JPH0630433A - Luminance signal/chrominance signal separating device - Google Patents

Abstract

PURPOSE:To obtain a two-dimensional adaptive type luminance signal/ chrominance signal separating device having a feature capable of preventing the generation of dot interference in a non-correlation part for the horizontal and vertical parts of a chrominance signal. CONSTITUTION:A band pass filter(BPF) 5 separates a horizontal high frequency signal from a composite video signal. Respective 1H delay circuits 6, 7 delay the separated signal to synchronize 0H, 1H and 2H signals close to each other in the vertical direction. Inversion circuits 8, 9 respectively invert the 0H and 2H signals. A logical operation circuit 10 logically computes a center value. The center value is added to the 1H signal by an adder 11 to obtain a carrier chrominance signal. A vertical BPF 20 constituted of 1H delay circuits 17, 18 and a weighted adder 19 separates a vertical high frequency component from a video signal and a carrier chrominance signal is obtained through delay circuits 21, 22, inversion circuits 23, 24, a logical operation circuit 25, and an adder 26. A switching circuit 28 switches the outputs of respective adders 11, 26 in accordance with a correlation detecting signal outputted from a correlation detecting circuit 27 and outputs the selected signal to a chrominance signal output terminal 13.

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 an NTSC composite video signal into a luminance signal and a carrier color signal by in-field processing.

[0002]

2. Description of the Related Art In recent years, a luminance signal chrominance signal separation apparatus based on intra-field processing has a line correlation comb based on so-called one-dimensional luminance signal chrominance signal separation that is performed only by a low pass filter (LPF) and a band pass filter (BPF). Technical innovation has been made to a two-dimensional luminance signal / color signal separation device using a filter. Further, today, a so-called adaptive luminance signal / color signal separation device, which uses a plurality of comb filters and adaptively selects each comb filter and one-dimensional filter according to the degree of correlation, is becoming the mainstream technology.

A conventional adaptive luminance signal / color signal separating device is disclosed in, for example, Japanese Patent Laid-Open No. 58-10913.

A conventional luminance signal / color signal separation device will be described below. FIG. 4 is a block diagram of this conventional luminance signal / color signal separation device. In FIG. 4, 1
Is an input terminal for inputting a composite video signal. A band-pass filter 5 has a group delay characteristic of T / 2 (T is a carrier wave period of a carrier color signal) and separates a high frequency signal including a carrier color signal from the input composite video signal. Two
Is a delay circuit used for timing adjustment, and delays the input composite video signal by T / 2. 6,7 is 1H
A delay circuit (H is a horizontal scanning period) delays the carrier color signals by 1H and 2H, respectively. Reference numeral 3 is a 1H delay circuit used for timing adjustment, and further delays the composite video signal output from the delay circuit 2 by 1H. Reference numerals 8 and 9 denote phase inversion circuits that invert the phase of the carrier color signal. 10
Is a logical operation circuit, which logically operates the median value of the three input signals a, b, and c. Reference numeral 11 denotes an adder circuit, which is an output signal of the 1H delay circuit 6 and an output signal of the logical operation circuit 10.
Each of the two signals is added with a weight of ½. A subtraction circuit 4 subtracts the output signal of the addition circuit 11 from the output signal of the 1H delay circuit 3 with a weight of ½. A luminance signal output terminal 12 outputs the output signal of the subtraction circuit 4. A color signal output terminal 13 outputs the output signal of the adder circuit 11.

