JPH03293889A - Luminance signal/chrominance signal separation filter - Google Patents

Abstract

PURPOSE:To reduce the influence of leakage of a luminance signal and a chrominance signal to mutual channels and to reduce dot disturbance by using a luminance signal/chrominance signal filter properly based on the correlation of the image in the vertical and horizontal directions of a composite color television signal, CONSTITUTION:When low correlation in the vertical direction and high correlation in the horizontal direction exist in a remarked sampling point, the chrominance signal is separated by a horizontal di rection chrominance signal extraction filter 19, and when the low correlation in the horizontal direction and the high correlation in the vertical direction exist in the remarked sampling point, the chrominance signal is separated by a vertical direction chrominance signal extraction filter 16. This filter is comprised in such a way that the chrominance signal is separated by a horizontal and vertical direction chrominance signal extraction filter 17 when neither correlation exists. Thereby, it is possible to reduce the influence of the leakage of the luminance signal and the chrominance signal in an area where the image in the vertical direction is changed steeply to the mutual channels, and to reduce the dot disturbance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a luminance signal and chrominance signal separation filter that separates a luminance signal and a chrominance signal from a composite television signal of, for example, the NTSC system.

[Prior Art] FIG. 8 is a block diagram showing an example of the configuration of a conventional luminance signal/chrominance signal separation filter.
An input terminal into which an SC system composite color television signal is input; (2) an A/D converter that converts the analog composite color television signal into a digital signal; (3);
(4) is the first. A second one-line delay circuit, (5) a compensation delay circuit, (6) a vertical filter, (7) a bandpass filter, (8).

(]C0 is an output terminal, and (9) is a subtraction circuit.

Next, the operation will be explained.

The composite color television signal input to the input terminal (1) is passed through the A/D converter (2) to the vertical filter (
6) and the first one-line delay circuit (3
) is given to

The output of the first 1-line delay circuit (3) is given as is to the vertical filter (6), and is further delayed by l lines in the second 1-line delay circuit (4).
Vertical filter (6).

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

The output of the bandpass filter (7) is derived from the output terminal (8) as a color signal 205 and is applied to one input of the subtraction circuit (9). The other input of the subtraction circuit (9) receives the output of the first one-line delay circuit (3).The compensation delay circuit (5) is a circuit for compensating for the delay in the bandpass filter (7).

A luminance signal (207) is output from the subtraction circuit (9) and applied to the output terminal <10).

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

The input signal 201 of the composite color television signal, which is sampled in synchronization with the color subcarrier at the sampling frequency fs = 4·fsc (fsc is the color subcarrier frequency), is displayed on the screen at the ninth
The result will be a two-dimensional array as shown in the figure. That is, fsc =
(455/2) f H, the phase of the color signal C is inverted by 180'' for each line, and four samples are extracted in one synchronization. Here, in the figure, Y is the luminance signal, C1, C2 shows the color signal, the white circle is Y+CI,
The circle with diagonal lines is Y-CI.

The white triangle is Y102, and the hatched triangle is Y-C2. Now, it is assumed that Z-1 and Z- are used as symbols to represent a delay of one sample and a delay of one line, respectively, using two transformations. Here, Z −'= exp(−j2
πf/4fsc).

Also, since fsc= (455/2) f H, 1
=910.

At this time, the first and second one-line delay circuits (3).

l line delayed signal (202) delayed using (4)
, the 2-line delayed signal (203) and the current input signal (20
1), a vertical direction filter (6) extracts a line support signal (204) that supports each line including the color signal. The transfer function Hv(Z) of the vertical filter (6) is Hv(Z)□(-1/4)(1-Z-).In other words, the coordinates (m, n ) line support signal He (m, n) as Hc (m, n) -- (1/4
)(S(m,nn-1)-25(,n)+S(+++,
n+1)). Since the line support signal includes the luminance signal Y, the bandpass filter (7) separates the color signal C (+a, n), which is a high frequency component, from the line support signal He (layer, n). The color signal (205) thus obtained is sent to the subtraction circuit (9).

The subtraction circuit (9) subtracts the color signal C (m, n) from the signal S (hat n) obtained by delaying the l-line delayed signal (202) by the compensation delay circuit (5) according to the bandpass filter (7). ,
The luminance signal Y(m,n) is separated as follows.

