JP3285892B2 - Offset subsampling decoding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an offset subsampling decoder for restoring an offset subsampled signal.

[0002]

2. Description of the Related Art At present, various band compression techniques have been proposed in order to effectively use a transmission band of a transmission line. Among them, an offset sub-sampling method is preferred as a method suitable for band compression of a television signal. is there.

[0003] MUSE which is a band compression method of HDTV
(Multiple Sub-Nyquist SamplingEncoding) method ("Development of MUSE method"
Vol. 2), the transmitting side performs inter-frame offset sampling and inter-field offset sampling. As shown in FIG. 4, the television signal transmitted for this purpose is composed of the first to fourth fields and forms a high-definition television signal. The field frequency is 1/60 second. The black circle in FIG.
In FIG. 4B, a white square indicates a pixel in the third field, and a white square indicates a pixel in the fourth field. FIG. 4 shows a group of these pixels.
The image shown in FIG. Further, on the receiving side, for still images, frame interpolation (generating a screen combining black circles and black square pixels or a screen combining white circles and white square pixels) and field interpolation (FIG. 4A) (Or generation of a screen as shown in FIG. 4B). For a moving image, if such processing is performed, a double image is obtained.
Field interpolation, i.e., using pixels only within the field, to generate pixels at pixel gaps. Here, for the determination of a moving image and a still image and the signal selection switching of a moving image and a still image to be obtained as a decoded output, a motion detection signal obtained from a signal difference between one frame and a signal difference between two frames is used.

In the MUSE system, the interpolated fields are used, and the detection of the moving portion should use the difference between the fields.
The data of the peer value before the field is not transmitted. Therefore, motion detection is usually performed using signals between frames,
A signal delayed by one field is added to the one-frame detection signal and the two-frame detection signal to obtain a motion detection signal.

In the MUSE system, one cycle is performed in two frames because offset sampling between frames and offset sampling between fields are performed. Therefore, in the case of a still image, an image for one field is interpolated and restored from information for four fields of the current field, one field before, two fields before and three fields before. When motion detection is obtained during these four fields, the motion part is processed as a field interpolated moving image.

However, as described above, a motion in a frame unit is detected but a motion in a field unit is not detected. Therefore, the motion detection signal for each field is further added to the signal obtained by one-frame detection and two-frame detection.
The signal delayed by the field is added and substituted.

FIG. 3 shows the configuration of the offset subsampling decoding device. The original signal supplied to the input terminal 1 is input to one end of an inter-frame interpolation circuit 204 and a field interpolation circuit 205 and serially passes through frame delay circuits 200a and 200b having a delay amount of one frame. Is input to one end of the motion part detection circuit 201. Further, the output of the frame delay circuit 200a is input to the other end of the motion part detection circuit 201 and the interpolating circuit 204.

In the motion detection circuit 201 , a frame delay time
The difference between the signal on the input side and the signal on the output side of the road 200b is
This difference is output as a motion detection signal. This difference
If the difference is large, move the image.If the difference is small, change the image.
Can be judged as a part without motion (still image part)
You. This motion detection signal is output by a frame interpolation circuit 202.
Interpolated between frames and occurs in the specific transmission format of the MUSE system.
Motion detection signal interpolating the offset position between the pixels
Is generated as Further, the frame interpolation circuit 202
The motion detection signal, which is the output, is supplied to the field delay circuit 20
3, input to the addition circuit 209. Field delay circuit
203, an adder 209 synthesizes pixels between fields.
Data sample positions differ between fields.
Integration of false motion detection signal due to
are doing.

A frame interpolation circuit 204 performs frame interpolation using the original signal and the one-frame delay signal of the frame delay circuit 200a. The output of the inter-frame interpolation circuit 204 is output from the inter-field interpolation circuit 20 for performing inter-field interpolation.
7, and is input to the other end of the inter-field interpolation circuit 207 via a field delay circuit 206 having a delay amount for one field. The output of the inter-field interpolation circuit 207 is input to one end of the switching circuit 208, and the output of the field interpolation circuit 205 for performing field interpolation is input to the other end of the switching circuit 208.

