JPS63206089A - Y/c separating device - Google Patents

Abstract

PURPOSE:To remove the interference of a cross-color and a dot crawling by detecting a vertical correlation and a horizontal correlation, and selecting and outputting a luminance signal and a chroma signal separated by plural Y/C separating systems in accordance with respective correlation detecting outputs. CONSTITUTION:A complex video signal COMP 3 sampled by the 4-fold frequency of a color sub-carrier frequency is supplied to a frequency matching and deviating type Y/C separating part 15 and a luminance signal YF aud a chroma signal CF separated in accordance with a frequency separating system are outputted. The COMP 3 is fed to a vertical correlation type Y/C separating part 17, one of respective types of the comb line filter separating system is selected in accordance with the extent of the vertical correlation and the direction with the vertical correlation and a luminance signal YC and a chroma signal CC are sent to a switch circuit 16. On the other hand, a horizontal correlation flag HF is supplied from a horizontal correlation detecting circuit 19 to the switch circuit 16, and when the horizontal correlation exists, separating signals YF and CF of a frequency separating part 15 are selected and outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a Y/C separation device, and is particularly suitable for application to a two-dimensional application type device that performs in-field processing.

[Prior Art] Conventionally, Y/C separation methods include a frequency separation method that uses the frequency spectrum of a composite video signal to separate a luminance signal and a chrominance signal on the frequency axis using, for example, a band pass filter and a low pass filter; There is a comb filter separation method that separates a luminance signal and a chrominance signal using the correlation between signal lines.

Each of these re-separation methods is different from the frequency separation method.In screen conditions where the luminance signal contains high-frequency components near the color subcarrier frequency, leakage occurs between the color signal and the luminance signal, resulting in so-called cross-color deterioration in image quality. The comb filter separation method has the disadvantage that the separation is insufficient due to the collapse of the correlation that is the premise of this method, resulting in deterioration of image quality called dot crawl, where dots flow at the edges of the image. have

Therefore, in the past, Y/C separation circuits of both types were provided in parallel, and a suitable method was selected depending on the horizontal correlation and vertical correlation. As a horizontal correlation detection circuit and a vertical correlation detection circuit that perform switching between such separation methods, the seventh
The ones shown in Fig. 8 and Fig. 8 were used.

In FIG. 7, 4 of the color subcarrier frequency fSC is
The composite video signal COMP1 sampled at the double frequency 4fSC with the phase aligned with the BY axis is applied to a delay stage 5 formed by cascade-connecting delay circuits 1 to 4 which delay the signal by a sampling period. Here, since sampling is performed as described above, in the horizontal direction, for example, the 9th
Components Y- (B-Y), Y+ (R-Y
), Y+(B-Y), Y-(R-Y) are repeatedly sampled, and the input video signal COMP1 is
<Do) and the video signal (DK) outputted via the final stage delay circuit 4 have the same phase by adding or subtracting the same color difference signal to the luminance signal.

Note that point PM is the point of interest.

Therefore, the horizontal correlation detection circuit subtracts the in-phase portion of the video signal in a subtraction circuit 6, converts it into an absolute value via an absolute value circuit 7 to obtain a difference DIF, and converts this difference DIF into a comparison circuit 1.
2, a horizontal correlation signal COH is obtained by comparing it with the reference signal REF.

In the vertical correlation detection circuit, as shown in FIG. 8, the composite video signal COMP2 is applied to a delay stage 10 formed by vertically connecting delay circuits 8 and 9 which delay the signal by one horizontal scanning period. Here, since sampling is performed as described above, the data DH, DR which has a color difference signal component that is the same as the color difference signal component of the point of interest and whose phase is opposite to the color difference signal component of the point of interest.
are obtained before and after the data DM of the point of interest in the vertical direction. Therefore, the vertical correlation detection circuit 11 obtains a luminance signal above the point of interest from the data DM and DH, obtains a luminance signal below the point of interest from the data DR and DM, and compares the difference between these luminance signals with a reference value. The vertical correlation signal COv is obtained in this manner.

