JPH01277092A - Motion detecting circuit - Google Patents

Abstract

PURPOSE:To perform motion adaptive YC separation in which a few amount of deterioration is generated in picture quality by constituting a motion detecting circuit so as to suppress motion detecting sensitivity at a low level when vertical correlation in a field is low. CONSTITUTION:An in-field vertical correlation detection circuit 11 inputs a V signal, and detects a vertical high frequency component centering a vertical frequency, and outputs an in-field vertical correlation detecting signal l111. The signal l111 is inputted to a V signal motion detection circuit 6 and a C signal motion detection circuit 7, and controls the input/output characteristics of the circuits 6 and 7. The circuit 5 outputs a Y signal motion detecting signal 112 from a V signal, and the circuit 7 outputs a C signal metion detecting signal 113. A synthetic circuit 8 selects the signal with a large value out of the signals 112 and 113, and outputs a control signal 114 with a motion coefficient kl. A Y and a C signal mixing circuits 9 and 10 perform computation by receiving the signal 114, and output a motion adaptive YC separation Yl signal 115 and a motion adaptive YC separation Cl signal 116 from output terminals 2 and 3, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applicable to complex television signals in which a color signal is frequency multiplexed into a high frequency region of a luminance signal.

From the luminance signal (hereinafter referred to as "Y signal")
The present invention relates to a motion detection circuit that detects the amount of motion of a pixel signal in a motion adaptive YC separation device for separating a color signal (hereinafter referred to as a "C signal" or simply "c").

[Prior art] A motion adaptive YC separation device using a conventional motion detection circuit is 1
It locally determines whether an image is a still image or a moving image, and performs YC separation suitable for the pixel signals of each part.

In the current N"l" SC 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 receiver, and incomplete separation causes image quality deterioration such as cross color and dot crawl.

For this reason, with the development of large-capacity digital memories in recent years, the use of delay circuits (hereinafter referred to as "delay circuits") that have a delay time equal to or longer than the vertical scanning frequency of television signals has become increasingly popular. Various adaptive YC separation devices have been proposed as signal processing devices for improving image quality.

FIG. 10 is a block circuit diagram showing an example of a conventional motion adaptive YC separation device. In the figure, the input terminal (1) 2 receives the NTSC system ■ signal (101), the intra-field YC separation circuit (4), the inter-frame YC separation circuit +5), and the Y signal i3 motion detection circuit. (6) and C
Each signal tj is selected at the input end of the signal motion detection circuit (7). The intra-field YC separated by the intra-field filter (not shown) in the intra-field YC separation circuit (4).
And, the intra-field YC separated C signal Cf (1 port 3) is,
and the first input terminal of the Y signal mixing circuit (9), respectively, and the C
A first input of the signal mixing circuit (10) is powered. In addition, an interframe Y, C separated Y signal Y F (+04) which is YC separated by an interframe filter (not shown) in an interframe YC separation circuit (5), and an interframe YC separated C signal CI-' (+05 ) are the second input terminal of the Y signal mixing circuit (9) and the C signal mixing circuit (!), respectively.
0). On the other hand, Y (Y signal motion amount detected by No. 3 motion detection circuit (6) (+06
) is manually input to one input terminal of the synthesis circuit (8), and the C signal movement ffi detected by the C signal motion detection circuit (7) (+071 is input to the other input terminal of the synthesis circuit (8) The motion (,
The flame detection signal K [108] 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 is inputted to the third input terminal of the Y signal mixing circuit (61, C
i) The motion amount detection circuit (7) and the synthesis circuit (8) constitute the motion amount detection circuit (20).

The motion adaptive YC separation Y which is the output of the Y filter mixing circuit (9)
(No. 3 t109) is sent out from the output terminal (2) and is also the motion adaptive YC signal that is the output of the C signal mixing circuit (10).
The separated C signal 1109) is sent out from the output end (3).

Next, the operation of this conventional example will be explained.

The motion detection circuit (20) synthesizes the outputs of the Y signal motion detection circuit (6) and the C signal motion detection circuit (7) in the synthesis circuit (8) in order to separate the signal (lull) into Y and C.
(2) Determine whether the signal (+01) represents a still image or a signal representing movement. Y signal motion detection circuit (6)
For example, the first! As shown in the figure, one frame delay circuit (6
3) and a subtracter (64) to find a one-frame difference in the Y signal, pass it through a low-pass filter (hereinafter referred to as F, rLPFJ) (651), and then use an absolute value circuit (66) to find its absolute value. This absolute value is converted by a nonlinear conversion circuit (67) into a signal (+061) indicating the movement of the low frequency component of the Y signal.
As shown in Figure 2, a two-frame difference is obtained using a two-frame delay circuit (73) and an attenuator (74), and then passed through a band-pass filter (hereinafter referred to as rBPFJ), followed by an absolute value circuit ( 76) calculates its absolute value, and converts this absolute value into a signal (10
? ). The synthesis circuit (8) is configured to select and output the larger value of, for example, the Y signal motion rl signal (106) and the C signal motion development signal (107).

