JPH06351041A - Device for separating brightness signal and chrominance signal - Google Patents

Abstract

PURPOSE:To normally separate a chrominance signal and a brightness signal, to reduce the cross color of a video signal and to improve picture quality by detecting the correlation between the lines of PAL signals in a correlation detection circuit, selecting an optimum comb filter and separating a chrominance signal. CONSTITUTION:A mixing circuit 310 generates a chrominance signal by using the output signal of a third comb filter 309 when it is detected that the video signal of a line to be noticed and the video signal before and after the signal are high in a correlation by a correlation detection circuit and it is detected that a phase difference is a prescribed value or below by a phase detection circuit. Because cross color generates only if the third comb filter 309 is used when it is detected that the correlation of the video signal of the line to be noticed and the video signal before and after the signal is high in the correlation detection circuit and it is detected that the phase difference exceeds the prescribed value in a phase detection circuit, the chrominance signal is generated by using the output signals of first and second comb filters 307 and 308. Therefore, even if the video signals where colors change between scanning lines are inputted, cross color is drastically reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a luminance signal / color signal separating apparatus for separating a luminance signal and a color signal from a composite PAL signal.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing the overall configuration of a conventional luminance signal / color signal separation device for separating a luminance signal and a color signal from a composite PAL signal. In FIG.
The input terminal 101 is a terminal for inputting a composite PAL signal. 1H memory 102, 103, 104, 10
Reference numeral 5 is a memory that delays the input signal by one horizontal period (1H), and the input terminal 1 is connected to the 1H memory 101, and the 1H memories 102 to 105 are connected in series in this order. Here, the video signal input to the input terminal 101 is V1, and the 1H memories 102, 103, 10
The video signals output by 4, 105 are respectively V2, V3, V
4 and V5.

Correlation detection circuit 106 outputs video signals V1, V
2, V3, V4 and V5 are input respectively and each video signal V1
It is a circuit for detecting the correlation of patterns in V5, and its output is given to a switching circuit described later.

The adder 107 is a circuit for adding the video signals V1 and V3. Similarly, the adder 108 outputs the video signal V2
V4 is a circuit for adding, and the adder 109 is a video signal V
This is a circuit for adding 3, V5. Adders 107 and 10
The outputs of 8 and 109 are given to the multipliers 110, 111 and 112, respectively.

The multiplier 110 is a circuit for amplifying the signal of the adder 107 with an amplification factor of 1/2. Similarly, the multiplier 111 is a circuit that amplifies the signal of the adder 108 at an amplification rate of 1/2, and the multiplier 112 outputs the signal of the adder 109 at an amplification rate of 1/2.
It is a circuit that amplifies with. Here, as shown by the broken line portion, the adder 107 and the multiplier 110 form a comb filter COM1 that generates the luminance signal Y1, and the adder 108 and the multiplier 11
Reference numeral 1 constitutes a comb filter COM2 for generating the luminance signal Y3, and adder 109 and multiplier 112 constitute a comb filter COM3 for generating the luminance signal Y2.

The switching circuit 113, based on the control signal output from the correlation detection circuit 106, has luminance signals Y1, Y2 and Y3.
It is a circuit for selecting and switching any one of the above. That is, the switching circuit 113 selects the luminance signal Y3 when the correlation between the video signals V2 and V4 is strong, and selects the luminance signal Y1 when the correlation between the video signals V1 and V3 is strong, and the correlation between the video signals V3 and V5. If is strong, the luminance signal Y2 is selected.

The filter circuit 114 is a circuit for inputting the video signal V3 output from the 1H memory 103 and the brightness signal output from the switching circuit 113, and separating the video signal to be processed at present into a brightness signal and a color signal. is there. That is, the filter circuit 114 uses the video signal V3 including the luminance signal Y and the color signal C.
Is input via a high-pass band-pass filter (BPF) and a high-pass filter (HPF) not shown. Then, the luminance signal Y selected by the switching circuit 113 from this input signal
Is generated to generate a color signal C, and the color signal C is subtracted from the video signal V3 to newly generate a luminance signal Y. In the filter circuit 114, the luminance signal Y
And the color signal C are output from the output terminals 115 and 116, respectively.

Next, FIG. 7 shows a configuration example of the correlation detection circuit 106. In FIG. 7, input terminals 201, 202, 203,
204 and 205 are the video signals V1, V2, V3 and V of FIG.
4 and V5 are input terminals, respectively, and are high-pass filters (HPF) 206, 207, 208, 209, 210.
Are respectively connected to the input ends of. HPF 206, 207, 2
Reference numerals 08, 209 and 210 are filters that pass signals in the high frequency band including the frequency (about 4.43 MHz) of the color subcarrier in the PAL signal.

