JPS62172876A - Motion detecting system for multiplex subsample transmission signal - Google Patents

Abstract

PURPOSE:To improve picture quality of a received picture by switching the usage band area of an inter-one frame difference detection signal to either of areas based on a result detected from a motion area by a difference between two frames, in a decoder. CONSTITUTION:A sampling transmission signal is inputted to a frame memory 19, and the inter-one frame difference detection signal is generated by a difference calculator 20. The inter-one frame difference detection signal is selected with a switch S3 so as to be taken out through an LPF21 of wide band area, and a single LPF22, or an LPF22 cascade-connected with the LPF21, and is inputted to an absolute value circuit 23, and an absolute value is taken out as a movement detection output signal.

Description

[Detailed description of the invention] (The following is a blank space) 3 Invention 0) +', rK411 ft, : i2 light [
Industrial Application Field 1 The present invention relates to a motion detection method for a transmission signal that does not contain inter-frame aliasing components in the low frequency range,
In particular, it is applied to a decoder for such a transmission signal. The application range of such decoders is satellite broadcasting and packaged media.

Doesn't matter whether it's VSB- or M.

[Prior Art] One of the methods for band compression of television signals is a multiple subsample transmission method using interframe and interfield offset subsampling, such as MUSE (Mu
ltiple 5ub-Nyquist Sample
There is a current high-definition television signal multiplex sub-sampled transmission method called ngEncoding, which effectively realizes band compression. The details are described in, for example, "Technical Research Report of the Institute of Electronics and Communication Engineers, Image Engineering IE84-72 J.

[Problems to be Solved by the Invention] In the current multiplex sub-sampling transmission system, since sub-sampling goes around in two frames, when motion detection is performed on the receiver side, one frame difference signal is (there is no partner), so the difference signal between two frames must be used, resulting in incomplete motion detection.

For this reason, a multiplex sub-sampling transmission method has been proposed, which performs motion detection using a complete one-frame difference signal, reduces the receiver configuration to 8, and significantly improves the image quality. -108132).

That is, the multiplex subsample transmission method according to this proposal is a television signal subsample transmission method that compresses the transmission band using interfield and interframe offset subsamples, in which the television video signal is first subjected to interfield offset subsampling, After processing the obtained signal using a low-pass filter having a cutoff frequency lower than the sampling frequency of the interframe offset subsampling,
It is characterized by subsampling. The transmission signal obtained in this manner does not include an interframe aliasing component in its low frequency range. Therefore, on the receiver side, the low frequency component is extracted from such a transmission signal, and the difference signal between adjacent frames (one frame difference signal) is detected by the extracted low frequency component signal. It is obtained as a signal for Therefore, accurate motion detection can be performed using such a one-frame difference signal.

FIG. 2 shows the configuration of a decoder on the receiver side for a transmission signal that does not include interframe aliasing components in the low frequency band as described above.

In FIG. 2, l is a signal detection synchronization detection circuit,
A transmission signal (interframe subsampling frequency = 16 MIIZ) that does not include interframe aliasing components in the low frequency range as described above is input manually from the signal input terminal 12, and a synchronization signal is generated to control the synchronization of the tree decoder. .

Sl is a switch for subsample shift,
The transmission number 43 input manually to the input 0N512 receives the signal 1 whose motion is compensated by the frame memory 2 and the motion compensation circuit 3.
A frame-delayed signal is inserted to obtain an inter-frame interpolated signal of 32M) Iz sampling (obtained at A in the figure). Note that the switch St is not a simple switch, but can be given noise reduction characteristics by incorporating 16 MHz human power at an appropriate mixing ratio.

The inter-frame interpolated signal of 32 Mtlz sampling from the switch St is input to the motion detection circuit 4 as one input, and is also input to the field interpolation circuit 5 via the switch S2 cooperating with the switch Sl. The signal is then input to a mix (MIX) circuit as one of the human inputs.

The transmission signal from the input terminal 12 is input to the other input terminal of the motion detection circuit 4 . The motion detection circuit 4 generates a motion detection signal based on the two human force signals.