The switching circuit 208 combines the output of the inter-field interpolation circuit 207 and the output of the inter-field interpolation circuit 205 at a ratio corresponding to the output of the adder 209, and derives a restored signal to the output terminal 2.

By the way, comparing the resolution of a moving image with that of a still image, a still image constitutes one screen from data for four fields, whereas a moving image constitutes one screen from data for one field. It has only about 1/4 resolution for still images. Normally, human vision reduces the resolution of a moving object, so such a difference in resolution between a still image and a moving image is allowed. The image becomes noticeably unnatural.

[0012]

As described above,
When restoring the interframe offset subsampled signal and the interfield offset subsampled signal, the MUS
Because of the transmission method unique to the E method (one round in four fields), a motion part cannot be detected in field units.

However, at the transition from a moving image to a still image and from a still image to a moving image, a motion component must exist for each field. Conventionally, when either the motion signal of the current field or the motion signal of the previous field indicates a motion as a substitute for the motion detection in a field unit, moving image processing has been performed. Therefore, there is a problem that a still image is originally processed as a moving image, and as a result, a moving image area is increased. This can be understood from the fact that the input and output of the field delay circuit 203 are used. In addition, since the resolution of a moving image is about 1/4 of the resolution of a still image, there is also a problem that a transition between a moving image and a still image results in an unnatural image.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is possible to reduce a region where a still image is erroneously processed as a moving image and to reduce unnaturalness at a switching between a moving image and a still image. It is an object of the present invention to provide an offset sub-sampling decoding device capable of performing the above-described operation.

According to the present invention, there is provided an offset sub-sampling decoding apparatus for decoding a high-definition television signal band-compressed by offset sub-sampling that makes one cycle in n fields. Insertion means, first field interpolation means for interpolating the high-definition television signal in a field, and a motion detection signal using an inter-frame signal of the high-definition television signal. and <br/> interframe motion detection signal obtained by interpolating the offset position by interpolation in between frames, a motion detecting means for motion detection signal between the frames to obtain a field delay motion detection signal one field delay, in between the frame from the interpolation means
Television signal and first field interpolation means
A television signal from, but selecting derived based on the motion detection signal between the frames, the frame Mado
If the detection signal indicates image motion, the first
The television signal from the field interpolation means
If indicated, the television from the frame interpolation means
First means for selectively deriving a television signal, field interpolating means for interpolating a television signal from the first means between fields, and second means for interpolating an output of the first means in a field. and field interpolation means, and a television signal from the television signal and the second field interpolation means from interpolation means in between said field selection derived based on said field delayed motion detection signal
Wherein the field delay motion detection signal indicates motion.
The telecommunication from the second field interpolation means.
If the vision signal indicates stationary, the field
A second method for selectively deriving a television signal from the interpolating means
Means.

[0016]

According to the above-mentioned means, it is possible to cope with the movement in units of frames and fields. That is, when the motion between the frames of the current field is not detected and the motion between the frames one field before is detected, the inter-frame interpolation and the field interpolation are performed, and the inter-field interpolation is not performed. This is because movement between fields may occur. However, since motion between frames is not detected, the resolution is improved about twice as compared with the conventional case where only field interpolation is performed.

Further, when changing from a moving image to a still image, the processing changes sequentially from a state of only field interpolation to a state of frame interpolation and field interpolation through interframe interpolation. Changes can be moderated.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the offset sub-sampling decoding apparatus according to the present invention.
The original signal supplied to the input terminal 1 is input to one end of an inter-frame interpolation circuit 104 and a field interpolation circuit 105 and serially passed through frame delay circuits 100a and 100b having a one-frame delay period. It is input to one end of the motion part detection circuit 101. Further, the output of the frame delay circuit 100a is input to the other end of the motion portion detection circuit 101 and the frame interpolation circuit 104.