As a result, is expressed as a motion coefficient in the form (0≦≦1); for example, if the image is determined to be a completely still image, then: 0. In addition, if the image is determined to be a complete moving image, the Y4: No. 4 mixing circuit (9)
and is given to the C signal mixing circuit (lO) as a control signal (+08).

Generally, when one 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) uses, for example, a one frame delay circuit (52) and an adder (53) as shown in FIG.

The YF multiplied signal 104) is extracted by calculating the frame sum, and the CF signal (+05) is extracted by subtracting the YF multiplied signal 104) from the subtractor (54).

Also, generally when the image is a moving image.

Perform intra-field YC separation using intra-field correlation to separate Y and C signals by 1f! N: Yes. Y in the field
The C separation circuit (4) uses, for example, a one-line delay circuit (42) and an adder (43) as shown in FIG.

The Yf signal +1021 is extracted by calculating the l line sum, and the C'signal (103) is extracted by subtracting the Y'signal!102) from the human power using a subtracter (44).

In the motion adaptive YC separator, such inter-frame YC
The separation circuit (5) and the intra-field YC separation circuit (4) are arranged side by side, and the Y signal mixing circuit (
9) performs the following operation q to output a motion adaptive YCC separated signal (1091).

Y=to-Yf+(1-k)Yl” here.

Yf: In-field YC portion 11i1Y signal output (102
)YF: Interframe YC separated Y signal output (104). Similarly, the control signal (108) causes the C signal mixing circuit (lO) to perform the following calculation to generate motion adaptive Y.
C-separated C signal (110) is output.

C=to -Cf+ (1-k) Ct.

here.

C": YC molecule in field 1ilc signal output (103
10F: Interframe YC separation C signal output +1051.

Motion adaptive Y signal (+09) and motion adaptive C (No. 3 +110)
1 are sent out from the output terminal (2) and the output terminal (3), respectively.

Problem J to be Solved by the Invention - The conventional motion detection circuit consists of a Y-signal motion detection circuit and a C-signal motion detection circuit.
The motions respectively detected by the signal motion detection circuit; y r (
, Hs; and C [signal, as well as YF signal and CF multiplied signal by YC separation by intra-frame YC separation, so 1T of Y belief! When an image with vertical vertical frequency components and diagonal high frequency components moves slightly (for example, when the image shakes slightly due to camera vibration, etc.), the high frequency components of the signal Since the motion -1 is detected by the C signal motion detection circuit (7) and the motion clear is detected by the Y signal motion detection circuit (6) at the same time, the motion coefficient k becomes a large value.

For this reason, the iy value of intra-field YC separation increases to the required silver-1, resulting in a decrease in resolution and the problem of deterioration of image quality such as cross color.

This invention was made to solve the problems mentioned in 1.
It is an object of the present invention to provide a motion detection circuit capable of reproducing images with high resolution and little deterioration in image quality such as cross color.

[Means for Solving the Problems] The motion detection circuit according to the present invention includes a means for detecting the amount of motion between frames of one pixel, a means for detecting intra-field vertical correlation, and a means for detecting the intra-field vertical correlation. E accordingly
and means for controlling the motion detection sensitivity of the inter-frame motion detection means.

1 Effect J The inter-frame movement detecting means in this invention detects the inter-frame movement of the pixel of interest.

Further, the intra-field vertical correlation detection means detects the intra-field vertical correlation by detecting a difference between lines adjacent to each other within the field.

Now, the horizontal direction of the screen is the X axis, the vertical direction of the screen is the y axis,
If the L axis, which is the time axis, is taken in the direction perpendicular to the plane composed of the axis and the y axis, a three-dimensional space-time can be considered that can be composed of the X axis, the y axis, and the L axis. In addition, the horizontal frequency axis μ
It is possible to consider a three-dimensional frequency space that can be composed of a μ-axis, a cy-axis, and an f-axis, which are perpendicular to n: the y-axis, which is a vertical frequency axis, and the r-axis, which is a time frequency.

