JP2907494B2 - Method converter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system converter for converting a high-definition television signal (MUSE system) band-compressed using a sub-Nyquist sampling system into a current standard television signal. Things.

2. Description of the Related Art As an effective technology for compressing and transmitting a wideband high-definition television signal to a practical band capable of transmission, MUSE (Mult
An iple Sub-Nyquist sampling Enco-ding method has been proposed (Ninomiya, et al., "One-Channel Transmission System for High-Definition Television (MUSE)", Television Society Technical Report TEBS95).
-2 pages 37 to 42).

As described in this paper, this system is a system in which a wide-band high-definition television signal is subjected to 4: 1 sub-Nyquist sampling that makes one cycle in four fields, thereby performing band compression to about 1/4 and transmitting the signal. This band-compressed high-definition television signal (hereinafter referred to as a MUSE signal) is superimposed on the four fields using intra-field, inter-field, and inter-frame interpolation by the MUSE decoder on the receiving side to obtain the original high-bandwidth high-definition signal. Restored to TV signal.

When recording high-definition television broadcasts, MUSE-style VC
R (Video Cassette Recoder) or broadband high-definition VCR
Is required. However, these VCRs are expensive and may take a considerable amount of time to spread to ordinary households. Therefore, for the time being, it is considered effective to use a VCR compatible with the standard TV signal (NTSC system) that is currently in widespread use. For that purpose, a system converter for converting the MUSE signal into a standard television signal is required.

First, an outline of the MUSE system television receiver will be described with reference to FIG. In FIG. 3, 1 is an input terminal for inputting a MUSE signal, and 2 is an A / D for A / D converting the MUSE signal.
It is a conversion circuit. Reference numeral 3 denotes a still image processing circuit connected to the A / D conversion circuit 2, and includes a frame interpolation circuit 31 and a field interpolation circuit 32. Reference numeral 4 denotes a moving image processing circuit connected to the A / D conversion circuit 2 and has a built-in field interpolation circuit 41.
A motion detection circuit 5 is also connected to the A / D conversion circuit 2, and is connected to the mixing circuit 6 together with the still image processing circuit 3 and the moving image processing circuit 4. Reference numeral 7 denotes a TCI decoder connected to the mixing circuit.

In the conventional MUSE receiver configured as described above, the MUSE signal input from the input terminal 1 is applied to the A / D conversion circuit 2, and the output signal is used as a frame interpolating circuit having a frame memory. Still image processing circuit 3 composed of a field interpolation circuit 32 having a field memory 31
Are supplied to the moving image processing circuit 4 and the motion detection circuit 5 each composed of a field interpolation circuit 41 having a line memory. The signal of the still image area is subjected to interpolation processing in the still image processing circuit 3 using the transmitted information of the sample points for the four fields, and is supplied to one input of the mixing circuit 6.
The signal in the moving image area is subjected to interpolation processing in the moving image processing circuit 4 using only the transmitted information of the sample points in the field, and is supplied to the other input of the mixing circuit 6. The motion detection circuit 5 detects the amount of motion based on the correlation between one frame or two frames of the MUSE signal, and controls the mixing circuit 6 based on the detected amount of motion. The mixing circuit 6 performs a mixing process on the signals of the still image processing circuit 3 and the moving image processing circuit 4 in accordance with the amount of motion from the motion detection circuit 5, and performs TCI (Time-Compressed-I
supply to the decoder 7. The TCI decoder 7 performs a decoding process for returning the time axis compressed and time division multiplexed color signals to the original time axis, and outputs a high definition television signal from the output terminal 8.

By the above processing, the MUSE signal is restored to the original broadband high-definition television signal.

Next, the MUSE system television signal is transferred to a standard television (NTSC
Method) The operation of a conversion device for displaying on a receiver or recording on a VCR of a standard television signal will be described with reference to FIG. Here, the conversion of the luminance signal will be described.
In FIG. 4, reference numeral 1 denotes an input terminal for inputting a MUSE signal;
Is an A / D conversion circuit, 100 is an aliasing removal circuit, 110 is a scanning line number conversion circuit, and 120 is an aspect conversion circuit, which are connected in this order.