Y (m, n) = IS (m, n) - C (m, n) In this case, the transfer function Hh (Z) of the bandpass filter (7) is, for example, Hh (Z) = (-1/32 ) (1-Z-')'(1+
Z-')''(i+z-'').

[Problems to be Solved by the Invention] Since the conventional luminance signal/chrominance signal separation filter is configured as described above, the characteristics of the vertical filter and the horizontal filter are fixed and combined. That is, the luminance signal and the color signal are separated by a bandpass filter (7) in both the vertical and horizontal directions.

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, causing problems such as dot interference and other deterioration of the reproduced image. .

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

[Means for Solving the Problems] A luminance signal and chrominance signal separation filter according to the present invention delays a composite video signal sampled at a predetermined frequency synchronized with a horizontal scanning frequency to separate a luminance signal and a chrominance signal. a plurality of one-line delay means for simultaneously obtaining sample values of a sample point of interest to be separated and a plurality of reference sample points surrounding the sample point of interest on the screen; a horizontal color signal extraction filter that extracts a frequency component corresponding to a component of a color subcarrier in a direction to obtain a first color signal; and a horizontal color signal extraction filter that receives sample values of the sample point of interest and a predetermined reference sample point, and includes at least: a vertical color signal extraction filter for extracting a frequency component corresponding to a component of a color subcarrier in the vertical direction to obtain a second color signal; a horizontal/vertical color signal extraction filter that extracts a third color signal; and inputs the sample values of the sample point of interest and a predetermined reference sample point, and extracts at least one non-correlated mainly luminance signal in the horizontal direction. horizontal direction luminance signal uncorrelated energy detection means for detecting energy, horizontal direction luminance signal uncorrelated energy detection means for detecting horizontal direction low (both mainly color signal uncorrelated energy), and said horizontal direction luminance a times the uncorrelated energy of the signal (a
: an integer) and b times the decorrelation energy of the horizontal color signal (b: an integer), a first horizontal decorrelation energy detection means that selects the larger one as the horizontal decorrelation energy DHI; A second method in which the sum of the non-correlation energy of the horizontal luminance signal and the non-correlation energy of the horizontal color signal is horizontal non-correlation energy DH2.
horizontal direction uncorrelated energy detection means, and a vertical brightness signal uncorrelated device for detecting uncorrelated energy of at least one mainly brightness signal in the vertical direction, using the sample values of the sample point of interest and a predetermined reference sample point as input. energy detection means; vertical color signal decorrelation energy detection means for detecting decorrelation energy of at least one primarily color signal in the vertical direction;
: an integer) and d times the decorrelation energy of the vertical color signal (d: an integer), a first vertical decorrelation energy detection means that selects the larger one as the vertical decorrelation energy DVI; a second vertically uncorrelated energy detecting means that determines the sum of the uncorrelated energy of the vertical luminance signal and the uncorrelated energy of the vertical color signal as vertical uncorrelated energy DV2; and at least DVI≧mxDH2 When the inequality (m: an integer) holds, a color signal extracting means that makes the final color signal the first color signal; and when the inequality of at least DHI≧nDV2 (n: an integer) holds, the final color The present invention includes color signal extraction means for making a signal the second color signal, and color signal extraction means for making the final color signal the third color signal when the above inequality does not hold.

[Function] The luminance signal color signal separation filter of the present invention separates the color signals by the horizontal color signal extraction filter when the sample points of interest have weak correlation in the vertical direction and strong correlation in the horizontal direction, and the sample points of interest separate. When the correlation is weak in the horizontal direction and strong in the vertical direction, the color signal is separated by the vertical color signal extraction filter, and when neither is the case, the color signal is separated by the horizontal color signal extraction filter and the vertical color signal extraction filter. By separating the signals, it is possible to reduce the influence of leakage of the luminance signal and color signal into each other channel in areas where the image changes drastically in the vertical direction, and to reduce dot interference.

[Example〕 Hereinafter, this invention will be explained based on the drawings.