Figure 2 (al) is a diagram of this three-dimensional frequency space viewed from the positive direction of the r-axis, and Figure 2 (b) is a diagram viewed from the positive direction of the μ-axis, with the diagonally shaded area in the figure. is a region where there is a spectrum of an image with a small intra-field direct correlation that can be detected by the difference between lines adjacent to a line in the field.The detection sensitivity control means is used to control the frequency at which one image moves minutely and falls into this region. component, the motion amount determination criterion is changed so that the larger the amount of this frequency component, the lower the motion detection sensitivity of the interframe motion detection means.As a result, if one image has minute movement, it is a still image. Since the YC separation between frames is performed based on this determination, image quality deterioration can be greatly reduced.Furthermore, if the image is a large amplitude signal and moves significantly, a large frame difference will occur, so the intra-field vertical correlation is small. However, the motion detection sensitivity will not decrease and the image will not be erroneously judged as a still image.On the other hand, if the image has a small amplitude, the intra-field line difference will take a small value, so the intra-field East Orthogonal correlation will be large. Since it is determined that the motion detection sensitivity is high, it becomes possible to detect the motion Thi even if the small amplitude signal moves greatly.

[Embodiments of the invention] An embodiment of the present invention will be described below.

FIG. 1 is a block circuit diagram of this embodiment.

In the figure, the same symbols as in Figure 1θ indicate the same or corresponding parts, and (11) is an intra-field vertical correlation detection circuit that detects the intra-field vertical correlation of the V signal, and Figure 3 is its block circuit diagram. It is.

4 is a block circuit diagram of the Y signal motion detection circuit (5), and FIG. 5 is a block circuit diagram of the C signal motion detection circuit (7). The difference between the detection circuits is that the nonlinear conversion circuits (68) and (78) each receive an intra-field vertical correlation detection signal β.
An input terminal is provided, and the motion conversion sensitivity is controlled by the intra-field vertical correlation detection signal i.

The operation of this embodiment will be described below with reference to two conventional examples and one point.

As shown in FIG. 3, the intra-field quadrature correlation detection circuit (11) receives the V signal (101) from the input terminal r~(21), and inputs the V signal (101) to the one-line delay circuit (23) and the subtracter (2).
4), respectively. The 1-line delayed signal in the 1-line delay circuit (23) is applied to the other input terminal of the subtracter (24) for subtraction. The absolute value circuit (25) takes the absolute value of the one-line difference signal of the V signal obtained by the subtracter (24) and supplies it to the coefficient unit (26). Coefficient 3 (26) sends out an intra-field vertical correlation detection signal β (+111) corresponding to the input absolute value from the output terminal (22).

Intra-field vertical correlation detection circuit configured in this way (
11) detects the frequency component whose spectrum exists in the shaded area on the frequency space shown in Fig. 2, that is, the vertical frequency (525/4) [normal high frequency component centered at fiphJ]. .

The intra-field vertical correlation detection signal β(l l +) is Y
Input terminal (63) of signal motion detection circuit (6) and C4
It is manually inputted from the input terminal (73) of the No. 3 motion detection circuit (7) and controls the input/output characteristics of the nonlinear conversion circuits [6B) and 17B). The human output characteristics of these two nonlinear conversion circuits (68) and (78) are configured to have variable characteristics as shown in FIG. 6, for example. In other words, characteristic a indicates the characteristic when the intra-field vertical correlation detection signal 1 (III) is at its minimum, and there is no movement until the human power level from the absolute value circuits (65) and (67) reaches the value A. Amount detection signal (11
2), (The output level at +131 is O (i.e., the frame correlation is high, and it is zero at the time of movement), and as it becomes larger than 8, the output level gradually increases (i.e., the correlation between 5 frames gradually decreases). , a characteristic in which the amount of motion gradually increases (increases) and finally saturates, and is characteristic as the level of intra-field vertical correlation detection signal 1 (III) increases, as shown in c and d to the output starting point. is shifted to the right, and the absolute value circuits (661, (76)) are adjusted so that it will not be determined that there is movement unless a large amount of human power is applied.

The Y signal motion detection circuit (6) detects the false motion of the Y signal from the V signal (101) using the human output characteristics shown in FIG. C
The signal motion detection circuit (7) adds a detection signal (1) to the C signal motion.
13) is output.

The synthesis circuit (8) receives the human-powered Y signal motion detection signal (+1
2) and C signal motion amount detection signal +1131, the larger value is selected and the control signal (11
Output as 43.

The Y signal mixing circuit (9) and the C signal mixing circuit (10) receive this control signal (114) and calculate Y=kn−Y f+ (1−kl YI?C=kj!・
cf+ (1-kjN CF calculation is performed to generate a motion-adaptive YC-separated YJ2 signal (+151) that does not have low resolution due to minute movements of one image, and a motion-adaptive YC-separated YJ2 signal that does not cause image quality deterioration such as cross color etc. The signal (+161) is output from output terminals (2) and (3), respectively.

In addition, in the above embodiment, even if image deterioration such as cross color of an image with vertical high frequency components is allowed, 21
■If you want to prevent the resolution from decreasing due to images, etc.,
The coefficient unit (2) in the intra-field quadrature correlation detection circuit (11)
6) It is sufficient to set the human output characteristic to a low level as shown in the characteristic e shown in Fig. 7, or conversely, even if a double-width image is allowed, deterioration of image quality due to cross color etc. can be prevented as much as possible d- , if desired, the gain can be set high as shown in the input/output characteristic f shown in FIG.