First, the input MUSE signal is supplied to the A / D conversion circuit 2, and the output signal is input to the anti-aliasing filter 100. The aliasing removal filter 100 removes aliasing of high-definition components in the vertical direction that occurs when scanning lines are thinned out. The signal from which the high-definition component in the vertical direction has been removed is thinned out by the scanning line number conversion circuit 110 and converted into the number of 525 scanning lines of the current standard television signal. This can be easily realized by, for example, writing to a memory at a signal rate of a high-definition television signal using a write / read asynchronous memory or the like, and reading the memory at a signal rate of a standard television signal. Scan line number conversion circuit 110
Is supplied to the aspect conversion circuit 120, and the output signal of 16: 9
From MUSE format to 4: 3 NTSC format. The conversion method is to display all the information as shown in FIG. 5 (FIG. 5A) or to display the information to wait for the lack of left and right (FIG. 5B).

There is also an EDTV system for achieving high image quality, and 16: 9 widening is considered as one target in the content. As a method corresponding to such a receiver, the above-described aspect ratio conversion circuit 120 becomes unnecessary.

The standard television signal converted as described above can be projected on a standard television receiver or recorded using a VCR.

Problems to be Solved by the Invention However, in the configuration described above, the MUSE method is
Since the band is compressed by the sub-Nyquist sampling method that makes one round in the field, the aliasing component of the still image area appears in the standard television signal as it is, which causes a problem that the image quality is deteriorated. That is, the aliasing component caused by the inter-frame offset subsampling of the MUSE method causes image quality deterioration as flicker in the conventional conversion device.

Further, in a receiver for converting a standard television signal into a non-interlaced scan and displaying the converted signal, the aliasing component described above appears jagged in the vertical direction. (Because the horizontal high frequency component is folded in the vertical direction, for example, a vertical line on the screen becomes a vertical line having a phase difference for each scanning line.)

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and has as its object to provide a system conversion apparatus that prevents image quality deterioration due to band compression of the MUSE system.

Means for Solving the Problems In order to solve the above problems, a system converter of the present invention converts a high-definition television signal, which has been band-compressed by a sub-Nyquist sampling method that makes one round in four fields, into a standard television signal. An A / D conversion circuit which receives a band-compressed high-definition television signal and performs A / D conversion, and an output signal of the A / D conversion circuit which is input and performs moving image processing by a field interpolation circuit. A first moving image processing circuit, a first still image processing circuit for processing a still image by a frame interpolation circuit and a field interpolation circuit, and a motion amount detection based on an inter-frame correlation of a band-compressed high-definition television signal. First
A motion processing circuit, a first mixing circuit that controls a mixing ratio of output signals from the first moving image processing circuit and the first still image processing circuit based on a motion amount detected by the first motion detection circuit; A first filter for limiting a vertical high frequency component of a signal from the circuit; and a first scanning line number conversion circuit for converting the signal from the first filtering device to the number of scanning lines of a standard television signal. It was done.

Further, the system conversion apparatus of the present invention has one field in four fields.
An A / D converter that converts high-definition television signals band-compressed by the rotating sub-Nyquist sampling method to standard television signals, and performs A / D conversion when the band-compressed high-definition television signals are input. Circuit, a second filter to which an output signal of the A / D conversion circuit is input to limit a vertical high frequency component, and a signal from the second filter is converted into the number of scanning lines of a standard television signal. A second scanning line number converting circuit, a second moving image processing circuit to which the signal having been subjected to the scanning line number conversion is input and performing moving image processing by a field interpolation circuit, and a frame to which the signal having been subjected to the scanning line number conversion is inputted. A second still image processing circuit that performs still image processing with an interpolation circuit and a field interpolation circuit, a second motion detection circuit that detects a motion amount based on an inter-frame correlation of the signal obtained by converting the number of scanning lines, This second motion detection circuit detects The motion amount that is is obtained and a second mixer circuit for controlling the mixing ratio of the second video processing circuit and the signal from the second still picture processor.

Operation The present invention has the above-described configuration and achieves the first MUSE decoder.
Since the number of scanning lines is converted using the high-definition television signal obtained from the mixing processing circuit, it is possible to obtain a standard television signal from which image quality deterioration due to band compression of the MUSE system has been removed.

In addition, after performing the conversion processing of the number of scanning lines, in order to perform moving image processing, still image processing, motion detection processing, and mixing processing, the MU
It is possible to obtain a standard television signal in which image quality deterioration caused by band compression of the SE system is prevented, and it is possible to reduce the circuit scale.