The motion part detection circuit 101 has a frame delay
High-definition television signals on the input and output sides of circuit 100b
Signal difference and output this difference as a motion detection signal.
You. This motion detection signal is sent to the frame interpolation circuit 102.
Input, interpolated between frames, and
Motion signal is also reinterpolated as a new interpolated motion detection signal.
Be built. This reconstructed motion detection signal is switched
Input to the control terminal of the
Is input to a field delay circuit 103 that performs a delay.
Motion detection signal obtained from field delay circuit 103
Is input to the control terminal of the switching circuit 109. Fee
Field delay circuit 103 is a field interpolation circuit to be described later.
107, the operation delay of the field interpolation circuit 108
Power timing is gaining.

The inter-frame interpolation circuit 104 obtains an inter-frame interpolation signal using the original signal and the one-frame delay signal from the frame delay circuit 100a , and inputs the signal to one end of the switching circuit 106. The field interpolation circuit 105 obtains a field interpolation signal using only the data of the current field, and inputs the signal to the other end of the switching circuit 106.

The switching circuit 106 converts an inter-frame interpolation signal of the inter-frame interpolation circuit 104 and a field interpolation signal of the field interpolation circuit 105 into an inter-frame motion detection signal obtained by the inter-frame interpolation circuit 102. The signals are combined at a ratio corresponding to the output, and supplied to the inter-field interpolation circuit 107 and the inter-field interpolation circuit 108.

The inter-field interpolation circuit 107 obtains an inter-field interpolation signal using the data of the current field and the data of one field before, and inputs the inter-field interpolation signal to one end of the switching circuit 109.
The field interpolation circuit 108 obtains a field interpolation signal using only the data of the current field, and inputs the signal to the other end of the switching circuit 109.

The switching circuit 109 converts the inter-field interpolation signal and the inter-field interpolation signal into the field delay circuit 1
The signal is synthesized at a ratio corresponding to the output of the field delay motion detection signal No. 03, and the restored signal is derived to the output terminal 2. Hereinafter, the operation of this device will be described.

First, the motion detection signal of the current field and 1
When both the motion detection signals before the field indicate the motion, the switching circuits 106 and 109 select and derive the outputs of the field interpolation circuits 105 and 108, respectively.

Second, the motion detection signal of the current field and 1
When both the motion detection signals before the field indicate stationary, the switching circuits 106 and 109 output the output of the inter-frame interpolation circuit 104 and the inter-field interpolation circuit 107, respectively.
Select and derive the output of

Third, when the motion detection signal of the current field indicates stationary and the motion detection signal one field before indicates motion, the switching circuits 106 and 109 output the output of the frame interpolation circuit 104, The output of the interpolation circuit 108 is selectively derived. In this case, the resolution is about twice that in the case of the moving image processing.

Fourth, when the motion detection signal of the current field indicates motion and the motion detection signal of one field before indicates static, the switching circuits 106 and 109 output the output of the field interpolation circuit 105 and the inter-field The output of the interpolation circuit 107 is selectively derived.

In the fourth case, in this embodiment, the field interpolation and the field interpolation are performed. However, it is considered that the resolution at this time hardly increases. Therefore, under this condition, only the field interpolation is performed. A configuration for performing this is also conceivable.

FIG. 2 shows a second embodiment of the offset subsampling decoder according to the present invention.
1 is different from FIG. 1 in that the switching circuit 106 is provided in the subsequent stage of the switching circuit 109.
5 is different from that of FIG. 1 in that the method of interpolation is the same as that of FIG.

By adopting the configuration shown in FIG. 2, the fourth case, that is, the motion detection signal of the current field indicates the motion and
When the motion detection signal before the field indicates stillness, only the field interpolation may be performed.

In the configuration shown in FIG. 1, the output of the frame interpolating circuit 102 and the output of the field delay circuit 103 may be logically synthesized and input to the control terminal of the switching circuit 109.