Absolute value circuit (ABS) 218, 219, 2
20, 221, 222 are HPFs 206, 207,
It is a circuit which receives the output signals of 208, 209 and 210 and generates an absolute value of the signal. That is, the ABS 218 outputs the video signal | V1 | and the ABS 219 outputs the video signal | V2 |
The ABS 220 produces a video signal | V3 |, the ABS 221 produces a video signal | V4 |, and the ABS 222 produces a video signal | V5 |. Here, the HPF 206 and the ABS 218 form a signal waveform shaping circuit SSC1. Similarly HPF
207 and ABS 219 connect the signal waveform shaping circuit SSC2,
HPF 208 and ABS 220 are signal waveform shaping circuit SSC
3, the HPF 209 and the ABS 221 constitute a signal waveform shaping circuit SSC4, and the HPF 210 and the ABS 222 constitute a signal waveform shaping circuit SSC5.

The subtractor 223 is a circuit for subtracting the video signal | V3 | from the video signal | V1 |. Similarly, the subtractor 22
4 is a circuit for subtracting the video signal | V4 | from the video signal | V2 |, and a subtractor 225 is a circuit for subtracting the video signal | V5 | from the video signal | V3 |. Subtractors 223 and 2
The outputs of 24 and 225 are given to ABSs 226, 227 and 228. ABS 226-228 is ABS 218-2
A circuit for generating an absolute value of an input signal, similar to 22,
Each output is a low pass filter (LPF) 229, 23.
It is given to 0,231. LPF 229, 230, 23
Reference numeral 1 is a filter that passes low frequency components of the input signal, and the respective outputs are given to the comparison circuit 232.

The comparison circuit 232 includes LPF229 and LPF2.
6, a circuit for inputting the signal of the LPF 231 and outputting a control signal for switching based on the magnitude of the signal to the switching circuit 113 of FIG. 6 via the output terminal 233. That is, the comparison circuit 232
Outputs a control signal to select the comb filter COM2 when the output of the LPF 230 is sufficiently small. Otherwise, if the output of the LPF 229 is smaller than the output of the LPF 231, a control signal is output to select the comb filter COM1. The output of LPF 231 is LPF.
If it is smaller than the output of 229, the control signal is output to select the comb filter COM3.

The operation of the conventional luminance signal / color signal separation device having the above-described structure will be described with reference to FIGS. 6 and 7 and FIGS. 8 and 9. As a simple example, FIG. 8A shows an image of one frame in which one red color is drawn from XX to the upper part.
It is a screen in which the solid blue color is displayed at the bottom. Moreover, FIG. 8 (b)
Are the lines L-2, L-1, and L adjacent to the upper part of the red-blue boundary XX, and the three lines adjacent to the lower part of the boundary XX are the lines L-2, L-1, and L, respectively. L + 1,
It is explanatory drawing displayed as L + 2 and L + 3.

Now, assume that a video signal V of the PAL standard including a luminance signal Y and a color signal C is input to the input terminal 101 of FIG. This video signal V is stored in the 1H memories 102, 103,
Video signals V1 to V5 of adjacent five lines in total are output at the same time. If the video signal of the line L that is the current signal processing target is V3,
As shown in FIG. 8B, the video signal on the line L-2 is V5.
And the video signal of line L-1 is V4, line L + 1
Is V2, and the video signal on the line L + 2 is V1.

When these video signals V1, V2, V3, V4, V5 are input to the correlation detection circuit 106 of FIG. 7, the video signal V3 of interest and the video signals V1, V in the vicinity of the vertical direction are inputted.
The correlation with 2, V4 and V5 is detected. Adder 107
The video signals V1 and V3 are input to and the sum thereof is generated. In the PAL signal, since the polarities of the color signals C separated by two lines are inverted, the color signal C is canceled by the adder 107, and only the component of the luminance signal Y is output. The brightness signal with the increased amplitude is halved in amplitude by the multiplier 110, and the brightness signal Y1 having substantially the same amplitude as the original signal is obtained from the comb filter COM1.

Similarly, a luminance signal Y3 synthesized from the video signals V2 and V4 is obtained from the comb filter COM2. Further, a luminance signal Y2 synthesized with the video signals V3 and V5 is obtained from the comb filter COM3.

On the other hand, in the correlation detection circuit 106 shown in FIG. 7, the input terminals 201, 202, 203, 204, 20
The video signals V1, V2, V3, V4, and V5 are input to 5, respectively. The signal shaping circuits SSC1 and SSC2 use the video signal V
The high frequency components (components near the subcarrier frequency) of 1 and V2 are extracted and their absolute values | V1 | and | V3 | are output.

In the PAL signal, the phase of the color signal C separated by two lines is inverted, so if the video signal V of the line of interest is
If the video signal V1 of 3 and the line below this is the same,
The output of the subtractor 223 becomes zero. Further, even if the video signals V1 and V3 have the same luminance signal, the output of the subtractor 223 becomes zero. When the correlation between the video signals V1 and V3 is strong in this way, the output of the subtractor 223 becomes small and AB
The outputs of S226 and LPF 229 are also small.

Subtractor 224, ABS 227, LPF 23
0, the subtractor 225, the ABS 228, and the LPF 231 also operate in the same manner. When the correlation between the video signals V2 and V4 is strong, the output of the LPF 230 becomes small and the video signal V3
When the correlation between V5 and V5 is strong, the output of the LPF 231 is small.

