JPH0787577B2 - MUSE system television system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is designed to smoothly switch from a moving image to a still image or vice versa without causing a sense of discomfort in image quality.
SE system television system.

[Prior Art] Research and development of high-definition television is approaching a practical period. MUSE (Multiple Sub−Nyquist Sampling Encodin
g) The method is a method developed by the Japan Broadcasting Corporation.

In this method, the transmitting side switches between the still area and the moving area of the screen and performs different processing. Almost in synchronization with this switching, a 1-bit noise reducer control signal is injected into the control signal in the MUSE signal and transmitted to the receiving side. By the way, the noise reducer arranged on the receiving side uses a correlation between normal frames and a non-linear processing circuit as shown in the circuit example of FIG. In this circuit, data for 4 fields is stored in the frame memory 25, and a subtraction circuit 23 obtains a difference signal (frame difference signal) from the input signal of a signal delayed by 4 fields,
The frame difference signal is multiplied by a coefficient of 1 or less via the non-linear processing circuit 24 and added to the input signal by the adder circuit 22. The non-linear processing circuit 24 has a coring characteristic that makes the output zero for small signals, and removes noise in a non-linear manner. On the receiving side, the control signal extraction circuit 21 receives the noise reducer control signal from the digital MUSE baseband signal, and when this signal is "1", the nonlinear processing circuit 24 is controlled to set the coefficient by which the frame difference signal is multiplied to zero. Turn off the noise reducer, or use the above coefficient as a decimal number close to zero to apply weak noise reduction. This is because the effect of the noise reducer is particularly effective in the static area, and in the moving area, the frame difference signal is mistaken for noise due to excessive noise reduction processing, and rather the high frequency components of the image are lost and blurring occurs. This is because it is better not to perform noise reduction in the area because noise is not so noticeable.

[Problems to be Solved by the Invention] In the above-mentioned conventional MUSE type television system, the noise reducer control signal sent from the transmitting side is 1 bit, and the noise reducer on the receiving side is turned on / off by binary control. It For images with originally good S / N, such as images taken in the studio, there is not much difference in image quality between ON and OFF, so there is no problem even if the control is binary. However, for other images with a large effect of noise reducer, the difference in image quality between the two types is large only by the noise reduction of two types of ON and OFF, and it is specified that the noise reducer is not operating, that is, the moving region. When it does, the deterioration of the image quality in the part where the movement is poor becomes noticeable.

The object of the present invention is not to simply turn the noise reducer on and off in a binary manner, but to switch the noise reduction characteristics stepwise in the on state to make the S / N change as gentle as possible, and It is an object of the present invention to provide a MUSE type television system which does not make an observer uncomfortable by applying noise reduction adapted to the movement of an image.

[Means for Solving the Problems] The MUSE type television system of the present invention is a signal generation for inputting an output of a motion part detection circuit as a transmission side encoder and generating a noise reducer control signal of a plurality (n) bits. By providing a circuit and multiplying the frame difference signal handled by the noise reducer by the information of the plurality of bits of the noise reducer control signal as a coefficient of 0 to 1 as a receiving side decoder, multi-valued A non-linear processing circuit for making corrections (according to the n-th power of 2) is provided, and the noise reduction characteristic of the noise reducer is changed stepwise according to the noise reducer control signal generated on the transmission side.

[Operation] On the transmitting side, when there is a detection signal in the moving part detection circuit,
A plurality (n) -bit noise reducer control signal is injected into the control signal generated for each field. On the receiving side, the noise reducer control signal causes the noise reducer to multiply the coefficient by which the frame difference signal is multiplied within the range of 0 to 1 (2 n powers).
Correct to. Therefore, the noise reducer does not turn on / off in a binary manner, but the noise reduction characteristic is switched stepwise with time.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is a block diagram of a transmitter encoder. High-quality TV RGB input signals with TCI encoder 1
After the TCI signal (time axis compression multiplex signal), it is passed through the static domain pre-filter 2 and the dynamic domain pre-filter 3, the respective filter outputs are mixed by the mixing circuit 4, and the sub sampling circuit 5
Sampling with the pattern of MUSE system, the multiplex circuit 6,
Combined with other signals and output as MUSE baseband signal. The moving part on the screen is detected by the motion detecting circuit 8 using the frame memory 7, and the mixing circuit 4 is controlled to switch between the still area and the moving area. On the other hand, the output of the moving part detecting circuit 8 is input to the noise reducer control signal generating circuit 9, and its output 9a, that is, a plurality of bit signals corresponding to the degree of the moving part is injected into the control signal in the multiplexing circuit 6. The noise reducer control signal 9a is included in the control signal for each field, and takes a value of 2n powers according to the degree of the moving part.

Next, a block diagram of the noise reducer on the receiving side is shown in FIG. 1B. The noise reducer is the same as the conventional example except the nonlinear processing circuit. The MUSE baseband signal is converted into a digital signal in the A / D converter 10 and transmitted to the signal processing system via the noise reducer 11. Frame memory
The subtraction circuit 112 obtains a difference signal (frame difference signal) 112a between the signal delayed by four fields at 111 and the input signal, guides this frame difference signal to the non-linear processing circuit 113, and the noise reducer generated at the transmission side. Multiply a coefficient from 0 to 1 according to the control signal. Non-linear processing circuit 11
Reference numeral 3 denotes a ROM whose address is specified by the frame difference signal and a noise reducer control signal of a plurality of bits, and as shown in FIG. 2, reads out the numerical value written in the specified address and adds it. 110
Supply to.

