JP2612596B2 - Motion signal processing circuit and spatiotemporal filter circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image motion detection circuit, and in particular, detects motion of an image from a video signal, and performs Y / C separation and scanning line interpolation according to the motion. The present invention relates to a motion detection circuit that supplies an optimal control signal to a signal processing circuit that performs such operations.

[Conventional technology]

There is a technique in which interlaced scanning performed in the NTSC system is interpolated by a receiver and converted into a sequential scanning signal on a receiver side and displayed. If an interpolated scanning line signal is created using a scanning line signal one field before using a field memory and converted into sequential scanning, line flicker occurring at the edge of a horizontal line can be removed. However, this inter-field interpolation can obtain a great effect on a still image, but in the case of a moving image, it causes a great deterioration such as generation of a comb-like double image.

In the example disclosed in Japanese Patent Application Laid-Open No. 58-205377, the motion of an image is detected based on a difference signal between one frame, and interpolation between fields is performed if the motion of the image is small, and transmission is performed if the motion of the image is large. Motion adaptive processing such as creating an interpolated scanning line signal using the scanning line signal in the field thus performed. In this example, the problem of not being able to cope with the fast motion of the object is addressed by performing low-pass filtering on the detected motion amount.

For example, as shown in FIG. 2, when the image J of the object moves from the top to the bottom of the screen P, the interlaced scanning is performed with the vertical axis being the vertical direction of the screen and the horizontal axis being the time axis. FIG. 3 shows the movement of the object image using lines.

In FIG. 3, circles indicate scanning lines 1 (cross-sectional views). When an interpolation scanning line indicated by a triangle mark in the M-th field is created, it is necessary to perform intra-field interpolation because it is a moving image. However, as is apparent from FIG. M-1) Scan line 1 in field
_When the difference between _M-1 and the scanning line 1 _{M + 1} in the (M + 1) -th field is taken, the difference becomes zero because the information of both scanning lines is the same,
Therefore, the movement of the position of the triangle cannot be detected from the inter-frame difference signal. Therefore, inter-field interpolation, which is still image processing, is performed on a moving image, and the above-described deterioration occurs.

In addition, for a fine pattern, erroneous detection of a movement may occur similarly even if the movement is relatively slow.

In the prior art for solving the above problem, for example, FIG.
4B, when the object J moves, the motion amount detected by taking the inter-frame difference signal is as shown in FIG. 4 (b). Since detection is performed, processing for correction is performed to obtain the corrected motion amount shown in FIG. 4C.

However, in this method, a similar pattern movement amount is generated depending on a picture, and moving image processing is performed on a still image, so that there is a possibility that the resolution is reduced or flicker occurs.

For example, when the two frames W ₁ and W ₂ move slowly as shown in FIG. 5 (a), the detected motion amounts are the same as those in FIG. 4 (b). 4 Since the processing is the same as that shown in FIG. 4C, the moving image processing is performed on the signal S between the frames even though the signal S is a still image.

The speed up to which the detection error can be prevented is set in advance by circuit constants. Therefore, there is no effect on the movement at a speed exceeding this.

As a means for correcting such a detection error of the motion detection circuit, as shown in Japanese Patent Application No. 60-274943, a one-frame differential signal is converted into a low-pass filter in the horizontal and vertical directions (hereinafter referred to as "L.
Called PF. ) And through the LPF in the time direction,
There are some that expand the moving image area in the space / time direction. FIG. 6 shows a configuration example of such a spatiotemporal filter. In the figure, 601 is an input terminal, 602 is an output terminal, 603 is a vertical filter, 604 is a time filter, 605 and 609 are maximum value selection circuits, 606 is a 1H (H is a horizontal scanning cycle) delay circuit, and 607 is 262H.
A delay circuit 608 is a coefficient circuit. The basic operation of this circuit will be described below.

The input terminal 601 receives, for example, a signal obtained by taking the absolute value of the two-frame difference signal or a signal for motion detection by taking the absolute value of the low-frequency component of the frame difference signal.

The input signal is composed of a time-direction LPF composed of a 262H delay circuit 607, a coefficient circuit 608 (0 <α <1) and a maximum value selection circuit 609, a 1H delay circuit 606, and a maximum value selection circuit 605. The moving image area is expanded in the time / vertical direction by passing through the vertical LPF
Controls the motion-adaptive scanning line interpolation, the Y / C separation circuit, and the like according to the motion signal output from. FIG. 7 shows how the movement is spread by the spatiotemporal filter shown in FIG. Assuming that the magnitude of the frame difference signal detected on the scanning line indicated by the black circle in the (M-2) th field is 1, the LPF 604 in the time direction makes α times (0 <α1) in the (M-1) th field. ) And spreads while attenuating in the time direction. In addition, the vertical LPF 603 takes the maximum value of the amount of movement between adjacent scanning lines, and the moving image area also expands in the vertical direction. As described above, the moving image area is expanded in the spatio-temporal direction, thereby coping with a quick movement.