FIG. 1 is a schematic block diagram showing an NTSC luminance signal chrominance signal separation filter according to an embodiment of the present invention.
In the figure, (11) is an input terminal to which an NTSC composite color television signal is given, and (12) is an A that converts the analog composite color television signal inputted via input terminal (11) into a digital signal. /D converter, (13) is the first 1-line delay circuit that inputs the output signal of the A/D converter (12), (14) and (15) are the first
The second circuit inputs the output signal of the one-line delay circuit (13) of
1-line delay circuit and compensation delay circuit, (16), (1
7), (18) are the output signals of the A/D converter (12) (
ioi), a vertical color signal extraction filter that receives the output signal (102) of the first one-line delay circuit (13), and the output signal (103) of the second one-line delay circuit (14), horizontal and vertical. directional color signal extraction filter, image correlation determination circuit, (19) is the first 1-line delay circuit (1
3) is a horizontal color signal extraction filter that inputs the output signal (102), and (20) is a vertical color signal extraction filter (
16) a compensation delay circuit inputting the output signal (104);
(21) is a horizontal/vertical color signal extraction filter (17)
a compensation delay circuit (22) inputting the output signal (108) of
) is the output signal (
The compensation delay circuit (23) inputs the output signal (106) of the compensation delay circuit (20), (21), (22) according to the output signal (110) of the image correlation determination circuit (18).
05), (107), and (109), (24) is the output terminal of the switch circuit (23), and (25) is the output signal (112) of the compensation delay circuit (15) and the switch. Output signal (III) of circuit (23)
) and outputs an output signal (113). (26) is the output terminal of the subtraction circuit (25).

FIG. 2 shows an example of the image correlation determination circuit (18). In FIG. 2, (27) is a horizontal color signal uncorrelated energy extraction circuit, and (28) is a horizontal luminance uncorrelated energy extraction circuit. circuit, (29) is a vertical color signal uncorrelated energy extraction circuit, (30) is a vertical luminance uncorrelated energy extraction circuit, (31), (32), (33)
, (34), (39), (40) are multiplication circuits, (
35), (38) are maximum value circuits, (36), (37
) is an adder circuit, (41), (42) are a comparison circuit, (4
3) is a determination circuit.

The output signal of the A/D converter (12) in FIG.
101) is a horizontal luminance signal uncorrelated energy extraction circuit (28) and a vertical chrominance signal uncorrelated energy extraction circuit (28).
29) and a vertical luminance signal decorrelation energy extraction circuit (30).

Output signal (102) of first 1-line delay circuit (13)
are a horizontal color signal uncorrelated energy extraction circuit (27), a horizontal luminance signal uncorrelated energy extraction circuit (28), and a vertical luminance signal uncorrelated energy extraction circuit (30).
) is given to

Output signal (103) of second 1-line delay circuit (14)
is the horizontal luminance signal decorrelation energy extraction circuit (28)
, a vertical color signal uncorrelated energy extraction circuit (29), and a vertical luminance signal uncorrelated energy extraction circuit (30).
) is given to

The output signal DCH of the horizontal color signal uncorrelated energy extraction circuit (27) is divided into three sides, one of which is connected to the addition circuit (36).
The other is multiplied by a constant kl by a multiplication circuit (31) and given to a maximum value circuit (35). The output signal DYH of the horizontal luminance signal non-correlation energy extraction circuit (28) is divided into three parts, one of which is sent to an addition circuit (36) and the other to a multiplication circuit (32) where the constant is multiplied by 2 and sent to the maximum value circuit (35).
) is given to The output signal of the maximum value circuit (35) is the first
The comparator circuit (
41). The output signal of the adder circuit (36) is multiplied by a constant by 5 in the multiplier circuit (39) as the second horizontally uncorrelated energy DH2, and then sent to the comparator circuit (4).
2) is given.

The output signal DCV of the vertical color signal uncorrelated energy extraction circuit (29) is divided into three sides, one of which is connected to the addition circuit (37).
The other one is multiplied by 3 by a constant by a multiplication circuit (33) and given to a maximum value circuit (38). The output signal DYV of the vertical luminance signal non-correlation energy extraction circuit (30) is divided into three parts, one of which is sent to an adder (37) and the other to a multiplier (34) where the constant is multiplied by 4 and sent to a maximum value circuit (38).
) is given to The output signal of the maximum value circuit (38) is the first
As the vertical decorrelation energy DVI of the comparator circuit (
42). The output signal of the adder circuit (37) is multiplied by a constant by 6 in the multiplier circuit (40) as second vertically uncorrelated energy DV2, and then sent to the comparator circuit (40).
1) is given.