With respect to the luminance signal / color signal separating apparatus having the above-described configuration, the composite video signal input from the input terminal 1 whose operation will be described below is subjected to the luminance signal high frequency component and the carrier color by the band pass filter 5. The high frequency signal, which is a mixture of signals, is separated. The high frequency signal is delayed by the 1H delay circuits 6 and 7, and the high frequency signals of three lines that are vertically adjacent are synchronized. If the high-frequency signals of the three lines are 0H, 1H, and 2H signals, respectively, the luminance signal and the carrier color signal have an interleaving relationship with the horizontal scanning frequency. Although the lines are in phase with each other, the carrier color signals have an opposite phase relationship between lines. Therefore, by inverting the 0H and 2H signals in the inverting circuits 8 and 9, the carrier color signal is made to have the same phase relationship between the lines, and the luminance signal high frequency component is converted to the opposite phase relationship.
After that, these three high frequency signals are input to the logical operation circuit 10, the three signal levels are compared, and the logical operation is performed so as to output the signal level in the middle (median-median),
Further, this median value and the 1H signal output from the 1H delay circuit 6, which is the reference signal, are added by the adder circuit 11. By doing so, the luminance signal high-frequency component is removed from the high-frequency signal in which the luminance signal high-frequency component and the carrier color signal are mixed, and only the carrier color signal is extracted. The carrier color signal thus obtained is output to the color signal output terminal 13 and the subtraction circuit 4, and the delay circuit 2 and the 1H delay circuit 3 are output.
The luminance signal is separated by subtracting it from the composite video signal whose timing is adjusted by delaying at
It is output to the luminance signal output terminal 12.

Since the conventional luminance signal color signal separation device thus constructed is a line correlation comb filter as a basic configuration, the horizontal resolution of the luminance signal is sufficiently secured, and an adaptive processing called logical operation is also introduced. Therefore, there is a problem that there is no problem of dot interference or occurrence of color fringing in the vertical non-correlation part of the color signal.

[0007]

However, in the above-mentioned conventional configuration, although the dot interference in the vertical non-correlation part of the color signal is improved, the dot interference in the horizontal non-correlation part cannot be improved. This is a conventional structure, and in FIG. 4, the bandpass filter 5 is included in the signal path of the chrominance signal, whereby the signal of the horizontal uncorrelated portion of the chrominance signal cannot pass, and the chrominance signal is separated in the luminance signal. That is, the horizontal decorrelation signal of the above leaks as dot interference. In the bandpass filter 5, inversion circuits 8 and 9 must invert the phase of the carrier color signal in order to perform a logical operation in the subsequent stage.
Therefore, it was an essential element because it was introduced also for the purpose of removing the DC component of the signals input to the inverting circuits 8 and 9.

The present invention solves the above-mentioned conventional problems, and provides a two-dimensional adaptive luminance signal / chrominance signal separating device having a feature that dot interference does not occur in both horizontal and vertical non-correlation portions of a color signal. The purpose is to

[0009]

In order to achieve this object, a luminance signal / chrominance signal separation device of the present invention delays an input composite video signal by n stages in the horizontal direction and the vertical direction, respectively (n + 1). ^The delay means for generating two delay signal groups and the delay signal groups are weighted so as to separate high frequency components in the horizontal direction, respectively, and vertically (n +
1) first horizontal filter means for generating a number of signal groups;
First vertical filter means for separating a first color signal by logically operating the signal group output from the first horizontal filter means, and high frequency components are separated in the vertical direction from the delayed signal group. Thus, the second vertical filter means for generating (n + 1) number of signal groups in the horizontal direction and the signal group output from the second vertical filter means are logically operated to obtain the second Second horizontal filter means for separating the color signals, correlation detecting means for detecting a direction in which the horizontal correlation and the vertical correlation are stronger from the input composite video signal, and the output signal of the correlation detecting means. It is configured to have a switch means for switching between the first color signal and the second color signal.

[0010]

