JP2989362B2 - Motion detection circuit and motion detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for detecting a motion of a television signal receiving apparatus which has been subjected to band compression processing by a multiple sub-sampling method. In particular, it relates to a motion detection circuit of a MUSE signal receiver.

[0002]

2. Description of the Related Art As a technique for compressing a band of a high-definition video signal, a multiple sub-Nyquist sampling encoding method is used.
(MUSE method) (Multiple Sub-Nyquist Sampling Encod
ing) has been developed by NHK (Japan Broadcasting Corporation) and broadcasted by a broadcasting satellite (BS).

The MUSE system is a band compression system for transmitting high-definition video signals on one channel of satellite broadcasting having a bandwidth of 27 MHz. In the MUSE system, a high-quality video signal is subjected to sub-Nyquist sampling processing by a band compression encoder to convert the signal into a band-compressed signal having a bandwidth of 8.1 MHz.
The MUSE system is introduced in the following literature.

(A) NHK technology research Vol. 39, No. 2, 1987
Issue No. 172 No. 18 (76)-53 (111) Ninomiya, Otsuka, Izumi,
Koshi, Iwadate, "Development of MUSE method" (B) Nikkei McGraw-Hill magazine, "Nikkei Electronics, November 2, 1987, No.433," pp. 189-212, Ninomiya, "Hi-Vision Using Satellites" Broadcasting transmission system MUS
E] FIG. 3 shows an example of a MUSE signal receiver that is well known in the above-mentioned literature.

FIG. 3 shows a schematic circuit configuration. (1
0) is a MUSE signal input terminal. (12) is A
/ D converter. (14) is a still image processing circuit. The still image processing circuit (14) performs frame interpolating processing and field interpolating processing.

(16) is a moving image processing circuit. This moving image processing circuit (16) performs a field interpolation process. (18) is a motion detection circuit. (20) is a mixing circuit. (22) is a TCI processing / matrix circuit. This TCI processing matrix circuit (22)
It performs expansion of the color difference signal, matrix operation, and the like.

(24) is a D / A converter. (2
6) is an RGB signal output terminal. The MUSE signal applied to the input terminal (10) of the MUSE signal receiver is converted into a digital signal by an A / D conversion circuit (12). The converted MUSE signal is subjected to inter-frame interpolation and inter-field interpolation in a still image processing circuit (14).

Further, MUSE converted into a digital signal
The signal is subjected to field interpolation in a moving image processing circuit (16). MUS converted to digital signal
The E signal is also input to the motion detection circuit (18), and a motion area is detected. The mixing circuit (20) detects the motion picture decoded signal from the motion picture processing circuit (16) and the still picture decoded signal from the still picture processing circuit (14) by motion detection from the motion detection circuit (18). Proportional mixing according to the signal.

The output of the mixing circuit (20) is TC
The I processing matrix circuit (22) expands the color difference signal and performs a matrix operation to generate a digital RGB signal. This digital RGB signal is converted into an analog RGB signal for driving a monitor display by a D / A conversion circuit (24). FIG. 4 schematically shows a known motion detection circuit (18).

In FIG. 4, (30) is a two-frame difference detection circuit, (32) is a one-frame difference detection circuit, and (34) is a MAX circuit. Here, the two-frame difference detection circuit (3
0) extracts difference information between the video signal of the current frame and the video signal of two frames before using the memory for two frames. This is because, as is well known, the sampling pattern of the MUSE signal is an inter-frame offset and an inter-field offset sub-sample pattern that makes one round in four fields, so that a two-frame difference detection is performed. This makes it possible to obtain a difference at the same sampling point on the screen and obtain accurate motion information.

Also, as is well known, the one-frame difference detection circuit (32) is used for the movement of a special image pattern which may cause a detection error of the two-frame difference detection circuit (30). Used for auxiliary use.
The one-frame difference detection circuit (32) extracts difference information between a current frame and a video signal one frame before by using a memory for one frame. But MU
In the SE signal, the sampling point is shifted between the signal of the current frame and the signal of one frame before, and the aliasing component is mixed in a region of 4 MHz or more in the signal component.
Therefore, the one-frame difference detection circuit (32) calculates the one-frame difference after low-pass filter processing for limiting the band of the input signal to 4 MHz by internal processing.