[Problems to be solved by the invention]

In the spatio-temporal filter as shown in the above prior art, when considering the center of gravity, the center of gravity in the vertical direction is located at the position shown by the arrow in FIG. Although it fits in, the output terminal 6
When the motion adaptive Y / C separation and the scanning line interpolation circuit are commonly controlled by the control signal obtained from 02, there is a problem that optimal control cannot be performed on the scanning line interpolation circuit.

An object of the present invention is to provide a motion signal processing circuit that provides an optimal control signal to a motion adaptive signal processing circuit.

[Means for solving the problem]

The purpose is to set the center of gravity of the spatiotemporal filter to H /
This is achieved by providing means for moving by two, and providing independent control terminals for motion adaptive Y / C separation and scanning line interpolation.

The above object is also achieved by providing a spatial filter and at least a temporal filter for enlarging a moving image area in a vertical axis direction of an image, and obtaining a motion control signal of a motion adaptive signal processing circuit from an output of the spatial filter. .

[Action]

The center of gravity moving means moves the center of gravity of the spatiotemporal filter vertically.
Since it moves by H / 2, the center of processing and the motion adaptive interpolation circuit match. The control signal output terminal for Y / C separation and the control signal output terminal for scanning line interpolation output control signals having the same processing center of gravity, respectively, so that optimal motion adaptive control can be performed.

Also, since the spatial filter enlarges the moving image area at least in the vertical axis direction of the image and moves the center of gravity in the vertical direction, it is possible to obtain a control signal in which the center of gravity is moved and the vertical enlargement is performed at the same time. Motion adaptive control.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 8th
FIG. 1 shows a configuration example of a spatiotemporal filter according to the present invention. In the figure, 801 is an input terminal, 802 is a Y / C separation control signal output terminal, 803 is a scanning line interpolation control signal output terminal, 804 is a vertical LPF, 805 is a time direction LPF, and 806 is a maximum value. Select circuit, 807 is 1H delay circuit, 808 is 262H delay circuit, 809
Is a coefficient circuit, 810 is a maximum value selection circuit, 811 is a center of gravity shift circuit, 812 is a maximum value selection circuit, and 813 is a 1H delay circuit. The circuit shown in FIG. 8 is obtained by adding a center-of-gravity shift circuit 811 and a control signal output terminal for scanning line interpolation to the conventional circuit shown in FIG. FIG. 9 shows how the control signal obtained from the scanning line interpolation control signal output terminal 803 in FIG. The inter-frame difference signal input from the input terminal 801 has a vertical LPF 804 and a temporal L.F.
Because the band is limited in the time and vertical directions by the PF,
The motion area expands in the time / vertical direction, and the center of gravity shifts in the vertical direction by H / 2 by the center of gravity moving circuit 811 to shift the center of gravity to a portion indicated by an arrow. Thereby, the scanning line interpolation circuit and the processing center of the vertical direction coincide with each other, so that optimum control can be performed. However, the configuration of FIG. 8 has a problem that the circuit scale of the center-of-gravity shifting circuit is increased as compared with the conventional circuit.
In particular, the 1H delay circuit 106 has a large circuit scale when formed as an integrated circuit. Therefore, the LPF 804 in the vertical direction in FIG.
And that the center-of-gravity shift circuit 811 has basically the same configuration, and both are shared to reduce the circuit scale.
FIG. 1 shows a configuration that is also used. In the figure, 101 is an input terminal, 102 is a Y / C separation control signal output terminal, 103 is a scanning line interpolation control signal output terminal, 104 is a vertical LPF, 10
5 is an LPF in the time direction, 106 is a 1H delay circuit, 107 is a maximum value selection circuit, 108 is a coefficient circuit, 109 is a 262H delay circuit, and 110 is a maximum value selection circuit. This embodiment combines the vertical LPF 804 and the center-of-gravity shift circuit 811 of the embodiment shown in FIG. 8, and can be used for each of the Y / C separation and scanning line interpolation circuits without increasing the circuit scale. In addition, it is possible to supply an optimal control signal having the same processing center of gravity. It is also effective as a motion detection circuit for encoding and transmitting an image.