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

FIG. 1 is a block diagram showing a configuration of a system conversion apparatus according to a first embodiment of the present invention. In FIG. 1, 1 is
An input terminal for inputting a MUSE signal, 2 is an A / D converter circuit, 3 is a first still image processing circuit, 4 is a first moving image processing circuit, 5 is a first moving image processing circuit.
A motion detection circuit, 6 is a first mixing circuit, 7 is a TCI decoder,
Reference numeral 8 denotes a different output terminal for a high-definition television signal, which has the same configuration as that of FIG. 101 is a first vertical low-pass filter connected to the first mixing circuit 6. Reference numeral 110 denotes a first scan conversion circuit and a 120 aspect ratio conversion circuit, which have the same configuration as that of FIG.
It is connected to the. The operation of the thus configured system conversion apparatus according to the present embodiment will be described below. In FIG. 1, the decoding process of the MUSE is the same as that described in the conventional example, and the description is omitted. The output signal of the first mixing circuit 26 is supplied to a first vertical low-pass filter 101 as a filter including a plurality of line memories and an arithmetic circuit,
The vertical high frequency component of the signal from the first mixing circuit 6 is limited, the component of aliasing interference caused by the thinning of the scanning lines is removed, and the signal is supplied to the first scanning line number conversion circuit 110. The first scanning line number conversion circuit 110 performs 1
The frame is converted from 1125 frames to 525 frames and supplied to the aspect ratio conversion circuit 120. The aspect ratio conversion circuit 120 performs an aspect ratio process for displaying on a 4: 3 standard television as in the conventional case, and sends out a standard television signal from an output terminal 130.

As described above, according to this embodiment, since the signal in the still image area before the system conversion is a signal on which inter-frame and inter-field interpolation processing has been performed, aliasing caused by inter-frame and inter-field offset subsampling is performed. Since there is no component, the image quality deterioration such as flicker does not occur in the standard television signal obtained by converting the signal.

Further, according to the present invention, a high-definition television signal decoded by the MUSE decoder can be enjoyed using a high-definition television display or the like, and a high-quality standard television signal can be obtained.

Further, in the scanning line number conversion circuit for converting into a standard television signal, in this embodiment, conversion is performed to 525 lines / frame. However, by converting to 525 lines / field and processing in a 16: 9 state, EDTV is performed. It can also be converted to a TV signal compatible with widening of the system.

FIG. 2 is a block diagram showing a configuration of a system conversion apparatus according to a second embodiment of the present invention. In FIG. 2, 1 is
An input terminal for inputting a MUSE signal, 2 is an A / D conversion circuit, 200 is a second vertical low-pass filter, 210 is a second scanning line number conversion circuit, 220 is a second still image processing circuit, and 230 is a second moving image processing circuit , 240 is a second motion detection circuit, 250 is a second mixing circuit, 260
Is a second TCI decoder and a 270 second aspect conversion circuit, which are connected in a different order from the case of FIG.

The operation of the thus-configured system converter of this embodiment will be described below. The MUSE signal input from the input terminal 1 is applied to the A / D conversion circuit 2, and the output signal is supplied to a second vertical low-pass filter 200 as a filter including a plurality of line memories and an arithmetic circuit. .
The second vertical low-pass filter 200 eliminates aliasing interference of vertical high-frequency components caused by thinning out the number of scanning lines, and its output signal is supplied to a second number-of-scanning-lines conversion circuit 210.
Converted from 5 to 525. Second scanning line number conversion circuit 210
Is supplied to the second still image processing circuit 220, the second moving image processing circuit 230, and the second motion detection circuit 240. The second still picture circuit 220 is composed of a frame memory and a field memory of 525 lines / frame, performs inter-frame interpolation and inter-field interpolation processing, and supplies the result to one input of the second mixing circuit 250.
The second moving image processing circuit 240 is constituted by a line memory, performs an interpolation process in a field, and supplies the result to the other input of the second mixing circuit 250. Similarly, the second motion detection circuit 240 performs difference processing between one frame and two frames with 525 scanning lines, detects the amount of motion, and supplies it to the second mixing circuit 250. The second mixing circuit 250 controls the mixing ratio of the output signals of the second moving image processing circuit 230 and the second still image processing circuit 220 according to the amount of motion, and outputs the standard television signal through the TCI decoder 260 and the aspect ratio conversion circuit 270. The signal is output from the output terminal 280.

