JPH0832031B2 - Motion compensated sub-sample transmission system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention predicts the amount of motion correction between fields on the receiving side by approximation from the motion information transmitted in a MUSE high-definition television signal, The present invention relates to a motion compensation sub-sample transmission system applied when interpolating a missing point between fields.

[Prior Art] This type of motion-compensated subsample transmission method that has been proposed so far was announced by NHK Science and Technology Research Laboratories and NHK Broadcasting Science Research Laboratories at the foundation commemorative lecture in June 1984. There is something mentioned in a preliminary document called "New Transmission System (MUSE) of Quality Television". FIG. 11 shows the configuration of the motion compensation sub-sample transmission system.

In FIG. 11, (1) is a video input terminal for inputting a video signal having a sampling rate of 16.2 MHz, (2) is a sub-sample switch, and the video signal input to the input terminal (1) is a predetermined sample. Hold the position and perform one round of sub-samples at 4 fields at a sample rate of 16.2 MHz. (3) is a motion vector detection circuit, which detects a motion vector between fields separated by one frame from the video signal input to the terminal (1) according to the motion,
Generate one vector per field. Reference numeral (5) is a switch, which is switched at the timing of the video signal subsampled and transmitted in the subsample switch (2) and the subsample of 32.4 MHz output signal of the motion compensation field memory (8) described later. (6) is a non-motion compensation field memory, which passes through the switch (5) above 32.4
The signal for one frame at the sample rate of MHz is stored.
Reference numeral (8) is a motion correction field memory, which stores a signal for one frame at a sample rate of 16.2 MHz output from the non-motion correction field memory (6), and performs motion correction using a motion vector.

(13) is an inter-field interpolation filter, which is an output signal of the non-motion compensation field memory (6) and a switch (5).
The missing sample points are interpolated based on the signal that has passed.
(12) is an intra-field interpolation filter, which interpolates the missing sample points based on the signal passed through the switch (5). (14) is a switch, which is connected to the lower contact when motion compensation is not performed and is an inter-field interpolation filter (13).
When the motion is corrected or the motion is detected, it is connected to the upper contact to pass the output signal of the in-field interpolation filter (12). (15)
Is a video output terminal for outputting a signal which passes through the switch (14) at a sample rate of 64.8 MHz by interpolating a missing sample point.

 Next, the operation of the above configuration will be described.

The new transmission method for high-definition television is sub-Nyquist sampling, which makes a cycle of four fields, and its required bandwidth is 8.1 MHz.

In the video signal transmission system of the configuration shown in FIG. 11, the video signal input from the video input terminal (1) is intermittently switched by the switch (2) to transmit the video signal by sub-sample, and at the same time, the motion vector detection circuit ( According to 3), the motion vector between the fields separated by one frame for one field is detected and separately transmitted.

On the other hand, when the signal of the first field is transmitted to the upper terminal of the switch (5) on the receiving side, the non-motion correction field memory (6) stores the signals of the second field and the fourth field one cycle before. On the other hand, the motion correction field memory (8) stores the signals of the first field and the third field one cycle before. When the motion vector is transmitted, the contents of the motion compensation field memory (8) move two-dimensionally according to the vector amount. Since the motion vector represents the amount of motion correction, the content of the motion correction field memory (8) is subjected to motion correction with reference to the transmitted first field signal.

The switch (5) is switched at the timing of the sub-sample of 32.4 MHz, and the phase is inverted for each field and also by the motion vector. Therefore, in the above case, the signal of the first field transmitted in the above case and the signal of the third field one cycle before the motion correction by the motion vector pass through the switch (5).

The signal that has passed through the switch (5) is input to the intra-field interpolation filter (12). Inter-field interpolation filter (12) performs inter-field interpolation and switches (14)
When is connected to the upper contact, the video signal with the sample rate of 64.8MHz interpolated in the field is output from the video output terminal (15). The switch (14) is connected to the upper contact when the motion correction is performed and when the motion is detected. In the former, the switch is switched in the unit of field, and in the latter, the switch (14) is switched in the unit of pixel.

The signal that has passed through the switch (5) and the output signal of the non-motion correction field memory (6) are input to the inter-field interpolation filter (13) for inter-field interpolation. When motion compensation is not performed, that is, switch (14)
Video output terminal (15) when is connected to the lower contact
To output a video signal with a sample rate of 64.8 MHz interpolated between fields.