The comparison circuit 232 uses these LPFs 22.
The switching circuit 11 shown in FIG. 6 according to the outputs of 9, 230 and 231.
The control signal is output to 3. Here, the LPF 230 of FIG.
, The correlation detection circuit 106 outputs a control signal to the switching circuit 113 so as to select the comb filter COM2. Otherwise, LPF2
When the output of 29 is smaller than the output of LPF 231, the correlation detection circuit 106 outputs a control signal to the switching circuit 113 so as to select the comb filter COM1. Also, LPF2
If the output of 31 is smaller than the LPF 229, the correlation detection circuit 106 outputs a control signal to the switching circuit 113 so as to select the comb filter COM3.

The switching circuit 113 switches one of the luminance signals Y1, Y2 and Y3 according to the output of the correlation detection circuit 106 and outputs the luminance signal Yn. The filter circuit 114 is
A band-limited color signal C and luminance signal Y are generated from the video signal V3 of interest and the luminance signal Yn output from the switching circuit 113, and output through output terminals 116 and 115, respectively.

A specific operation example of the correlation detection circuit 106 and the switching circuit 113 will be described with reference to FIG. In FIG. 8B, lines L-2 to L are red, and lines L + 1 to L + 3 are blue. If the line with the pixel of interest is L-2 and the video signal on this line L-2 is V3, the color signals C of the video signals V5, V4, V2, and V1 are the same red. In this case, the switching circuit 113 selects the comb filter COM2. If the line with the pixel of interest is L-1, the video signal of this line is considered to be V3. In this case as well, the LPF 23 of FIG.
Since the output of 0 becomes small, the comb filter COM2 is selected in the switching circuit 113.

Next, consider the case where there is a pixel of interest in the line L. As shown in FIG. 8B, when the video signal on the line L is V3, the color signal C of the video signals V5, V4, V3 becomes red and the color signal C of the video signals V2, V1 becomes blue.
In this case, since the video signals V2 and V4 have different colors, they are not the same signal and the output of the LPF 230 becomes large.
Further, since the video signals V3 and V1 have different colors, they are not the same signal, and the output of the LPF 229 becomes large. On the other hand, since the video signals V3 and V5 have the same color, they become the same signal, and the output of the LPF 231 becomes small. In this case, the switching circuit 113 selects the comb filter COM3. Since the video signal V of the same color is used in this way, the color signal C and the luminance signal Y with little deterioration are separated.

Similarly, when there is a pixel of interest in the line L + 1, the output of the LPF 230 and the output of the LPF 231 are large, but the output of the LPF 229 is small. In this case, the comb filter COM1 is selected. Since the video signals of the same color are used here as well, the color signal C and the luminance signal Y with little deterioration are separated.

Furthermore, when the pixel of interest is on the line L + 2 or the line L + 3, the output of the LPF 230 becomes small, and the comb filter COM2 is selected to perform separation with little deterioration. As described above, in the conventional luminance signal color signal separation device, for the video signal as shown in FIG. 8, the comb filters COM1 to COM3 are adaptively switched to separate the color signal C and the luminance signal Y with less deterioration. .

[0025]

However, in the conventional luminance signal chrominance signal separating apparatus configured as described above, when an image having an oblique stripe pattern is input, the luminance signal Y is mixed in the chrominance signal C. However, there is a problem in that the image quality is deteriorated due to cross color. This phenomenon will be described with reference to FIG.

9 (a), (b) and (c) are temporally enlarged portions of the luminance signal Y of three lines having diagonal stripes. Here, it is assumed that the phase of the luminance signal Y having a high frequency component is inverted line by line. That is, assuming that the luminance signal Y shown in FIG. 9B is the current processing target line L, as shown in FIGS. 9A and 9C, the adjacent upper line L-1 and lower adjacent line L + 1 are ,
The phase is inverted in the positive and negative directions with respect to the luminance signal Y on the line L, respectively.

When such a video signal V is input to the correlation detection circuit 106 of FIG. 7, the video signals V2 and V4 are the same, so the output of the subtractor 224 becomes small. Then, the switching circuit 113 in FIG. 6 selects the comb filter COM2. The luminance signal Y3 thus obtained is as shown in FIG. 9 (d). That is, the polarity of the luminance signal Y3 is inverted from that of the luminance signal Y of the line of interest in FIG. When the switching circuit 113 outputs the luminance signal Y which is the inverse of the original luminance signal, the color signal C becomes the original video signal (FIG. 9B).
9 (d), the chrominance signal C generated here has twice the amplitude of the original luminance signal Y as shown in FIG. 9 (e). Very large cross color results.

The present invention has been made in view of the above-mentioned conventional problems, and when a video signal V of a PAL standard is input with a striped video signal V, the brightness is obtained by using a comb filter. It is an object of the present invention to realize a luminance signal / color signal separation device that separates the signal Y from the color signal C and prevents the output level thereof from exceeding the original video signal level even if cross color occurs.