The comparator circuit (41) is connected to the first horizontally uncorrelated energy D.
Compare HI and the second vertical uncorrelated energy DV2 with 6・DV2, which is a constant multiplied by 6, and find that DHI≧6・DV
2, the output signal (115) is set to high level, and at other times, set to low level.

The comparator circuit (42) is connected to the first vertically uncorrelated energy D.
Compare VI and the second horizontal uncorrelated energy DH2 with 5・DH2, which is obtained by multiplying the constant by 5, and calculate 5・DH2 for DVI≧.
2, the output signal (114) is set to high level, and at other times, set to low level.

The output signal (115) of the comparison circuit (41) and the comparison circuit (4
The output signal (114) of 2) is given to the determination circuit (43).

The output signal (110) of this determination circuit (43) is sent out as the output of the image correlation determination circuit (18).

FIG. 3 is a circuit diagram showing an example of the determination circuit (43) shown in FIG.
It is composed of circuits (46) and (47). The output signal (115) of the comparison circuit (41) is applied to one of the AND circuits (44) and the input of the N07 circuit (47).

Also, the output signal (114) of the comparison circuit (42) is N07
is applied to the circuit (46). The output of this N07 circuit (46) is output from the AND circuit (44) and the AND circuit (45).
given to one input of each. N07 circuit (47
) is applied to the other input of the AND circuit (45).

The output signal of this AND circuit (44) and the AND circuit (45)
) is the output signal of the image correlation determination circuit (18).
110).

FIG. 4 is a block diagram showing an example of the horizontal color signal uncorrelated energy extraction circuit (27) shown in FIG.
It is made up of. The output signal (102) of the first one-line delay circuit (13) is then outputted to a delay circuit (48) having a delay amount of one cycle of the color subcarrier and a subtraction circuit (4).
9).

The output signal of the delay circuit (48) is given to the other input of the subtraction circuit (49). The output signal of the subtraction circuit (49) is given to an absolute value circuit (50), and this absolute value circuit (50)
The output DCH becomes the output of the horizontal direction color signal non-correlation energy extraction circuit (27).

FIG. 5 is a block diagram showing an example of the horizontal luminance signal decorrelation energy extraction circuit (28) shown in FIG. 2, including a vertical low-pass filter (51), a delay circuit (52),
(53), subtraction circuits (54), (55), absolute value circuits (56), (57), and maximum value circuit (58).

and an output signal (101) of the A/D converter (12),
Output signal (102) of first 1-line delay circuit (13)
and the output signal (1
03) is applied to the vertical low-pass filter (51).

The output of this vertical low-pass filter (51) is given to one input of a delay circuit (52) having a delay amount of 1/2 the period of the color subcarrier and a subtraction circuit (54). The output of the delay circuit (52) is sent to the delay circuit (53) and the subtraction circuit (5
4) and one input of the subtraction circuit (55).

The output of the delay circuit (53) is given to the other input of the subtraction circuit (55).

The output of the subtraction circuit (54) is given to an absolute value circuit (56), and the output of this absolute value circuit (56) is given to a maximum value circuit (58).
) is given to Further, the output of the subtraction circuit (55) is given to an absolute value circuit (57), and the output of this absolute value circuit (57) is given to a maximum value circuit (58). Maximum value circuit (
The output DYH of 58) becomes the output of the horizontal luminance signal decorrelation energy extraction circuit (28).

FIG. 6 is a block diagram showing an example of the vertical color signal uncorrelated energy extraction circuit (29) shown in FIG.
, and an absolute value circuit (62). And A
The output signal (101) of the /D converter (12) is given to a horizontal low-pass filter (59). The output signal (103) of the second one-line delay circuit (14) is applied to a horizontal band-pass filter (60).

The output of this horizontal band-pass filter (59) is applied to one input of a subtraction circuit (61), and the output of the horizontal band-pass filter (60) is applied to the other input of the subtraction circuit (61). The output of this subtraction circuit (61) is given to an absolute value circuit (62), and the output DCV of this absolute value circuit (62) is applied to the vertical color signal uncorrelated energy extraction circuit (29).
) is the output.