The above two-frame difference detection circuit (30), 1
Each output of the frame difference detection circuit (32) is output to the MAX circuit (3
In 4), the larger absolute value is selected, and the motion detection circuit (1) is selected.
8). With the configuration of the motion detection circuit (18) described above, accurate motion detection for most of the video signals is possible. However, in the case of a signal input as shown in FIG. 5, for example, a detection error occurs.

The operation will be briefly described with reference to FIG. The input signal patterns are shown in FIGS.
Here, the input signals a, b, and c are respectively 2 frames before, 1
Before the frame, that of the current frame. The vertical stripe pattern of about 8 MHz on the screen shows a waveform when the pattern moves from left to right.

In order to obtain a difference between two frames, a difference between the input signal a and the input signal c is calculated. When the relationship between the speed of the movement as shown in the pattern and the interval between the vertical stripes is established, as shown in FIG. Regardless of the area (g in the figure), no two-frame difference signal is generated. On the other hand, when the difference between the signal of the input signal b and the signal of the input signal c is calculated as one frame difference, as described above, the one-frame difference detection circuit (32) uses 0 to 4 MHz for the input signal.
As a result, only one frame difference signal having a low amplitude is generated on both sides of the actual motion area as shown in e.

As described above, the one-frame difference detection circuit,
A conventional motion detection circuit equipped with a frame difference detection circuit (1
In 8), it is difficult to detect the moving region of the moving object shown in the example of FIG. If the interval between the vertical stripes of the moving object is wide and 4 MHz or less, even if the relationship of the movement speed is the movement of one vertical stripe in two frames, in this case, the one-frame difference detection circuit will operate normally. There is no problem because the detection result is obtained.

[0016]

Conventionally, 4 MHZ
A vertical stripe pattern or an oblique stripe pattern having a vertical stripe pattern component of z or more takes two frames in the horizontal direction (1/1).
Under the condition of moving one vertical stripe in (15 seconds), it was not possible to accurately detect a moving area, halftone dot disturbance occurred in a reproduced video, and image quality was deteriorated.

The present invention prevents this halftone dot interference.

[0018]

A motion detecting circuit for a MUSE signal according to the present invention comprises: a two-frame difference detecting circuit (30) for outputting a two-frame difference signal of the MUSE signal;
A one-frame difference detection circuit (32) for outputting a one-frame difference signal of a low-frequency component of the USE signal, and a still-image processing circuit for outputting a still-image decoded signal for a still-image portion of the MUSE signal (14) a moving image processing circuit (16) for outputting a moving image decoded signal for a moving image portion of the MUSE signal;
A vertical low-pass filter (42a) to which the still picture decoded signal is input, and the vertical low-pass filter (42a)
(42b) for matching the output signal from the filter with the frequency band of the decoded video signal, the filtered still image signal and the decoded video signal from the filter circuit (42b). A comparison circuit (44a) for outputting a third difference signal when the amplitude level of the decoded signal for moving image is large, a second difference signal, the one-frame difference signal, and the third difference An output circuit (34, 44) for creating a motion detection signal from the signal
c).

In the motion detection method for a MUSE signal according to the present invention, a still image portion is transmitted after being subjected to offset subsampling between fields and frames, and a moving image portion is transmitted after being subjected to offset subsampling between lines, In the motion detection method for a sub-sampled video signal having a low-frequency region without aliasing, a still-image video signal is generated by interpolating the sub-sampled video signal between frames and fields. A video signal for a moving image is created by subjecting a sample video signal to field interpolation, and the video signal for a still image and the video signal for a moving image in a frequency range higher than the low frequency band within the band of the video signal for a moving image. And the amplitude level of the still image video signal is
A motion detection signal is output when the amplitude level of the video signal is lower than the amplitude level of the video signal.

