JPS6239991A - Moving part detecting circuit - Google Patents

Abstract

PURPOSE:To prevent an animation which should be reproduced from being reproduced as a still picture by controlling the gate timing of a differential signal in pseudo one frame in accordance with a movement compensating quantity. CONSTITUTION:A differential signal DE1 in pseudo one frame after an absolute value is taken by an absolute value detecting circuit 38 is applied to a gate circuit 39, gated by a gate signal SG obtained from the output signal SO of a temporal filter 27 and given to a selecting circuit 34. The gate signal SG is obtained by slicing the output signal SO of the temporal filter 27 by a prescribed slice level L by a comparator 40 and applied to the gate circuit 39. Thereby, among high level components included in the differential signal DE1, the component obtained during a still picture is removed and only the component obtained during the animation period is taken out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a motion part detection circuit in a television broadcasting system that compresses and transmits a television signal band according to an offset subsampling method.

[Technical Background of the Invention] In recent years, high-definition television systems have been developed that aim to improve image quality by increasing the density of information. The band of the television signal handled by this system is very wide, and it is necessary to compress the band when transmitting it.

As a compression method for the transmission band of a television signal, there are, for example, Offsera 1 to Zabsample methods.

In this method, in a certain frame (hereinafter referred to as the first frame), sampling data of the phase specified by the "○" mark is transmitted with respect to the sampling phase set as shown in FIG. In the next frame (hereinafter referred to as the second frame), →pumpling data of the phase defined by the "mouth" mark is transmitted.

FIG. 7 is a circuit diagram showing the configuration of a television receiver that receives television signals transmitted according to such an offset subsampling method.

First, the received television signal RD is sent to the signal separation circuit 11
and is separated into a video signal V, a motion correction signal M, an audio signal S, and a control signal C, respectively.

The video signal (2), which is a ring frame signal, is supplied to a moving picture signal processing circuit 13 and a switching circuit 14, which will be described later.

In addition to the previous current frame signal FO, the switching circuit 14 also receives signals F1 and 2 of the previous frame output from the image memory circuit 15.
The signal F2 of the previous frame is guided. The switching circuit 14 changes the current frame signal FO by replacing the signal F2 of the two frames before with the signal FO of the current frame.
At the same time, the signal F1 of one frame before is sent out.

These frame signals FO and F1 are sent to the still image signal processing circuit 12. The image memory circuit 15 and the moving part detection circuit 1
6 each.

The image memory circuit 15 is basically a memory whose capacity is equivalent to one frame, and the image memory circuit 15 is a memory whose capacity is equivalent to one frame. It inputs F1 and outputs the signal F1 of one frame before and the signal F2 of two frames before. These image memory circuits 15 output frame signals F1. F2 is led to the moving part detection circuit and used together with the frame signals FO and F1 mentioned above when detecting a moving part, which will be described in detail later.

Now, in the receiver shown in FIG. 7 which processes television signals of the Off-Sera 1 to sub-sampling systems, the signal processing methods are different for the still image system and the moving image system. That is, the still image signal processing circuit 12 uses both the current frame signal F0 and the previous frame signal F1, and as shown in FIG. 6, these are input and superimposed one after the other to form a frame image.

On the other hand, in video reproduction, if past sampling data is used, a double image will result, so the video system signal processing circuit 13 performs image processing using the sampling data of the current frame FO. . In this case, data interpolation is performed using an interpolation filter for data shortages.

In this way, the two types of video signals VS and Vm obtained according to the still image system and the moving image system, respectively, are appropriately processed in the mixing circuit 17 according to the output signal [)m of the moving part detection circuit 16 that detects the moving part of the image. The signals are mixed to become a video signal VO for actual image reproduction.

Note that when processing an image obtained when a television camera pans slowly, even if the subject is a stationary object, the image on the screen is changing, so it is processed as a moving image. As described above, video processing uses only the sampling data FO of the current frame, and the resolution is lower than that of still image processing. Therefore, the following motion correction is performed to prevent the above resolution from deteriorating.

Motion correction is performed by controlling the amount of delay of the image memory circuit 15 in accordance with the motion correction signal M obtained from the signal separation circuit 11. The motion compensation signal M is a signal indicating the amount and direction of movement of a stationary object within the screen, and is obtained based on the motion compensation solid 1 hell inserted in advance into the television signal RD. The image memory circuit 15 shifts and reads out the previous frame signal by the amount that the screen has moved in accordance with the motion correction signal N4. This allows images of past sample points and current sample points to be superimposed during panning, allowing processing as a still image and maintaining resolution.