[Problems to be Solved by the Invention] However, since the conventional horizontal correlation detection circuit detects correlation using the in-phase component of the video signal,
Information about the video signals between these in-phase video signals is not used, and there is a risk that the correlation detection output may cause misjudgment. That is, for example, 2 of the color subcarrier frequency fsc
When black and white are inverted at double the frequency, the in-phase video signals both have a black level and a correlated detection output is sent out, but since there is a white level in the middle, there is no correlation and a false detection output is sent out. I'll send it out. Further, according to the conventional apparatus, a video signal at a position distant from the video signal of the point of interest is used for correlation detection, and the detection accuracy is also low from this point of view.

In addition, conventional vertical correlation detection circuits can only detect the presence or absence of vertical correlation, and cannot detect the direction of vertical correlation or the degree of correlation. It cannot be applied to anything.

Therefore, even if a separated signal is selected based on the detection outputs of the horizontal correlation detection circuit and the vertical correlation detection circuit, the horizontal correlation detection accuracy and the vertical correlation detection accuracy are low, resulting in image quality deterioration such as cross color and dot crawl. was left behind.

The present invention has been made in consideration of the above points, and it strictly detects horizontal correlation and vertical correlation and appropriately switches the separation method, without increasing cross color interference and without degrading vertical resolution. An object of the present invention is to provide a Y/C separation device capable of removing vertical dot crawl.

[Means for solving the problem] In order to solve the problem, in the present invention, a plurality of Y/Y signals, at least one of which separates a luminance signal and a chroma signal from a composite video signal, follow a frequency separation method.
The data of the composite video signal sampled at four times the color subcarrier frequency and in phase with one of the color difference signal component axes is input to the C separation unit, and five consecutive points in the vertical direction centering on the point of interest are input. a vertical correlation detection circuit that detects vertical correlation from the above data; a first separation section selection means that selects one of the Y/C separation sections based on the detection output of the vertical correlation detection circuit; , a horizontal correlation detection circuit that detects horizontal correlation from data of five or more consecutive points in the horizontal direction centered on the point of interest, and a first A first method for validating the Y/C separator selected by the separator selection means and, when there is a horizontal correlation, invalidating the selection by the first separator selection means and selecting a Y/C separator according to the frequency separation method. 2 separation section selection means.

[Operation] The vertical correlation detection circuit and the horizontal correlation detection circuit each accurately detect correlation using data at five or more points in the respective directions. The first separation section selection means selects an appropriate Y/C separation section from the plurality of Y/C separation sections based on the detection output of the vertical correlation detection circuit, and the second separation section selection means selects an appropriate Y/C separation section from the plurality of Y/C separation sections based on the detection output of the vertical correlation detection circuit. Based on the detection output of the circuit, if there is no horizontal correlation, the first
If there is a horizontal correlation, the selection of the first separation section selection means is made valid, and when there is a horizontal correlation, the selection of the first separation section selection means is made invalid and a Y/C separation section according to the frequency separation method is selected.

As a result, since correlation detection is strictly performed, switching due to false detection is reduced and an appropriate separation section can be selected according to the image, reducing image quality deterioration such as cross color and dot crawl. be able to. Further, since the horizontal direction correlation, which is easy for humans to identify changes, is prioritized for switching, it is possible to obtain an image that is easy for the user to view.

[Example] Hereinafter, an example of the Y/C separation device according to the present invention will be described in detail with reference to the drawings.

(Basic Configuration) FIG. 1 shows the basic configuration of the present invention. In FIG. 1, a composite video signal COMP3 sampled at a frequency four times the color subcarrier frequency fsc and aligned in phase with one color difference signal component axis is applied to the Y/C separation device. This video signal COMP3 is given to the frequency separation section 15 and separated into a luminance signal YF and a chroma signal CF according to the frequency separation method, and the switch circuit 16
given to. Further, the video signal COMP3 is given to a vertical correlation detection type Y/C separator 17 to determine the degree of vertical correlation.
One of various comb filter separation methods is selected depending on the direction of vertical correlation and the degree of vertical correlation, and the luminance signal YC and chroma signal CC are separated and provided to the switch circuit 16.