The switch S2 takes out the signal of only the sampling point corresponding to the current field from the signal from the switch St, interpolates it within the field by the intra-field interpolation circuit 5 consisting of a low-pass filter, and inputs it to the mix circuit 6.

The mix circuit 6 uses the output signal of the motion detection circuit 4 to determine the amount of motion (from the field interpolation circuit 5).
A moving image signal and a still image signal (from switch S1) are mixed.

The interfield interpolation circuit 9 interpolates the one-field delayed signal obtained by the field memory 7 and the motion compensation circuit 8 into the output signal from the mix circuit 6 to obtain an interfield interpolation signal sampled at 48 MHz. This is inputted to the frequency conversion/mixing circuit 10 as one input.

The 32M1lz sampling signal from the mixer circuit 6 manually inputted to the other side of this frequency conversion/mixing circuit IO is converted to a sampling frequency of 48M1(Z) in this circuit IO, and then sent to the interfield interpolation circuit 9.
(by the output signal from the motion detection circuit 4) according to the amount of motion, and the TCI (T'ime-
The compressed signal is input to the decoder 11, where it is converted into a desired television signal and output from the output terminal.

The problems to be solved by the present invention are that, in the decoder as described above, (1) motion detection becomes incomplete when a small object moves;

(2) Efficient construction method of motion detection low-pass filter.

(3) Motion area detection becomes incomplete with respect to color signals.

It is.

[Means for Solving the Problems] That is, the present invention provides a decoder for a multiplex sub-sampled transmission signal that does not include aliasing components between frames in the low frequency range.
Based on the motion region detection result based on the difference between two frames, the band used for the one-frame difference detection signal for obtaining the motion detection signal is switched to either a region containing the aliasing component or a region not including the aliasing component.

[Embodiment 1] Multi-subsample transmission color '+ (patent application 1986) as described above
0-106132), the low range (0-4M1l
Z part) does not include an aliasing component between frames. . Therefore, on the receiver side (decoder), when such a transmission signal is passed through a corresponding low-pass filter and the absolute value of the inter-frame difference is taken, a signal corresponding to the movement of the image (referred to as a motion signal) is obtained.

However, it is practically difficult to create a perfect low-pass filter with a short number of taps, and
The entire frequency range of IIz cannot be used effectively, so a low-pass filter with a cut-off frequency lower than 4MIIz must be used. For this reason, if a small object moves, motion detection may be incomplete.

In contrast, the present invention proposes, as a first embodiment, a method that supplementarily uses difference detection between two frames. FIG. 1 shows a system diagram of Example 1 (corresponding to cylinder No. 4 in FIG. 2).

In FIG. 1, reference numeral 14 denotes a frame motion detection circuit, and the signals at locations A and B shown in FIG. 2 are manually inputted to two input terminals of the circuit. A threshold circuit 15 thresholds the output signal from the detection circuit 14 at an appropriate level.

16 is a frame memory, 17 is a motion correction circuit, and 18 is an OR gate, and the output of this OR gate 18 controls switching of the switch S3.

19 is a frame memory, 20 is a subtracter, and the signal at the location B in FIG. 2 (i.e., 1
6M1 (transmission signal of z sampling) is input, and the subtracter 20 generates a one-frame difference detection signal. This inter-frame difference detection signal is transmitted through a wideband (for example, 6 dB drop at 8 MIIz) 10th bus filter 21 alone or a narrowband 20th bus filter 2 cascade-connected with this 10th pass filter 21.
2 (by means of a cascade of 1st and 20th-pass filters, the overall response is no more than 4 MIIz) and is selected by switch S3 to be output through the Absolute 110 circuit 23, and this Absolute J fai circuit 23, the absolute value is taken out as a motion detection output signal.

In principle, in this first embodiment, the part where the difference between two frames is significant is wider by allowing components of 4 MHz or more to be mixed into the band used for the difference detection signal between one frame as a motion detection signal. By using a low-pass filter, motion detection can be performed perfectly even for minute movements.

As shown in FIG. 2, in the decoder of the multiplex sub-sampled transmission signal, there is a signal delayed by two frames (it passes through the frame memory 2 twice before being replaced by the manual signal by the switch S1).

