital signal sequence S (i, j) (102) digitized by the A/D converter (1) is first filtered by the horizontal/vertical direction selective filter (2). The operation of this horizontal/vertical direction selective filter will be explained with reference to FIG. Digital signal sequence S (i,
j) Attention sample point C(i
, j) (104) is indicated by the [stock] mark in FIG. In order to find the value of C(i, j), we set the position one line above and below the current position (O in the figure).
) sample value S (i, j+1).

S (i, j-1) and sample values S (i+2.j) at positions two sample points apart on the left and right (marked Δ in the figure).

Using the four sample values of S (i-2, j), the difference numerators v and TH of the video signals in the vertical and horizontal directions are calculated.

Tv = S (i, j+t) −s (i, j
-1)T)l =S (i+2.j)-s (i
−2,j) and these signals Tv (121)
, TH (122) is.

The absolute values l Tv l (123) and l THl are determined by the absolute value circuits (15) and (17), respectively.
(124).

Next, these absolute values ITv 1 (123), I
Ts 1 (124) is input to the determination circuit (21),
The judgment circuit (21) selects the switch (22) according to the following conditions.
) by switching the subtracters (19), (20)
Select the output signals (119) and (120) of C
For the signal (100), that is, for S (i, j), the sample values S (i, j + 1), S (i, j - 1) at the phase inversion sample positions of the neighboring C signals in the vertical and horizontal directions.

Using S (i+2.j) and S (i-2, j), find the absolute difference value in the vertical direction and the absolute value in the horizontal direction of the video signal, and calculate the two sample values in the direction where these values are smaller. The following filter calculation is performed using the filter, and adaptive control is performed to remove low frequency components of the video signal.

)16(i,j)--! S(i,j-1)+! S(i,
j)-! S (i, j+1) Therefore, this horizontal Φ vertical direction selection type filter performs calculation using the sample value in the vertical direction when the switch (22) is connected to the ■ side terminal, and
When connected to the side terminal, calculations are performed using horizontal sample values.

As a result, the low frequency components of the vertical or horizontal video signal at the sample position S (i, D are removed,
The HC signal (119) or VcC signal 120) is immediately obtained as the C signal (100).The Y signal (toe) at this time is the output signal (105) of the delay element (3) in FIG. (104) is calculated by the following equation.

Y (i, j) = S (i, J) −〇 (
i, j) Figure 16 shows the passbands of the Y signal and C signal when using the conventional adaptive YC separation filter shown above. On the frequency axis, fl is the vertical spatial frequency, the area marked with horizontal lines is the passband for the Y signal, and the rest is the passband for the C signal.

[Problems to be Solved by the Invention] Since the conventional adaptive YC separation filter is configured as described above, as shown in FIG. 6, the horizontal and vertical frequencies are respectively fsc/2. A Y signal with an oblique component of fj/4 (ft is a vertical spatial frequency) or more is blocked, and a Y signal with a horizontal component having a horizontal frequency near fsc is blocked if there is even a slight vertical component. On the other hand, the vertical component Y signal with a vertical frequency near fi/2 is also blocked if there is even a slight horizontal component. In this way, regardless of whether it is a still image or a moving image, the band of the Y signal is limited, so there is a problem that the resolution is low.

This invention was made to solve the above-mentioned problems, and it is an adaptive type that can improve the horizontal and vertical resolution of still images, and can also appropriately prevent image quality deterioration and cross color generation in videos. The purpose is to obtain a YC separation filter.

[Means for Solving the Problems] The adaptive YC separation filter according to the present invention includes both horizontal and vertical filters and a time filter in addition to the horizontal and vertical filters in the conventional adaptive YC separation filter. The horizontal and vertical uncorrelated energies DH(Z) and DV(
H) and the absolute difference value DT in the 1-hour direction, and calculate this D
If T is larger than the time threshold constant KT, DH(
Z) and DV(Z) as horizontal and vertical threshold constants KH
, KV, and select the output of the horizontal filter when the correlation is particularly strong in the horizontal direction, the output of the vertical filter when the correlation is particularly strong in the vertical direction, and the output of the horizontal and vertical filters in other cases. , also D
If T is smaller than KT, select the output of the temporal filter and extract it as the first signal component, subtract the first signal component from the composite video signal to extract the second signal component, and calculate the luminance. It is configured to separate signals and color signals.

[Operation] The horizontal correlation detection means, vertical correlation detection means, and time correlation detection means in the present invention calculate the horizontal uncorrelation energy DH(Z) from the values of the sample point of interest and its neighboring sample points in the horizontal-vertical and temporal directions. , vertical uncorrelated energy Dν(
Z) and the absolute time difference value DT, and the horizontal threshold constant KH.

Vertical threshold constant Kv and temporal threshold constant KT
Based on the results of these comparisons, if the temporal difference absolute value DT is larger than KT and the correlation in the horizontal direction is particularly large, the judgment means selects the output of the horizontal filter and determines that DT is equal to KT. If DT is larger than KT and the correlation in the vertical direction is particularly large, select the output of the vertical filter, and if DT is larger than KT and the correlation in both the horizontal and vertical directions is not significantly different, select the output of both the horizontal and vertical filters. If DT is smaller than KT, the output of the time direction filter is selected and output as the first signal component. The subtracter combines the first signal component with the composite video signal in terms of the amount of delay, and then subtracts the first signal component and extracts the second signal component.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

In Figure 1, (1) represents an analog NTSC signal (10
1) into a digital signal (102), (23) is a horizontal/vertical time direction selective filter that removes the Y signal component from the output of this A/D converter (1), (24) ) is a delay element (4) for compensating the delay in this horizontal/vertical/time direction selective filter (23).
) is the output of the Mizuko vertical/time direction selective filter (1G
4) and the output (105) of the delay element (24).

In Figure 2, which shows a block diagram of the horizontal, vertical, and temporal direction selective filter (23), (31) converts the input signal (102) into (1 frame) - (1 line) (hereinafter referred to as r
IF-L, which is abbreviated as IF-IHJ)
The H delay device (33) converts the output (129) of the IF-IH delay device (31) into (l line) - (2 sample points) (hereinafter rl
IH-20 to be delayed by (abbreviated as H-2DJ)
7 delayer (35) is the output of LH-20 delayer (33) (
130) for two sample points! ! 2D delay device to delay (
38) delays the output (131) of the 2D delay device (35) by two sample points? D delay device (30 is 2D delay device (3B
) is delayed by (l lines) - (2 sample points), and (32) delays the output (133) of IH-20 delay device (34) by (l frames) - ( IF-IH delay device (31).

The sample values obtained by (32), LH-20 delay devices (33), (34) and 2D delay devices (35), (3B) are transferred to horizontal correlation detection circuit (37), vertical correlation detection circuit (3B) , a time correlation detection circuit (39), a horizontal filter (40), a vertical filter (41), and a time filter (43) as follows.

That is, the horizontal correlation detection circuit (37) has an IF-I
The output (129) of the H delay device (21) and the IH-20! The output (133) of the extender (30) is given to the vertical correlation detection circuit (38), and the output (133) of the IF-IHa! extender (31) is given to the vertical correlation detection circuit (38).
129) and the output (133) of the LH-20 delay device (34).
), and the time direction correlation detection circuit (39) receives the input signal (102) and the output (1) of the IF-IH delay device (32).
34) is given. Further horizontal filter (40)
The output (130) of the IH-20 delay (33) and the 2D
Output (132) of delay device (3B) and 2D delay device (35)
output (131) is given, and the first color signal (14
1) is output, and the vertical filter (41) has the IF
- Output (129) of IHI extender (31) and LH-20
The output (133) of the delay device (34) and the 2D delay device (35)
) is applied to the output (131) of the second color signal (14).
2) is output, and this signal is passed through the horizontal band filter (42).
The input signal (102) and the IF-
The output (134) of the LH delay circuit (32) and the output (131) of the 2D delay circuit (35) are applied to output a fourth color signal (140).

The determination circuit (44) includes the output (135) of the horizontal correlation detection circuit (37) and the output (13) of the vertical correlation detection circuit (38).
7) and the output (139) of the one-time correlation detection circuit (33), and outputs an output (140) according to the determination result to the switch circuit (45).

The switch circuit (45) includes a horizontal filter (40).
The output (141) of the vertical filter (41), the output (142) of the vertical filter (41), and the output (142) of the vertical filter (41) passed through the horizontal band filter (42) (
143) and the output (140) of the temporal filter (43)
and the output (140) of the determination circuit (44) are input,
According to the output (140) of the determination circuit (44), the first to fourth color signals (141), (142), (143), (1
44) and outputs a color signal (100).

FIG. 3 is a block diagram showing an example of the configuration of the horizontal correlation detection circuit (37).
) multiplies the output (129) of the 1F-LH delay device (21) by y! The multiplication factor circuit (302) includes a 2D delay device (35
) output (131) is multiplied by 1% and multiplied by a coefficient circuit (303)
multiplies the output (133) of the IH-20 delay device (34) by %. The adder (304) receives each output (3
30), (331) and (332) are added. 2
The D delay device (305) outputs the output (33
3) is delayed by 2JfJ tree points, and the 2D delay device (30 &)
The output (334) of the 2D delay device (305) is further
Delay by sample point. The subtracter (307) is connected to the adder (3
From the output (333) of 04), the 2D delay device (30El)
The local multiplication coefficient circuit (30B) multiplies the output (33B) of the subtracter (307). The absolute value circuit (309) receives the output (3) of the maximum coefficient circuit (308).
37), that is, the horizontal non-correlation energy DH(Z) (338) of the video signal. Subtraction circuit (3
10) is the horizontal threshold constant K generated by the threshold constant generation circuit (312), (339) to DH(Z)
is subtracted and a signal (135) indicating which is larger is output.

FIG. 4 is a block diagram showing an example of the configuration of the vertical correlation detection circuit (38). In FIG. 6, the subtracter (401) is
1l- from the output (129) of the IF-IHI extender (31)
The output (133) of the 2D delay device (34) is subtracted, and the multiplier circuit (4G2) subtracts the output (43G) of the subtracter (402).
), and the 2D delay device (403) is a station multiplication coefficient circuit (
402) output (431) is delayed by 2B4 points,
The D delay device (404) outputs the output (
432) is further delayed by 2 Jfs. The 3A multiplication coefficient circuit (405) outputs the multiplication coefficient circuit (402) (
The multiplication coefficient circuit (40B) multiplies the output (435) of the 2D delay device (403) by 1, and the multiplication coefficient circuit (407) multiplies the output (435) of the 2D delay device (404) by 1. 433
) is multiplied by ζ. The adder (40B) adds the outputs (434), (435) and (43B) of these coefficient circuits. The absolute value circuit (4013) is an adder (408)
The absolute value of the output (437), that is, the vertical decorrelation energy Dυ(Z) (438) of the video signal is output.

The subtraction circuit (41G) receives a vertical threshold constant K v (439) input from the threshold constant generation circuit (412).
DV(Z) (438) is subtracted from the value, and a signal (13?) indicating which one is larger is output.

FIG. 5 is a block diagram showing an example of the configuration of the time correlation detection circuit (39). In FIG. 0, the subtraction circuit (501) extracts the output ( 134), and the absolute value circuit (503) calculates the absolute value of the output (510) of the subtraction circuit (501), that is,
The absolute value of the time direction difference of the video signal (511) is output. The subtraction circuit (502) is connected to the threshold constant generation circuit (502).
04) is input from the fifth threshold constant KT (512
), DT (511) is subtracted and a signal (139) indicating which one is larger is output.

FIG. 6 is a block diagram showing an example of the configuration of the horizontal filter (40).
l) multiplies the output (130) of the IH-2D delay device (33) by -1, and the multiplier coefficient circuit (f102) multiplies the output (131) of the 2D delay device (35) by -1. Multiplier circuit (
E103) multiplies the output (132) of the 2D delay device (36) by -1 and outputs the result. The adder (eo4) receives these outputs (81G), (El 11) and (131
2) and outputs the first color signal (141).

FIG. 7 is a block diagram showing an example of the configuration of the vertical filter (31).
1) is the output (129) of the l F-IH delay device (31)
The station multiplication coefficient circuit (702) multiplies 2D delay device (
The output (131) of
03) is IH-201! Output (133) of extender (34)
) is multiplied by -1 and output. The adder (704) adds these outputs (710), (711) and (712) and outputs a second color signal (142).

FIG. 8 is a block diagram showing an example of the configuration of the time direction filter (43).
1) multiplies the input signal (102) by -1, the submultiplying coefficient circuit (802) multiplies the output (131) of the 2D delay device (35) by 1, and the -% multiplication coefficient circuit (803): The output (134) of the IF-IH delay device (32) is multiplied by -1 and output. The adder (804) receives these outputs (810), (811
) and (812) to output a fourth color signal (144).

FIG. 9 is a block diagram showing an example of the configuration of the horizontal band filter (32). In the figure, (901) is a 2D delay device that delays the output (142) of the vertical filter (41) by two sample points, and (902) is the 2D delay device (901).
A 2D delay device and -X multiplication coefficient circuit (903) which further delays the output (911) by two sampling points multiplies the output (142) of the vertical direction filter (41) by -1 and outputs the multiplication coefficient circuit (
904) multiplies the output (911) of the 2D delay device (901), and the -% multiplication coefficient circuit (905) multiplies the 2D delay @ (
The output (912) of 902) is multiplied by -1 and output. The adder (90B) receives these outputs (91G).

(911) and (912) are added to obtain the third color signal (1
43) is output. In the above configuration, the vertical filter (41) and the horizontal bandpass filter (42) constitute a horizontal/vertical filter (4B), and the third color obtained through this filter (4B) The signal (143) is
The color signal components of neighboring sample points in both the horizontal and vertical directions are equalized.

Next, the operation will be explained. In this example, since the filter operation is performed in three-dimensional space and time, the analog NTS
The signal sequence when the C signal is digitized is S (1+
J tk)' (t=112131...m, j=1
．． 2.3...no, k= 1.2.3・u), as shown in Figures 10 and 11, the grid-like 3
It becomes a dimensional array. Another Y signal.

It is assumed that the following relationship exists between the C signals. However, 1+3 is the same as 'tJ, and k indicates the array number of the sample point in the time direction.

S (i, j, k) = Y (i, j, k) + C
(i, j, k) Among the signals of each part in FIG. 13
2) is S (i-2,j, k), signal (129)
is S (i.

j-1, k), the signal (133) is S (i, j+1
°k), the signal (102) corresponds to S (t, j, −2), and the signal (134) corresponds to S (i, j, +2).

Assume that Z-1 and Z-good are used as symbols to indicate a delay of 1 sample and a delay of 1 line, respectively, using two transformations.

Here, Z-1=exp (-j2πF/4fsc).

Also, since fsc=(455/2) ・fH, 1=
It becomes 910.

Using the above sample values, the uncorrelated energy of the video signal in the horizontal and vertical directions D H (Z) (331), D V (
Z ) (438) and the time-direction difference DT (511) are calculated in a horizontal correlation detection circuit (37), a vertical correlation detection circuit (38), and a time correlation detection circuit (39), respectively.

DH(Z)=I(-1/8)(1-2-')(1+2-
”)2 lDυ(Z)-1(-1/8)(10Z-2)
2 (1-Z-2)1DT -1s (i, j, -2) -3 (i, j, +2) 1 Above DH (Z), DV
(Z) has filter characteristics that block direct current components in the vertical and horizontal directions, and block frequency components of the color subcarrier frequency in the horizontal and vertical directions, respectively.

Next, correlation detection circuits (37), (38), (3
9), constant generation circuits (312), (412)
, (504), the threshold constant K H+ K
v + K t and the obtained absolute values DH (Z), D
A difference signal between V(Z) and DT is given to a determination circuit (44).

That is, in the horizontal detection circuit (37), the difference of 5 minutes between the constant KH (339) given by the constant generation circuit (312) and the output DH (Z) (338) of the absolute value circuit (309) is the signal ( 135), and the determination circuit (30
is input. (see Figure 3), vertical correlation detection circuit (2
Similarly, in 8), the constant K v (439) and DV
(Z) (438) is output as a signal (138). (See Figure 4) Similarly, in the 0 time correlation detection circuit (29), the constants KT (512) and D T (511
) is output as a signal (139). (See Figure 5) The 0 judgment circuit (44) switches the switch circuit (45) according to the conditions A and H below to determine the output (141) of the horizontal filter (32) and the output of the vertical filter (31). (142), selects the output (143) of the horizontal band filter (32) and the output (144) of the temporal filter (33), and outputs the C signal (100
Output as .

A, When Dy>KT [1] If DH(Z)≦KH and DV(Z)>Kυ,
Select horizontal filter output (141).

[2] If DV(Z)≦υ and DH(Z)>KH, then
Select vertical filter output (142).

■Otherwise, horizontal band filter output (143)
Select.

B. When DT≦KT, select the output (144) of the zero time direction filter (33).

In other words, horizontally uncorrelated energy DH(Z) and vertically uncorrelated energy DV(Z
), calculate the absolute time difference DT, and if the absolute time difference DT is larger than the time threshold constant,
Image correlation is detected using horizontal and vertical uncorrelation energy and horizontal and vertical threshold constants. If the correlation is particularly strong only in the horizontal direction, select the horizontal filter. If the correlation is particularly strong only in the vertical direction, select the horizontal filter. Select a vertical filter and perform the next filter operation.

Hc = (-1/41(1-2-2)2Vc = (-
1/4)-(1-Z-L)2HVc= (-1/111
t)11-Z-2)2・(1-Z-1)2 Furthermore, if the time direction difference absolute value DT is smaller than the time direction threshold constant KT, the time direction filter is selected and the next filter operation is performed. .

Tc = (-1/4) (1-Z-s)2 (however, Z
-S is the symbol representing l frame delay m = 910X
It is 525. ) As a result, low frequency components of the video signal in the horizontal direction, vertical direction, horizontal direction, both vertical directions, or time direction at the sample point position of S (i, j, k) are removed,
A C signal (1G4) is obtained. Also, the Y signal at this time (
10B) is determined by the following calculation as the difference between the output signal (128) of the delay element (3) and the C signal (104) in FIG.

y (i, j, k) = s (i, j, k) - c (i
. The characteristics of the adaptive YC separation filter can be further improved by increasing the order of the circuit for determining , and the horizontal and vertical one-time direction filters.

In addition, in the above embodiment, the horizontal/vertical/time direction selection filter (23) removes low frequency components of the video signal to extract the C signal (100), and the subtractor (0 extracts the Y signal (10B). However, this cannot be done even if the horizontal/vertical/time direction selective filter (23) removes the high frequency components of the video signal to extract the Y signal, and the subtractor (4) extracts the C signal. good.

[Effects of the Invention] As described above, according to the present invention, by utilizing the three-dimensional characteristics of a television signal, horizontal and vertical・
Since the configuration was configured to use time-selective filters,
This has the effect of providing a YC separation filter with improved responsiveness to local changes in television signals, higher resolution, and less occurrence of cross color than the conventional adaptive YC separation.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing a schematic configuration of an adaptive YC separation filter in an embodiment of the present invention, and FIG. 2 is a block circuit diagram of a horizontal/vertical/horizontal/vertical/time direction selective filter in this embodiment. , FIGS. 3 to 9 respectively show the horizontal correlation detection circuit in the embodiment of FIG. 2,
Vertical correlation detection circuit 9 A block circuit diagram of a configuration example of a time correlation detection circuit, a horizontal direction filter, a vertical direction filter, a time direction filter, and a horizontal band filter, FIG. 10 and FIG. Fig. 12 is a diagram showing the arrangement of sample positions of NTSC signals on a single field screen; Fig. 13 is a diagram showing the phase and sample position of color signals regarding the operating principle of a horizontal/vertical selective filter. Fig. 14 is a block circuit diagram showing the schematic configuration of a conventional adaptive YC separation filter, and Fig. 15 is a horizontal and vertical diagram of the conventional adaptive YC separation filter. FIG. 16, a block circuit diagram of the direction selective filter, is a diagram showing the passbands of the Y signal and C signal when a conventional adaptive YC separation filter is used. (1)...A/D converter, (0...adder, (23
)...Horizontal/vertical/time selective filter, (20...
・Delay element, (37)...Horizontal correlation detection circuit, (38
)...Vertical correlation detection circuit, (33)...Temporal correlation detection circuit, (40)...Horizontal filter, (41)...
...Vertical filter, (42)...Horizontal band filter, (43)...Temporal filter, (44)...
Judgment circuit, (45)...Switch circuit, (4B)...
・Both horizontal and vertical filters. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) Means for converting an NTSC color television signal into a digital composite video signal at a sampling frequency that is four times the color subcarrier frequency, and the digital composite video signal using the sample point of interest and its neighboring sample values in the horizontal direction. A horizontal filter that extracts a first signal component of either the luminance signal component or the chrominance signal component of the signal, and the sample point of interest and its neighboring sample values in the vertical direction are used to extract the first signal component. Using the vertical filter to be extracted and the sample values of the sample point of interest and its neighbors in both horizontal and vertical directions,
a horizontal/vertical filter that extracts a first signal component, a temporal filter that extracts a first signal component using sample values of the sample point of interest and its neighbors in the time direction; Using sample points, remove the DC component in the horizontal direction, the frequency component corresponding to the color subcarrier component, and the frequency component corresponding to the color subcarrier component in the vertical direction, and calculate their absolute values to calculate the horizontal uncorrelated energy. horizontal correlation detection means that detects D_H(Z), compares the horizontal direction uncorrelated energy D_H(Z) with a horizontal direction threshold constant K_H, and outputs the comparison result; Using neighboring sampling points, remove the vertical DC component, the frequency component corresponding to the color subcarrier component, and the frequency component corresponding to the horizontal color subcarrier component, and calculate their absolute values to calculate the vertical non-current component. The correlated energy D_V(Z) is detected and the vertical uncorrelated energy D_V(Z) and the vertical threshold constant K_
Vertical correlation detection means for comparing the magnitude with V and outputting the comparison result, and sampling points adjacent to the sample point in the time direction where the phase of the color subcarrier is reversed from the sample point of interest. time correlation detection means for determining the absolute value D_T of the difference in the time direction of a point, comparing the magnitude of this time direction difference absolute value D_T with a time direction threshold constant K_T, and outputting the comparison result; Based on the results, vertical correlation detection results and time correlation detection results, perform the following A and B.
a switch circuit for outputting a first signal component selected from the four types of first signal components based on the selection result; a delay means for delaying the first signal component by an amount corresponding to the delay amount of the first signal component; and a subtractor for subtracting the selected first signal component from the delayed composite video digital signal to obtain a second signal. An adaptive luminance signal/chrominance signal separation filter comprising means. If A, D_T≦K_T, the fourth color signal of the time direction filter is selected. B, D_T>K_T and [1] D_H(Z)≦K_H_1 and D_V(Z)>
In the case of K_V_2, the first color signal of the horizontal filter is selected. [2] D_V(Z)≦K_V_1 and D_H(Z)>
In the case of K_H_2, the second color signal of the vertical filter is selected. [3] In cases other than [1] and [2], select the third color signal of the horizontal and vertical filters.