Further, in the motion detecting method for a MUSE signal according to the present invention, each of a decoded video signal for a still image and a decoded video signal for a moving image of the MUSE signal is subjected to filtering, and a difference signal of these filtered outputs is obtained. Detecting a motion area.

[0021]

The 4M of the decoded signal for the still image and the decoded signal for the moving image
From Hz to about 12 MHz, both have the same amplitude characteristics.
In the present invention, a vertical LPF process and a horizontal BPF process are performed on a decoded signal for a still image, and an amplitude level difference between the decoded signal for a still image and the decoded signal for a moving image band-limited to the same frequency pair is determined. Compare this amplitude level difference,
When it is larger, it is determined as a motion area.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS MUS equipped with a motion detection circuit according to the present invention
An E signal receiver is shown in FIG. The same parts as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. (38) is a motion detection auxiliary circuit. The motion detection auxiliary circuit (38)
Operates naturally as a part of a motion detection circuit for detecting a motion area, but is named differently here to distinguish it from the conventional motion detection circuit (18).

(38a) (38b) (38c) (38
d) is a terminal of the motion detection auxiliary circuit (38).
(40) and (42) are filter processing circuits. (4
4) is a comparison output circuit. Filter processing circuit (4
The input signal to 2) is a still image processing circuit (14)
, A still image decoded signal that has been subjected to inter-frame interpolation and inter-field interpolation for the MUSE signal.

As the input signal to the filter processing circuit (40), a moving picture decoded signal obtained by performing a field interpolation process on the MUSE signal in the moving picture processing circuit (16) is used. A filter unit (40) for each of these input signals
(42) is subjected to a filtering process and a low-pass filtering process in the vertical direction to extract a component of 4 to 12 MHz in the horizontal direction.

Each filter processing circuit (40) (42)
The output is applied to a comparison output circuit (44), where the output of the moving image filter processing (42) has a larger amplitude level than the output of the still image filter processing, and the amplitude level difference is greater than a certain value. In this case, a value selected according to the level difference is added to the output of the motion detection circuit (18),
0).

An example of a schematic configuration of the motion detection auxiliary circuit (38) will be described with reference to FIG. (40a) (42
a) is a vertical LPF. (40b) and (42b)
It is a horizontal BPF. (40c) and (42c) are LPFs for widening the horizontal width.

(44a) is a level comparison circuit.
(44b) is a level conversion ROM. (44c)
Is a MAX circuit. Vertical LPF (40a) (42
In a), a vertical correlation is obtained. That is, in the case of a halftone image, the level is flat.

Further, each horizontal BPF (40b) (42b)
Perform the processing and adjust the frequency from 4 MHz to 4 Hz to correspond to the horizontal frequency component of the vertical stripe pattern that may cause the above-mentioned interference.
Only a frequency component of about 12 MHz is passed. It should be noted that the reason for cutting the frequency below 4 MHz is that the motion component below 4 MHz can be detected by the one-frame difference detection circuit described above. In addition, the reason why frequencies above 12 MHz are cut is that the upper limit of the substantial frequency of the decoded video signal is 12 MHz (in the literature, the upper limit of the decoded video signal is
About 16 MHz).

The output of the horizontal BPF (40b) (42b) is expanded by a horizontal width widening LPF (40c) (42c) to widen the signal width. As a result, the output is smoothed. These two outputs are supplied to a level comparison circuit (44a).
When the amplitude level of the moving image signal is larger than a predetermined value (threshold value) compared to the amplitude level of the still image signal, the difference value is converted to a level conversion ROM ( 44b).

The level comparison circuit (44a) detects the difference between the two inputs and converts the difference into an absolute value. When the absolute value level is larger than the set value, the absolute value level is set to the level. Output to the conversion ROM (44b). In the level conversion ROM (44b), the motion detection circuit (18)
And outputs a third difference signal that has been converted to a level that matches the motion detection signal from.

Then, in the MAX circuit (44c),
The larger of the third difference signal and the conventional motion detection signal is selectively output and used as the final motion detection signal. The essential points of the operation of this embodiment will be described. Regarding the video signal processed by the still image processing circuit (14) and the moving image processing circuit (16), the reproduction signal band (0 to about 12 MHz) of the moving image processing circuit in the horizontal frequency components In both cases, no large difference occurs in the amplitude characteristics.