[0029]

The invention according to claim 1 of the present application is a luminance signal color signal separation device for inputting a PAL standard video signal and separating it into a luminance signal and a color signal. The first comb filter for inputting the video signal and the video signal after two lines to separate it into the luminance signal and the carrier color signal, the video signal for the line of interest and the video signal for two lines before, respectively, and the luminance signal And a carrier color signal, and a third comb filter for inputting the video signal of the line of interest and the video signals one line before and one line after, respectively, and separating the luminance signal and the carrier color signal. And whether or not the phase difference between the high-frequency components of the video signal of the line of interest and the video signal one line before, and the video signal of the line of interest and the video signal one line after, exceeds a predetermined value. Phase detection circuit and focus And a video signal of a line of interest in the correlation detection circuit, which detects the correlation between the video signal of one line and the video signals of two lines before and after that line, and the correlation of the video signal of one line before and after that line. When it is detected that the correlation with the video signal after two lines is high,
When a color signal is generated using the output signal of the first comb filter and it is detected that the video signal of the line of interest and the video signal of the line two lines before are detected to be highly correlated, the output signal of the second comb filter When a color signal is generated using, the correlation detection circuit detects a high correlation between the video signal of the line of interest and the preceding and subsequent video signals, and the phase detection circuit detects that the phase difference is less than or equal to a predetermined value. A color signal is generated using the output signal of the third comb filter, and when the phase detection circuit detects that the phase difference exceeds a predetermined value, the color signal is output using the output signal of the first or second comb filter. And a filter circuit that generates a luminance signal using the color signal output from the mixing circuit and the video signal of the line of interest.

In the invention of claim 2 of the present application, the phase detection circuit includes a first adder for adding the video signal of the line of interest and the video signal of the line located thereafter, and the video signal of the line of interest and its A second adder that adds the video signals of the lines located in the front and a first adder that outputs true if the absolute value of the output of the first adder is less than the threshold value, and outputs false if the absolute value is greater than or equal to the threshold value. And a second comparator that outputs true if the absolute value of the output of the second adder is less than the threshold and outputs false if the absolute value of the output of the second adder is greater than or equal to the threshold, and the first and second comparators. And an OR circuit that outputs a logical sum of the outputs of the above as a phase detection signal.

In the invention of claim 3 of the present application, the correlation detection circuit includes a first subtractor for calculating a difference value between absolute values of the video signal of the line of interest and the video signals of the lines located two lines behind. A second subtractor for calculating a difference between absolute values of the video signal of the line of interest and the video signals of the front and rear lines, and the video signal of the line of interest
The magnitudes of the low-frequency components of the output absolute values of the first to third subtractors are compared with the third subtracter that calculates the difference value of the absolute values of the video signals of the lines located before the line. And a comparison circuit that determines whether the correlation between the line of interest and two lines before or after the line of interest is high, or whether the correlation before and after the line of interest is high.

[0032]

According to the present invention having such characteristics, the PA
When the L standard video signal is given, the first comb filter uses the video signal of the line of interest and the video signal of two lines later to separate it into a luminance signal and a carrier color signal. Similarly, the second comb filter uses the video signal of the line of interest and the video signal two lines before, and the third comb filter uses the video signal of the line of interest and the video signals one line before and one line before,
Each of them is separated into a luminance signal and a carrier color signal. The phase detection circuit is configured such that the phase difference between the high frequency components of the video signal of the line of interest and the video signal one line before, and the high frequency components of the video signal of the line of interest and the video signal one line after, has a predetermined value. Detects whether or not it exceeds. Further, the correlation detection circuit detects the correlation between the video signal of the line of interest and the video signals of the two lines before and after the line, and the correlation between the video signal of the line of interest and the video signals of the lines before and after the one line. Next, the mixing circuit generates a color signal using the output signal of the first comb filter when the correlation detection circuit detects a high correlation between the video signal of the line of interest and the video signal of two lines after. . Further, when it is detected that the video signal of the line of interest and the video signal of the line two lines before have a high correlation, the mixing circuit generates a color signal using the output signal of the second comb filter. Furthermore, the mixing circuit detects that the correlation detection circuit detects a high correlation between the video signal of the line of interest and the preceding and succeeding video signals, and the phase detection circuit detects that the phase difference is less than or equal to a predetermined value. A color signal is generated using the output signal of the filter. If the correlation detection circuit detects that the video signal of the line of interest and the preceding and following video signals have a high correlation, and the phase detection circuit detects that the phase difference exceeds a predetermined value, the third comb filter is used. If used, cross color will occur, so the first or second
A color signal is generated by using the output signal of the comb filter.
In this way, even if a video signal whose color changes between scanning lines is input, the cross color is greatly reduced.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A luminance signal / color signal separating apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of the luminance signal / color signal separation device of this embodiment. In the figure, an input terminal 301 is a terminal for inputting a composite PAL signal, and the 1H memory 3
02 is connected to the input terminal. 1H memory 302, 30
Reference numerals 3, 304 and 305 denote memories that delay the input signal by one horizontal period (1H), and are connected in series in this order.
The video signal of the input terminal 301 is S1, and the 1H memory 30
The video signals output by 2, 303, 304, and 305 are S2, S3, S4, and S5, respectively.

