JPH07184169A - High definition television signal reception processing circuit - Google Patents

Abstract

PURPOSE:To reduce deterioration in picture quality even when the C/N is deteriorated by selecting an output of a 2nd contour correction circuit from an output of a 1st contour correction circuit when the output of a transmission noise detection circuit indicates the deteriorated C/N. CONSTITUTION:A MUSE signal received by an input terminal 1 is given to a synchronization processing circuit 3 via an A/D converter circuit 2, which detects a synchronizing signal. A transmission noise detection circuit 12 provides an output of a detection signal of a transmission noise and a motion detection circuit 4 detects a motion for each picture element. A mixing circuit 7 mixes signals processed by a moving picture processing circuit 5 and a still picture processing circuit 6 based on the motion from the circuit 4. First and second contour correction circuits 8,13 use a specific digital filter respectively and to boost a specific frequency thereby emphasizing the contour. When the reception state is excellent, an output of the circuit 8 is used and when the reception state is not excellent, an output of the circuit 13 is used through the use of a changeover circuit 14 and a signal Y is outputted to a conversion circuit 10. The circuit 10 receives color difference signals R-Y,B-Y from the chrominance processing circuit 9 and converts them into R,G,B signals and they are outputted via a D/A converter circuit 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-definition television signal reception processing circuit.

[0002]

2. Description of the Related Art In recent years, there has been an increasing interest in band compression transmission systems in order to efficiently transmit wideband high-definition television signals within a limited transmission band. For example, as one of the band compression transmission systems, MUSE (Mult) that band-compresses high-definition television (high-definition) signals.
The iple Sub-Nyquist Sampling Encoding method has been proposed by the Japan Broadcasting Corporation (NHK). Details of the contents are described in Ninomiya “MUSE-High-Definition Transmission System” edited by Institute of Electronics, Information and Communication Engineers.

A conventional high-definition television signal reception processing circuit will be described below with reference to the drawings. Figure 3
FIG. 4 is a block diagram of a conventional high-definition television signal reception processing circuit.

In FIG. 3, 1 is an input terminal for a MUSE signal, 2 is an A / D conversion circuit for converting into a digital signal, 3 is a synchronous processing circuit for detecting a sync signal, and 4 is a motion detection circuit for detecting a motion. 5, 5 is a moving image processing circuit for processing moving images, 6 is a still image processing circuit for processing still images, 7 is a mixing circuit for mixing moving images and still images, 8 is a contour correction circuit for correcting contours, and 9 is A color processing circuit for decoding time-division multiplexed line-sequential color difference signals, 10 is an inverse matrix conversion circuit for performing inverse matrix conversion from a luminance signal and color difference signals, and 11 is a D / A conversion circuit for converting into an analog signal.

The operation of the high-definition television signal reception processing circuit configured as described above will be described below. MU input to the MUSE signal input terminal of FIG.
The SE signal is converted into a 10-bit digital signal by the A / D conversion circuit 2. The synchronization processing circuit 3 detects a synchronization signal (frame pulse) as shown in FIG. 4 from the digital signal and outputs a synchronization detection signal. The motion detection circuit 4 detects the amount of motion for each pixel from the digital signal.
Further, the moving image processing circuit 5 performs two-dimensional interpolation processing on the digital signal in the field. The still image processing circuit 6 performs interframe interpolation or the like on the digital signal. The mixing circuit 7 mixes the output of the moving image processing circuit and the output of the still image processing circuit according to the amount of motion output from the motion detection circuit.

Next, the contour correction circuit 8 boosts a specific frequency (for example, 24 MHz) by a digital filter to emphasize the contour. Further, the color processing circuit 9 mixes the output of the moving image processing circuit and the output of the still image processing circuit according to the amount of motion output from the motion detection circuit, and further extracts the time-division multiplexed line-sequential color difference signal. , Decompression, decoding, etc., and converted into color difference signals (RY / BY). Next, the inverse matrix circuit 10 performs an inverse matrix on the luminance signal output from the contour correction circuit and the color difference signal output from the color processing circuit to convert it into R, G, and B signals. Further, it is converted into an analog signal by the D / A conversion circuit 11, and the R, G, B signals are output.