FIG. 10 shows a second embodiment according to the present invention. In the figure, 1001 is an LPF in the horizontal direction, 1002 and 1003 are one-sample delay circuits, 1004 and 1005 are coefficient circuits, 1006 is a maximum value selection circuit, and otherwise, it is the same as that shown in FIG. is there. The LPF 1001 in the horizontal direction is a one-sample delay circuit 100
The coefficient data 1004, 1005 multiplies the two data on both sides by β times (0 <β <1) with respect to the sample data of three adjacent motion signals obtained from 2, 1003, and the maximum value selection circuit
By passing through 1006, the moving image area can be expanded in the horizontal direction, and it is possible to cope with even faster movement. In addition, since the horizontal expansion coefficient β is present in the loop constituting the spatiotemporal filter, the motion signal is horizontal, vertical,
There is an advantage that it can be spread radially in time and three-dimensional directions, and the boundary from the moving image area to the still image area can be smoothed. this is,
This has the effect of reducing unnaturalness due to image movement.

Coefficient circuits 1004 and 1005 in the horizontal LPF 1001
Has been described as multiplying the input signal by β (0 <β <1), but a similar effect can be obtained with a simple circuit configuration by subtracting a fixed value from the input signal by a subtraction circuit. No.
FIG. 11 shows a configuration example of such a horizontal LPF.
In the figure, 1101 is an input terminal, 1102 and 1103 are subtraction circuits, and 1104 is a subtraction signal input terminal (in this circuit, fixed value -2
Is shown. ), 1105 and 1106 are underflow processing circuits, 1107 is a comparison circuit, 1108 is a selector, and 1109 is an output terminal. This circuit includes one sample delay circuit 10 out of three data obtained from one sample delay circuits 1002 and 1003.
For the data obtained from the input of 02 and the output of 1003,
The subtraction circuits 1102 and 1103 perform a subtraction of −2, and compare three data obtained from the outputs of the underflow processing circuits 1105 and 1106 and the one-sample delay circuit 1002 with a comparison circuit.
This is performed in 1107, and the largest one is output from the selector 1108. In this way, the moving image area can be enlarged in the horizontal direction.

Similarly, the coefficient circuit 108 in the LPF 105 in the time direction can be realized using a subtraction circuit. Such a LP in the time direction
FIG. 12 shows a configuration example of F. In the figure, reference numeral 1201 denotes an input terminal, 1202 denotes a subtraction circuit, 1203 denotes a subtraction signal signal terminal (the case of -2 is shown in the figure), 1204 denotes an output terminal, and 1205
Is an underflow processing circuit, 1206 is a selector, and 1207 is a comparison circuit. Subtraction (−2) is performed on the input signal instead of the coefficient α times (0 <α <1). It goes without saying that the same effect can be obtained even if the position of the subtraction circuit is connected after the 262H delay circuit 109.

The subtraction circuit and the underflow processing circuit can be easily realized by a logic gate circuit as shown in FIG. In the figure, 1301 to 1304 are input terminals, 1305-1308 are output terminals, 1309 is a subtraction circuit (-2), 1301 is an underflow processing circuit, 1311 is an inverter circuit, 1312 is a NOR circuit, 131
3, 1314 is EX-OR circuit, 1315 is NAND circuit, 1316 to 1319 is A
ND circuit. The operation of this circuit will be described below. Encoded with 4 bits from input terminals 1301-1304 (natural binary number)
The moved amount is input. In the subtraction circuit 1309, an operation of -2 is performed. For example, when a motion amount of magnitude 2 is input to the input terminals 1301 to 1304, “D ₀ , D ₁ , D ₂ , D ₃ ” =
It becomes “0100”, 2 is subtracted by the subtraction circuit 1309, and “0000”
Is obtained from the subtraction circuit 1309. Underflow processing circuit
At 1310, processing is performed so that the output becomes “0” for a value that becomes a negative number by subtracting 2.

In the embodiments described above, the maximum value of the data obtained from the input / output terminals of the delay circuit and the delay circuit was used to expand the moving image area in the horizontal / vertical and time directions. The same effect can be obtained by performing (integration).

Further, in the embodiment shown in FIG.
The same effect can be obtained even if the order of 01 and the vertical filter 104 is exchanged.

