JPH03276991A - Motion adaptive luminance signal and chrominance signal separation filter - Google Patents

Abstract

PURPOSE:To prevent the degradation of resolution by separating a luminance signal Y and a chrominance signal C by switching an inter-field operation, intra-field operation and a intra-field process using a chrominance signal extraction filter after detecting the correlation between fields. CONSTITUTION:Differences between fields which are outputted from subtracters 19, 21, and 22, are turned to the absolute values through LPFs 22, 23, and 24 by absolute value circuits 25, 26, and 27, and are inputted to a maximum value selection circuit 38 and a minimum value selection circuit 39 to detect the correlation. The output of the circuit 39 is inputted to a first signal selection circuit 29. Meanwhile, since the output of the circuit 29 is a three-dimensional high frequency component in the direction where the correlation is detected, the signal C can be removed by passing the output through a two-dimensional comb line filter constituted of an one-line delay circuit 31, adders 32 and 35, and LPF 34. By adding the outputs of a subtracter 30 and the adder 35 by an adder 36, an intra-field Y/C separation signal Y is obtained. Meanwhile, a V signal delayed in a two-picture element delay circuit 14 is inputted to an intra-field Y signal extraction filter 28, and then, an intra-field Y/C separation Y signal can be obtained.

Description

[Detailed Description of the Invention] [Field of Application] This invention provides a method for converting a luminance signal (hereinafter referred to as "signal") from a composite color television signal (hereinafter referred to as "■ signal") in which a color signal is frequency multiplexed into a high frequency region of a luminance signal. (Y signal or simply referred to as Y) and color signal (hereinafter referred to as C signal or simply C)
This invention relates to a motion-adaptive luminance signal and chrominance signal separation filter for separating .

[Prior Art] A motion-adaptive YC separation filter is a filter that locally determines whether an image is a still image or a moving image, and performs YC separation suitable for pixel signals of each part.

In the current NTSC signaling system, a composite signal is obtained by frequency multiplexing the C signal into the high frequency region of the Y signal. For this reason, YC separation is required in the television receiver, and incomplete separation causes image quality deterioration such as cross color and dot crawl.

Therefore, with the recent development of large-capacity digital memories, motion-adaptive YC separation using delay circuits (hereinafter simply referred to as delay circuits) having a delay time equal to or longer than the vertical scanning frequency of television signals has been developed. Various signal processing circuits have been proposed for improving image quality.

FIG. 12 is a block diagram showing an example of a conventional motion adaptive YC separation filter. In the figure, an NTSC V signal 101 is input to an input terminal l, and input terminals of an intra-field YC separation circuit 4, an inter-frame YC separation circuit 5, a Y signal motion detection circuit 6, and a C signal motion detection circuit 7. each is given.

In the field YC separation circuit 4, the field YC separated by the field filter (not shown)
C-separated Y signal 102 and intra-field YC separated C signal 1
03 are respectively input to the first input terminal of the Y signal mixing circuit 9 and the first input terminal of the C signal mixing circuit IO.

In addition, in the interframe YC separation circuit 5, the interframe YC separated by the interframe filter (not shown) is
Separated Y signal 104 and interframe YC separated C signal 105
are input to the second input terminal of the Y signal mixing circuit 9 and the second input terminal of the C signal mixing circuit 10, respectively.

On the other hand, the Y signal motion amount 106 detected by the Y signal motion detection circuit 6 is input to one input terminal of the synthesis circuit 8,
Further, a signal 107 indicating the amount of C signal motion detected by the C signal motion detection circuit 7 is input to the other input terminal of the synthesis circuit 8 .

The motion detection signal 108 synthesized by the synthesis circuit 8 is input to the third input terminal of the Y signal mixing circuit 9 and the third input terminal of the C signal mixing circuit 10, respectively, and the Y signal motion detection circuit 6 and the C signal The motion detection circuit 7 and the synthesis circuit 8 constitute a motion detection circuit 80.

A motion adaptive YCC separation multiplied signal 09, which is an output of the Y signal mixing circuit 9, is sent out from the output terminal 2.

Further, a motion adaptive YC separated C signal 110 which is an output of the C signal mixing circuit 10 is sent out from the output terminal 3.

Next, the operation will be explained. The motion detection circuit 80 is
When separating the signal 101 into Y and C signals, the outputs of the Y signal motion detection circuit 6 and the C signal motion detection circuit 7 are synthesized by the synthesis circuit 8, and it is determined whether the signal lot is a signal representing a still image or a signal representing movement. Determine whether it is a signal.