Now, to detect the moving part of the image, frame FO,
What is necessary is to find the difference in sampling data between F1. But these two frames FO.

Since the sampling phase differs between F1, a pseudo difference signal (hereinafter referred to as a pseudo 1-frame difference signal)
DEII cannot be obtained. According to this pseudo one-frame difference signal, depending on the content of the image, it may be detected as a moving image even though it is a still image.

Such a problem can be solved by calculating the difference between frames FO and F2 having the same sampling phase. However, in this case, the part that should be reproduced with a video is
A new problem arises in that the image is reproduced as a still 1L image.

The above-mentioned problem will be explained using FIG. 8. The figure (a) is sampling data that shows the position of an object moving at a constant speed (hereinafter referred to as a moving object) on the screen at one frame interval. The figure (b) is the ideal moving part detection signal ( The ideal one-frame difference signal) Dmi is shown in the same figure (c
) is frame FO.

The two-frame difference signal DE2FO for each of Fl,
DE2F1 is shown. Difference signal D22FO is frame FO
, F2, and the difference signal DE2F1 is a difference signal between frames F1 . This is a differential signal between F3. These differential signals D
In mi, DE2FO, and DE2F1, the high-level component corresponds to video reproduction, and the low-level component corresponds to M for still images.
Corresponds to l.

Here, the difference signal D between two frames corresponding to the current frame FO
Comparing E2FO and the ideal moving portion detection signal Dmi, in the former, the portion X corresponding to the moving object position in frame F1 is at a low level. Therefore, in this portion X, a still image is reproduced. As a result, even though the image of part X is originally a moving image, there are two frames FO.

Since it is constructed using sampling data of Fl, 2
This results in a heavy image.

Therefore, when using the two-frame difference signal DE2, it is necessary to interpolate the missing high-level component of portion X. In principle, this interpolation is performed by temporally stretching the two-frame difference signal DE2FO corresponding to the current frame F○ and the two-frame difference signal DE2F1 corresponding to the previous frame F○1 using memory. It will be done.

FIG. 8 ((1) shows a difference signal in which a high-level component is inserted with respect to portion

[Problems in the Background Art] As explained above, in principle, conventionally, the difference signal between two frames corresponding to two frames FO and Fl, , E2
1. Prevents parts that should be reproduced in a video from being reproduced in still images.

However, even with this configuration, the above problem cannot be solved when, for example, the camera is panned to follow a moving object.b In other words, if a moving object moving at a constant speed is
As shown in (a), consider the case where the camera is panned so that it is always fixed at a predetermined position on the screen. In addition,
Here, we will consider the scanning line indicated by the broken line.

Frame F1. read out from the image memory circuit 15 by motion correction. The sampling data of F2 and the current frame FO are as shown in FIG. 9(b). In addition, the same figure (
b) When the moving object moves to the right of the screen (in this case,
It is assumed that the sampling data of the frame F1 is shifted to the left when viewed on the screen due to the motion correction mentioned above. In this case, the ideal moving part detection signal Dmi and the difference signal DE2 between two frames between the current frame and one frame before
FO and DE2F1 are as shown in FIGS. 3(c) and 3(d), respectively.

The relationships shown in FIGS. 9(b), 9(c), and (tl) are as follows for frame F1. F2. . . . etc. as the current frame, the same is true because the moving object position is always fixed at a predetermined position, as shown in FIG.

Now, when panning is performed by following a moving object, the frame FO is set as shown in FIG. 9 ((1,).

2-frame difference signal DE2Fo for Fl.

Both DE2F1 end up being equal. Therefore, it becomes impossible to interpolate the high-level missing portion X using both signals DE2FO and DE2F1, and a double image will be reproduced in this portion X.

[Objective of the Invention] This invention was made to address the above-mentioned circumstances, and even when performing motion compensation, it is possible to reliably prevent parts that should be reproduced as a moving image from being reproduced as a still image. An object of the present invention is to provide a moving part detection circuit that can detect moving parts.

“Summary of the Invention” The present invention replaces the high-level missing portion of the two-frame difference signal DE2FO with respect to the current frame FO with respect to the previous frame FO.
A moving part detection signal is obtained by interpolating the two-frame difference signal DE2F1 with respect to 1 with a temporally expanded signal, and either this detection signal or a pseudo one-frame difference signal using this signal as a gate signal. In addition to the configuration used for detecting a moving part, the timing of the gate is controlled in accordance with the amount of motion correction, thereby achieving the above object.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention.

The circuit shown in FIG. 1 is configured to use both a two-frame difference signal and a pseudo one-frame difference signal to detect a moving part.