Note that the human output characteristics of the coefficient unit (26) are constant, and the human output characteristics of the nonlinear conversion circuit (68) in the Y signal motion detection circuit (6) and the nonlinear conversion circuit in the C signal motion detection circuit (7) are (78) By changing the human output characteristics like the input/output characteristics g, or h in Fig. 8, the coefficient multiplier (2
The same effect as changing the characteristic 6) can be obtained. It should be noted that the human output characteristics g and h shown in FIG. It goes without saying that a combination of the two may also be used.

Also, due to the 5 pixel position, the Y signal movement detection circuit (6)
In order to prevent the input/output characteristics of the nonlinear conversion circuit (681, +78) in the motion detection circuit (7) from changing, a buffer as shown in FIG. 9 is installed after the nonlinear conversion circuit (68) and (78). A circuit (12) may also be inserted.

This buffer circuit (12) is connected to the input terminal -f-(31), for example.
Y (No. 6 motion detection signal + 112) manually input from 1,
The output terminal is converted to a smooth No. 1.1 signal through a slip circuit (33) composed of PF, etc., and further reduces the number of bits using a clip circuit (34) to reduce the number of bits if necessary. (32) is configured to be input to the synthesis circuit (8), and malfunctions due to noise etc. can be reduced.

In the above embodiment, the Y signal motion detection circuit (6)
Detect the amount of movement between each frame of the FA.

The C signal motion detection circuit (7) detects the motion between two frames of the C signal, and the synthesis circuit (8) selects the larger motion detection signal and outputs it as a control signal k1 (+141). However, depending on the purpose, only one of the motion detection circuits may be provided and the other motion detection circuit and synthesis circuit (8) may be omitted.

Furthermore, in the above embodiment, the intra-field correlation detection circuit (!
Although 1) is configured to detect the correlation with pixels in the vertical direction one line before, it is not necessarily limited to the area before the hot line, but is configured to detect the correlation with pixels on two lines or more lines before. Furthermore, a configuration may be adopted in which the average correlation with each pixel of a plurality of lines is detected.

[Effects of the Invention J As described above, according to the present invention, since the motion detection sensitivity is lowered when the intra-field vertical correlation is small, the resolution decreases due to minute movements in one image, cross color etc. This has the effect of providing a motion detection circuit that can perform motion adaptive YC separation, etc. with little deterioration in image quality.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of an embodiment of the present invention, FIG. 2 is a diagram showing the frequency domain detected by the intra-field multiple quadrature correlation detection circuit of this embodiment, and FIG. A block circuit diagram of the vertical correlation detection circuit, FIG. 4 is a block circuit diagram of the Yf word motion detection circuit of this embodiment, and FIG. 5 is a block circuit diagram of the C4;-, S motion detection circuit of this embodiment. FIG. 6 is a diagram showing the characteristics of the nonlinear conversion circuit of this embodiment, and FIG. 7 is a diagram showing an example of the human output characteristics of the coefficient machine constituting the intra-field vertical correlation detection circuit of this embodiment.
FIG. 8 is a diagram showing another characteristic example of the nonlinear conversion circuit of this embodiment, FIG. 9 is a block circuit diagram of the buffer circuit of this embodiment, and FIG. 10 is a motion adaptive YC using a conventional motion detection circuit.
The block circuit diagram of the separation device, FIG. 11, is the Y of this conventional example.
FIG. 12 is a block circuit diagram of the C signal motion detection circuit of this conventional example, and FIG. 13 is a block circuit diagram of the conventional example and the embodiment of the present invention shown in FIG. FIG. 14 is a block circuit diagram of the YC separation circuit. Similarly, FIG. 14 is a block circuit diagram of the intra-field YC separation circuit. (6)...Y signal motion detection circuit, (71.C signal motion detection circuit, (8)...combining circuit, (11)...intra-field vertical correlation detection circuit, (20)...movement Detection circuit, (231...L line delay circuit, (24
1, (641, +741-...Subtractor. (251, (661, (761...Absolute value circuit, (2
6)...Coefficient unit, (63)...l frame delay circuit, (65)...i I) r=', (681, 11
8) , , Nonlinear conversion circuit, (75) -13PF-
'. Note that in each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) Means for detecting the amount of interframe movement of a pixel of interest in a television signal that performs interlace scanning, and detecting the correlation between the pixel of interest and pixels in the same field located near it in the vertical direction. and means for controlling the motion amount detection sensitivity of the inter-frame motion detection means based on the detected intra-field vertical correlation.