The Y signal motion detection circuit 6, for example, as shown in FIG.
■ Signal 101 is input from input terminal 51 and delayed by one frame in l-frame delay circuit 53, and the directly input V signal 101 is subtracted by subtracter 54 to obtain ■ signal 10.
1, and apply a low-pass filter (hereinafter referred to as
After passing through 55 (referred to as LPF), its absolute value is determined by an absolute value circuit 56, and this absolute value is converted to Y by a nonlinear conversion circuit 57.
It is converted into a signal 106 indicating the amount of motion of the low frequency component of the signal and outputted to the output terminal 52.

Further, the C signal motion detection circuit 7 receives a signal obtained by delaying the V signal 101 inputted from the input terminal 11 by two frames by a two frame delay circuit 41 as shown in FIG. 14, and a directly inputted V signal. 101 is subtracted by a subtracter 42 to obtain a two-frame difference, which is passed through a band pass filter (hereinafter referred to as BPF) 43, its absolute value is determined by an absolute value circuit 44, and this absolute value is converted to a nonlinear A conversion circuit 45 converts the C signal into a signal 107 indicating the amount of movement, and outputs the signal 107 from an output terminal 49.

The synthesis circuit 8 is configured to select and output the larger value of the Y signal motion amount 106 and the C signal motion amount 107, for example.

This discrimination result is expressed in the form of a motion coefficient k (0≦≦1); for example, if the image is determined to be a completely still image, k = 0, and if the image is determined to be a completely moving image, k = 0. is given as a control signal 108 such that k=1.

Generally, when the image is a still image, interframe YC separation using interframe correlation is performed to separate the Y signal and C
Separate the signals.

The interframe YC separation circuit 5 adds a signal obtained by delaying the V signal 101 input from the input terminal 61 by one frame by the one frame delay circuit 64 and the V signal 101 input directly as shown in FIG. 15, for example. The YF signal 104 is extracted by calculating the sum of 1 frames, and the output terminal 62
At the same time, by subtracting the YF signal 104 from the V signal 101 input from the input terminal 61 in the subtracter 66, the Cf signal 105 is extracted and output from the output terminal 63.

Further, in general, when the image is a moving image, intra-field YC separation using intra-field correlation is performed to separate the Y signal and the C signal. The in-field YC separation circuit 4 is
For example, as shown in FIG. 16, the V signal 101 inputted from the input terminal 71 is delayed by one line in the one line delay circuit 74, and the directly inputted ■signal 101 is added in the adder 75 to form a one line sum. , and extract the Yf signal 102,
The Cf signal 103 is output from the output end 72 and is output from the output end 73 by subtracting the Yf signal 102 from the V signal 101 input from the input end 71 in the subtracter 76 .

In the motion adaptive YC separation filter, such an intra-field YC separation circuit 4 and an inter-frame YC separation circuit 5 are arranged side by side, and the motion coefficient k synthesized by the synthesis circuit 8 is used to
The signal mixing circuit 9 is caused to perform the following calculations, and a motion adaptive YCC separation multiplied signal 09 is outputted from the output terminal 2.

Y=kYf+ (1-k)YF where, Yf: In-field YC separated Y signal output 102, YF near L/-4 YC separated Y signal output 104.

Similarly, the control signal 108 causes the C signal mixing circuit 10 to perform the following calculations, and outputs a motion adaptive YC separated C signal 110 from the output terminal 3.

C=kCf+ (1-k)CF Here, Cf: Intra-field YC separated C signal output 103, CF near L/-m YC separated C signal output 105.

Of this motion adaptive YC separation filter, the C signal motion detection circuit 7 can also be realized with a configuration as shown in FIG. In the figure, a V signal 101 is inputted from the input terminal 11, and two types of color difference signals R-Y and B are inputted by the color demodulation circuit 46.
−Y is demodulated.

These two types of color difference signals R-Y and B-Y are time-division multiplexed at a certain frequency by a time-division multiplexing circuit 47, delayed by two frames by a two-frame delay circuit 41, and then divided into two frames by a subtracter 42. By subtracting the output of the delay circuit 41 and the output of the time division multiplexing circuit 47, a two-frame difference is obtained.

This two-frame difference is passed through an LPF 48 to remove the Y signal component, an absolute value circuit 44 takes the absolute value, and a nonlinear conversion circuit 45 performs nonlinear conversion to obtain the motion detection amount of the C signal.
07 can be sent out from the output end 49.

[Problems to be Solved by the Invention] Since the conventional motion adaptive YC separation filter is configured as described above, it is possible to combine the amounts of motion detected by the Y signal motion detection circuit 6 and the C signal motion detection circuit 7, respectively. Based on the YC amount, the YC separation circuit 4 determines the
The f-times signal Cf signal and the YF-times signal CF signal from the inter-frame YC separation circuit 5 are mixed.

Therefore, because the filter characteristics for still images and those for moving images are completely different, there is an extreme change in resolution when moving from a still image to a moving image, or from a moving image to a still image. There was a problem in that the image quality was noticeably degraded.