First, a moving part detection operation when no motion correction is performed will be described.

In FIG. 1, the terminal 21 has a frame FO.

A signal constituted by Fl is given to the terminal 22,
Frame F1. A signal constructed by F2 is provided. These two signals are each passed through a low pass filter LP.
After high frequency components are removed at F23.24, the subtraction circuit 25
Subtraction processing is performed. As a result, a two-frame difference signal DE2 is obtained, and its absolute value is determined by the absolute value detection circuit ABS2.
It is taken at 6. The output signal of this absolute value detection circuit 26 is
Input to temporal filter ■.

This temporal filter ■ is the part X explained in FIG.
This is to interpolate the missing high-level components. The operation of this temporal filter 27 will be explained with reference to FIG. Similar to FIG. 8, FIG. 2 assumes an object moving at a constant speed on the screen, and shows the output signal So of the temporal filter in this case.

In the first frame, the two-frame difference signal DE2 output from the absolute value detection circuit 26 passes through the selection circuit 28 as it is and is stored in two memories. After being held for one frame period in this memory 29, it is multiplied by a (0<a×1) in a multiplier circuit 30 and then sent to a selection circuit 29.
is input. The selection circuit 28 compares the levels of this input signal and the two-frame difference signal DE2FO of the current frame FO output from the absolute value detection circuit 26, and outputs the larger one.

By repeating the above operations, the temporal filter 27 outputs the portion x as shown in FIG. 2(d).
A signal So with the high level component interpolated is obtained.

In the temporal filter (2), 31 and 32 are circuits that generate write address data and read address data for the memory 29, respectively. These address generation circuits 31 and 32 output address data in synchronization with the frame period of the received signal. Moreover, the switching circuit 33 is
The above two address data are alternatively selected during the data write period and the data read period of the memory 29.

The output signal So of the temporal filter ill obtained in this way is given to the selection circuit 34, and is also used to gate the pseudo one-frame difference signal DEI used auxiliary.

Here, to explain the generation of the pseudo one-frame difference signal DE1, the sub-sample switch circuit 35 extracts the sampling data of the current frame FO from the input signal of the terminal 21 and gives it to the interpolation filter 36. Assuming that the FO is the first 'frame as shown in FIG. A signal corresponding to the sampling position is obtained.
By performing subtraction processing with the output of No. 3, a pseudo one-frame difference signal DE1 is obtained.

Pseudo one-frame difference signal DE obtained in this way
After the absolute value of 1 is taken by the absolute value detection circuit 38, it is applied to three gate circuits. And this gate circuit 39
, the signal S obtained from the output signal So of the temporal filter 27.

is gated by and applied to the selection circuit 34.

The above gate signal S. is obtained by slicing the output signal Sn of the temporal filter at a predetermined slice level using the comparator 40, and
given to.

In this way, by gating the pseudo one-frame difference signal 1') El by the gate signal So obtained from the output signal So of the temporal filter, the static What was obtained during the video is removed, and only what was obtained during the video is extracted.

The selection circuit 371 outputs the one having a higher level among the two human force signals as a moving portion detection signal Dn+.

Next, a motion portion detection operation during motion correction, which is a feature of the present invention, will be explained.

When performing panning that follows a moving object as described above during motion correction, the output signal S of the temporal filter
From n, for the reason explained with reference to Figure 9 above,
High level components are missing in part X. Further, it is not possible to generate a gate signal for use together with the pseudo one frame signal DE1.

Therefore, in FIG. 1, the gate signal S. The above problem is solved by temporarily storing the motion compensation signal M in the motion compensation memory 43 and controlling the timing of reading from the memory 43 according to the motion compensation signal M.

That is, in FIG. 1, the gate signal SG output from the comparator 42 is
The motion correction memory 43 is written in accordance with the write address data output from the read address generation circuit 45, and read out from the memory 43 in accordance with the read address data output from the read address generation circuit 45. Here, the write address generation circuit 44 always generates address data at a constant timing in synchronization with the frame period of the reception signal RD. On the other hand, read address generation circuit 45
The data generation timing is controlled according to the motion correction signal M input from the terminal 46. The switching circuit 47 is
During a data write period to the memory 43, the above data write address is selected, and during a period when data is read from the memory 43, the above data read address is selected and applied to the memory 43.

In this way, by controlling the gate timing of the pseudo one-frame difference signal DE1 according to the motion correction signal, the high-level component corresponding to the portion X in this difference signal DE1 can be reliably extracted, and the double image can be prevented from occurring.

Here, the reason why the pseudo one-frame difference signal 1) El is passed through the delay circuit 40 is as follows.