According to the present invention, the first color signal having no color fringing in the vertical direction, which is obtained by logically operating the signal group output from the horizontal filter means, and the signal output from the vertical filter means according to the above configuration. In order to output an output color signal by switching the second color signal having no color blur in the horizontal direction, which is obtained by logically operating the group, by the detection signal in the direction having stronger horizontal correlation and vertical correlation, It is possible to improve the occurrence of dot interference in both decorrelation parts.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a luminance signal / color signal separating apparatus according to the present invention. In FIG. 1, reference numeral 1 is an input terminal for inputting a composite video signal. Reference numeral 5 denotes a horizontal bandpass filter, which is composed of delay circuits 14 and 15 and a weighting addition circuit 16 and separates a horizontal high frequency signal including a carrier color signal from the input composite video signal. 6,
Reference numeral 7 is a 1H delay circuit, which outputs a horizontal high frequency signal to 1
H, 2H delay. Reference numerals 8 and 9 denote phase inversion circuits that invert the phase of the carrier color signal. A logical operation circuit 10 logically operates the median value of the three input signals a, b, and c. Reference numeral 11 denotes an adder circuit, which adds the two signals of the output signal of the 1H delay circuit 6 and the output signal of the logical operation circuit 10 with a weight of ½. Reference numeral 20 denotes a vertical bandpass filter, which is composed of 1H delay circuits 17 and 18 and a weighting addition circuit 19 and separates a vertical high frequency signal including a carrier color signal from the input composite video signal. 21,
Reference numeral 22 denotes a delay circuit, which applies T / H to the vertical high-frequency signals.
2. Delay by T. Reference numerals 23 and 24 denote phase inversion circuits which invert the phase of the carrier color signal. Reference numeral 25 denotes a logical operation circuit, which logically operates the median value of the three input signals a, b, and c. An adder circuit 26 adds two signals of the output signal of the delay circuit 21 and the output signal of the logical operation circuit 25 with weighting of ½. Reference numeral 27 denotes a correlation detection circuit that detects a direction in which the horizontal correlation and the vertical correlation are stronger from the input composite video signal. A switching circuit 28 switches the output signals of the adder circuit 11 and the adder circuit 26 according to the output signal of the correlation detection circuit 27. 2 and 3
Is a delay circuit and a 1H delay circuit used for timing adjustment, and outputs the input composite video signal to (T / 2 + 1
H) Delay. 4 is a subtraction circuit, which is a 1H delay circuit 3
The output signal of the switching circuit 28 is subtracted from the output signal of 1 by weighting 1/2. A luminance signal output terminal 12 outputs the output signal of the subtraction circuit 4. A color signal output terminal 13 outputs the output signal of the switching circuit 28.

The operation of the luminance signal / color signal separating apparatus of the present embodiment having the above-described structure will be described below. The composite video signal input from the input terminal 1 is delayed by the delay circuits 15 and 14 and horizontally delayed by 0T, T / 2,
The signals of three pixels apart from each other by T are synchronized, and the three pixel signals are respectively weighted by the weighting addition circuit 16 to be -1/4, 1
A horizontal high-frequency signal in which the luminance signal horizontal high-frequency component and the carrier color signal are mixed is separated by adding weights of / 2 and -1/4. The horizontal high frequency signal is a 1H delay circuit 6, 7
, The horizontal high-frequency signals of three lines that are vertically adjacent to each other are synchronized, and the horizontal high-frequency signals of the three lines are converted into 0H, 1H, and 2H signals, respectively. By inverting the 2H signal, the carrier color signal is made to have the same phase relationship between the lines, and the luminance signal horizontal high frequency component is converted to the opposite phase relationship. Thereafter, these three horizontal high frequency signals are input to the logical operation circuit 10, the three signal levels are compared and logical operation is performed so as to output the median value, and further the median value and the 1H delay circuit 6 which is the reference signal. Output of 1H
The signal is added by the adder circuit 11. By doing so, the luminance signal horizontal high-frequency component is removed from the horizontal high-frequency signal in which the luminance signal horizontal high-frequency component and the carrier color signal are mixed, and only the carrier color signal is extracted. On the other hand, the composite video signal input from the input terminal 1 is further processed by the 1H delay circuits 17 and 18
At the same time, the signals of three lines separated by 0H, 1H, 2H in the vertical direction are simultaneously synchronized, and the three line signals are respectively weighted by a weighting addition circuit 19 to -1, / 4, -1, and -1.
A vertical high frequency signal in which the luminance signal vertical high frequency component and the carrier color signal are mixed is separated by adding with a weighting of / 4. The vertical high-frequency signals are delayed by delay circuits 21 and 22, and the horizontal high-frequency signals of three pixels adjacent in the horizontal direction are synchronized, and the horizontal high-frequency signals of the three pixels are respectively converted to 0T and T /.
2 and 1T signals, 0T in inverting circuits 23 and 24,
By inversion of the 1T signal, the carrier color signal is made to have the same phase relationship between the lines, and the luminance signal high frequency component is converted to the opposite phase relationship. Thereafter, these three high frequency signals are input to the logical operation circuit 25, the three signal levels are compared and logical operation is performed to output the median value, and the median value and the output of the delay circuit 21 which is the reference signal are further output. The T / 2 signal is added by the adder circuit 26. By doing so, the luminance signal vertical high-frequency component is removed from the vertical high-frequency signal in which the luminance signal vertical high-frequency component and the carrier color signal are mixed, and only the carrier color signal is extracted. The operation of this signal processing will be described in more detail with reference to FIG.