This invention was made in order to solve the above-mentioned problems, and it is a motion-adaptive type that can reproduce images with high resolution and little image quality deterioration, even when the above-mentioned processing is changed frequently. The purpose is to obtain a YC separation filter.

[Means for Solving the Problems] The motion adaptive YC separation filter according to the present invention locally detects correlation between fields when a motion detection circuit detects a moving image, and performs interfield calculation based on the detection result. an intra-frame YC separation circuit that adaptively switches between a plurality of intra-frame processes including band limiting of a luminance signal using and intra-field calculations, and outputs an intra-frame YC-separated Y signal and an intra-frame YC-separated C signal; It has been established.

[Operation] The intra-frame YC separation circuit of the present invention detects the correlation between fields when the motion detection circuit determines that it is a moving image, and uses four types of YC separation circuits including the intra-field YC separation circuit depending on the magnitude of the correlation. By selecting one of the intraframe YC separation circuits, an intraframe YC separation Y signal and an intraframe YC separation C signal are output.

[Example] Hereinafter, the present invention will be explained based on the drawings. FIG. 1 is a block diagram showing a motion adaptive YC separation filter according to an embodiment of the present invention.

In FIG. 1, the intra-field YC separation circuit 4 in FIG. 12 is replaced with an intra-frame YC separation circuit 50, and the other parts have been explained in the conventional example and will therefore be omitted.

A detailed block diagram of an embodiment of the intra-frame YC separation circuit 50 in FIG. 1 is shown in FIG.

In the figure, a V signal 101 is input to an input terminal 11. This V signal 101 is applied to two pixel delay circuits 14 and 2.
It is input to the input terminal of the 62-line delay circuit 15.

The signal delayed by two pixels by the two-pixel delay circuit 14 is input to the intra-field Y signal extraction filter 28, and
The subtracters 19, 20, 21, and 3037 are respectively input to the first input terminals thereof.

The output signal of the intra-field Y signal extraction filter 28 is the second
is input to the first input terminal of the signal selection circuit 60 of.

V delayed by 262 lines by the 262 line delay circuit 15
The signals are input to the input terminals of the l-line delay circuit 16 and the 4-pixel delay circuit 17, and to the second input terminal of the subtracter 19, respectively.

The V signal delayed by one line by the one line delay circuit 16 is 2
It is input to the input terminal of the pixel delay circuit 1B. The V signal delayed by 4 pixels by the 4-pixel delay circuit 17 is input to the second input terminal of the subtracter 20 .

The V signal delayed by two pixels by the two-pixel delay circuit 18 is input to the second input terminal of the subtracter 21 .

The output signal of the subtracter 19 is input to the first input terminal of the first signal selection circuit 29 and the input terminal of the LPF 22 . The output signal of the subtracter 20 is input to the second input terminal of the first signal selection circuit 29 and the input terminal of the LPF 23. Subtractor 21
The output signal is input to the third input terminal of the first signal selection circuit 29 and the input terminal of the LPF 24.

The output of the LPF 22 is connected to the input terminal of the absolute value circuit 25.
The output of LPF 23 is input to the input terminal of absolute value circuit 26, and the output of LPF 24 is input to the input terminal of absolute value circuit 27.

The output of the absolute value circuit 25 is connected to the first input terminal of the maximum value selection circuit 38 and minimum value selection circuit 39, and the output of the absolute value circuit 26 is connected to the second input terminal of the maximum value selection circuit 38 and minimum value selection circuit 39. The output of the absolute value circuit 27 is input to the third input terminals of a maximum value selection circuit 38 and a minimum value selection circuit 39, respectively.

The output of the maximum value selection circuit 38 is input to the first input terminal of the threshold value determination circuit 40. The output of the minimum value selection circuit 39 is input to the second input terminal of the threshold value determination circuit 40 and the fourth input terminal of the first signal selection selection circuit 29. The output of the minimum value selection circuit 39 inputted to the fourth input terminal of the first signal selection selection circuit 29 is
The third input is selectively controlled from.

The output of the first signal selection circuit 29 is the one-line delay circuit 3
1, the second input of the subtracter 30, and the adder 32.
The signals are respectively input to the first input terminals of the subtracter 33. ■The output of the line delay circuit 31 is sent to the adder 32. The signals are input to the second input terminals of the subtracter 33, respectively. The output of adder 32 is input to a first input terminal of adder 35. The output of the subtracter 33 is input to the input terminal of the LPF 34. The output of the LPF 34 is input to the second input terminal of the adder 35.

The output of the subtracter 30 is input to the first input terminal of the adder 36, and the output of the adder 35 is input to the second input terminal of the adder 36. The output of the adder 36 is sent to the second signal selection circuit 60
is input to the second input terminal of.