〔The invention's effect〕

As described above, according to the present invention, it is possible to obtain an optimal control signal whose center of gravity matches the motion adaptive signal processing circuit without increasing the circuit scale.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram showing a falling object image, FIG. 3 is an explanatory diagram showing erroneous detection of image movement, and FIG. FIG. 5 is an explanatory view showing a problem of the conventional example, FIG. 6 is a block diagram showing a conventional spatio-temporal filter, and FIG. FIG. 8 is a characteristic diagram showing characteristics of a spatial filter, FIG. 8 is a block diagram showing one embodiment of the present invention,
9 is a characteristic diagram of the interpolation control signal of FIG. 8, FIG. 10 is a block diagram showing an embodiment according to the present invention, and FIG. 11 is a horizontal LPF.
FIG. 12 is a block diagram showing a time LPF, and FIG. 13 is a block diagram showing a subtraction circuit and an underflow processing circuit. 105: LPF in the time direction 104: LPF in the vertical direction 811: Circuit for moving the center of gravity 1001: LPFs 102, 103 in the horizontal direction: output terminals for motion control.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Katsumata 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Home Appliances Research Laboratory, Hitachi, Ltd. (72) Kazuo Ishikura, Inventor Kazuo Ishikura 1-280, Higashi-Koigakubo, Kokubunji-shi, Tokyo Tokyo, Japan (72) Inventor Nao Suzuki 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi Video Engineering Co., Ltd. In company

Claims (8)

(57) [Claims] A motion signal processing circuit for receiving a motion detection signal of an image detected based on at least one frame difference signal of a television signal and obtaining a control signal for controlling a motion adaptive signal processing circuit. It has a first input terminal and a second input terminal, enlarges a signal input to the first input terminal in the time axis direction of an image, and synthesizes and outputs a signal input to the second input terminal. A temporal filter, and a spatial filter that enlarges a moving image area in at least a vertical axis direction of the image; an output signal of the spatial filter is input to a first input terminal of the temporal filter; A spatio-temporal filter is configured by inputting the motion detection signal of the image, and inputting the output signal of the temporal filter to the spatial filter, and obtaining a motion control signal from the output of the spatial filter. It can signal processing circuit. 2. The spatial filter according to claim 1, wherein the spatial filter is constituted by a single vertical filter for enlarging a moving image area in the vertical direction of the image or a series connection with a horizontal filter for enlarging the moving image area in the horizontal direction of the image. The motion signal processing circuit according to claim 1, wherein 3. A motion signal processing circuit which receives a motion detection signal of an image detected based on at least one frame difference signal of a television signal and obtains a control signal for controlling a motion adaptive signal processing circuit. 1. A time that has two input terminals and a time that a signal input to the first input terminal is enlarged in the time axis direction of an image and combined with a signal input to the second input terminal and output A filter, a vertical filter for enlarging a moving image area in the vertical axis direction of the image, and a horizontal filter for enlarging the moving image area in the horizontal direction of the image, and a first input terminal of the time filter,
An output signal of the vertical filter is input, a motion detection signal of the image is input to the second input terminal, an output signal of the temporal filter is input to the horizontal filter, and an output of the horizontal filter is output to the vertical filter. A motion signal processing circuit wherein a spatio-temporal filter is formed by inputting to a filter, and a motion control signal is obtained from an input or output of the vertical filter. 4. The motion-adaptive signal processing circuit includes at least a motion-adaptive scanning line interpolation circuit, and obtains a motion control signal of the motion-adaptive scanning line interpolation circuit from an output of the vertical filter. The motion signal processing circuit according to claim 3, wherein 5. A horizontal filter, comprising: at least two one-sample delay elements; a subtraction circuit for subtracting a predetermined value from data obtained from input / output of the one-sample delay element; 5. The motion signal processing circuit according to claim 1, further comprising a maximum value selection circuit for obtaining a maximum value of data output from the subtraction circuit. 6. The time filter has a delay circuit for at least one field, a subtraction circuit for subtracting a predetermined value from an input signal, a plurality of inputs, and a maximum value of a plurality of input signals. , And an input signal from the first input terminal is
The output signal of the series-connected circuit of the subtraction circuit and the delay circuit is input to the maximum value selection circuit, and the other input of the maximum value selection circuit is the second signal. The motion signal processing circuit according to any one of claims 1 to 4, wherein a signal is input from the input terminal of (1), and a maximum value is output as an output signal of the time filter. 7. The vertical filter includes a delay circuit for at least 1H (H is a horizontal scanning cycle) and a maximum value selection circuit having a plurality of inputs and selecting a maximum value of a plurality of input signals. 5. A signal obtained from an input / output terminal of the delay circuit is input to an input terminal of the maximum value selection circuit, and a maximum value is selected as an output signal of the vertical filter. The motion signal processing circuit according to any one of the above. 8. A time filter which inputs a motion detection signal of an image, expands and attenuates the motion detection signal in the time axis direction of the image, and expands the motion detection signal in the horizontal and vertical axis directions of the image.
Feedback connection with a spatial filter that attenuates in the horizontal axis direction,
A spatio-temporal filter circuit for generating a control signal for a motion adaptive signal processing circuit.