FIG. 2 is a schematic diagram for explaining the operation of this embodiment. Now, the carrier color signal is sampled every T / 2 (carrier frequency of the T carrier color signal), and the sampled pixel signals are divided into three pixels in the horizontal direction and three pixels in the vertical direction (three lines). It is modeled as S1 to S9 as described above. These pixel signals have the delay circuits 14, 15 and 21, 22 and the 1H delay circuits 17, 18 in the configuration of FIG.
And 6,7. In these pixel signals S1 to S9, S1, S3, S5, S7 and S9 have the same phase relationship, and S2, S4, S6 and S8 have the opposite phase relationship. Then, first, three pixel signals in the horizontal direction (S1,
S2, S3) (S4, S5, S6) (S7, S8, S
The combination 9) is weighted and added by the weighting addition circuit 16 to separate the three horizontal wide-area signals in the vertical direction of 0H, 1H, and 2H. In this case, since the calculation method is weighted addition, transient deterioration, so-called color fringing, occurs in the horizontal direction. Then, the three horizontal wide-area signals in the vertical direction are logically operated by the logical operation circuit 10 to separate the carrier color signals. Here, since the logical operation is performed in the vertical direction, the color bleeding in the vertical direction does not occur in the carrier color signal obtained from the adder circuit 11. Next, the pixel signals S1 to S9 are (S1, S4, S7) (S
2, S5, S8) (S3, S6, S9) are weighted and added in the weighting addition circuit 19,
Three vertical wide-area signals are separated in the horizontal direction of 0T, T / 2, and 1T. In this case, since the calculation method is weighted addition, transient deterioration, so-called color fringing, occurs in the vertical direction, but does not occur in the horizontal direction. And
The three vertical wide area signals in the horizontal direction are applied to the logical operation circuit 25.
The carrier color signal is separated by performing a logical operation at. Here, since the logical operation is performed in the horizontal direction, the adder circuit 2
No horizontal color fringing occurs in the carrier color signal obtained from No. 6. Then, the carrier color signal in which no color fringing occurs in the vertical direction and the carrier color signal in which no color fringing occurs in the horizontal direction are switched according to the strength of the horizontal correlation and the vertical correlation, and output. The color signal output terminal 13 can output a carrier color signal in which color fringing does not occur in both the horizontal and vertical uncorrelated portions. As a result, the luminance signal output terminal 12 can obtain a luminance signal in which dot interference does not occur in both the horizontal and vertical uncorrelated portions.

Next, a second embodiment of the present invention will be described with reference to FIG.
It will be explained based on. FIG. 3 is a block diagram showing a second embodiment of the present invention. In the embodiment having the configuration shown in FIG. 1, five 1H delay circuits are used. Since the 1H delay circuit is generally expensive, as a result, the configuration of FIG. 1 makes the present invention more expensive than the conventional one. In the embodiment having the configuration of FIG. 2, the number of 1H delay circuits used is reduced. In FIG. 2, 1 is an input terminal and 17, 18
Is a 1H delay circuit, 19 is a weighting addition circuit, 21, 22
Is a delay circuit, 8, 9, 23, 24 are inverting circuits, 10, 2
Reference numeral 5 is a logical operation circuit, 10 and 26 are addition circuits, 27 is a correlation detection circuit, 28 is a switching circuit, 4 is a subtraction circuit, 12 is a luminance signal output terminal, and 13 is a color signal output terminal. The configuration is similar. Further, 29 is a delay circuit, which is similar to the delay circuit 2 in FIG. 1 and delays the composite video signal by T / 2 for timing adjustment. The difference from FIG. 1 is that input terminals 1 and 1H
The bandpass filters 30, 31, and 32 are provided in the subsequent stages of the delay circuits 17 and 18, respectively. The bandpass filters 30, 31, 32 are all the same as the bandpass filter 5 of FIG.