The switch circuit 16 is given a horizontal correlation flag HF from the horizontal correlation detection circuit 18, and this correlation flag HF
When the horizontal correlation indicates that there is a horizontal correlation, the separated signals YF and CF are selected by the frequency separator 15, and when the correlation flag HF indicates that there is no correlation, the vertical correlation detection type Y/C separator 17 selects the separated signals YF and CF.
It operates to select the separated signals YC and CC.

Therefore, if there is vertical correlation but no horizontal correlation,
This means that the output of the vertical correlation detection type Y/C separator 17 is not selected, and priority is given to the horizontal correlation. This is actually
This is to further prevent deterioration of the image quality in the horizontal direction because human vision has the property of being able to discern changes in image quality in the horizontal direction with higher sensitivity than changes in image quality in the vertical direction.

Also, unlike conventional devices, the vertical correlation detection circuit and horizontal correlation detection circuit 18 in the vertical correlation detection type Y/C separator 17 are configured to provide vertical data and horizontal data of five or more points before and after the point of interest. is used to accurately detect the correlation, and to appropriately select the output signal.

(Specific configuration of the embodiment) A specific configuration of the embodiment constructed based on this basic configuration is shown in FIG. Composite video signal COMP4 is I
Delay stage 22 formed by cascade-connecting H delay circuits 20 and 21
is given to the point of interest PM and the points PH and P adjacent to the point of interest PM in the vertical direction by this delay stage 22.
Data DH, DM, and DR of R are taken out.

The data DM is given to the subtraction circuit 23 as an input to be subtracted, and the data DH is given to the subtraction circuit 23 as a subtraction input, and after being subtracted in the subtraction circuit 23, it is doubled via the doubling circuit 24 to obtain a luminance signal component. The canceled chroma signal C1 having a predetermined level is obtained and applied to the switch circuit 25 as a first selection input. Further, the data DM is given to the subtraction circuit 26 as an input to be subtracted, and the data DR is given to the subtraction circuit 26 as a subtraction input, and after being subtracted in the subtraction circuit 26, it is doubled via a doubling circuit 27 to produce a luminance signal. A chroma signal C2 whose components are canceled to have a predetermined level is obtained and applied to the switch circuit 25 as a second selection input. Furthermore, subtraction [5J
The subtracted outputs of paths 23 and 26 are added in an adder circuit 28 to obtain a chroma signal C3 in which the luminance signal component is canceled out from the data DH, DM, and DR, and the chroma signal C3 is applied to the switch circuit 25 as a third selection input.

The switch circuit 25 further includes a point of interest PM so as to supply a composite video signal to a subsequent frequency separation section.
The data is multiplied by 4 through the quadrupling circuit 29 and provided as the fourth selection input.

The switch circuit 25 selects an input based on first and second vertical correlation flags VFI and VF2 provided from a vertical correlation detection circuit 32 whose detailed configuration is shown in FIG. 3 via AND circuits 30 and 31.

In other words, if there is a vertical correlation around the line LN that includes the point of interest PM, select the chroma signal C3 obtained from the three lines LN-1 to LN+1 centered on the line LN, and If there is a vertical correlation only below the line LN including the point of interest PM, select the chroma signal C2 obtained from the two lines, the line LN including the point of interest PM and the line LN+1 below it, and select the chroma signal C2 obtained from the line LN including the point of interest PM. If there is a vertical correlation only above the point of interest PM
The chroma signal C1 obtained from two lines, the line LN including the line LN and the line LN-1 above it, is selected, and if there is no vertical correlation, the data of the point of interest PM multiplied by 4 is selected.