According to the above embodiment, in any case, when the motion detection signal of the current field indicates stationary and the motion detection signal of one field before indicates motion, inter-frame interpolation and field interpolation are performed. Will be The resolution at this time is about 2 times as compared with the case where the conventional frame interpolation is not performed.
Double.

Further, when the screen changes from a moving image to a still image, the processing sequentially changes from a state of only field interpolation to a state of frame interpolation and field interpolation through interframe interpolation. The change in resolution can be made gentle.

[0035]

As described above, according to the offset sub-sampling decoder according to the present invention, a state in which a still image and a moving image cannot be distinguished, that is, no motion is detected in the current field and no motion is detected in the previous field. Since the interpolation between frames is performed even in the state where the image is displayed, the resolution is not deteriorated even when the image is originally a still image. In addition, even if motion is detected in the previous field, field interpolation using data between fields is not performed, so that the possibility of deterioration of a double image or the like is small. Furthermore, when moving from a video to a still image, the resolution changes twice in two steps,
It is possible to reduce the unnaturalness of the image switching.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of an offset sub-sampling decoding device according to the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the offset sub-sampling decoding device according to the present invention.

FIG. 3 is a configuration diagram showing a conventional offset subsampling decoding device.

FIG. 4 is an explanatory diagram of a MUSE signal.

[Description of Signs] 1 ... input terminal, 2 ... output terminal, 100, 200 ... frame delay device, 101, 201 ... moving portion detection circuit, 10
2, 104, 202, 204 ... frame interpolation circuit, 1
03, 203 ... field delay circuits, 105, 108,
205, 208 ... field interpolation circuit, 106, 10
9,208 ... switching circuit, in between 107 and 207 ... field interpolation circuit.

Continuing from the front page (72) Inventor Toshiro Omura 2-2-1 Jinnan, Shibuya-ku, Tokyo Inside the Japan Broadcasting Corporation Broadcasting Center (72) Inventor Koyama Kogetsu 1-9-1-2 Hara-cho, Fukaya-shi, Saitama Toshiba Fukaya Factory (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 7/015

Claims (2)

(57) [Claims] 1. An offset sub-sampling decoding device for decoding a high-definition television signal band-compressed by offset sub-sampling that makes one cycle in n fields, wherein said high-definition television signal is inter-frame interpolated. First field interpolation means for interpolating the high-definition television signal in a field; and obtaining a motion detection signal using an inter-frame signal of the high-definition television signal. interpolation
Motion detection means for obtaining an inter-frame motion detection signal obtained by interpolating the offset position and a field- delayed motion detection signal obtained by delaying the inter-frame motion detection signal by one field; and a television signal from the inter-frame interpolation means. The television signal from the first field interpolation means and the television signal are selectively derived based on the inter-frame motion detection signal .
The inter-frame motion detection signal indicates image motion.
If so, the first field interpolation means
If the television signal is stationary, the frame
First means for selectively deriving a television signal from the inter-frame interpolation means; inter-field interpolation means for inter-field interpolating the television signal from the first means; a second field interpolation means interpolating the field output of the first means, the television from the television signal and before <br/> Symbol second field interpolation means from interpolation means in between said field John signal
The door, selected on the basis of the field delay motion detection signal
The field delay motion detection signal
The second field interpolation means
If the television signal indicates stationary,
Selective derivation of television signal from field interpolating means
Offset subsampling decoding apparatus characterized by comprising a second means for. 2. The motion detecting means: a means for obtaining a motion detection signal from a difference between a signal obtained by delaying the high definition television signal by one frame and a signal obtained by delaying the frame by two frames; Insert and offset position
Perform the interpolation, the characteristics and the inter-frame interpolation circuit for obtaining a motion detection signal between frames, said inter-frame motion detection signal 1 field delay was and a field delay circuit for obtaining the field delay motion detection signal The offset sub-sampling decoding device according to claim 1, wherein