FIG. 12 shows the states of the signals 12a to 12f in FIG. 11 when the d ₁ field is input to the video input terminal (1) without motion compensation. However, when the signal is expressed as a field, it flows in the order of a ₀ , b ₀ , c ₀ , d ₀ , a ₁ , b ₁ , c ₁ , d ₁ . In the figure, A indicates an interpolated value interpolated from a ₁ , b ₁ , c ₁ , d ₁ by an interpolating function f _A which is a processing between fields. The motion compensation is performed, the video input terminal (1) shows the state of FIG. 11 of the 13a~13f signals when d ₁ field is input in FIG. 13. In the figure, the horizontal line above the signal indicates that motion compensation has been performed, and B indicates the interpolated value interpolated from ₁ and d ₁ by the interpolating function f _B that is in-field processing.

[Problems to be Solved by the Invention] When the conventional motion compensation sub-sampling transmission method as described above is used, since the relationship between adjacent fields is not taken into consideration at the time of performing motion compensation, the missing sample points Interpolation must be done in-field with an in-field interpolation filter. Therefore, there is a problem that the resolution is lowered when the motion correction is performed.

The present invention has been made in order to solve the above-mentioned problems, and similarly to the case where motion compensation is not performed by predicting the motion vector between each field from the motion vectors transmitted in the past by approximation. An object of the present invention is to provide a motion-compensated sub-sample transmission system capable of suppressing a decrease in resolution by using an inter-field interpolation filter even when performing motion compensation.

[Means for Solving Problems] The motion compensation sub-sample transmission system according to the present invention is
A motion for transmitting a sample value of a video signal intermittently subsampled so as to make a cycle in a plurality of fields while maintaining a predetermined sample position, and motion information (I) between fields separated by one frame in units of one field. A corrected sub-sample transmission method, in which the transmitting side delays the sample value of the video signal by 1 field with respect to the motion information (I) and transmits the same, for the field of interest on the receiving side. The motion information (II) between fields separated by one field, the motion information (I) for the field of interest and the motion information (I) transmitted one field before.
And the motion information (I) and the motion information (I
It is characterized in that the missing points are interpolated by using the motion-corrected sample values in the past multiple fields from I) and.

[Operation] According to the present invention, the fact that there is no abrupt change in the transmitted motion vector is used to approximately predict the motion vector between fields separated by one field on the receiving side. Interpolation can be performed by the inter-field interpolation filter, which can prevent the resolution from being lowered during motion compensation.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a motion compensation sub-sample transmission system according to an embodiment of the present invention. In FIG. 1, (1) shows a video input terminal for inputting a video signal having a sample rate of 64.8 MHz, (2) is a sub-sample switch, which performs a sub-sample in which the video signal input to the input terminal (1) is cycled at 4 fields at a sample rate of 16.2 MHz while maintaining a predetermined sample position. (3)
Is a motion vector detection circuit, which detects a motion vector between fields separated by one frame from the video signal input to the input terminal (1), and generates one vector in one field. (4) is a first 1-field delay device, which delays the video signal sub-sampled by the switch (2) by 1 field.

A switch (5) is a video signal output from the first 1-field delay unit (4) and transmitted, and a first signal described later.
Output signal of motion compensation field memory (8) of 32.4MH
Switch at the timing of the subsample of z. (6) is a non-motion correction field memory, which stores a signal for one frame having a sample rate of 16.2 MHz passing through the switch (5).

(7) is a second one-field delay device, which delays the motion vector output from the motion vector detection circuit (3) and transmitted by one field. (8) is a first motion compensation field memory, which stores the signal for one frame at the sample rate of 16.2 MHz output from the non-motion compensation field memory (6) and stores it in the second one field delay unit (7). ) Is used to perform motion compensation. Reference numeral (9) is an adder for adding the motion vector output from the motion vector detection circuit (3) and transmitted to the second motion vector.
The motion vector of one field before, which is the output of the one-field delay device (7), is added. (10) is a divider that divides the motion vector added by the adder (9) by 4.

(11) is the second motion compensation field memory, which has a sample rate of 16.2 MHz passing through the switch (5) of 1
The signals for the frames are stored, and the motion correction is performed by the predicted motion vector between the fields separated by one field, which is output from the adder (10). (12) is an intra-field interpolation filter, which interpolates the missing sample points based on the signal passed through the switch (5). An inter-field interpolation filter (13) interpolates a missing sample point based on the signal passed through the switch (5) and the signal output from the second motion correction field memory (11).

(14) is a switch, which is normally connected to the lower contact to allow the output signal of the second motion compensation field memory (11) to pass through, and when motion is detected, connect it to the upper contact on a pixel-by-pixel basis. Passes the output signal of the inter-field interpolation filter (12). In (15), the missing sample points are interpolated 6
With the sample rate of 4.8MHz, the above switch (14)
Is a video output terminal for outputting a signal passing through.