As described above, after converting the number of scanning lines and then performing still image processing, moving image processing, and motion detection processing, a high-quality standard television signal without aliasing interference can be obtained even for a still image. Further, since still image processing is performed by reducing the number of scanning lines to about half, the capacities of the frame memory and the field memory may be reduced to half. Therefore, the circuit scale can be reduced.

Advantageous Effects of the Invention As described above, according to the present invention, at least a moving image processing circuit that receives a band-compressed high-definition television signal and performs moving image processing, and a still image process that receives the band-compressed high-definition television signal and inputs the same A still image processing circuit, a motion detection circuit that detects a motion amount based on the inter-frame correlation of the band-compressed high-definition television signal, and a signal from the moving image processing circuit based on the motion amount detected by the motion detection circuit. A mixer that controls the mixing ratio of the signals from the still image processing circuit, a filter that limits the high-frequency component of the vertical frequency component of the signal from the mixing circuit, and a standard television that transmits the signal from the filter. A scanning line number conversion circuit for converting the number of scanning lines of a signal is provided to perform a system conversion, or after performing a conversion process of the number of scanning lines of a MUSE signal, a moving image process, a still image process, and a motion detection process. ,mixture To perform the management, it can cause the deterioration of image quality caused by the bandwidth compression of the MUSE system to obtain a standard television signal that has been removed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a system conversion device according to a first embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of a system conversion device according to a second embodiment of the invention, and FIG. FIG. 2 is a diagram showing a configuration of a MUSE-type decoder in a conventional example.
FIG. 4 is a diagram showing the structure of a conventional system conversion device using the MUSE system, and FIG. 5 is a diagram for explaining a display method when the MUSE system is converted to the NTSC system. 2 ... A / D conversion circuit, 3 ... First still image processing circuit, 31 ...
… Frame interpolator, 32… field interpolator,
4 first moving image processing circuit, 41 field interpolation circuit, 5 first motion detection circuit, 6 first mixing circuit, 10
1... First vertical low-pass filter (filter for vertical high-pass component), 110... First scanning line number conversion circuit, 200... Second vertical low-pass filter (filter for vertical high-pass component), 210 ......
2nd scanning line number conversion circuit, 220... 2nd still image processing circuit, 2
30 second video processing circuit, 240 second motion detection circuit, 2
50 ... second mixing circuit.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuo Isobe 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-2-238786 (JP, A) JP-A-3-3 272285 (JP, A) JP-A-3-283784 (JP, A)

Claims (2)

(57) [Claims] 1. A system converter for converting a high-definition television signal band-compressed by a sub-Nyquist sampling method, which makes one round in four fields, into a standard television signal, wherein a band-compressed high-definition television signal is inputted. An A / D conversion circuit for performing A / D conversion, a first video processing circuit to which an output signal of the A / D conversion circuit is input and performing video processing by a field interpolation circuit, a frame interpolation circuit, and a field interpolation A first still image processing circuit that performs still image processing by a circuit, a first motion processing circuit that detects a motion amount based on an inter-frame correlation of a band-compressed high-definition television signal, and a first motion detection circuit that detects the motion amount. A first mixing circuit that controls the mixing ratio of the output signals from the first moving image processing circuit and the first still image processing circuit based on the amount of motion, and a first that limits the vertical high frequency component of the signal from the first mixing circuit. With the filter The first signal system conversion apparatus characterized by comprising a first scan line number conversion circuit for converting the number of scanning lines of the standard television signal from the wave filter. 2. A system converter for converting a high-definition television signal band-compressed by a sub-Nyquist sampling method, which makes one round in four fields, into a standard television signal, wherein a band-compressed high-definition television signal is inputted. An A / D conversion circuit for performing A / D conversion; a second filter to which an output signal of the A / D conversion circuit is input to limit a vertical high frequency component; and a signal from the second filter. A second scanning line number conversion circuit for converting the number of scanning lines of a standard television signal, a second moving image processing circuit for receiving the signal converted for the number of scanning lines and performing a moving image processing by a field interpolation circuit; A second still image processing circuit to which the converted signal is input and which performs still image processing by an inter-frame interpolation circuit and an inter-field interpolation circuit; and a motion amount based on an inter-frame correlation of the signal obtained by converting the number of scanning lines. Second motion detection same path to detect And a second mixing circuit for controlling a mixing ratio of signals from the second moving image processing circuit and the second still image processing circuit based on the amount of motion detected by the second motion detection circuit. apparatus.