In this way, the selection signal selected by the switch circuit 25 is given as a first selection input to the switch circuit 34 via the bandpass filter 33 whose passing center frequency is the color subcarrier frequency fsc.
The signal is directly applied to the switch circuit 34 as a second selection input without passing through the bandpass filter 33. here,
The bandpass filter 33 functions to separate a chroma signal according to a frequency separation method when the incoming signal is data of a composite video signal, and functions to reduce dot crawl when the incoming signal is a chroma signal.

The switch circuit 34 receives the third vertical correlation flag VF3 provided from the vertical correlation detection circuit 32 via the AND circuit 35.
The switching operation is based on the following. The switch circuit 34 selects an input signal that does not go through the band-pass filter 33 when there is a strong vertical correlation, and selects an input signal that goes through the band-pass filter 33 when there is no vertical correlation or when there is some vertical correlation. select.

The output signal from this switch circuit 34 is sent out as an output chroma signal via a bandpass filter 36.

The bandpass filter 36 particularly functions to remove unnecessary components other than the chroma signal component when the vertical correlation is significant.

Further, the output signal from the switch circuit 34 is transmitted to the subtraction circuit 37.
is given as a subtraction input. The subtraction circuit 37 also has
A composite video signal whose phase is synchronized with this chroma signal, that is, data DM of the target point PM, is provided as an input to be subtracted via the quadrupling circuit 38. In this manner, a luminance signal is obtained in the subtraction circuit 37 and output as an output luminance signal. AND circuit 30.31.35
In this case, a horizontal correlation flag HF is selected from the three horizontal correlation detection circuits whose detailed configuration is shown in FIG. Given. Therefore, the AND circuits 30, 31, and 35 close when there is a horizontal correlation, and the vertical correlation flag VFI~
VF3 is made to have the same contents as those without vertical correlation, and is left to Y/C separation by the frequency separation unit in the subsequent stage. In addition, if there is no horizontal correlation, the vertical correlation flags VFI to VF3
to select a chroma signal and a luminance signal using vertical correlation.

The vertical correlation detection circuit 32 has the configuration shown in FIG. 3 so as to be able to select the output signal as described above. The vertical correlation detection circuit 32 in this embodiment uses all of the data DC to DW of the two points PC, PH1PR, and PW before and after the point of interest PM, including the point of interest PM, in order to appropriately switch the Y/C separation method. Detecting vertical correlation.

(Vertical correlation detection circuit 32) In FIG.
OMP5 is a delay circuit 4 that delays by one horizontal scanning period.
1 to 44 are input to a delay stage 45 formed by cascade-connecting the signals DC to DW, and two data DC to DW are obtained in the vertical direction centering on the point of interest PM as shown in FIG.

The data DM is given to the subtraction circuit 46 as an input to be subtracted, and the data DC is given to the subtraction circuit 46 as a subtraction input, and after being subtracted, it is given to the absolute value circuit 47, where it is converted into an absolute value and becomes the difference signal DIFI. It is converted and applied to comparison circuits 48 and 49.

The comparison circuit 48 is also supplied with a reference signal REF1, and takes a logic "0" indicating no correlation when the difference signal DIF1 is greater than the reference signal REF1;
The first correlation signal VCOI, which takes logic "1" indicating that there is a correlation when FI is smaller than the reference signal REFI, is sent to the decoder 5.
Output to 0. On the other hand, the four comparison circuits receive the reference signal R.
A reference signal REF2 smaller than EFI is given,
When the difference signal DIFI is greater than the reference signal REF2, it takes a logic "0" indicating no correlation; on the other hand, when the difference signal DIFI is smaller than the reference signal REF2, it takes a logic "0" indicating there is a correlation.
A second correlation signal VCO2 having the value "1" is output to the decoder 50.

Here, since the difference signal DIFI represents the difference between the data DM at the point of interest PM and the data DC at the point PC above it, the correlation signals VCOI and VCO2 indicate the correlation above the point of interest PM.