The output of the threshold determination circuit 40 is sent to the second signal selection circuit 60.
is input to the third input terminal of the second signal selection circuit 60, thereby selectively controlling the first and second inputs of the second signal selection circuit 60.

The output of the second signal selection circuit 60 is the intra-frame YC separated Y
It is output from the output terminal 12 as a signal 112. Further, the output of the adder 36 is input to the second input terminal of the subtracter 37. The output of the subtracter 37 is the intra-frame YC separated C signal 113
It is outputted from the output terminal 13 as .

Next, the operation will be explained.

The horizontal direction of the screen is the y-axis, and the vertical direction of the screen is the y-axis.
If the t-axis, which is the time axis, is taken in the direction perpendicular to the plane composed of the axes, a three-dimensional space-time can be considered that can be composed of the y-axis, the y-axis, and the t-axis.

Figure 4 is a diagram representing three-dimensional space-time, and Figure 4 (a
) is a plane composed of the t-axis and the y-axis, and FIG. 4(b) is a plane composed of the y-axis and the y-axis. FIG. 4(a) also shows interlaced scan lines, with dashed lines indicating one field and solid lines indicating that the color subcarriers are in phase.

Furthermore, the solid lines and broken lines in FIG. 4(b) indicate the scanning lines of n field and n-1 field, respectively, and there are four types of ``○'', ``・'', ``△'', and ``mu'' on the scanning line. The mark indicates the color subcarrier frequency fsc (= 3.58
The color subcarriers when digitized at four times the frequency (MHz) indicate sample points with the same phase.

Now, if the sample point of interest is represented by "◎", the color subcarrier phase is 180 degrees at around 2 sample points in the same field, field n, and at four points a, b, c, and d above and below the l line.
It's different.

Therefore, a line comb filter using a digital circuit or an adaptive Y
A C separation filter etc. can be configured.

Further, as shown in FIG. 4(a), since the color subcarrier phases differ by 180 degrees at the same sample point one frame apart, an interframe YC separation filter can also be configured.

Furthermore, as can be seen from Fig. 4(b), in the n-1 field one field before the sample point of interest, the phase is opposite around the sample point one line above or two sample points one line below. Inter-field YC separation is possible by calculating any one of these three points A, B, and B with the point of interest.

In addition, considering the μ-axis which is the horizontal frequency axis, the μ-axis which is the vertical frequency axis, and the f-axis which is the time-frequency axis as the frequency axes corresponding to the above y-axis, y-axis, and t-axis, we consider the μ-axis which is orthogonal to each other. A three-dimensional frequency space can be considered that can be composed of , μ axis, and f axis.

FIG. 5 shows a projection of the three-dimensional frequency space. FIG. 5(a) is a diagram of the three-dimensional frequency space viewed from an oblique direction, FIG. 5(b) is a diagram of the three-dimensional frequency space viewed from the negative direction of the f-axis, and FIG. 5(c) is a diagram of the three-dimensional frequency space viewed from an oblique direction. is a diagram of the above three-dimensional frequency space viewed from the positive direction of the μ axis.

FIGS. 5(a) to 5(C) show the spectral distribution of the V signal on a three-dimensional frequency space. Figure 5(a)
As can be seen from ~(c), the spectrum of the Y signal spreads around the origin of the three-dimensional frequency space, the spectrum of the C signal is one signal at the color subcarrier frequency fsc, and the Q signal is orthogonal two-phase modulated. Therefore, they are located in four spaces as shown in FIGS. 5(a) to 5(C).

However, when the V signal is viewed on the μ-axis as shown in FIG. 5(c), the C signal exists only in the second and fourth quadrants.

This corresponds to the fact that the solid line representing the same phase of the color subcarriers rises with time in FIG. 4(b).

Nevertheless, in the conventional example, when motion of an image is detected, YC separation is performed using correlation within the field, so band limitation in the μ-axis and ν-axis directions is possible, but band limitation in the f-axis direction is It was not possible to add directional band limits.

Therefore, the frequency space in which the Y signal originally exists is separated as the C signal, and the band of the Y signal in the moving image becomes narrow.

Therefore, by introducing YC separation using inter-field processing as described above, it is possible to widen the band of the Y signal in a moving image.

In FIG. 4(b), in the n-1 field, there are two sample points A, B, and A, which are located in the vicinity of the sample point of interest "◎" and whose color subcarrier phases differ by 180 degrees. Inter-field YC separation is possible by calculation with any of these three points.

First, it is possible to extract high-frequency components on the three-dimensional frequency space including the C signal based on the difference between the sample point of interest "◎" and the sample point "." A in FIG. 4(b). This is followed by a 1-line delay circuit 31. Adder 32.35, subtracter 33, LPF
The C signal can be removed by passing it through a two-dimensional comb filter composed of 34. The Y signal is obtained by adding this result to the low frequency component in the three-dimensional frequency space that does not include the C signal, which is the output of the subtracter 30. Further, the C signal is obtained by subtracting the Y signal from the V signal. This is referred to as inter-field YC separation A.