That is, the motion correction signal M is a vector signal, and has positive and negative values in the vertical and horizontal directions on the screen.

Gate signal S in memory 43. If the read timing is controlled by delay control in the case of a positive value and advance control in the case of a negative value, it is impossible to advance the signal in the memory 43 and other actual circuit elements.

Therefore, by delaying the pseudo one-frame difference signal DE1 in the delay circuit 40, the gate signal S relative to the pseudo one-frame difference signal DE1. This makes it possible to create an advanced phase of .

In other words, the delay amount of the read timing of the gate signal So when the correction amount of the motion correction signal M is zero and the delay circuit 40
By making the delay amounts of the memory equal and controlling the readout timing according to the correction amount of the motion correction signal M based on this delay, the memory The gate signal Sθ read from 43 is advanced or delayed.

Note that the output signal S of the temporal filter 27.

The delay circuit 34 for delaying the signal So is for matching the phase of the signal So with the phase of the pseudo one frame difference signal DE1 outputted from the delay circuit 40.
It has the same amount of delay as 0.

The motion part detection operation during the motion correction described above will now be explained with reference to FIG. This figure, like the previous figure 9,
An example of this is a case where the camera is panned to a moving object moving to the right.

The output signal So of the temporal filter 27 (Fig. 5 (
(a)) is delayed by the delay circuit 34, and the signal shown in FIG.
). In addition, the pseudo one-frame difference signal DE1 output from the two absolute value detection circuits ((C
) is delayed by the delay circuit 40 and becomes as shown in (1) in the figure.The gate signal Sa (see (e) in the figure) output from the comparator 42 is output from the memory 43 as follows. The output phase of the memory 43 when the correction amount is zero is the same as the output phase of the delay circuit 34 shown in <b> of the same figure.
) The output phase of the memory 43 shown in ) is advanced by one minute during the actual correction with respect to the output phase when the correction amount is zero. In this way, by advancing the gate signal So by the correction amount P, the high level component corresponding to the portion x explained in FIG. As shown in FIG. 5(a), it passes through the gate circuit 41.As a result, the moving part detection signal Dm output from the selection circuit 35 has the missing high-level component of the part X interpolated, and is a double image. can be prevented from occurring.

[Effects of the Invention] As explained above, according to the motion part detection circuit of the present invention, the gate timing of the pseudo one-frame difference signal is controlled according to the amount of motion correction, so that it is possible to However, it is possible to reliably prevent parts that should be reproduced in a video from being reproduced in a still image.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention, and FIG.
Figures 5 to 5 are diagrams for explaining the operation of Figure 1, Figure 6
The figure is a diagram to explain the offset subsampling method.
FIG. 7 is a circuit diagram showing the configuration of an offset sub-sampling type television receiver, and FIGS. 8 and 9 are diagrams for explaining the conventional moving part detection operation. 21.22.46...Terminal, 23.24...Low pass filter, 25.38...Subtraction circuit, 26.39...
... Absolute value detection circuit, 27-... Temporal filter,
34.40... Delay circuit, 35... Selection circuit, 36
. . . Subsample switch circuit, 37 . . . Interpolation filter, 41 . . . Gate circuit, 42 . Read address generation circuit, 47... switching circuit. Applicant's representative Patent attorney Takehiko Suzue ~21- Figure ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 's3 Figure ○ (52) ○ (2) ;○・tsu■)○○○(52) ○ζ
2]) ○○○,, /J> ○○○○○・○0・1)○
(Ts0 ・1−) ○ ・Ts) ○ ○ ○ Ci ○ ○
Figure 4

Claims (1)

[Claims] a first difference detection means for detecting a two-frame difference signal indicating a difference between a first frame signal of a television signal transmitted according to the offset subsampling method and a second frame signal two frames before the first frame signal; By substantially adding the first two-frame difference signal sequentially supplied by the difference detection means and the previous second two-frame difference signal, the difference signal is removed from the first two-frame difference signal. interpolating means for interpolating difference information between the first frame signal and a third frame signal one frame before the first frame signal with respect to the first two-frame difference signal and outputting the interpolated signal as a motion detection signal; a second difference detection means for detecting a pseudo one-frame difference signal indicating a difference between the first frame signal and the third frame signal, and a motion detection signal outputted from the interpolation means as the first frame signal. gate control means for shifting the signal and outputting it as a gate signal by means of a motion correction signal indicating a deviation in image content between the third frame signal and the third frame signal; A moving part detection circuit comprising: selection means for comparing the output signal of the gate means and the motion detection signal and successively outputting the larger signal as the moving part detection signal.