The correlation determination circuit 306 is composed of a correlation detection circuit 306a and a phase detection circuit 306b as described later. The correlation detection circuit 306a is the correlation detection circuit 1 of the conventional example.
Similar to 06, this is a circuit for inputting the video signals S1, S2, S3, S4, S5, respectively, and detecting the correlation of the patterns in each of the video signals S1 to S5, and the output is given to the mixing circuit described later.

The first comb filter 307 is a circuit for inputting the video signals S1 and S3 and separating them into a luminance signal Y and a chrominance signal C of a line to be subjected to signal processing, like the comb filter COM1 of the conventional example. is there. However, in this embodiment, the color signal C
Will be described only. Similarly to the comb filter 307, the second comb filter 308 is a circuit that inputs the video signals S3 and S5 and separates them into a luminance signal Y and a color signal C. Third
The comb filter 309 is a circuit that inputs the video signals S2, S3, and S4 and separates them into a luminance signal Y and a color signal C.

Circuit diagrams of the comb filters 307, 308 and 309 are shown in FIGS. 2A, 2B and 2C, respectively. In the comb filter 307 of FIG. 2A, the input terminal 40
Reference numerals 1 and 402 denote input terminals for the video signals S1 and S3, respectively. The subtractor 403 is a circuit that subtracts S1 from the video signal S3, and its output is given to the multiplier 404. The multiplier 404 is a circuit that amplifies the output signal of the subtractor 403 with an amplification factor of 1/2, and its output is output from the output terminal 405.

In the comb filter 308 shown in FIG. 2 (b), input terminals 406 and 407 have video signals S3 and S, respectively.
5 input terminals. The subtractor 408 is a circuit that subtracts S5 from the video signal S3, and its output is given to the multiplier 409. The multiplier 409 is a circuit for amplifying the output signal of the subtractor 408 with an amplification factor of 1/2, and its output is output terminal 4
It is output from 10.

In the comb filter 309 shown in FIG. 2C, the input terminals 411, 412, 413 are input terminals for the video signals S2, S4, S3, respectively. The adder 414 is a circuit that adds the video signals S2 and S4, and the output thereof is given to the multiplier 415. The multiplier 415 is an adder 414
Is a circuit that amplifies the output signal of 1 at an amplification rate of 1/2, and its output is given to the subtraction input terminal of the subtractor 416. The subtractor 416 calculates the multiplier 4 from the video signal S3 at the input terminal 413.
This is a circuit for subtracting the output signal of 15 and its output is output from the output terminal 417.

FIG. 3 is a circuit diagram showing another configuration example of the comb filter 309. In this figure, input terminals 421, 42
Reference numerals 2 and 423 are input terminals for the video signals S2, S4 and S3, respectively. The subtractor 424 is a circuit that subtracts S4 from the video signal S2. The adder 425 is a circuit that adds the video signals S2 and S4. The multiplier 426 is a circuit that amplifies the output signal of the subtractor 424 with an amplification factor of 1/2, and its output is given to the shift circuit 427. The multiplier 428 is a circuit that amplifies the output signal of the adder 425 with an amplification factor of 1/2.
The output is given to the subtraction input terminal of the subtractor 429. The subtractor 429 is a circuit that subtracts the output signal of the multiplier 428 from the video signal S3 of the input terminal 423.

The shift circuit 427 shifts the phase of the input signal by 90 degrees.
The circuit that shifts the output is provided to the adder 430. The adder 430 is a circuit that adds the output signal of the shift circuit 427 and the output signal of the subtractor 429. The multiplier 431 amplifies the output signal of the adder 430 with an amplification factor of 1/2, and its output is given to the output terminal 432.

Next, the correlation determination circuit 306 of FIG. 1 will be described with reference to FIGS. FIG. 4 shows the correlation detection circuit 306.
5A is a block diagram showing the configuration of the phase detection circuit 306b. In these figures, input terminals 501, 50
2, 503, 504, and 505 are video signals S1 and S, respectively.
Input terminals for inputting 2, S3, S4 and S5. HP
F506, 507, 508, 509, and 510 are high-pass filters that receive the video signals S1, S2, S3, S4, and S5, respectively, and pass the high-frequency components including the subcarrier frequencies of the color signals.

Further, the first adder 511 of FIG.
7 and 508, the second adder 512 outputs the HPF50
This is a circuit that adds the outputs of 8 and 509.
Given to 13,514. ABSs 513 and 514 are circuits that generate absolute values of signals from the adders 511 and 512. The first comparator 515 is a circuit that compares the output signal of the ABS 513 with a threshold value that is input from the outside.
If the output signal of 3 is less than the threshold value, it is an H level signal, and if it is more than the threshold value, it is an L level signal. The second comparator 516 is also a circuit that compares the output signal of the ABS 514 with a threshold value, and is a circuit that outputs an H level signal when the output signal of the ABS 514 is less than the threshold value and an L level signal when the output signal of the ABS 514 is greater than or equal to the threshold value. The OR circuit 517 is a circuit that ORs the outputs of the comparators 515 and 516.