Figures 6(a) to (c), like Figures 5(a) to (c), represent a three-dimensional frequency space, and the inter-field Y
It shows the frequency space in which the Y signal and C signal obtained by C separation A exist.

Second, high-frequency components on the three-dimensional frequency space including the C signal can be extracted from the difference between the sample point of interest "◎" and the sample point "." A in FIG. 4(b). Add to this the above 2
The C signal can be removed by passing it through a dimensional comb filter.

Thereafter, the Y signal and C signal are obtained by the same processing as above. This is referred to as inter-field YC separation B.

Figures 7(a) to (c) also have inter-field YC separation B.
It shows the frequency space in which the Y signal and C signal obtained by the above exist. Looking at FIGS. 7(a) to (c), it appears that the separated Y signal contains a portion of the C signal, but since the Y signal and the C signal have a strong correlation with each other, the Y signal contains the C signal. Very few signals are included.

Thirdly, the high frequency component on the three-dimensional frequency space including the C signal can be extracted from the difference between the sample point of interest "◎" and the sample point "." in FIG. 4(b). Add to this the above 2
The C signal can be removed by passing it through a dimensional comb filter.

Thereafter, the Y signal and C signal are obtained by the same processing as above. This is referred to as inter-field YC separation C.

Figures 8(a) to (c) also have inter-field YC separation C.
It shows the frequency space in which the Y signal and C signal obtained by the above exist. Looking at Figures 8(a) to (c), it appears that the separated Y signal contains a portion of the C signal, but for the same reason as in Figure 7, the Y signal contains the C signal. are extremely rare. In the present invention, in order to adaptively switch and control the intra-field YC separation and these three types of inter-field YC separation, the correlation between the sample point of interest "◎" and the sample points "・JA, I, and need to be detected.

Since it is the V signal that is digitized, in order to detect the correlation, it is sufficient to pass each difference through an LPF, detect the correlation of the low frequency components of the Y signal, and use it as a control signal.

Next, the operation of the intra-frame YC separation circuit configured as shown in FIG. 2 will be explained. In this invention, when the motion detection circuit 80 determines that the image is a moving image, the moving image processing includes intra-frame YC separation that includes an intra-field operation and three types of inter-field operations instead of intra-field YC separation. It is characterized by using the most suitable one.

In FIG. 2, a V signal 10 input from an input terminal 11
1 is delayed by 2 pixels in the 2-pixel delay circuit 14, and 262
The line delay circuit 15 delays the signal by 262 lines.

The V signal delayed by 2 pixels in the 2-pixel delay circuit 14 and 262
By subtracting the output of the line delay circuit 15 using a subtracter 19, an inter-field difference for inter-field YC separation C is obtained.

By subtracting the V signal delayed by 2 pixels by the 2-pixel delay circuit 14 and the output of the 4-pixel delay circuit 17 by the subtracter 2o, an inter-field difference for inter-field YC separation B is obtained.

By subtracting the V signal delayed by two pixels by the two-pixel delay circuit 14 and the output of the two-pixel delay circuit 18 by the subtracter 21, an inter-field difference for inter-field Yc separation A is obtained.

The above three types of inter-field differences are input to the first signal selection circuit 29, and selected by the output of the minimum value selection circuit 39, which will be described later.

The inter-field difference which is the output of the subtracter 19 is also 2,
It passes through an LPF 22 with a passband of 1 MHz or less, is converted into an absolute value by an absolute value circuit 25, is inputted to a maximum value selection circuit 38 and a minimum value selection circuit 39, and is then inputted to the attention point and sample point in FIG. 4(b). Detect correlation between two.

The inter-field difference which is the output of the subtracter 20 is also 2,
It passes through an LPF 23 with a passband of 1 MHz or less, is converted into an absolute value by an absolute value circuit 26, is inputted to a maximum value selection circuit 38 and a minimum value selection circuit 39, and is then outputted to the attention point and sample point in FIG. 4(b). Detect the correlation between

The inter-field difference which is the output of the subtractor 21 is also 2,
It passes through an LPF 24 with a passband of 1 MHz or less, is converted into an absolute value by an absolute value circuit 27, and is input to a maximum value selection circuit 38 and a minimum value selection circuit 39, and then the attention point and sample point in FIG. 4(b) are determined. detect the correlation between

The maximum value selection circuit 38 selects the maximum value among the above three types of absolute value outputs, and the minimum value selection circuit 39 selects the minimum value among the above three types of absolute value outputs. The first signal selection circuit 29 is selectively controlled by the output of the minimum value selection circuit 39. That is, when the output of the absolute value circuit 25 is the minimum, the first signal selection circuit 29 selects the output of the subtracter 19 as
When the output of the absolute value circuit 26 is the minimum, the output of the subtracter 20 is selected, and when the output of the absolute value circuit 27 is the minimum, the output of the subtracter 21 is selected.