FIG. 7 is a block diagram showing an example of the vertical luminance signal uncorrelated energy extraction circuit (30) shown in FIG.
6), (87), Absolute value circuit (68), (69),
It is composed of a maximum value circuit (70).

The output signal (101) of the A/D converter (12) is given to a horizontal low-pass filter (63), and the output signal (102) of the first 1-line delay circuit (13) is fed to a horizontal low-pass filter (63). The output signal (103) of the second one-line delay circuit (14) is applied to a horizontal low-pass filter (65).

The output of the horizontal low-pass filter (63) is sent to the subtraction circuit (
66), and the output of the horizontal low-pass filter (64) is given to the other input of the subtraction circuit (66) and one input of the subtraction circuit (67), and the horizontal low-pass filter (64) The output of the filter (65) is a subtraction circuit (67)
is given to the other input of

The output of the subtraction circuit (66) is given to the absolute value circuit (68), the output of the subtraction circuit (67) is given to the absolute value circuit (69), and the outputs of these absolute value circuits (68) and (69) is given to the maximum value circuit (70), and the output DYV of this maximum value circuit (70) becomes the output of the vertical luminance signal decorrelation energy extraction circuit (30).

Next, the operation of the above embodiment will be explained.

When an NTSC composite color television signal is applied through the input terminal (11), the A/D converter (12)
is the sampling frequency fs of this composite color television signal
=4 fsc.

The sampled composite color television signal is
It is applied to the line delay circuit (13) and further passes through the second 1-line delay circuit (14) to determine the sample value at a certain sample point of interest and the values of the sample value on the screen above and below the sample point of interest. Sample values at three sample points are extracted simultaneously.

That is, when the composite color television signal (sample value) S(m, n) at the position of coordinates (m, n) appears at the output of the first 1-line delay circuit (13), the second 1-line delay circuit (13) A signal (m, n-1) appears at the output of the delay circuit (14), and a signal S(m, n-1) appears at the output of the A/D converter (12).
n+1) appears (see Figure 1O). These 3 on the screen
A luminance signal and chrominance signal separation filter is constructed based on the sample values of sample points across the line.

This first. Second 1-line delay circuit (L3), (14
) The sample values extracted by the vertical color signal extraction filter (16), the horizontal color signal extraction filter (19),
The signals are applied to the horizontal/vertical color signal extraction filter (17) and the image correlation determination circuit (step 8) as follows. That is, the output signal (101) of the A/D converter (12) is input to the vertical color signal extraction filter (16), the horizontal/vertical color signal extraction filter (17), and the image correlation determination circuit (18). , the output signal (102) of the first one-line delay circuit (13), and the second one-line delay circuit (102)
The output signals (103) of 4) are respectively provided. Further, the horizontal direction color signal extraction filter (19) includes a first one.
An output signal (102) of the line delay circuit (13) is provided.

At this time, for example, a vertical color signal extraction filter (16
) is expressed using a transfer function, Cv(Z) = (−
1/4) (1-Z-)", and the horizontal color signal extraction filter (19) is expressed as Ch(Z") = (-1/4) (1-Z-"),
," and the horizontal/vertical color signal extraction filter (17) is expressed as Chv (Z) = (-1/4) (1-Z-")"
This is a filter expressed as (-1/4)(1-Z-)'.

The output signal (10) of the vertical color signal extraction filter (16)
4) is the output signal (105) of the compensation delay circuit (20), and the output signal (19) of the horizontal color signal extraction filter (19).
106) is the output signal (107) of the compensation delay circuit (22)
The output signals (108) of the horizontal and vertical color signal extraction filters (17) are respectively given to the switch circuit (23) as the output signals (109) of the compensation delay circuit (21).

Here, it is determined which of the color output codes of the vertical color signal extraction filter (16), the horizontal color signal extraction filter (19), and the horizontal/vertical color signal extraction filter (17) is selected. The operation will be explained.

Regarding the sample point of interest, the correlation between images in the vertical and horizontal directions is detected, and when the correlation is particularly strong in the vertical direction, the output signal (104) of the vertical color signal extraction filter (16) is detected.
Select the output signal (105) of the compensation delay circuit (20) based on In other cases, select the output signal (107) of the horizontal/vertical color signal extraction filter (107).
Based on the output signal (108) of (compensation delay circuit (21)
) to select the output signal (109) of the switch circuit (23).