 Next, the operation of the above configuration will be described.

FIG. 2 shows the motion vector generated in the motion vector detection circuit (3) according to the video input from the video input terminal (1) on the transmission side. In the figure, x represents the horizontal axis of the screen and y represents the vertical axis of the screen. Further, each field of the video signal is represented by a _{1 to} d ₂ , and when the signal is represented by a field ... a ₀ , b ₀ , c ₀ , d ₀ , a ₁ , b ₁ , c ₁ , d ₁ , a ₂ , B ₂ ,
It flows in the order of c ₂ , d ₂ . The motion vectors between fields separated by one frame are ... A ₁ , B ₁ , C ₁ , A ₂ ,
B ₂ ……. Also, the inter-field motion vectors separated by one field obtained in the drawing are ... b ₁₀ , c ₁₀ , d
It is represented by ₁₀ , a ₂₀ ……. The following relationship is established between the inter-field motion vector separated by one frame and the inter-field motion vector separated by one field.

Here, for example, b ₁₀ can be rewritten as the following equation.

If the second term on the right side of the above equation is sufficiently small, b ₁₀ can be predicted as follows.

Here, for example, consider only the four-field relationship of a _{1 to} d ₁ . However, the inter-field motion vectors separated by one frame are transmitted in one field by a digital signal of 5 bits in the horizontal direction and 3 bits in the vertical direction. That is, the size of the inter-field motion vector separated by one frame is described in terms of pixel length, which is within the range of horizontal components −15 to +16 and vertical components −3 to +4. Both have discrete components that are integers. When this is illustrated, as shown in FIG. 3, the inter-field motion vectors separated by one frame are within the range surrounded by the broken line. However, the origin in FIG. 3 is an arbitrary pixel of a field.

If the parallel movement of the image due to panning is smooth,
The inter-field motion vector separated by one field between the a ₁ field and the b ₁ field is within the range surrounded by the chain line in FIG. Here, the relative relationships of the three fields a _{1 to} c ₁ are changed in three ways as shown in FIG. 4, FIG. 6 and FIG.
For each of these, the position of the d ₁ field and the prediction accuracy of the motion vector are examined.

First, FIG. 4 shows the case where the inter-field motion vector A ₁ transmitted one frame apart has the maximum magnitude. At this time, a motion vector a between fields separated by one field
₁₀ and b ₁₀ are also the maximum, and the relative positions of the a _{1 to} c ₁ fields are determined. At this time, the d ₁ field exists within the range of the three-dot chain line in the figure, but when there is no sudden movement change
The d ₁ field lies within the shaded area.

Furthermore, if the parallel movement of the image such as panning is smooth, the d ₁ field is likely to exist at the position indicated by the black circle in the figure. As an example, FIG. 5 shows the prediction vector (A ₁ + B ₁ ) / 4 and the vector b ₁₀ when the d ₁ field is at the position shown in the figure. The prediction error at this time is the pixel length, and if there is a d ₁ field at the position represented by the black circle, the error will be less than that, so such prediction is appropriate.

Next, FIG. 6 shows the case where the component of the inter-field motion vector A ₁ separated by one frame is (x, y) = (10, 2). As in FIG. 4, the inter-field motion vector a ₁₀ separated by one field exists within the range surrounded by the chain line, and b ₁
When the field is at the point shown, the inter-field motion vector b ₁₀ separated by one field exists within the range surrounded by the chain double-dashed line. In fact, since the c ₁ field is within the chain double-dashed line as shown, such movement by panning is possible. At this time, the d ₁ field exists within the range surrounded by the three-dot chain line in the figure,
Similar to the description in the figure, it is within the shaded area, and there is a high possibility that it exists at the position indicated by a black circle. As an example, FIG. 7 shows the prediction vector (A ₁ + B ₁ ) / 4 and the vector b ₁ when the d ₁ field is at the position shown in the figure.
The prediction error at this time is one pixel length on the diagonal, and if the d ₁ field is at the position represented by the black circle, the error will be less than that. Therefore, the prediction is valid also in the case of FIG.