That is, when the above-mentioned vertical stripe pattern is stationary (in the band of 0 to about 12 MHz), the reproduced signal is almost the same. Although there is no problem with the reproduction output of the processing circuit (16), halftone dot disturbance occurs in the reproduction output of the still image processing circuit (14), and the amplitude is extremely increased by performing the above-described vertical LPF and horizontal BPF processing. Goes down.

Therefore, the amplitude level difference between the decoded signal for a still image subjected to the vertical LPF and the horizontal BPF processing and the decoded signal for a moving image whose band is limited to the same frequency pair as the decoded signal for the still image is compared. When the amplitude level of the decoded image signal is smaller than that of the decoded video signal, it can be determined that halftone dot interference or the like has occurred. By utilizing this, regardless of the presence or absence of the output of the conventional motion detection circuit (18), a region having such an extremely different amplitude is processed as a motion region.

Although the filter processing circuit (40) and the filter processing circuit (42) have the same configuration in the above embodiment, the present invention is not limited to this. In this embodiment, the signal is smoothed by the horizontal widening LPFs (40c) (42c).
Alternatively, the pulse width of the output signal at the subsequent stage of a) or the level conversion ROM (44b) may be widened.

In this embodiment, the horizontal BPF (40b)
Has the same pass band as the horizontal BPF (42b), but may be a 4 MHz horizontal HPF from the gist of the present application.
However, in terms of design, it is easier to perform processing with the same filter processing circuit.

[0036]

According to the present invention, it is possible to detect a moving area even for a moving object as shown in FIG. 5, and to prevent a deterioration in image quality due to interference on a reproduced screen.

[Brief description of the drawings]

FIG. 1 is a diagram showing a MUSE receiver according to one embodiment of the present invention.

FIG. 2 is a diagram of a motion detection auxiliary circuit (38) of the embodiment of FIG. 1;

FIG. 3 is a diagram showing a conventional MUSE receiver.

FIG. 4 is a diagram of a conventional motion detection circuit.

FIG. 5 is a diagram for explaining an operation of a conventional motion detection circuit.

[Explanation of symbols]

(14) Still image processing circuit, (16) Moving image processing circuit, (18) Motion detection circuit, (30) 2 frame difference detection circuit (32) 1 frame difference detection circuit (34) MAX circuit (first) (38) motion detection auxiliary circuit (motion detection circuit), (40) filter processing circuit (first filter processing circuit), (40a) vertical LPF (second vertical filter). (40b) Horizontal BPF (second filter circuit) (42) Filter processing circuit (second filter processing circuit), (42a) Vertical LPF (vertical low-pass filter), (42b) Horizontal BPF (filter (44) Comparison output circuit, (44a) Level comparison circuit (comparison circuit), (44c) MAX circuit (second maximum value detection circuit, maximum value detection circuit, output circuit).

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshikazu Asano 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) H04N 7 / 015

Claims (9)