In FIG. 4, ABSs 518, 519, 5
20, 521, 522 are HPFs 506, 507,
It is a circuit that inputs signals of 508, 509, and 510, respectively, and generates an absolute value of the signals. The first subtractor 523 is a circuit that subtracts the output signal of the ABS 520 from the output signal of the ABS 518. The second subtractor 524 is also the ABS 51
9 is a circuit that subtracts the output signal of ABS 521 from the output signal of 9. The third subtractor 525 is a circuit that subtracts the output signal of the ABS 522 from the output signal of the ABS 520.

ABSs 526, 527 and 528 are circuits for generating the absolute values of the output signals of the subtracters 523, 524 and 525, and their outputs are LPFs 529 and 53, respectively.
0,531. LPF 529, 530, 53
Reference numeral 1 is a low-pass filter that passes low-frequency components from the signals of ABS526, 527, and 528, respectively.

The comparison circuit 532 is a circuit for outputting the mixing control signal to the mixing circuit 310 of FIG. 1 through the output terminal 533 based on the magnitude of the output signal of the OR circuit 517 and the signals output by the LPFs 529, 530, 531. is there. That is, in the comparison circuit 532, the output of the OR circuit 517 is at the L level, and the output of the LPF 530 is the LPF 529 or 531.
If it is smaller than the output of, the mixing control signal for increasing the mixing ratio of the output signal of the comb filter 309 is output.
Also, regardless of the output level of the OR circuit 517, the LPF5
When the output signal of 29 is the minimum compared with the LPFs 530 and 531, the mixing control signal for increasing the mixing ratio of the output signal of the comb filter 307 is output. Similarly, OR circuit 5
Regardless of the output level of 17, the mixing control signal for increasing the mixing ratio of the output signal of the comb filter 308 is output when the output signal of the LPF 531 becomes the minimum. Further LP
Even if the output of F530 is the minimum, if the output of the OR circuit 517 is at H level, the output of the comb filter 309 is not used and the mixing control signal for mixing the output signals of the comb filters 307 and 308 is output.

Next, in the circuit shown in FIG. 1, the color signals separated by the comb filters 307, 308, 309 are converted into C1,
Let C2 and C3. The mixing circuit 310 is the correlation determination circuit 30.
The color signals C1 and C
This circuit controls the mixing ratio of C2 and C3 and performs weighted addition of color signals.

The filter circuit 311 inputs the color signal C output from the mixing circuit 310 and the video signal S3 output from the 1H memory 303, filters the signal frequency component using the built-in HPF and BPF, and also outputs the luminance signal Y. And a color signal C and outputs a luminance output Y from an output terminal 313. The color demodulation circuit 312 inputs the color signal C output from the filter circuit 311 and separates it into color difference signals U and V. The color difference signal U is output from the output terminal 314 and the color difference signal V is output terminal 3.
It is a circuit that outputs from 15.

The operation of the luminance signal / chrominance signal separation device having the above configuration will be described. Input terminal 301 of FIG.
When the PAL standard video signal V including the luminance signal Y and the color signal C is input, the video signal V is stored in the 1H memory 30.
2, 303, 304, and 305 are input in this order, and video signals S1 to S5 of adjacent 5 lines in total are simultaneously obtained.
Here, the video signal of the line L which is the current target of the signal processing is S3.

The comb filter 307 controls the video signals S1 and S3.
From the luminance signal Y1 and the color signal C1. Figure 2
In the comb filter 307 shown in (a), the input terminal 4
When the video signals S1 and S3 are input to 01 and 402, respectively, in the PAL signal, the phases of the color signals separated by two lines are inverted, so that the subtractor 403 cancels the luminance signal component and increases the amplitude. Only the signal component is output. The amplitude of this signal is halved by the multiplier 404, and the color signal C1 having the same amplitude as the color signal C of the input terminal 301 is output.
Is output from the comb filter 307.

Similarly, the video signals S3 and S5 are shown in FIG.
The color signals C2 are input to the comb filters 308 shown in (b) and output from the output terminal 410.

On the other hand, the video signals S2, S3 and S4 are shown in FIG.
They are respectively input to the comb filter 309 shown in (c). In the adder 414, the video signals S2 and S4 are added to cancel the component of the color signal C. Further, since the component of the luminance signal Y is doubled in the adder 414, it is converted into the luminance signal Y having the same amplitude as the original signal by the multiplier 415. When the luminance signal Y is input to the subtractor 416, the input terminal 41
3 is subtracted from the video signal S3 (Y + C), and the color signal C3 of the signal line of interest is output.