Further, the second reference signal REF2 is converted into the first reference signal REF2.
Since it is smaller than I, the first correlation signal VCO1 indicates whether there is a correlation above the point of interest PM, and the second correlation signal VCO1 indicates whether there is a strong correlation above the point of interest PM. This is what the correlation signal VCO2 indicates.

Further, data DH and DR are given to a subtraction circuit 51,
After being subtracted in the subtraction circuit 51, the signal is converted into an absolute value through the absolute value circuit 52, converted into a difference signal DIF2, and is applied to the comparison circuits 53 and 54. Comparison circuits 53 and 54
performs the same operation as the above-mentioned comparison circuits 48 and 49,
Point of interest PM based on the difference signal DIF2 of data in the center
A third correlation signal V indicating whether there is a correlation in the vicinity
A fourth correlation signal VCO4 indicating whether or not there is a strong correlation between CO3 and the vicinity of the point of interest PM is output to the decoder 50.

Further, data DM and DW are given to a subtraction circuit 55,
After being subtracted in the subtraction circuit 55, it is converted into an absolute value through the absolute value circuit 56 and converted into a difference signal DIF3, which is applied to the comparison circuits 57 and 58. Comparison circuits 57 and 58
performs the same operation as the above-mentioned comparison circuits 48 and 49,
The fifth item indicates whether there is a correlation below the point of interest PM.
A sixth correlation signal VC06 indicating whether or not there is a strong correlation below the point of interest PM is output to the decoder 50.

The decoder 50 is composed of, for example, a ROM, and converts the incoming correlation signals VCOI to VCO6 according to the tables TAB1 and TAB2 shown in FIGS. 5 and 6 to convert them into the first to third correlation flags VFI to VF3 described above.
Output.

The decoder 50 performs a conversion operation based on the following design concept. The correlation shown by the correlation signals VC01 to VCO6 is
The correlation COU above the point of interest PM, the neighborhood of the point of interest PM (
Table TAB
1, as shown in column CL1. Here, "x" indicates no correlation, "O" indicates correlation, and "." indicates strong correlation.

Based on the information in this column CLI, Y/C as follows
Decide on the separation method.

(1) If there is no correlation in the center, select the Y/C separated signal using the frequency separation method regardless of the state of correlation in the upper and lower parts. Note that rHJ in column CL2 represents this case.

(2) If there is a correlation only in the central region, a 2H-type comb filter separation method using three lines before and after including the line LN including the point of interest PM is adopted. That is, the chroma signal C3 and the luminance signal corresponding thereto are selected. In addition,
"V" in column CL2 represents a 2H type comb filter separation method.

(3) If there is a correlation in the center and one above or below, the line LN that includes the point of interest PM
adjacent line LN-1 or LN in a direction correlated with
An IH type comb filter separation method using +1 is adopted. That is, if there is a correlation in the upper direction, the chroma signal C1 and the corresponding luminance signal are selected, and if there is a correlation in the lower direction, the chroma signal C2 and the corresponding luminance signal are selected. Note that r in column CL2
VUJ and "VL" each represent an IH-type comb filter separation method using a line LC including the point of interest PM and a line LN-1 above it or a line LN+1 below it.

In this case, if both the central correlation and either the upper or lower correlation are very high, the output is output without going through a bandpass filter to remove vertical dot crawl, and in other cases selects a method for outputting through a bandpass filter. Furthermore, column C
In L2, the method in which rVUJ and rVLJ are surrounded by circles represents a method that does not involve a bandpass filter.

(4) If there is a correlation in all of the central, upper, and lower parts, select the 2H-type comb filter separation method. In this case, if the central, upper, and lower correlations are all highly correlated, a 2H comb filter separation method that does not involve a bandpass filter is selected to remove dot crawl in the vertical direction; In this case, a 2H comb filter method is selected in which the signal is output via a bandpass filter. In column CL2, the system in which "V" is surrounded by a circle represents a 2H-type comb filter system that outputs data without passing through a band-pass filter.