(57) [Claims] 1. A motion detection circuit for a MUSE signal, comprising: a two-frame difference detection circuit for outputting a two-frame difference signal of the MUSE signal; and a one-frame difference signal of a low-frequency component of the MUSE signal. A 1-frame difference detection circuit (32), a still image processing circuit (14) for outputting a still image decoded signal for a still image portion of the MUSE signal, and a moving image for a moving image portion of the MUSE signal. A moving image processing circuit (16) for outputting a decoded signal, a vertical low-pass filter (42a) to which the decoded signal for still image is input, and an output signal from the vertical low-pass filter (42a) A filter circuit (42b) for matching the frequency band of the decoded video signal; and the filtered still image decoded signal and the decoded video from the filter circuit (42b). Comparing the item, when the amplitude level of the moving image decoding signal is large,
A comparison circuit (44a) that outputs a third difference signal; and an output circuit (34, 44c) that creates a motion detection signal from the two-frame difference signal, the one-frame difference signal, and the third difference signal. A motion detecting circuit for a MUSE signal, comprising: 2. The output circuit (34, 44c) is a maximum value detection circuit that outputs a maximum value of the two-frame difference signal, the one-frame difference signal, and the third difference signal. The motion detection circuit for a MUSE signal according to claim 1. 3. The maximum value detection circuit (34, 44c).
A first maximum value detection circuit (34) for outputting the maximum value of the two frame difference signal and the one frame difference signal; and an output signal from the first maximum value detection circuit (34) and the third difference 3. The MU according to claim 2, further comprising a second maximum value detection circuit (44c) for outputting a maximum value of the signal.
SE signal motion detection circuit. 4. A second vertical low-pass filter (40a) to which the moving picture decoded signal is inputted with the same characteristics as the vertical low-pass filter (42a). 2. The MUSE signal motion detection circuit according to claim 1, wherein the moving image decoded signal filtered in step (1) is output to the comparison circuit (44a). 5. A moving image decoding apparatus comprising a second filter circuit (40b) to which the moving picture decoded signal is input and for removing the low frequency component, wherein the moving picture decoded signal filtered by the second filter circuit (40b) is provided. The MUSE signal according to claim 1, wherein the filter circuit (42b) removes the low-frequency component and a high-frequency component exceeding a frequency band of the moving image decoded signal while outputting to the comparison circuit (44a). Motion detection circuit. 6. A second input of the decoded signal for the moving image portion having the same characteristics as the vertical low-pass filter (42a).
A vertical low-pass filter (40a); a second filter circuit (40b) to which an output signal of the second vertical low-pass filter (40a) is input and which removes the low-frequency component; ) Removes the low-frequency component and the high-frequency component exceeding the frequency band of the decoded video signal, and outputs the decoded video signal filtered by the second filter circuit (40b) to the comparison circuit (44a). 2. The circuit according to claim 1, wherein the circuit outputs the signal. 7. A still image portion is transmitted after being subjected to field-frame offset sub-sampling, and a moving image portion is transmitted after being subjected to inter-line offset sub-sampling.
And a motion detection method for a sub-sampled video signal having a low-frequency region having no aliasing in a low-frequency range. The method according to claim 1, further comprising: Creating a decoded signal for a moving image by subjecting the sub-sampled video signal to field interpolation, and decoding the decoded signal for a still image and the decoded signal for a moving image in a frequency range higher than the low frequency band within the band of the decoded signal for the moving image. A motion detection method comprising: obtaining a difference from a signal; and outputting a motion detection signal when the amplitude level of the decoded signal for still image is lower than the amplitude level of the decoded signal for moving image. 8. A two-frame difference signal of the input MUSE signal, a one-frame difference signal of the MUSE signal, a still image decoding signal from the still image processing circuit (14) of the MUSE signal, and A motion detection method characterized in that each of a MUSE signal and a decoded signal for a moving image from a moving image processing circuit (16) is subjected to a filtering process, and a motion region is detected based on a difference signal of these filter processing outputs and . 9. A motion detection circuit for a MUSE signal, a two-frame difference detection circuit (30) for outputting a two-frame difference signal of the MUSE signal, and a one-frame difference signal for a low-frequency component of the MUSE signal. A 1-frame difference detection circuit (32), a still image processing circuit (14) for outputting a still image decoded signal for a still image portion of the MUSE signal, and a moving image for a moving image portion of the MUSE signal. A video processing circuit (16) for outputting a decoded signal; and a first filter processing circuit (40) for performing at least a vertical low-pass filter on the decoded video signal and removing the low frequency component. At least a second filter processing circuit (42) for obtaining, from the decoded signal for still image, a signal in the same band as the output of the first filter processing circuit (40); Comparing the filtered decoded signal for the still image from the second filter processing circuit (42) with the decoded signal for the moving image filtered from the first filter processing circuit (40); A comparison circuit (44) that outputs a third difference signal when the amplitude level of the decoded signal for use is large.
a) and an output circuit (34, 44c) for creating a motion detection signal from the two-frame difference signal, the one-frame difference signal, and the third difference signal. circuit.