Detection of the image correlation and control of the switch circuit (23) are performed by an image correlation determination circuit (18). This image correlation determination circuit (18) controls the switch circuit (23) by the following operations.

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

DCI'1(Z)=ll-Z-'1 DYH(Z)=max(1(1/4)(l+Z-)"(
1-Z)-"[1/4)・(1+Z-)'-(Z-"-
Z)l)DCV(Z)-1(1-Z-")"-(1+Z
-” )IDYV(Z)-max(1(1/4)・(
1+Z-”)”(l-Z-)l.

(1/4)・(1+Z−2)”−(Z−−Z) At this time, the horizontal direction uncorrelated energy DHI.

DH2, vertical decorrelation energy DVI;

DV2 is expressed as follows.

DH1=max(b, DCtl, a, DYH)D
■2=DCH+DY■ DVI=raax (d, DCV, c, DYV
)DV2=DCV+DYV At this time, the comparison circuit (42) of the image correlation determination circuit (18)
) determines that there is a correlation in the horizontal direction and no correlation in the vertical direction when DVI≧5−DH2, and sends a signal “1” to the determination circuit (43). Also, when DVl<K5-DH2, it is determined that there is no correlation in the horizontal direction, and the determination circuit (4
3) Send a signal “0” to

On the other hand, when DHI≧6-DV2, the comparison circuit (41) of the image correlation determination circuit (18) determines that there is a correlation in the vertical direction and no correlation in the horizontal direction, and sends a signal to the determination circuit (43). Send ``l''. Also, when DHI is 6-DV2, it is determined that there is no correlation in the vertical direction, and the judgment circuit (4
3) Send the signal “0°” to

The determination circuit (43) controls the switch circuit (23) as follows according to the above correlation detection result. That is,
The relationship between the input and output of the determination circuit (43) is as shown in Table 1.

[Table 1 below: In this case, the switch circuit (23) is the AND circuit (44)
When the output signals of the AND circuit (45) are both 0'',
The output signal (107) of the compensation delay circuit (22) is made to flow.

When the output signal of the AND circuit (44) is 21', the AND circuit (
When the output signal of 45) is “0”, the compensation delay circuit (20
) output signal (105) is made to flow.

When the output signal of the AND circuit (44) is "0", the AND circuit (
When the output signal of 45) is '1', the compensation delay circuit (2
1 output signal (109) is made to flow.

Therefore, in the embodiment shown in FIG. 1, the filter characteristic C(Z) for color signal extraction is switched as follows depending on the presence or absence of correlation.

When there is horizontal correlation, C(Z)=Ch (Z) When there is no horizontal correlation and vertical correlation, C(Z) -Cv (Z) When there is no horizontal correlation and no vertical correlation, C(Z)=Chv (Z) In the above embodiment, the composite color television signal was sampled at a frequency four times as high as the color subcarrier synchronized with the horizontal scanning frequency. If the method is suitable, sampling may be performed not only at four times the color subcarrier but also at other frequencies.

Further, the digital filter used in the above embodiment is merely an example, and the filter may have a larger number of orders, for example.

In addition, in the above embodiment, the luminance signal and color signal separation filter of the NTSC system was described, but 1 in FIG.
The line delay circuits (13) and (14) may be changed to two line delay circuits (71) and (72) as shown in FIG. 8 and applied to the PAL system.

In addition, in the above embodiment, the output DCH of the horizontal color signal uncorrelated energy extraction circuit (27) was supplied to both the multiplier (3) and the adder (36), but the characteristics as shown in FIG. Two horizontal color signal decorrelation energy extraction circuits (27a) and (27b) with different values may be provided, and their outputs DCH1 and DCH2 may be supplied to the multiplier (31) and the adder (36), respectively. Similarly, in the vertical direction, two vertical color signal uncorrelated energy extraction circuits (29a) and (29b) are provided, and their output D
CV1 and DCV2 may be supplied to a multiplier (33) and an adder (37), respectively.