In order to select such a separation method, the decoder 50 obtains the correlation flags VFI to VF3 according to the tables TABI and TAB2 and uses the AND circuits 30, 31, and 35.
The signal is outputted to the above-mentioned switch circuits 25 and 34 via the circuit to switch between various separation methods.

(Horizontal correlation detection circuit 39) As mentioned above, in this embodiment, priority is given to horizontal correlation over vertical correlation. The horizontal correlation is detected using the data DK to Do of the five points PK to PO. Figure 4 shows five points of data D.
Horizontal correlation detection circuit 39 that detects horizontal correlation from K to Do
shows.

In FIG. 4, the Y/C separation unit and vertical correlation detection circuit 3
The composite video signal COMP5 synchronized with
Data D K to DO are applied to a delay stage 65 formed by cascade-connecting delay circuits 61 to 64 that delay by the sampling period, and data DK to DO are placed at two points in the horizontal direction, one before and the other in the horizontal direction, centering on the point of interest PM as shown in FIG. It is made to obtain. Data DK and DM are given to an adder circuit 68, and the adder circuit 6
8, and if there is a correlation, the color difference signal components are canceled and a luminance signal YL corresponding to a point PL delayed by one sampling period from the point of interest PM is output. Further, the data DN and DL are given to an adder circuit 69, and the adder circuit 6
If they are added together and there is a correlation, the color difference signal components are canceled and a luminance signal YM corresponding to the point of interest PM is output. Furthermore, the data DM and DO are given to an adder circuit 70, where they are added together. If there is a correlation, the color difference signal component is canceled out, and a luminance signal YN corresponding to a point PN which is one sampling cycle ahead of the point of interest PM. Output.

The luminance signal YM and the luminance signal YN are supplied to a subtraction circuit 71 for subtraction, and then supplied to an absolute value circuit 72 where the absolute value is taken and the difference in luminance signal level between the point of interest PM and the point PN on the right is calculated. A difference signal 1ΔY11 representing the difference is obtained and applied to the comparison circuit 73. The comparator circuit 73 compares this difference signal 1ΔYll with the reference signal REF7, and takes a logic "1" which means there is a correlation when the difference signal (ΔYll is small) and a logic qr□ which means there is no correlation when it is large. first correlation signal H
The COI is output to the NAND circuit 75. This correlation signal HC
Since O1 is obtained mainly from data on the right side of the point of interest PM, it indicates whether there is horizontal correlation on the right side.

The luminance signal YM corresponding to the point of interest PM and the luminance signal YL of a point PL to the left of the point of interest PM are supplied to a subtraction circuit 76 for subtraction, and then supplied to an absolute value circuit 77 to take the absolute value. A difference signal 1ΔY2+ representing the difference in luminance signal level between the point of interest PM and the left point PL is obtained and applied to the comparator circuit 78. The comparison circuit 78 compares this difference signal 1ΔY21 with the reference signals R and EF8, and when the difference signal 1ΔY21 is small, it takes a logic "1" meaning that there is a correlation, and when it is large, it takes a logic "0" that means there is no correlation. A second correlation signal HC to be taken
O2 is output to the NAND circuit 75. This correlation signal HCO
2 is obtained mainly from data on the left side of the point of interest PM, so it indicates whether there is a horizontal correlation on the left side.

Luminance signals YL of points PL and PN on the left and right that sandwich the point of interest PM
and YN are given to seven subtraction circuits and subtracted, and then
The absolute value is taken by the absolute value circuit 80 and the point of interest P
Difference signal 1ΔY31 representing the difference between the left and right luminance signal levels of M
is obtained and applied to the comparison circuit 81. The comparator circuit 81 compares this difference signal 1ΔY31 with the reference signal REF9, and when the difference signal 1ΔY31 is small, a logic “1” indicating that there is a correlation is generated.
”, and if it is large, it is a logical “0” which means there is no correlation.
A third correlation signal HCO3 that takes Since this correlation signal HCO3 is mainly obtained from data in the vicinity of the point of interest PM, it indicates whether there is horizontal correlation in the vicinity.