[0007]

However, the above-mentioned conventional method has a problem that noise is emphasized and image quality is deteriorated when C / N is poor.

The present invention solves the above-mentioned conventional problems and reduces the deterioration of image quality even when the C / N is poor.

[0009]

In order to achieve this object, a high-definition television signal reception processing circuit according to the first aspect of the present invention comprises a transmission noise detection circuit, a first contour correction circuit, and a first contour. A second contour correction circuit having a different boost frequency from the correction circuit and a switching circuit are provided, and when the C / N is poor, the output of the first contour correction circuit is switched to the second contour correction circuit.

Further, the high-definition television signal reception processing circuit of the second invention is provided with a transmission noise detection circuit and a coring circuit, and when the C / N is bad, the coring circuit is operated by the output of the transmission noise detection circuit. Controls the amount of coring for contour correction.

[0011]

With this configuration, in the first invention, when the C / N is bad, the output of the transmission noise detection circuit switches between the output of the first contour correction circuit and the output of the second contour correction circuit, and noise is generated. It is possible to realize a video with less.

In the second invention, when C / N is bad,
The coring circuit controls the coring amount for contour correction based on the output of the transmission noise detection circuit. That is, when the reception state is good, the coring amount of the contour correction is reduced by the coring circuit, and when the reception state is bad, the coring amount of the contour correction is increased to realize an image with less noise. be able to.

[0013]

【Example】

(Embodiment 1) First, an embodiment of the first invention will be described with reference to the drawings. FIG. 1 is a block diagram of a high-definition television signal reception processing circuit showing an embodiment of the first invention. In FIG. 1, 1 is an input terminal for a MUSE signal, 2 is an A / D conversion circuit for converting into a digital signal, 3 is a synchronization processing circuit for detecting a synchronization signal, 4 is a motion detection circuit for detecting motion, and 5 is a motion detection circuit. A moving image processing circuit for processing a moving image, 6 a still image processing circuit for processing a still image, 7 a mixing circuit for mixing a moving image and a still image, 8 a contour correction circuit for correcting a contour, 9 a time division multiplex A color processing circuit for decoding the line-sequential color difference signals, 10 is an inverse matrix conversion circuit for performing an inverse matrix conversion from a luminance signal and a color difference signal, 11 is a D / A conversion circuit for converting into an analog signal, 1
2 is a transmission noise detection circuit that detects transmission noise (C / N), 13 is a second contour correction circuit that corrects contours, and 14
Is a switching circuit for switching between the output of the first contour correction circuit and the output of the second contour correction circuit.

The operation of the high-definition television signal reception processing circuit having the above-described structure according to the first embodiment of the present invention will be described below.

The MUSE signal input to the MUSE signal input terminal of FIG. 1 is converted into a 10-bit digital signal by the A / D conversion circuit 2. The synchronization processing circuit 3 detects a synchronization signal (frame pulse) as shown in FIG. 4 from the digital signal and outputs a synchronization detection signal. In the transmission noise detection circuit 12, for example, several tens of samples are sampled from the clamp level (a) or the frame pulse (b) whose repetition level is specified for each field from the digital signal as shown in FIG. 4, and then compared with the specified level. If the difference is small, the transmission noise is small (reception status is good). If the difference is large, the transmission noise is large (reception status is bad).
A threshold value is set and a detection signal is output. The motion detection circuit 4 detects the amount of motion for each pixel from the digital signal.

Further, the moving picture processing circuit 5 performs two-dimensional interpolation processing on the digital signal in the field. The still image processing circuit 6 performs interframe interpolation or the like on the digital signal. The mixing circuit 7 mixes the output of the moving image processing circuit and the output of the still image processing circuit with the amount of motion output from the motion detection circuit.