Next, FIG. 8 shows the case where the component of the inter-field motion vector A ₁ separated by one frame is (x, y) = (3, 1). As in FIG. 4, the inter-field motion vector a ₁₀ separated by one field exists within the range surrounded by the chain line, and when the b ₁ field is at the point shown in the figure, the inter-field motion vector b ₁₀ separated by _one field is shown. Exists within a range surrounded by a chain double-dashed line. In fact, such movement by panning is possible because the c ₁ field is within the range enclosed by the chain double-dashed line as shown. At this time,
Although the d ₁ field exists within the range surrounded by the three-dot chain line in the figure, it exists within the range of the diagonal lines as in the description in FIG. 4, and it is highly possible that it exists at the position indicated by the black circle. As an example, FIG. 9 shows the prediction vector (A ₁ + B ₁ ) / 4 and the vector b ₁₀ when the d ₁ field is at the position shown in the figure. The prediction error at this time is one pixel length diagonally, and if there is a d ₁ field at the position represented by a black circle, the error will be less than that. Therefore, the prediction is also valid in the case of FIG.

From the above, the inter-field motion vector b ₁₀ separated by one field is predicted by approximation with the integer part of (A ₁ + B ₁ ) / 4 using the inter-field motion vectors A ₁ and B ₁ separated by one frame. The error is about one pixel diagonal or less. Considering the same, Can be predicted like. However, [] represents an integer part.

Moreover, in the prediction of the inter-field motion vector separated by one field, the error does not affect the subsequent prediction.
Even if the error increases temporarily due to a large vector change, it is possible to predict again with a small error if the vector change thereafter becomes gentle.

The motion correction performed by the above prediction will be described with reference to FIG.

First, when an a ₂ field signal is input to the video input terminal (1) of FIG. 1, the motion vector detection circuit (3) generates a motion vector c ₁ . On the other hand, the signal input to the video input terminal (1) is sub-sampled by the sub-sample switch (2) and further delayed by one field by the first one-field delay device (4). Therefore, the signal transmitted from the transmitting side at this time is the signal of d ₁ field which is the output of the first 1-field delay device (4) and the motion vector c ₁ which is the output of the motion vector detection circuit (3). Is.

On the other hand, on the receiving side, when the switch (5) receives a signal of d ₁ field, the non-motion compensation field memory (6)
The signals of a ₁ field and c ₁ field are stored in the first motion compensation field memory (8) and d ₀ field and b ₁ are stored in the first motion compensation field memory (8).
The field signal is stored. At this time, the transmitted motion vector is c ₁ , and the second 1-field delay unit (7) delays the motion vector by 1 field. Therefore, the motion vector B is stored in the first motion correction field memory (8). ₁ is entered. In this first motion compensation field memory (8), the d ₀ field and b ₁ field stored by the motion vector B ₁ are two-dimensionally moved, and the d ₁ field input to the switch (5) is obtained. The motion is corrected based on. As a result, the signal passing through the switch (5) is the signal of the d ₁ field and the b ₁ field corrected by the motion vector B ₁ .

On the other hand, in the adder (9), the motion vector B ₁ which is the output of the second 1-field delay device (7) and the transmitted motion vector C ₁ are added, and the adder (10) outputs 4 By dividing, the predicted value of the inter-field motion vector C ₁₀ is obtained.

The second motion compensation field memory (11) has a ₁ field, c ₁ field as in the non-motion compensation field memory (6).
The field signal is stored. The contents of the second motion correction field memory (11) are two-dimensionally moved by the predicted inter-field motion vector C ₁ and the motion correction is performed based on the d ₁ field.

Thus d ₁ field a ₁ the motion compensation has been performed based on the field, b ₁ field, c ₁ field, 4 fields worth of signals d ₁ field itself enters the field interpolation filter (13), between the field Enables interpolation. Normally the switch (14) is connected to the lower contact,
Although the inter-field interpolated signal is passed, inter-field interpolation cannot be performed for a moving image signal. Therefore, when motion is detected, the switch (1) is connected to the upper contact on a pixel-by-pixel basis, and the inter-field interpolation filter (12 ), The inter-field interpolation is performed only from the signal that has passed through the switch (5).

The signal interpolated at the missing sample points by the inter-field interpolation filter (13) or the intra-field interpolation filter (12) has a sample rate of 64.8 MHz, and the video output terminal (1
It is output from 5).

In such a motion compensation sub-sample transmission method that obtains inter-field motion vectors separated by one field by prediction on the receiving side, not only is it stable at the beginning and the end of panning, but also the motion vector transmitted is temporarily Even if a mistake is made, it will not have a bad effect later. It is also stable in special cases where the scene changes during panning and the image becomes a panning image. Furthermore, since the change of the motion vector due to panning is gradual, this method can be said to be very good.

In this system, the video signal transmitted by the first 1-field delay unit (4) on the transmission side is delayed by one field with respect to the motion vector, and the inter-field motion vector on the reception side is predicted. Easy going.

