JPH0832029B2 - Receiver for band-compressed image signal - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal receiver, and more particularly to an image signal receiver that has been subjected to band compression processing by multiple sub-Nyquist sampling.

2. Description of the Related Art A method of reducing the signal bandwidth by sub-Nyquist sampling when transmitting a wideband image signal such as a high-definition television signal
TEBS95-2Vol7.No44) has been proposed. This method is called a motion-compensated multiple sub-Nyquist sampling transmission method, in which the sampling phase is offset between fields, frames, and lines, and processing is performed such that the sampling phase makes one cycle in four fields. It transmits a signal, and the receiving side is equipped with a frame memory to store image signals transmitted sequentially over four fields and synthesizes these to restore a television image. In a television that performs interlaced scanning, the above-described inter-frame offset sub-sampling process and the restoration process of this signal are basic.

In the method of transmitting image signals by performing offset subsampling processing between fields and frames,
The decoding circuit for receiving this signal and reproducing the television image tends to be complicated, and it is practically practical to completely detect the moving portion of the image from the image signal subjected to band compression processing. It will be difficult. Therefore, it becomes effective to transmit the auxiliary signal for simplifying the configuration of the decoding circuit, that is, the control signal for the receiving device together with the image signal, and in the above-described system, various control signals such as the motion vector signal and the motion detection circuit control signal are provided. Is transmitted.

In order to receive a television signal of the above-mentioned system and restore an image, a frame memory is basically required in the receiving device. Therefore, the processing for interpolating the missing portion in the input signal can be performed by using this frame memory. This missing signal interpolation method is described in, for example, the technical report material "Home video disk by MUSE method" TEBS99-4 of the Institute of Television Engineers of Japan, and has a configuration as shown in FIG. In FIG. 2, the signal input terminal 1
The 16.2 MBPS signal supplied to is supplied to the interframe interpolation processing loop composed of the switch 2 and the field memories 3 and 4. The delay time of this loop is approximately 562H in field memory 1 and approximately 563H in field memory 2 for a total of 1
These memories are set to frames, and these memories are subjected to inter-frame interpolation processing by a switch 2 that performs a selection operation approximately every 30 nanoseconds, and the following 32 MBPS signals are obtained by time-division multiplexing image signals that differ by one frame. Send to the column. The switch 2 is transmitted with the image signal supplied through the sub-sample clock control circuit 6 and is switched by the switching signal 5 (hereinafter abbreviated as sub-sample clock) controlled by the inter-frame interpolating phase control signal of the receiving device. Perform interpolation processing. On the other hand, as described above, when a signal dropout occurs in the input signal, the switch 2 is set to the b side based on the predetermined signal dropout information (hereinafter abbreviated as dropout signal) supplied to the terminal 7. A control signal is supplied from the sub-sample clock control circuit 6 to the switch 2 so as to be fixed to. Therefore, the field memory 3 is again supplied with the signal of one frame before. That is, the missing signal is interpolated. The signal output by the interframe interpolation processing loop is
It is supplied to the space interpolation processing circuit 8, the motion detection circuit 9, and the mixing circuit 10. The spatial interpolation processing circuit 8 extracts the signal of the field from the signals subjected to the interframe interpolation processing, performs a predetermined spatial interpolation processing, and supplies the moving image portion to the mixing circuit 10. The motion detection circuit 9 detects a motion part by using inter-frame correlation of the image signal, and the detected motion signal has a temporal filter 14 composed of a maximum value (MAX) selection circuit 11, a field memory 12, and a coefficient circuit 13. Is expanded in the time axis direction, that is, in the field or frame direction, and then supplied to the mixing circuit 10. Mixing circuit 10 includes conductors 15 and 16
The signal of the still portion of the image and the signal of the moving image portion, which are supplied via the control unit, are mixed and controlled by the motion detection signal supplied via the conductor 17, and the restored high-definition television signal is sent to the signal output terminal 18. .

Problems to be Solved by the Invention Since the known band-compressed image signal receiving apparatus described above has a memory for inter-frame interpolation processing, this memory is used to detect a missing portion of an input signal at the terminal 7. The switch 2 can be fixed to the b side by the dropout signal supplied via the, and interpolation can be performed with the signal of two frames before. However, this process can completely correct a still image, but if the image is moving rapidly or the scene changes, interpolating with the signal of two frames before will cause an unnatural state on the screen, and Deterioration occurs.

Means for Solving the Problems In a receiving apparatus according to the present invention, when a band-compressed image signal and a dropout signal indicating a missing portion of this signal are input, a first delay for interframe interpolation is performed. A circuit, a dropout correction circuit including at least a second delay circuit for one horizontal scanning period or more, and a signal selection circuit that combines the first delay circuit and the dropout correction circuit to select an image signal and an output of the dropout correction circuit. A temporal detection filter including a motion detection circuit coupled to the first delay circuit, a third delay circuit extending its output in the time direction, and the signal selection circuit including an output signal of the third delay circuit and a dropout signal. And a receiving device for a band-compressed image signal which is controlled by the output of a signal selection control circuit processed by.

Operation According to the present invention, when the dropout signal indicating the missing portion of the image signal is input, the present invention outputs the output of the third delay circuit of the temporal filter of the motion detection process, that is, the motion information of the image signal one field before. The output of the signal selection control circuit, which is controlled by the dropout signal, controls the signal selection circuit, and when there is no movement, the output signal of the first delay circuit (field memories 3 and 4) is output; The output signal of the dropout correction circuit is selected and the correction control of the dropout portion is performed.

Embodiment FIG. 1 shows a block diagram of a receiving apparatus for band-compressed image signals in an embodiment of the present invention.

In FIG. 1, the same parts as those in the conventional example shown in FIG. 19 is a dropout correction circuit using a 2 horizontal scanning period delay circuit, 20 and 21 are second
A line memory that constitutes a delay circuit, 22 is an arithmetic circuit that creates an interpolation signal of the dropout section from the upper and lower scanning periods, 23 is an output terminal of the dropout correction circuit 19, and the first delay circuit (field memory 3 4) The image signal supplied to the output terminal B side of the signal input terminal 1 and the image signal supplied to the signal input terminal 1 are supplied to the terminal C side, and a signal selection circuit for selecting one of these signals, 25 is the third delay of the temporal filter. Circuit (field memory 12) and timing adjustment circuit 24
Output control signal and a signal selection control circuit controlled by the sub-sampling clock 5, and 24 adjusts a delay due to the dropout correction circuit 19 using a second delay circuit (20, 21 line memories) for two horizontal scanning periods. Is a timing adjustment circuit for.

The operation of the receiving apparatus of this embodiment configured as above will be described below.

In the normal case in FIG. 1, that is, when the dropout does not occur, the signal selection control circuit 25 outputs the sub-sample clock as it is, and the signal selection circuit 23 outputs the output (a) of the first delay circuit and the dropout. The output (c) of the 1-line memory 20 of the correction circuit 19 is switched in response to the sub-sampling clock 5. When a dropout occurs, that is, when the dropout signal is supplied to the terminal 7, it is determined by the output of the third delay circuit of the temporal filter 14 whether there is a moving portion in the image signal. Image), the control signal from the signal selection control circuit 25 is fixed so that the signal selection circuit 23 is fixed to the a side, and when there is movement (moving image), the signal selection circuit 23 is fixed to the b side.
Supply to 23. That is, the signal selection circuit 23 operates as shown in the table below.

Next, the operations of the spatial interpolation processing circuit 28, the mixing circuit 10 and the motion detection circuit 9 to which the output signal of the signal selection circuit 23 is supplied are the same as the conventional ones, and therefore detailed description thereof will be omitted.

As described above, according to the present invention, when the dropout signal 7 representing the missing portion of the image signal is input, the output signal and the dropout signal of the third delay circuit of the temporal filter 14 included in the conventional receiving apparatus are provided. The output signal of the dropout correction circuit is selected when the output signal of the third delay circuit represents a moving image, and the output signal of the first delay circuit is selected when the output signal of the third delay circuit represents a moving image. By generating the signal from the signal selection control circuit and performing the dropout correction as described above, it is possible to generate a better image signal than the conventional one for a moving image signal.
Further, it is possible to prevent deterioration of the vertical resolution for an image that does not move.

The dropout correction circuit 19 is a delay circuit for two horizontal scanning periods and generates correction signals from the upper and lower scanning periods. However, the delay circuit for one horizontal scanning period is to generate correction signals from the previous scanning period. Good.

EFFECTS OF THE INVENTION As described above, according to the present invention, the dropout correction can perform a good dropout correction even on an image or a still image in which the motion is vigorous, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a block diagram of a band-compressed image signal receiving apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional band-compressed image signal receiving apparatus. 1 ... Image signal, 3, 4 ... First delay circuit (field memory), 9 ... Motion detection circuit, 14 ... Temporal filter, 12 ... Third delay circuit, 19 ... Dropout correction circuit, 23 ...... Signal selection circuit, 25 …… Signal selection control circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yuichi Ninomiya 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside the broadcasting technology research institute of the Japan Broadcasting Corporation (72) Yoshimichi Otsuka 1-10 Kinuta, Setagaya-ku, Tokyo No. 11 Inside the Broadcasting Technology Research Institute of the Japan Broadcasting Corporation (72) Inventor Ikinori Yoshinori 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside the Broadcasting Technology Research Center of the Japan Broadcasting Association (56) Reference Japanese Patent Laid-Open No. 58-210777 (JP, A) Technical Report of the Television Society of Japan, TEBS99 -4 (Showa 59)

Claims (1)

[Claims] 1. A receiving apparatus to which an image signal subjected to band compression processing such as multiple sub-Nyquist sampling and a dropout signal representing a missing portion of the signal are input, and the receiving apparatus is an interframe internal frame. And a dropout correction circuit including a second delay circuit for at least one horizontal scanning period, the outputs of the first delay circuit and the dropout correction circuit are combined, and the image signal and the A signal selecting circuit for selecting an output of the 1 delay circuit or the dropout correcting circuit; a motion detecting circuit coupled to the first delay circuit; and a third delay circuit for extending the output in the time direction. And a temporal filter
The signal selection circuit includes a signal selection control circuit that sends a control signal so that the portion representing the moving surface selects the output of the dropout correction circuit and the portion representing the still image selects the output of the first delay circuit. A device for receiving a band-compressed image signal.