The NAND circuit 75 receives the incoming first to third correlation signals C0.
There is a horizontal correlation (“OJ
), the above-mentioned AND circuit 3
Sent on 0.31.35.

(Effects of Embodiment) According to the embodiment described above, when horizontal correlation is strictly detected and there is horizontal correlation, a frequency separation method is selected, and when there is no horizontal correlation, the frequency separation method is selected based on vertical correlation. Since the separation method is selected, image quality deterioration such as horizontal and vertical dot crawl and cross color can be reduced. Since priority is given to horizontal correlation, deterioration of image quality in the horizontal direction to which human vision is sensitive is particularly prevented, and an image that is easy to see can be obtained. In addition, since it detects not only the presence or absence of vertical correlation, but also the location and degree of correlation, it is possible to select a comb filter separation method that corresponds to the location and degree of correlation, which improves the image quality in the vertical direction. Deterioration can be further reduced.

(Other Examples) Note that the method of detecting horizontal correlation using five points is not limited to this, for example, horizontal correlation may be detected by comparing the vicinity of the point of interest with the outside thereof, and comparing the left and right sides of the point of interest. It may be something.

Furthermore, the method for detecting vertical correlation using data at five points is not limited to that of the above-described embodiment, and may be based on a comparison between the vicinity of the point of interest and the outside thereof, and a comparison above and below the point of interest.

Further, in the above embodiment, vertical and horizontal correlations are detected from data of five points, but vertical and horizontal correlations may be detected using data of more points.

Furthermore, the types of comb filter separation methods that can be selected depending on the vertical correlation are not limited to those described above, and more or fewer types may be provided.

[Effects of the Invention] As described above, according to the present invention, horizontal correlation and vertical correlation are strictly detected, and when there is horizontal correlation, the frequency separation method is selected, and when there is no horizontal correlation, Since the separation method is selected based on the vertical correlation, it is possible to obtain a Y/C separation device that can further reduce image quality deterioration such as horizontal and vertical dot crawl and cross color compared to conventional devices.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of a Y/C separation device according to the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, FIG. 3 is a block diagram showing a vertical correlation detection circuit, and FIG.
The figure is a block diagram showing the horizontal correlation detection circuit, Figures 5 and 6 are diagrams showing the input and output of the decoder of the vertical correlation detection circuit, and Figures 7 and 8 are the horizontal correlation detection circuit and vertical correlation detection circuit in the conventional device, respectively. FIG. 9 is a block diagram showing a correlation detection circuit and a route map showing a two-dimensional data array. 15... Frequency separation section, 16... Switch circuit, 1
7... Vertical correlation detection type Y/C separation part female part 8. 3...
-Horizontal correlation detection circuit, 32...Vertical correlation detection circuit.

Claims (1)

[Claims] A plurality of Y/C separators, at least one of which follows a frequency separation method, for separating a luminance signal and a chroma signal from a composite video signal, and one color difference signal component axis at four times the color subcarrier frequency. a vertical correlation detection circuit that receives data of the composite video signal sampled in phase with each other and detects vertical correlation from data of five or more consecutive points in the vertical direction centering on a point of interest; a first separation section selection means for selecting one of the above Y/C separation sections based on the detection output of the circuit; a horizontal correlation detection circuit that detects horizontal correlation from the horizontal correlation detection circuit; and based on the detection output of the horizontal correlation detection circuit, when there is no horizontal correlation, the separation unit selected by the first separation unit selection means is enabled; and second separating section selecting means for invalidating the selection by the first separating section selecting means and selecting the Y/C separating section according to the frequency separation method when there is a horizontal correlation. /C separation device.