Next, the operation when the comb filter 309 is configured by the circuit shown in FIG. 3 is performed by the video signals S2, S4 and S3.
Of these, the video signals S2 and S4 are signals separated by two lines, and therefore the output of the subtractor 424 is only the color component having the increased amplitude. Then, the amplitude is halved by the multiplier 426, and the color signal C3a having the same amplitude as the original signal is generated.

On the other hand, the output of the adder 425 becomes a luminance signal with increased amplitude, and the amplitude is halved by the multiplier 428,
A luminance signal Y3 having the same amplitude as the original signal is generated. Further, in the subtractor 429, the luminance signal Y3 of the multiplier 428 is subtracted from the processing target video signal S3 input from the input terminal 423 to generate a color signal C3b.

Now, the color signal C3a output from the multiplier 426.
Has a phase difference of 90 degrees with respect to the color signal C3b. Therefore, when the phase of the color signal C3a is changed by 90 degrees by the shift circuit 427 and the color signal C3b is added by the adder 430, a color signal C3 having the same phase as the color signal of the target line and increased in amplitude is obtained. When this signal is applied to the multiplier 431, the amplitude is halved, and the color signal C3 having substantially the same amplitude as the original signal is obtained from the output terminal 432.

Color signals C1 and C separated in this way
2, C3 are input to the mixing circuit 310 of FIG. Then, the mixing circuit 310 weights the output signals of the comb filters 307, 308, and 309 according to the output of the correlation determination circuit 306, and adds the signals.

Now, the correlation detection circuit 306a shown in FIG. 4 has five adjacent lines of video signals S1, S2, S3, S4, S5.
Respectively. These video signals S1 to S5 are HPF.
506 to 510, the high frequency component including the carrier color signal is extracted. Here, the correlation detection circuit 306a performs the same operation as the correlation detection circuit 106 shown in FIG.

In the phase detection circuit 306b of FIG. 5, the adder 511 adds the high frequency component video signals S2 and S3, and the ABS circuit 513 calculates the absolute value | S3 + S2 |. This value is input to the comparator 515, and the threshold value 1 and its magnitude are compared, for example. Absolute value | S3 + S2 | is threshold 1
If it is smaller, the comparator 515 outputs a signal of H level (1).

Further, the adder 512 adds the high frequency component video signals S3 and S4, and the ABS 514 outputs the absolute value | S.
3 + S4 | is calculated. Absolute value | S3 + S4 | is threshold 1
If it is smaller than the above, the comparator 516 outputs the H level (1).
Signal is output.

Next, the operation of the comparison circuit 532 of FIG. 4 will be described. The comparison circuit 532 includes LPF529 and LPF5.
30, comparing the magnitude of the output of LPF531, LPF52
When the output of 9 is the smallest, the comb filter 30 of FIG.
The mixing circuit 310 is controlled so that the mixing ratio of 7 becomes large. When the output of the LPF 531 is the smallest, the comparison circuit 532 controls the mixing circuit 310 so that the mixing ratio of the comb filter 308 becomes large. Also, LPF53
The output of 0 is the smallest, and the output of the OR circuit 517 is L
In the case of level (0), the comparison circuit 532 controls the mixing circuit 310 so that the mixing ratio of the comb filter 309 increases.

Video signals S2, S3, S inputted here
If 4 is a signal having a phase as shown in FIGS. 9A to 9C, the output of the adder 511 or the adder 512 has a very small value. In such a case, the output of the comparator 515 or the comparator 516 becomes H level, and the OR circuit 517
Output also goes high. This occurs when the phase of the video signal S is inverted in the line above or below the line L. Even if the output of the LPF 530 is the smallest, since the output of the OR circuit 517 is at the H level, the comparison circuit 532
The video signals S2, S3 and S4 are as shown in FIGS.
It is determined that the state is as shown in (c), and the comb filter 309
Of the comb filter 307 or the comb filter 308 without selecting the output of the mixing circuit 31.
Control 0. In this case, the sizes of the LPFs 529 and 531 are compared. If the output of the LPF 529 is small, the mixing ratio of the comb filter 307 is increased, and if the output of the LPF 531 is small, the mixing ratio of the comb filter 308 is increased.

The filter circuit 311 shown in FIG. 1 has a video signal S3 of interest and a color signal C output from the mixing circuit 310.
Is input, and a luminance signal Y and a band-limited color signal C are output. The generated luminance signal Y is output from the output terminal 313, and the color signal C is input to the color demodulation circuit 312 and demodulated into two color difference signals U and V. The color difference signals U and V are output from the output terminals 314 and 315, respectively.

By using the correlation determination circuit 306 as described above, the comb filter 309 is used when the neighboring pixel having the strongest correlation is used and the high frequency component video signal is inverted for each line as shown in FIG. Not to use the mixing circuit 31
Control 0.

[0063]

As described in detail above, according to the present invention, the correlation detection circuit detects the correlation between lines of the PAL signal and selects the optimum comb filter to separate the color signals. ing. Therefore, even when a high-frequency video signal whose phase is inverted or close to inversion is input for each line, the color signal and the luminance signal are normally separated, and the cross color of the video signal is reduced. The effect of improvement becomes greater.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a luminance signal / color signal separation device according to an embodiment of the present invention.