Therefore, by using the signal at point A and the signal at point B, the absolute value of the difference between two frames can be obtained in the frame motion detection circuit 14, and if the output value of this circuit 14 exceeds a certain threshold, The output of the OR gate 18 causes the switch S3 to be connected to the tenth bus filter 21.
Switch to the independent side and use a broadband one-frame difference detection signal. Here, in orake 18, 2
OR of the frame detection signal and the signal delayed by one frame (
The reason why the OR) is used is to prevent the mistake of determining that the tree is moving when it is stationary, since the difference between two frames is used. Also, although a frame memory is used, it is 1 bit and the sampling frequency may be low, so there is no problem in terms of circuit scale. Note that using 2-frame detection alone is incomplete by ORing with l-frame delay, but in the Bokuto style, it is used as an auxiliary method, and this is sufficient for most images. be.

[Embodiment 2] Although motion detection is perfect with the above-described configuration, since two-frame detection is used, portions that should not be determined to be motions are also determined to be motions. The reason for this is that the difference between two frames is the difference between the current frame and the frame before the previous one, and because a frame delay is used.The parts that are necessary and unnecessary as motion signals are shown in Figure 3. The relationship is as shown. For this reason, when a large object moves at high speed, a slight aftereffect remains. Although there is no major problem in terms of image quality, the configuration shown in FIG. 4 can be used to improve the quality.

In FIG. 4, 24 is a threshold circuit, 25
1 is a frame memory, 26 is a motion correction circuit, and 27 is an inhibit gate. In the configuration shown in FIG. The output (shown as C in FIG. 1) is the non-inverting input of inhibit gate 27.

That is, the threshold circuit 24 multiplies the 1-frame difference detection signal by an appropriate threshold to produce a 1-bit signal, which is delayed by 1 frame by the frame memory 25, and after motion compensation is performed by the motion compensation circuit 26.
The inhibit gate 27 inhibits the difference detection signal between two frames. Since the purpose of the two-frame difference detection is to help the signal in the part that is not originally involved in the one-frame difference detection, it is not necessary where the one-frame difference detection is already obtained. On the other hand, when the above-mentioned after-effects become a problem, the one-frame difference detection works reliably because a large object moves at high speed.

[Example 3] If you extract the 0 to 4 MIIz components of a multiple sub-sampled transmission signal that does not include inter-frame aliasing components in the low frequency range using a low-pass filter and then take the inter-frame difference, the frame memory will become unnecessary. required.

On the other hand, if this is attempted using the frame memory of the system shown in FIG. 2, low-pass filters are required on both the current field side and the previous field side (one frame before). In addition, a subtracter or the like is required to obtain the difference between frames.

However, if the system shown in FIG. 5 is used, it is possible to have all the functions for detecting differences between frames.

In the 51st mesh, 28 is an exclusive thin or gate, 29 is a low pass filter (0 to 4 MIIz),
30 is an absolute value circuit.

The signal at point A in Figure 2 is such that the data of the current frame and the previous frame are "injected" every 1 clock (7MH2) (
(alternating), so this is changed to 1 by gate 28.
If it is inverted every clock, a wideband (including aliasing) frame difference signal can be obtained. If this is passed through the low-pass filter 29 (and absolute value circuit 30) to the east, the purpose can be achieved.

[Example 4] Considering a subsample pattern in a multiplex subsample transmission signal that does not include folding components between frames in the low frequency range, it is assumed that a wideband signal is temporarily transmitted except for the folding in the diagonal direction using the configuration shown in Fig. 6. Even when used as a motion detection signal, the influence of sub-samples can be prevented.

That is, Fig. 6 Nioite, 31.32 CtlH (horizontal J
33 is an adder, 34 is a 172 multiplier, 35 is an exclusive OR gate with an inverting input terminal, 36 is an exclusive OR gate, 37 is an adder, and 38 is a 172 multiplier. (since the sampling is vertically inverted for each IH), the influence of the sub-samples can be eliminated by vertically inverting the signal at the location in FIG. 2A and taking the sum.