Furthermore, the output of the first signal selection circuit 29 is
is subtracted from the V signal that is the output of the two-pixel delay circuit 14 to obtain a three-dimensional frequency space low-frequency component in the direction in which the correlation is detected. On the other hand, since the output of the first signal selection circuit 29 is a three-dimensional frequency high-frequency component in the direction in which the correlation is detected,
l-line delay circuit 31, adder 32.35, subtracter 33
, the C signal can be removed by passing through a two-dimensional comb filter composed of LPF34. By adding the outputs of the subtracter 30 and the adder 35 in the adder 36,
An interfield YC separated Y signal can be obtained.

On the other hand, the V signal delayed by two pixels by the two-pixel delay circuit 14 is input to the intra-field Y signal extraction filter 28, and an intra-field YC separated Y signal is obtained by intra-field calculation.

The inter-field YC separated Y signal and the intra-field YC separated Y signal are input to the second signal selection circuit 60, and are selected by the output of the threshold determination circuit 40, which will be described later.

The output of the maximum value selection circuit 38 and the output of the minimum value selection circuit 39 are input to the threshold value determination circuit 40, and the maximum value of the three types of inter-field correlations selected by the maximum value selection circuit 38 is determined as the first value. If it is smaller than the threshold value α, or if the minimum value of the three types of inter-field correlations selected by the minimum value selection circuit 39 is larger than the second threshold value β, the second signal selection circuit 60 selects the intra-field YC Control is performed to select the separated Y signal. On the other hand, in the threshold determination circuit 40, the maximum value of the three types of inter-field correlations is greater than the first threshold α, or the minimum value of the three types of inter-field correlations is the second
If it is determined that the signal is smaller than the threshold value β, control is performed to select the interfield YC separated Y signal. However, it is assumed that there is a relationship α<β.

The output of the second signal selection circuit 60 is output as an intra-frame YC separated Y signal 112.

The subtracter 37 selects V, which is the output of the two-pixel delay circuit 14.
By subtracting the intraframe YC separated Y signal 112 from the signal, an intraframe YC separated Y signal 113 can be obtained.

Note that although in FIG. 2, the calculation including the one-line delay circuit 31 is used to remove the C signal, the same effect can be obtained by performing the calculation using a plurality of one-line delay circuits.

FIG. 3 shows YC in the frame in FIG. 1, which is this invention.
5 is a detailed block diagram of another embodiment of separation 50. FIG.

In FIG. 3, the only difference from FIG. 2 is the method of detecting correlation between fields. Here, as a method of detecting the correlation of the V signal, a method of detecting the direction in which the spectrum of the Y signal spreads in a three-dimensional frequency space is used.

Y for selecting and controlling three types of inter-field YC separation
The frequency range in which the spread of the signal spectrum is detected is illustrated by solid lines of 1 minute in each of FIGS. 9, 1O, and 11. FIG. 9 shows the frequency domain for detecting the spectrum spread of the Y signal for selecting the interfield YC separation A. This area can be detected by passing the LPF through the difference between the sample point of interest "◎" in FIG. 4(b) and the sample point rOJ located one line below the sample point "."A.

Figure 10 shows YC separation B for selecting interfield YC separation B.
This is the frequency domain in which the spread of the signal spectrum is detected.

This area can be detected by passing the BPF through the sum of the sample point of interest "◎" and the sample point "." A in FIG. 4(b).

Figure 11 shows YC separation C between fields.
This is the frequency domain in which the spread of the signal spectrum is detected.

This area can be detected by passing the BPF through the sum of the sample points of interest "◎" and the sample points "." in FIG. 4(b).

Next, of the intra-frame YC separation circuit having the configuration shown in FIG. 3, only the inter-field correlation detection circuit that is different from that shown in FIG. 2 will be described. In FIG. 3, the same parts as in FIG. 2 are given the same numbers.

Output of 262-line delay circuit 15 and 2-pixel delay circuit 14
The outputs of are added by adder 83, and the result is 2.1MH
It passes through a BPF 86 whose passband is z or more, and then is converted into an absolute value by an absolute value circuit 89, which is inputted to the first input terminals of the maximum value selection circuit 38 and the minimum value selection circuit 39, respectively, and the result is shown in FIG. 4(b). ) to detect the correlation between the point of interest and the sample points.