With such a configuration, in FIG. 1, the composite video signal is delayed by the delay circuits 15 and 14 so that the signals of three pixels 0T, T / 2, and T apart in the horizontal direction are synchronized, and The horizontal high-frequency signal is separated by adding the three pixel signals by the weighting addition circuit 16, and the horizontal high-frequency signal is delayed by the 1H delay circuits 6 and 7 to be adjacent in the vertical direction 0H, 1H, 2H. In the configuration of FIG. 3, the composite video signal is delayed by the 1H delay circuits 17 and 18 and delayed by 0H in the vertical direction. The signals of 3 lines of 0H, 1H, and 2H are synchronized by synchronizing signals of 3 lines separated by 1H and 2H, and separating the signals of the 3 lines by horizontal band signals by bandpass filters 30, 31, and 32, respectively. The horizontal high frequency signal of the line , So that a logic operation it. As a result, the 1H delay circuit 6 used in the configuration of FIG.
And 7 can be omitted. Also 1H
The delay circuit 2 can also be omitted by using the 1H delay circuit 17 also.

As described above, the present invention can be realized with a simple and inexpensive structure as shown in FIG.

The present invention is not limited to the above embodiment, but various modifications can be made.

[0019]

As described above, according to the present invention, a carrier color signal separated by a horizontal band pass process and a vertical logical operation process, and a carrier color signal separated by a vertical band pass process and a horizontal logical operation process. By switching the carrier color signals that are generated, it is possible to obtain carrier color signals that do not cause color bleeding in both the horizontal and vertical uncorrelated portions, and a luminance signal that does not cause dot interference in both the horizontal and vertical uncorrelated portions. Can be output.

[Brief description of drawings]

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

FIG. 2 is a schematic diagram illustrating the operation of the luminance signal / color signal separation device according to the first embodiment.

FIG. 3 is a block diagram showing a configuration of a luminance signal / color signal separation device according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing the configuration of a conventional luminance signal / color signal separation device.

[Explanation of symbols]

 1 input terminal 2,14,15,21,22 delay circuit 3,6,7,17,18 1H delay circuit 4 subtraction circuit 5,30,31,32 band pass filter 8,9,23,24 inverting circuit 10, 25 logical operation circuit 11, 26 adder circuit 12 luminance signal output terminal 13 color signal output terminal 16, 19 weighting adder circuit 27 correlation detection circuit 28 switching circuit

Claims (1)

[Claims] 1. An input composite video signal is fed in a horizontal direction,
Delay means for delaying each by n stages in the vertical direction to generate (n + 1) ² delay signal groups, and weighting operation for separating the high frequency components of the delay signal groups in the horizontal direction, respectively, and performing a weighting operation in the vertical direction. (N + 1)
First horizontal filter means for generating individual signal groups, first vertical filter means for separating the first color signals by logically operating the signal groups output from the first horizontal filter means, The delayed signal groups are weighted so as to separate high frequency components in the vertical direction, and then (n + 1) in the horizontal direction.
Second vertical filter means for generating a plurality of signal groups, second horizontal filter means for separating the second color signal by logically operating the signal group output from the second vertical filter means, From the input composite video signal, a correlation detection unit that detects a direction in which the horizontal correlation and the vertical correlation are stronger, and the first color signal and the second color signal based on the output signal of the correlation detection unit. A switch means for switching and a color signal output from the switch means as an output color signal, and after the input composite video signal is adjusted in timing, the luminance signal is separated by subtracting the output color signal to obtain an output luminance signal. And a luminance signal / color signal separation device including: