JPS6350285A - Receiver for band compression picture signal - Google Patents

Abstract

PURPOSE:To satisfactorily correct even a picture with an abrupt drop-out in terms of drop-out by selecting an output signal from a delay circuit for a part without movement and an output signal from a drop-out correction circuit for a part with movement. CONSTITUTION:When no drop-out signal occurs, a signal selection control circuit 25 outputs a subsample clock 5 as it is, and a signal selection circuit 23 switches the output (a) of a 1st delay circuit and the output (c) of a one-line memory 20 in the drop-out correction circuit 19 at the timing of the subsample clock 5. In case drop-out happens, whether a picture signal includes a moving part or not is decided by an output from the 3rd delay circuit of a temporary filter 14. A control signal is supplied to the signal selection circuit 23 from the signal selection control circuit 25 so that if there is no movement (still picture), the signal selection circuit 23 is fixed on a side (a): otherwise (moving picture), said circuit 23 is fixed on a side (b).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a television signal receiving apparatus, and more particularly to an image signal receiving apparatus subjected to band compression processing using multiple sub-Nyquist sampling.

Conventional technology When transmitting a wideband image signal such as a high-definition television signal, the signal bandwidth is reduced by sub-Nyquist sampling (Television Society of Japan technical report "High-definition television satellite one-channel transmission system JTE
BS95-2 Voβ7, No44) has been proposed. This method is called a motion-compensated multiple sub-Nyquist sampling transmission method, and the sampling phase is off-centered between fields, frames, and lines, and the sampling phase goes around in four fields. The receiving side is equipped with a frame memory to store the image signals transmitted sequentially over four fields, and combines them to restore the television image, using the known 2:1 In a television that performs interlaced scanning, the above-mentioned interframe offset subsampling processing and signal restoration processing are the basics.

In a system that transmits image signals by performing inter-field and inter-frame offset subsampling processing, the decoding circuit for receiving this signal and reproducing the television image becomes complex, and band compression processing is also required. In practice, it is difficult to completely detect moving parts of an image from among the image signals that are generated. Therefore, it is effective to transmit an auxiliary signal to simplify the configuration of the decoding circuit, that is, a control signal for the receiving device together with the image signal. is transmitted.

In order to receive the above-mentioned television signal and restore the image, a frame memory is basically required in the receiving device. Therefore, this frame memory can be used to interpolate missing portions in the input signal. The interpolation method for this missing signal is described in, for example, the Technical Report of the Television Society of Japan, in the home video disc JTKB399-a based on the imusE method, and has a configuration as shown in FIG. In FIG. 2, a 16.2 MBPS signal supplied to signal input terminal 1 is supplied to an interframe interpolation processing loop comprised of switch 2 and field memory 3.4. The delay time of this loop is set to approximately 562H in field memory 1 and approximately 563H in field memory 2, a total of 1 frame, and these memories perform interframe interpolation processing by switch 2, which performs a selection operation approximately every 3Q+1 seconds. has been applied, 32MB
It is sent to the next stage as a PS signal. This switch 2 operates between frames using a switching signal 6 (hereinafter abbreviated as sub-sample clock) which is transmitted together with the image signal supplied via a sub-sample clock control circuit 6 and is controlled by an inter-frame interpolation phase control signal of the receiving device. Perform interpolation processing. On the other hand, if a signal dropout occurs in the input signal as described above, the switch 2 is fixed to the b side based on the predetermined signal dropout information 7 (hereinafter abbreviated as dropout signal). A control signal is supplied from the sub-sample clock control circuit 6 to the switch 2.

Therefore, the field memory 3 is again supplied with the signal from one frame before. That is, interpolation of missing signals is performed.

The signal output from the interframe interpolation processing loop is supplied to a spatial interpolation processing circuit 8, a motion detection circuit 9, and a mixing circuit 10. The spatial interpolation processing circuit 8 extracts the signal of the field from among the signals subjected to the interframe interpolation processing, performs predetermined spatial interpolation processing, and supplies the motion image portion to the mixing circuit 10. The motion detection circuit 9 detects a motion part using frame correlation of the image signal, and the detected motion signal is M
The signal is expanded in the time axis direction, that is, in the field or frame direction, by a telepolar filter 14 composed of an AY selection 11, a field memory 12, and a coefficient circuit 13, and then supplied to the mixing circuit 1o.

The mixing circuit 10 mixes and controls the signal 15 of the still part of the image and the signal 16 of the moving image part using the motion detection signal 17, and sends out the restored high-quality television signal to the signal output terminal 18.

Problems to be Solved by the Invention The above-mentioned receiver for band-compressed image signals has a memory for inter-frame interpolation processing. By fixing the switch 2 to the b side with the signal 7, it is possible to interpolate with the signal two frames before. However, although this process can completely correct still images, when there are parts of the image that are moving rapidly or when the scene changes, interpolating with the signal from two frames earlier may cause the screen to appear unnatural. Image quality deteriorates.

Means for Solving Problems S According to the present invention, when an image signal subjected to band compression processing and a dropout signal representing the missing portion are input, a first signal for interframe interpolation is input. a dropout correction circuit including a delay circuit and a second delay circuit for at least one horizontal scanning period; and a signal selection circuit in which the first delay circuit and the dropout correction circuit are combined and selects an image signal and the output of the dropout correction circuit. a temporal filter including a motion detection circuit coupled to the first delay circuit, and a third delay circuit that expands the output of the motion detection circuit in the time direction; This is a receiving device for a band compressed image signal that is controlled by the output of a signal selection control circuit that processes the signal.

Effect of the present invention With the above-described configuration, when a dropout signal indicating a missing portion of an image signal is input, the output of the third extension circuit of the temporal filter for motion detection processing, that is, 1
The output of the signal selection control circuit, which is controlled by the motion information of the image signal before the field and the dropout signal, controls the signal selection circuit. The output signal of the dropout correction circuit is selected for the portion where there is movement, and correction control of the dropout portion is performed.

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

In FIG. 1, parts similar to those in the conventional example shown in FIG. 2 are given the same numbers and their explanations will be omitted. 19 is a dropout correction circuit using a two-horizontal scanning period delay circuit; 20 and 21 are line memories forming the second delay circuit; 22 is an arithmetic circuit that outputs the interpolation signal of the dropout section from the upper and lower scanning periods; 23 is a dropout interpolation circuit 19, a first delay circuit (field memory 3.4), and a signal selection circuit for selecting image signal 1; 26 is a third delay circuit (field memory 12) of a temporal filter and a timing adjustment circuit 2;
The signal selection control circuit 24 is controlled by the output signal 4 and the sub-sample clock 5, and the dropout correction circuit 19 24 adjusts the delay caused by using the second delay circuit (line memory 20, 21) for two horizontal scanning periods. This is a timing adjustment circuit for

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

In FIG. 1, when a dropout signal is not generated, the signal selection control circuit 25 outputs the sub-sample clock 5 as it is, and the signal selection circuit 23 outputs the output (A) of the first delay circuit and the dropout correction circuit 19. The output (/1) of the 1-line memory 20 is switched at the timing of the sub-sample clock 6.

When dropout occurs, it is determined whether there is a moving part in the image signal by the output of the third delay circuit of the temporal filter 14. If there is no movement (still image), the signal selection circuit 23 is set to In some cases (video), a control signal is supplied from the signal selection control circuit 25 to the signal selection circuit 23 so as to fix it on the mouth side. The operation of the signal selection circuit 23 is shown in the table below.

The operation after the signal selection circuit 23 is the same as the conventional one, and will therefore be omitted.

As described above, according to the present invention, when the dropout signal 7 representing the missing part of the image signal is input, the output signal of the third delay circuit of the temporal filter 14 provided in the conventional receiving device and the dropout The part where the output signal of the third delay circuit represents a moving image is the output signal of the dropout correction circuit, and the part where the output signal of the third delay circuit represents a still image is the output signal of the first delay circuit. By generating a signal from the signal selection control circuit so as to be selected and performing dropout correction, it is possible to reproduce a moving image signal to a more beautiful image than before.

Note that the dropout correction circuit 19 is a delay circuit for two horizontal scanning periods and generates a correction signal from the upper and lower scanning periods, but it is assumed that a delay circuit for one horizontal scanning period generates a correction signal from the previous scanning period. Good too.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, as described in detail, it is possible to perform good dropout correction even for images with severe dropout correction, and its practical effects are significant.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a receiving device for a band compressed image signal according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional receiving device for a band pressure M image signal. 1... Image signal, 3.4... First interception 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.

Claims (2)

[Claims] (1) A receiving device 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 this signal are input,
This receiving device includes a dropout correction circuit including a predetermined first delay circuit for interframe interpolation, a second delay circuit for at least one horizontal scanning period, and outputs of the first delay circuit and the dropout correction circuit. a signal selection circuit that selects the image signal and the output of the first delay circuit and the dropout correction circuit; a motion detection circuit that is coupled to the first delay circuit; and a third delay that extends the output in the time direction. a temporal filter comprising a circuit; and the signal selection circuit is controlled by the output of a signal selection control circuit processed by the output signal of a third delay circuit and a dropout signal. Device. (2) The signal selection circuit selects the signal so that the output signal of the third delay circuit selects the output of the dropout correction circuit for the portion representing a moving image, and selects the output of the first delay circuit for the portion representing a still image. 2. The band compressed image signal receiving device according to claim 1, wherein the control signal is sent from a control circuit.