The output of the 262-line delay circuit 15 is sent to the 2-pixel delay circuit 81.
．． 82 and is delayed by 4 pixels. The output of the 2-pixel delay circuit 82 and the output of the 2-pixel delay circuit 14 are added by an adder 84,
The result is a BPF of 87 with a passband of 2.1MHz or higher.
are further converted into absolute values by an absolute value circuit 90, and inputted to the second input terminals of the maximum value selection circuit 38 and the minimum value selection circuit 39, respectively, to determine the point of interest and sample point in FIG. 4(b). Detect the correlation between

The output of the 2-pixel delay circuit 81 and the output of the 2-pixel delay circuit 14 are subtracted by a subtracter 85, and the result is passed through an LPF 88 whose passband is 2°1 MHz or less, and then input to an absolute value circuit 9.
1 and is converted into an absolute value and inputted to the third input terminals of the maximum value selection circuit 38 and the minimum value selection circuit 39, respectively, as shown in FIG.
Detect the correlation between the point of interest in b) and sample point a.

The output of the maximum value selection circuit 38 is input to the first input terminal of the threshold value determination circuit 40 and the fourth input terminal of the first signal selection circuit 29. The output of the minimum value selection circuit 39 is input to the second input terminal of the threshold value determination circuit 40. The output of the threshold determination circuit 40 is input to the third input terminal of the second signal selection circuit 60.

The maximum value selection circuit 38 selects the maximum value among the above three types of absolute value outputs, and the minimum value selection circuit 39 selects the minimum value among the above three types of absolute value outputs. Based on the output of the maximum value selection circuit 38, the first signal selection circuit 29 selects the output of the subtracter 19 when the output of the absolute value circuit 89 is the maximum.
When the output of the absolute value circuit 90 is the maximum, the output of the subtracter 20 is selected, and when the output of the absolute value circuit 91 is the maximum, the output of the subtracter 2I is selected. The threshold value determination circuit 40 determines that the maximum value of the three types of inter-field correlations is the first value.
is smaller than the threshold value α or the minimum value of the three types of inter-field correlations is larger than the second threshold value β, the second signal selection circuit 60 outputs the intra-field YC separated Y signal. Control is performed to select the output of the C signal extraction filter 28. On the other hand, the threshold value determination circuit 40
If it is determined that the maximum value of the three types of inter-field correlations is greater than the first threshold α, or the minimum value of the three types of inter-field correlations is smaller than the second threshold β, then , an adder 3 which outputs an inter-field YC separated Y signal.
6 outputs are selected. However, it is assumed that there is a relationship α<β.