The non-linear processing 113 of the embodiment has a non-linear coring characteristic that the output is zero when the level of the frame difference signal is small, and n bits of the address are designated by the noise reducer control signal. Therefore, the original non-linear coring characteristic is controlled by the signal indicating the degree of motion of the image sent from the transmitting station side, that is, the noise reducer control signal, and the coefficient by which the frame difference signal is multiplied is in the range of 0 to 1. It will be corrected as 2 to the n-th power. Therefore, in contrast to the conventional system in which the noise reducer is substantially cut off in the moving region, the noise reduction characteristics of the noise reducer 11 are switched stepwise according to the movement of the screen. Therefore, for example, when the screen is switched from a still surface to a moving image, it gives an impression that noise is suddenly increased, or when the moving image is switched to a still image, The visual discomfort of suddenly switching to clear image quality as if impressing poor image quality is removed, and a consistently smooth image quality that forgets the presence of noise reduction can be provided.

The output signal and the input signal of the non-linear processing circuit 113 are added by the adding circuit 110 and transmitted to the motion system processing circuit of the next stage. Further, a horizontal sync pulse is detected by the sync separation circuit 5 in the figure, and a system clock synchronized with this pulse is regenerated and output by the PLL circuit 6.

As described above, according to the MUSE system television system described above, the noise reducer control signal of multiple bits is injected into the control signal sent from the transmitting side and extracted by the receiving side, and the transmitting side in the stationary area and the moving area. Even if the switching is performed, instead of simply turning on or off the non-linear processing circuit 113, the coefficient by which the noise reducer multiplies the frame difference signal is multivalued in the range of 0 to 1 by the noise reducer control signal of multiple bits. Since the noise reduction characteristics are switched stepwise by performing the dynamic correction, precise and highly accurate noise reduction is possible.

Further, since the non-linear processing circuit 113 is composed of a ROM, an address in which the frame difference signal and the noise reducer control signal are combined is specified, and the numerical value of 1 or less obtained by multiplying the frame difference signal by a required coefficient is read out. It is possible to perform accurate noise reduction by fully utilizing the characteristics of digital signal processing systems.

Further, the non-linear processing circuit is generally realized by a table lookup method using a ROM or the like, and an example of characteristics thereof is shown in FIG.

In the above embodiment, the circuit configuration of the noise reducer is not limited to that shown in this example, and may be any configuration as long as it includes a non-linear processing circuit.

[Effects of the Invention] As described in detail above, according to the present invention, the noise reducer control signal sent from the transmitting side is not a single bit but a plurality of bits, and the receiving side also uses the noise reducer to multiply the coefficient by which the noise reducer multiplies the frame difference signal. Since multi-value correction is performed in the range of 0 to 1 according to the control signal, there is no sudden change in image quality due to switching between the stationary area and the moving area, and it is very easy to see.
In particular, a sharp change in image quality is suppressed for images with poor S / N. For example, the difference in image quality when the noise reducer is turned on and off is noticeable in the still region, as in conventional binary control. It can give a very natural feeling.

[Brief description of drawings]

1A and 1B are circuit block diagrams of a transmitter encoder (a portion including a noise reducer) according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing an example of a non-linear processing circuit, and FIG. FIG. 4 is a circuit block diagram showing an example of a conventional noise reducer, and FIG. 4 is a diagram showing an example of nonlinear characteristics. 1 …… TCI encoder (11) 2 …… Still area pre-filter 3 …… Motion area pre-filter 4 …… Mixing circuit 5 …… Sampling circuit 6 …… Multiple circuit 7 …… Frame memory 8 …… Motion part detection circuit 10 …… A / D converter 11 …… Noise reducer 110 …… Addition circuit 111 …… Frame memory 112 …… Subtraction circuit 113 …… Non-linear processing circuit 12 …… Control signal extraction circuit

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Reiichi Kobayashi 1-8-17 Umeda, Kita-ku, Osaka City, Osaka Nihon Denki Home Electronics Co., Ltd. (72) Inventor Yuichi Ninomiya 1-chome, Kinuta, Setagaya-ku, Tokyo No. 10-11 Broadcasting Technology Institute of Japan Broadcasting Corporation (72) Inventor Yoshimichi Otsuka 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside Broadcasting Technology Laboratory of Japan Broadcasting Association (72) Inventor Yoshinori Izumi Setagaya-ku, Tokyo 1-10-11 Kinuta, Broadcasting Technology Research Institute of Japan Broadcasting Corporation (72) Inventor Seiichi Koshi 1-10-11 Kinuta, Setagaya-ku, Tokyo Broadcasting Research Institute of Japan Broadcasting Corporation (56) References 58-197983 (JP, A) JP-A 61-288678 (JP, A) Technical Report 7 [44] (Sho 59-3-22) P.A. 37-42 Norihiko Fukibuki "Digital Signal Processing of Images" First edition 3rd edition (Sho 58-7-15) Nikkan Kogyo Shimbun P. 115-118

Claims (1)

[Claims] 1. In a MUSE type television system,
As a transmission side encoder, a signal generation circuit that inputs the output of the motion part detection circuit and generates a plurality (n) -bit noise reducer control signal is provided, and as a reception side decoder, for the frame difference signal handled by the noise reducer, A non-linear processing circuit for multi-valued correction (according to the n-th power of 2) is provided by multiplying information obtained by normalizing the information of the noise reducer control signal of a plurality of bits as a coefficient from 0 to 1, and the noise reducer of the noise reducer is provided. A MUSE type television system characterized in that noise reduction characteristics are changed stepwise according to the noise reducer control signal generated on the transmission side.