[Effects of the Invention] As described above, according to the present invention, the luminance signal and chrominance signal separation filters are used differently depending on the correlation between the vertical and horizontal images of the composite color television signal. This has the effect of reducing the influence of color signal leakage to each other's channels and reducing dot interference.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing an NTSC luminance signal/chrominance signal separation filter according to an embodiment of the present invention, FIG. 2 is a block diagram of an image correlation determination circuit in the embodiment of FIG. 4 is a block diagram showing a horizontal color signal non-correlation energy extraction circuit; FIG. 5 is a block diagram showing a horizontal luminance signal non-correlation energy extraction circuit; FIG. 6 is a block diagram showing a vertical color signal uncorrelated energy extraction circuit, FIG. 7 is a block diagram showing a vertical luminance signal uncorrelated energy extraction circuit, and FIGS. 8 and 11 are other embodiments of the present invention. A schematic block diagram showing an example, FIG. 9 is a schematic block diagram of a conventional luminance signal chrominance signal separation filter, and FIG.
The figure is an explanatory diagram showing an arrangement on a screen of a signal sequence obtained by converting an NTSC system composite color television signal into a synchronized format using four times the color subcarrier. In the figure, (12) is an A/D converter, (13), (
14) is a 1-line delay circuit, (16) is a vertical color signal extraction filter, (17) is a horizontal/vertical color signal extraction filter, (18) is an image correlation determination circuit, and (I9) is a horizontal color signal extraction filter. filter, (23) is a switch circuit (color signal extraction means), (27) is a horizontal color signal uncorrelated energy extraction circuit, (28) is a horizontal luminance signal uncorrelated energy extraction circuit, and (29) is a vertical color signal extraction circuit. A signal non-correlation energy extraction circuit, (30) a vertical luminance signal non-correlation energy extraction circuit, and (43) a determination circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A sample point of interest at which a luminance signal and a chrominance signal are to be separated by delaying a composite video signal sampled at a predetermined frequency synchronized with the horizontal scanning frequency and the vicinity of the sample point of interest on the screen. a plurality of one-line delay means for simultaneously obtaining sample values of a plurality of reference sample points; a horizontal color signal extraction filter for obtaining a first color signal; and a horizontal color signal extraction filter that receives sample values of the sample point of interest and a predetermined reference sample point as input, and extracts at least a frequency component corresponding to a component of a vertical color subcarrier. a vertical color signal extraction filter for obtaining a second color signal; and a horizontal/vertical color signal for obtaining a third color signal by extracting frequency components corresponding to components of color subcarriers in both the vertical and horizontal directions. a signal extraction filter; horizontal luminance signal uncorrelated energy detection means for receiving the sample values of the sample point of interest and a predetermined reference sampling point as input and detecting uncorrelated energy of at least one mainly horizontal luminance signal; horizontal color signal uncorrelated energy detection means for detecting uncorrelated energy of at least one mainly color signal in the horizontal direction;
: an integer) and b times the decorrelation energy of the horizontal color signal (b: an integer), a first horizontal decorrelation energy detection means that selects the larger one and sets it as the horizontal decorrelation energy DH1; A second method in which the sum of the non-correlation energy of the horizontal luminance signal and the non-correlation energy of the horizontal color signal is horizontal non-correlation energy DH2.
horizontal direction uncorrelated energy detection means, and a vertical brightness signal uncorrelated device for detecting uncorrelated energy of at least one mainly brightness signal in the vertical direction, using the sample values of the sample point of interest and a predetermined reference sample point as input. energy detection means; vertical color signal uncorrelated energy detection means for detecting uncorrelated energy of at least one primarily color signal in the vertical direction;
: an integer) and d times the decorrelation energy of the vertical color signal (d: an integer), a first vertical decorrelation energy detection means that selects the larger one and sets it as the vertical decorrelation energy DV1; a second vertically uncorrelated energy detection means that determines the sum of the uncorrelated energy of the vertical luminance signal and the uncorrelated energy of the vertical color signal as vertical uncorrelated energy DV2; and at least DV1≧m When the inequality ×DH2 (m: an integer) holds true, a color signal extraction means that makes the final color signal the first color signal; color signal extraction means for setting a color signal as the second color signal; and color signal extraction means for setting a final color signal as the third color signal when the inequality does not hold. Luminance signal chrominance signal separation filter.