[Effects of the Invention] As described above, according to the present invention, when a motion detection circuit detects a moving image, the intra-frame YC separation circuit locally detects correlation between fields and performs inter-field calculation and intra-field calculation. Since the configuration is configured to perform YC separation by adaptively switching between three types of intra-frame processing including 3 types of intra-frame processing and intra-field processing using an intra-field C signal extraction filter, in video processing using a motion-adaptive YC separation filter, It is possible to perform optimal YC separation using image correlation, and there is an effect that a motion adaptive YC separation filter that performs YC separation with little deterioration in resolution can be configured even in moving images.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a motion adaptive YC separation filter according to an embodiment of the present invention, FIG. 2 is a block diagram showing a detailed configuration of the intra-frame YC separation circuit in FIG. 1,
FIG. 3 is a block diagram showing a detailed configuration of another embodiment of the intra-frame YC separation circuit in FIG. 1, and FIG. 4(a) shows a V 4th plan view configuring the signal arrangement on the t-axis and y-axis
Figure (b) is a plan view of the arrangement of the V signals in Figure 4 (a), which is composed of the y-axis and the Figure 5(b) is a diagram of the spectral distribution in Figure 5(a) viewed from the negative direction of the f axis, and Figure 5(c) is a diagram of the spectral distribution in Figure 5(a) viewed from the negative direction of the f axis. Figure 6(a) shows the spectral distribution of the Y signal and C signal obtained by the first inter-field YC separation according to the present invention, viewed from an oblique direction in three-dimensional frequency space. Figure, Figure 6 (
b) is a diagram of the spectral distribution in Figure 6(a) viewed from the negative direction of the f axis, and Figure 6(c) is a diagram of the spectral distribution in Figure 6(a) viewed from the positive direction of the μ axis. Fig. 7(a) is a diagram of the spectral distribution of the Y signal and C signal obtained by the second interfield YC separation according to the present invention viewed from an oblique direction on a three-dimensional frequency space, and Fig. 7(b) ) is a diagram of the spectral distribution in Figure 7(a) viewed from the negative direction of the f axis, and Figure 7(c) is a diagram of the spectral distribution in Figure 7(a) viewed from the positive direction of the μ axis. , FIG. 8(a) is a diagram of the spectral distribution of the Y signal and C signal obtained by the third interfield YC separation according to the present invention, viewed from an oblique direction on a three-dimensional frequency space, and FIG. 8(b) is a diagram of the spectral distribution in FIG. 8(a) viewed from the negative direction of the f axis, FIG. 8(c) is a diagram of the spectral distribution in FIG. 8(a) viewed from the positive direction of the μ axis, 9 to 11 are diagrams showing frequency regions of three types of correlation detection in other embodiments of FIG. 3, and FIG. 9(a) shows the frequency range of the first field
Figure 9 (b
) is a diagram of the frequency domain in Figure 9(a) viewed from the negative direction of the f axis, and Figure 9(c) is a diagram of the frequency domain in Figure 9(a) viewed from the positive direction of the μ axis. , FIG. 10(a) is a diagram of the frequency domain of correlation detection for selecting the second inter-field YC separation filter viewed from an oblique direction on a three-dimensional frequency space, and FIG. Figure 10 (C
) is a diagram of the frequency domain in Figure 1O (a) viewed from the positive direction of the μ axis, and Figure 11 (a) is a diagram of the third inter-field Y
A diagram of the frequency domain of correlation detection for selecting a C separation filter viewed from an oblique direction on a three-dimensional frequency space. Figure 11 (b) shows the frequency domain of Figure 11 (a) in the negative direction of the f axis. 11(c) is a diagram of the frequency region in FIG. 11(a) viewed from the positive direction of the μ axis, and FIG.
The figure is a block diagram of a conventional motion adaptive YC separation filter.
FIG. 13 is a block diagram showing the detailed configuration of the Y signal motion detection circuit in the motion adaptive YC separation filter of FIG. 12, and FIG. 14 is a block diagram showing the detailed configuration of the C signal motion detection circuit in the motion adaptive YC separation filter of FIG. FIG. 15 is a block diagram showing the detailed configuration of the interframe YC separation circuit in the motion adaptive YC separation filter of FIG. 12. FIG. 16 is a block diagram showing the detailed configuration of the interframe YC separation circuit in the motion adaptive YC separation filter of FIG. FIG. 17 is a block diagram showing a detailed configuration of an intra-field YC separation circuit in a filter. FIG. 17 is a block diagram showing another example of a conventional C signal motion detection circuit. 5... Inter-frame YC separation circuit, 6... Y signal motion detection circuit, 7... C signal motion detection circuit, 8... Synthesis circuit, 9... Y signal mixing circuit, 10... C signal mixing circuit, 50...Intra-frame YC separation circuit, 8o...
Motion detection circuit. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) In a circuit that separates the luminance signal and chrominance signal from a composite color television signal in which the chrominance signal is frequency-multiplexed into the high frequency region of the luminance signal, image movement is locally detected using the correlation between frames. A motion detection circuit that detects a still image, and when this motion detection circuit detects a still image, separates the interframe luminance signal and color signal using interframe correlation, and separates the interframe luminance signal and color signal. When the inter-frame luminance signal/color signal separation circuit that outputs the signal separation color signal and the motion detection circuit detect a moving image, the horizontal low frequency component of the difference at the point where the phase of the color subcarrier is opposite between fields is detected. The correlation is locally detected by Intra-frame luminance signal chrominance signal that outputs a chrominance signal separated luminance signal and outputs an intra-frame luminance signal chrominance signal separated chrominance signal by subtracting the intra-frame luminance signal chrominance signal separated luminance signal from the original composite color television signal. a separation circuit, and a luminance unit that mixes the inter-frame luminance signal chrominance signal separated luminance signal and the intra-frame luminance signal chrominance signal separated luminance signal based on the output of the motion detection circuit to output a motion-adaptive luminance signal chrominance signal separated luminance signal. A signal mixing circuit mixes the inter-frame luminance signal chrominance signal separated color signal and the intra-frame luminance signal chrominance signal separated chrominance signal based on the outputs of the motion detection circuit and outputs a motion-adaptive luminance signal chrominance signal separated chrominance signal. A motion-adaptive luminance signal/chrominance signal separation filter comprising a color signal mixing circuit. (2) Instead of the intra-frame luminance signal chrominance signal separation circuit,
When the motion detection circuit detects a moving image, it calculates the horizontal low frequency component of the difference at the point where the phase of the color subcarrier is the same between fields, and the horizontal high frequency component of the sum at the point where the phase is opposite. By locally detecting the correlation caused by An intra-frame luminance signal that outputs a luminance signal, a chrominance signal, and a separated luminance signal, and outputs an intra-frame luminance signal, a chrominance signal, and a separated chrominance signal by subtracting the intra-frame luminance signal, chrominance signal, and separated luminance signal from the original composite color television signal. 2. The motion adaptive luminance signal/chrominance signal separation filter according to claim 1, wherein the filter is replaced with a color signal separation circuit.