Next, the first contour correction circuit 8 boosts a specific frequency (for example, 24 MHz) by a digital filter to emphasize the contour. In addition, the second contour correction circuit 1
3 is a specific frequency (for example, 16
MHz) to enhance the contour. The switching circuit 14 outputs the first noise according to the output of the transmission noise detection circuit.
The output of the contour correcting circuit and the output of the second contour correcting circuit are switched.

That is, when the reception state is good, the output of the first contour correction circuit is used, and when the reception state is poor, the second contour correction circuit is used.
The output of the contour correction circuit of is used. In the color processing circuit 9, the output of the moving image processing circuit and the output of the still image processing circuit are mixed according to the amount of motion output from the motion detection circuit,
Further, the time-division multiplexed line-sequential color difference signals are extracted, expanded and decoded, and the like, and color difference signals (RY / BY) are output.
Convert to.

Next, the inverse matrix circuit 10 performs an inverse matrix on the luminance signal output from the contour correction circuit and the color difference signal output from the color processing circuit to obtain R, G, B.
Convert to signal. Further, it is converted into an analog signal by the D / A conversion circuit 11, and the R, G, B signals are output.

As described above, according to the embodiment of the first invention, the transmission noise detecting circuit 12, the first contour correcting circuit 8,
A second contour correction circuit 13 and a switching circuit 14 are provided, and C
When / N is bad, the output of the transmission noise detection circuit 12 switches the output of the first contour correction circuit 8 to the output of the second contour correction circuit, and an image with less noise can be realized.

(Embodiment 2) An embodiment of the second invention will be described below with reference to the drawings. FIG. 2 is a block diagram of a high-definition television signal reception processing circuit showing an embodiment of the second invention.

In FIG. 2, 1 is an input terminal for a MUSE signal, 2 is an A / D conversion circuit for converting into a digital signal, 3 is a synchronization processing circuit for detecting a synchronization signal, and 4 is a motion detection circuit for detecting a motion. 5, 5 is a moving image processing circuit for processing moving images, 6 is a still image processing circuit for processing still images, 7 is a mixing circuit for mixing moving images and still images, 8 is a contour correction circuit for correcting contours, and 9 is A color processing circuit that decodes time-division multiplexed line-sequential color difference signals, 10 is an inverse matrix conversion circuit that performs inverse matrix conversion from luminance signals and color difference signals, 11 is a D / A conversion circuit that converts into analog signals, 1
Reference numeral 2 is a transmission noise detection circuit that detects transmission noise (C / N), and 13 is a coring circuit that controls the amount of coring for contour correction. Here, coring refers to cutting a region having a small amplitude.

The operation of the high-definition television signal reception processing circuit configured as described above will be described below. MU input to the MUSE signal input terminal of FIG.
The SE signal is converted into a 10-bit digital signal by the A / D conversion circuit 2. The synchronization processing circuit 3 detects a synchronization signal (frame pulse) as shown in FIG. 4 from the digital signal and outputs a synchronization detection signal. In the transmission noise detection circuit 12, for example, several tens of samples are sampled from the clamp level (a) or the frame pulse (b) whose repetition level is specified for each field from the digital signal as shown in FIG. 4, and then compared with the specified level. If the difference is small, it is determined that the transmission noise is small (the reception state is good), and if the difference is large, the transmission noise is large (the reception state is bad), and a certain threshold value is set and a detection signal is output. The motion detection circuit 4 detects the amount of motion for each pixel from the digital signal.
Further, the moving image processing circuit 5 performs two-dimensional interpolation processing on the digital signal in the field. The still image processing circuit 6 performs interframe interpolation or the like on the digital signal. The mixing circuit 7 mixes the output of the moving image processing circuit and the output of the still image processing circuit with the amount of motion output from the motion detection circuit.