FIG. 2 is a block diagram (No. 1) showing a configuration of a comb filter used in the luminance signal / chrominance signal separation device of the present embodiment.

FIG. 3 is a block diagram (No. 2) showing the configuration of a comb filter used in the luminance signal / chrominance signal separation device of the present embodiment.

FIG. 4 is a block diagram showing a configuration of a correlation detection circuit used in the luminance signal / chrominance signal separation device of the present embodiment.

FIG. 5 is a block diagram showing a configuration of a phase detection circuit used in the luminance signal / color signal separation device of the present embodiment.

FIG. 6 is a block diagram showing an example of the overall configuration of a conventional luminance signal / color signal separation device.

FIG. 7 is a block diagram showing a configuration of a correlation detection circuit used in a conventional luminance signal / color signal separation device.

FIG. 8 is an explanatory diagram (No. 1) showing the operation of the luminance signal and color signal separation device according to the present invention.

FIG. 9 is an explanatory diagram (No. 2) showing the operation of the luminance signal / color signal separation device of the present invention and the conventional method.

[Explanation of symbols]

301, 401, 402, 406, 407, 411-4
13, 421-423501-505 Input terminal 302-305 1H memory 306 Correlation determination circuit 306a Correlation detection circuit 306b Phase detection circuit 307-309 Comb filter 310 Mixing circuit 311 Filter circuit 312 Color demodulation circuit 313-315, 405, 410, 417 , 432, 5
33 output terminals 403, 408, 416, 424, 429, 523-5
25 Subtractor 414, 425, 430, 511, 512 Adder 427 Shift circuit 404, 409, 415, 426, 428, 431 Multiplier 506-510 HPF 513, 514, 518-522, 526-528 Absolute value circuit 529- 531 LPF 515, 516 Comparator 517 OR circuit 532 Comparison circuit

Claims (3)

[Claims] 1. A luminance signal color signal separation device for inputting a PAL standard video signal to separate it into a luminance signal and a color signal, wherein a video signal of a line of interest and a video signal of two lines after are input respectively. , A first comb filter that separates a luminance signal and a carrier color signal, and a second comb filter that inputs a video signal of the line of interest and a video signal two lines before, respectively, and separates the brightness signal and the carrier color signal And a third comb filter for inputting the video signal of the line of interest and the video signals one line before and one line before, respectively, and separating it into a luminance signal and a carrier color signal, and a video signal of the line of interest and one line before A video signal, and a phase detection circuit that detects whether or not the phase difference between the high-frequency components of the video signal of the line of interest and the video signal one line later exceeds a predetermined value, and the video signal of the line of interest 2 lines before Correlation detection circuit for detecting the correlation with the video signal of the line and the correlation of the video signals of the lines before and after one line, and the correlation between the video signal of the line of interest in the correlation detection circuit and the video signal after two lines If it is detected that
When a color signal is generated using the output signal of the first comb filter and it is detected that the video signal of the line of interest and the video signal of the line two lines before are detected to be highly correlated, the color signal of the second comb filter is detected. A color signal is generated using the output signal, the correlation detection circuit detects that the video signal of the line of interest has a high correlation with the preceding and subsequent video signals, and the phase detection circuit detects that the phase difference is less than or equal to a predetermined value. In the case of being detected, a color signal is generated using the output signal of the third comb filter, and when the phase detection circuit detects that the phase difference exceeds a predetermined value, the color signal of the first or second comb filter is generated. A luminance comprising: a mixing circuit that generates a color signal using an output signal; and a filter circuit that generates a luminance signal using a color signal output from the mixing circuit and a video signal of a line of interest. Signal color signal separation device Place 2. The phase detection circuit includes: a first adder that adds a video signal of a line of interest and a video signal of a line located after that; and a video signal of the line of interest and a line located before it. A second adder that adds the video signals; a first comparator that outputs true if the absolute value of the output of the first adder is less than a threshold value and a false value if it is greater than or equal to the threshold value; A second comparator that outputs true if the absolute value of the output of the second adder is less than the threshold value, and outputs false if the absolute value of the output is greater than or equal to the threshold value; and outputs of the outputs of the first and second comparators. The luminance signal / color signal separation device according to claim 1, further comprising an OR circuit that outputs a logical sum as a phase detection signal. 3. The correlation detection circuit, a first subtractor for calculating the difference value of the absolute value of the video signal of the line of interest and the video signal of each line located two lines later, and the video of the line of interest A second subtractor that calculates the difference between the absolute value of the video signal and the absolute value of the video signals of the front and rear lines, and the absolute value of the video signal of the line of interest and the video signals of the lines located two lines before. A third subtractor for calculating a difference value of the values and the magnitude of the low frequency components of the output absolute values of the first to third subtractors are compared, and the line of interest and two lines before or after the line of interest are compared. The luminance signal color signal separation device according to claim 1, further comprising: a comparison circuit that determines whether the correlation with a line is high or the correlation before and after the line of interest is high.