[Embodiment 5] In a transmission system that does not include an interframe aliasing component in the low frequency range of a transmission signal, it is not possible to use one-frame difference detection for a color (C) signal at least at present. Therefore, for the C signal, two-frame difference detection is used, but as is well known, perfect detection is impossible. Therefore, for the C signal, use the motion signal (one-frame difference detection) detected for the Y (luminance) signal (or use it together with the signal detected for the two-frame difference for C). It is better to control the C signal. C signal and Y (No. 8 or generally high phase 1 pull J, < f-
@ /I"1 哄F tr'+ Shijiru J, < ,! conversion 4
．． 'l'17 平Ah 哄k Z In addition, in the present invention, when the encoder determines that the movement has completely stopped (for example, when transmitting still images), the influence of transmission path errors etc. is ignored. Therefore, the control signal on the encoder side allows all motion detection systems, 2-frame detection system (equivalent to the broadband side of l-frame detection) or l-frame detection system to be activated. The narrow band side of the frame detection system is stopped individually or in combination.

[Effects of the Invention] As explained above, according to the present invention, in a transmission method that does not include aliasing components between frames in the low frequency range of the transmission signal, the image quality of the received image is improved by perfecting motion detection. .

Further, according to the present invention, the circuit can be simplified, the price of the receiver can be reduced, and it can be easily integrated into an IC.

Furthermore, according to the present invention, there is only folding of the color signal,
The received image quality is further improved.

4. Simplification of the drawings Figure 1 is a principle system diagram according to an embodiment of the present invention, Figure 2 is a system diagram of a decoder for a transmission signal that does not include aliasing components between frames in the low frequency range, Figure 3 is an explanatory diagram of unnecessary motion detection accompanying the detection of the difference between two frames, Figure 4 is a diagram showing a circuit for removing the unnecessary detection part between two frames, Figure 5 is a diagram of the circuit for detecting the difference between one frame, FIG. 6 is a circuit diagram for detecting a difference between frames using vertical correlation.

14... Frame motion detection circuit, 15... Threshold circuit, 16... Frame memory, 17... Motion correction circuit, 18... OR gate, 19... Frame memory, 20... Differential device, 21.22...Low pass filter, i3...Absolute value circuit, S3...Switch.

Claims (1)

[Claims] 1) In a decoder for a multiplex subsample transmission signal that does not include an interframe aliasing component in the low frequency range, a multiplex subsample is characterized in that a motion detection signal is obtained based on the result of one frame difference detection. Motion detection method in transmitted signals. 2) In the motion detection method for multiplex sub-sampled transmission signals according to claim 1, an inter-frame difference detection signal for obtaining a motion detection signal based on a motion area detection result based on a difference between two frames. A motion detection method for a multiplex sub-sampled transmission signal, characterized in that the band used is switched to either a region containing aliasing components or a region not including aliasing components. 3) In the motion detection method for multiplex sub-sampled transmission signals according to claim 2, when the one-frame delayed signal of the one-frame difference detection signal is significant, two
A motion detection method for multiple sub-sampled transmission signals, characterized in that regardless of the result of motion area detection based on interframe differences, the band used for one frame difference detection signal is set to a region that does not include aliasing components. 4) In the motion detection method for sub-sampled transmission signals as described in claim 1, the interpolated signal is inverted every clock, and the resulting signal is passed through a low-pass filter. A motion detection method for a multiple sub-sampled transmission signal, characterized in that a motion detection signal is obtained by detecting a difference between frames by taking the absolute value of the motion detection signal. 5) In the motion detection method for multiple sub-sampled transmission signals according to claim 1, a motion detection signal obtained by inter-frame difference detection obtained for a luminance signal is
A motion detection method for a multiplex sub-sampled transmission signal, characterized in that the color signal is controlled by using a motion detection signal based on the difference between two frames obtained for the color signal. 6) In the motion detection method for multiple sub-sampled transmission signals as set forth in claim 1, all motion detection systems, two-frame detection systems, or one A motion detection method for multiple sub-sampled transmission signals characterized by stopping the narrowband side of a frame detection system individually or in combination.