Next, the contour correction circuit 8 boosts a specific frequency (for example, 24 MHz) by a digital filter to emphasize the contour. The coring circuit 13 controls the amount of coring of the contour correction circuit based on the output of the transmission noise detection circuit. In other words, if the reception is good,
The coring circuit reduces the coring amount for contour correction, and increases the coring amount for contour correction when the reception state is poor. Further, the color processing circuit 9 mixes the output of the moving image processing circuit and the output of the still image processing circuit according to the amount of motion output from the motion detection circuit, and further extracts the time-division multiplexed line-sequential color difference signal. , Decompression, decoding, etc., and converted into color difference signals (RY / BY). Next, the inverse matrix circuit 10 performs an inverse matrix on the luminance signal output from the contour correction circuit and the color difference signal output from the color processing circuit to convert it into R, G, and B signals. Further, it is converted into an analog signal by the D / A conversion circuit 11, and the R, G, B signals are output.

As described above, according to the embodiment of the second invention, the transmission noise detection circuit 12 and the coring circuit 13 are provided, and when the C / N is bad, the output of the transmission noise detection circuit 12 causes the coring. A circuit can increase the amount of coring for contour correction, and an image with less noise can be realized.

[0026]

According to the first invention, a transmission noise detection circuit, a first contour correction circuit, a second contour correction circuit,
A switching circuit is provided, and the output of the transmission noise detection circuit switches the output of the first contour correction circuit to the output of the second contour correction circuit when the C / N is poor, thereby realizing an image with less noise. You can

Further, according to the second invention, a transmission noise detection circuit and a coring circuit are provided, and when the C / N is poor due to the output of the transmission noise detection circuit, the coring amount of contour correction is performed by the coring circuit. It is possible to increase the image size and realize an image with less noise.

[Brief description of drawings]

FIG. 1 is a block diagram of a high-definition television signal reception processing circuit showing an embodiment of the first invention.

FIG. 2 is a block diagram of a high-definition television signal reception processing circuit showing an embodiment of the second invention.

FIG. 3 is a block diagram of a conventional high-definition television signal reception processing circuit.

FIG. 4 is a format diagram of a MUSE band compression transmission signal.

[Explanation of symbols]

 1 MUSE signal input terminal 2 A / D conversion circuit 3 Synchronization processing circuit 4 Motion detection circuit 5 Video processing circuit 6 Still image processing circuit 7 Mixing circuit 8 First contour correction circuit 9 Color processing circuit 10 Inverse matrix conversion circuit 11 D / A conversion circuit 12 transmission noise detection circuit 13 second contour correction circuit 14 switching circuit

Claims (2)

[Claims] 1. A receiving device for a band-compressed high-definition television signal, a synchronization processing circuit for performing synchronization detection, a moving image processing circuit for processing a moving image, and a still image processing circuit for processing a still image, A motion detection circuit that performs motion detection, a mixing circuit that mixes moving images and still images, a color processing circuit that decodes color difference signals, an inverse matrix conversion circuit that performs inverse matrix conversion from luminance signals and color difference signals, and transmission noise. A transmission noise detection circuit for detecting, a first contour correction circuit for correcting the contour of an image, a second contour correction circuit having a boost frequency different from that of the first contour correction circuit, and a switching circuit are provided, and C / N is provided. If the output is bad, the output of the transmission noise detection circuit switches the output of the first contour correction circuit to the output of the second contour correction circuit. circuit. 2. A receiving device for a band-compressed high-definition television signal, a synchronization processing circuit for performing synchronization detection, a moving image processing circuit for processing a moving image, and a still image processing circuit for processing a still image, A motion detection circuit that performs motion detection, a mixing circuit that mixes moving images and still images, a color processing circuit that decodes color difference signals, an inverse matrix conversion circuit that performs inverse matrix conversion from luminance signals and color difference signals, and transmission noise. A transmission noise detection circuit for detecting, a contour correction circuit for correcting the contour of the image, and a coring circuit circuit for controlling the coring amount of the contour correction are provided, and when the C / N is poor, the output of the transmission noise detection circuit is provided. A high-definition television signal reception processing circuit, characterized in that the coring circuit controls the coring amount for contour correction.