FIG. 10 shows the states of the signals from 10a to 10h in FIG. 1 when the a ₂ field signal is input to the video input terminal (1). In FIG. 10, the horizontal line above the symbol indicates that motion compensation has been performed, A is the interpolation value interpolated from ₁ , ₁ , ₁ , ₁ , d ₁ by the interpolation function f _A , and B is the interpolation function f _{B. 1} , d ₁
The interpolation value interpolated from is shown.

[Effects of the Invention] As described above, according to the present invention, the motion vector for one field is approximated from the motion vector to be transmitted and the motion is performed for each field without significantly changing the configuration on the receiving side. Since the correction is performed, the interpolation by the inter-field interpolation filter can be stabilized even when panning occurs, as in the still image state. Moreover, it is possible to perform interpolation with a small error, and thus it is possible to sufficiently suppress the resolution reduction during panning.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a schematic configuration of a motion compensation sub-sample transmission system according to an embodiment of the present invention, and FIG. 2 shows an example of a motion vector at the time of panning for explaining the operation of FIG. Vector diagram, FIG. 3 is a diagram showing the existence range of inter-field motion vector separated by one frame and inter-field motion vector separated by one field, FIG. 4, FIG.
FIGS. 8 and 9 are vector diagrams showing the relationship between inter-field motion vectors separated by one frame and inter-field motion vectors separated by one field, FIG. 5, FIG. 7, FIG.
FIG. 10 is a vector diagram showing an example of an inter-field motion vector separated by one field predicted from an inter-field motion vector separated by one frame and an actual inter-field motion vector separated by one field. FIG. 10 is a motion correction according to the present invention. A timing chart showing the signal flow of the sub-sample interpolation method, FIG. 11 is a block diagram showing an example of a schematic configuration of the conventional motion-compensated sub-sample interpolation method, and FIG. 12 is a conventional motion-compensated sub-sample interpolation method. Timing chart showing the signal flow when motion compensation is not performed
FIG. 13 is a timing chart showing a signal flow in the case of performing the motion compensation of the conventional motion compensation sub-sample interpolation method. (1) ... Video input terminal, (2) ... Switch, (3) ... Motion vector detection circuit, (4) ... First 1-field delay device, (5) ... Switch, (6) ... Non-motion correction field memory , (7) ... Second 1-field delay device, (8) ...
First correction field memory, (9) ... Adder, (10)
… Divider, (11)… Second motion compensation field memory,
(12) ... Inter-field interpolation filter, (13) ... Inter-field interpolation filter, (14) ... Switch, (15) ... Video output terminal. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (4)

[Claims] 1. A sample value of a video signal intermittently subsampled so as to make a cycle in a plurality of fields while maintaining a predetermined sample position, and motion information (I) between fields separated by one frame per field. Is a motion-corrected sub-sample transmission system for transmitting a signal and a delay transmission means for transmitting the sample value of the video signal with one field delay from the transmission side, and a received signal obtained by the delay transmission means. By predicting by using the motion information (I) for the field and the motion information (I) transmitted one field before, the motion information (II) between the fields separated by one field from the field of interest is predicted. Means for deriving and motion-corrected from the sample value in the field of interest, the motion information (I) and the motion information (II) A motion-compensated sub-sample transmission system comprising means for deriving sample values in a plurality of fields in the past and interpolating a missing point of a transmission signal using the motion-compensated sample values. 2. A motion compensation sub-sample transmission system according to claim 1, wherein motion information between fields separated by one field from a field of interest (II).
Is derived by approximating to 1/4 of the sum of the motion information (I) for the field of interest and the motion information (I) transmitted one field before the field of interest. Motion compensated sub-sample transmission system. 3. A motion-corrected sub-sample transmission method according to claim 1, wherein a sample value intermittently sub-sampled from the transmitting side so as to make a cycle of four fields while maintaining a predetermined sample position is provided. The motion information (II) for the field of interest is transmitted and the motion information (I) for the field of interest is transmitted at the receiving side.
And the motion information (I) transmitted one field before are used for prediction, and the motion is calculated from the sample value in the field of interest, the motion information (I) and the motion information (II). A motion-compensated sub-sample transmission system characterized by interpolating missing points of a transmission signal using sample values of the past three fields to be corrected. 4. The motion-corrected sub-sample transmission system according to claim 3, wherein the receiving side includes the motion information (II) for the field of interest and the motion information (I) for the field of interest and one field before. The motion-compensated sub-sample transmission method, wherein the motion-compensated sub-sample transmission method is derived by approximating to 1/4 of the sum of the motion information (I) transmitted to the mobile station.