JP2850125B2 - decoder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decoder constituting a receiver of a broadcasting system using a multiple sub-sampling transmission method.

2. Description of the Related Art Conventionally, a multiplex subsampling transmission method using offset subsampling has been used as a method of transmitting a wideband high-definition video (television) signal by band compression.
The MUSE (Multiple sub / Nyquist sampling Encoding) method has been proposed by the Japan Broadcasting Corporation.

By the way, in the studio standard for broadcasting stations of high-definition video signals, each signal band of red, green, and blue is 30 MHz. In order to compress these signal bands to about 8 MHz, in the above-mentioned MUSE method, sampling points are thinned out, and signal processing corresponding to a stationary region and signal processing corresponding to a moving region are performed by separate circuits. I have.

[Problems to be Solved by the Invention] As described above, since the signal processing for the static region and the signal processing for the moving region are performed by different circuits, a difference occurs in the signal band when the signals processed by these circuits are reproduced. This state is shown in FIG. 4 and FIG.

FIGS. 4 and 5 are diagrams showing the transmission region bandwidths of the stationary region and the moving region in relation to the horizontal spatial frequency and the number of vertical scanning lines.

From these figures, the horizontal spatial frequency is 24.3 in the stationary region.
MHz, and the moving region is 16.2 MHz, indicating that the band of the moving region is narrow. The difference between the bands is a phenomenon in which the moving region is blurred visually.

Accordingly, it is an object of the present invention to provide a decoder that reduces the blur of the visual moving area and improves the image quality.

[Means for Solving the Problems] A decoder according to the present invention is a decoder for a broadcasting system using a multiplex sub-sample transmission system, wherein a still image processing system and a moving image processing system are provided in parallel and both processings are performed. On the latter side of the system, there is provided a mix circuit that mixes the output signals of both processing systems with a mixing ratio according to the amount of motion, and the moving image processing system has a two-dimensional interpolation filter and an output signal from this filter. A contour signal adding circuit for adding a contour signal, wherein the coefficient for determining the amplitude of the contour signal is changed in accordance with the amount of motion.

[Operation] In the present invention, a contour signal adding circuit is provided in a signal processing system corresponding to a moving area at a stage preceding the mix circuit, and the contour signal adding circuit converts the contour signal according to a motion signal representing a motion amount. Since the amplitude is changed, the outline of the displayed image can be further clarified with a relatively simple circuit configuration as compared with the related art, and the blur of the visual dynamic region can be reduced.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram of a preferred embodiment of the present invention.

In the decoder 10, a video input signal of the MUSE system is input to a still area signal processing system 20 and a moving image area signal processing system 22, respectively.

The still area processing system 20 is configured by a frame interpolation circuit and a field interpolation circuit (not shown). The signal subjected to the frame interpolation processing by the frame interpolation circuit is transmitted to the next-stage field interpolation circuit. , And is supplied to a mix circuit 18.

The moving area signal processing system 22 includes a two-dimensional interpolation filter circuit 14 and a vertical / horizontal / vertical contour signal adding circuit 25. The output signal subjected to the two-dimensional interpolation processing by the two-dimensional interpolation filter circuit 14 is a vertical contour signal. The signal is supplied to the mix circuit 18 via the additional circuit 25.

As described above, in this embodiment, in the moving area signal processing system 22, the vertical / horizontal contour signal adding circuit 25 is provided at the subsequent stage of the two-dimensional interpolation filter circuit 14, so that the vertical contour is applied only to the video signal of the moving area. A signal is added. Moreover, in that case, the vertical / horizontal contour signal adding circuit 25 is
Is controlled in accordance with the motion signal supplied to the control signal, and the amplitude of the contour signal changes. On the other hand, no contour signal is added to the still area signal processing system 20. Therefore,
Blur of the video signal in the moving region having a narrow band is improved, and the difference between the images due to the video signals in the still region and the moving region is visually eliminated.

The mix circuit 18 mixes the output signal of the still area signal processing system 20 and the output signal of the moving area signal processing system 22 with a mixing ratio according to the motion signal representing the motion amount, and generates a video output signal.

FIG. 2 is a detailed block diagram of the vertical / horizontal contour signal addition signal 25.

The output signal of the two-dimensional interpolation filter circuit 14 is supplied to a one horizontal scanning period (1H) delay circuit 26 and an adder 28.

The output signal of the 1H delay circuit 26 is supplied to a second 1H delay circuit 30, a subtractor 32 and an adder 34, respectively.
The output signal of 28 is multiplied by で in a multiplier 36, and then subtracted by a subtractor 3
Supplied to 2.

The output signal of the subtractor 32 is supplied to the adder 34 via the coefficient unit 39 for the coefficient α.

That is, the adder 28 adds the video signal in the current horizontal scanning period and the video signal two scanning periods ago, and the multiplier 36 multiplies the addition result by 1/2. Therefore, the adder 28 and the multiplier 36 can obtain the average value of the video signal in the current scanning period and the video signal two scanning periods ago.

The subtracter 32 calculates the difference from the video signal one scanning period before the average value. Then, the coefficient α is added to this difference by a coefficient unit 39.
, And the result is used as a vertical / horizontal contour signal.

The adder 34 adds the contour signal output from the coefficient unit 39 to the video signal one scanning period earlier. The signal of this addition result becomes an output signal of the moving area signal processing system 22 and is supplied to the mix circuit 18.

Here, the amplitude of the contour signal related to the image quality improvement is determined by the coefficient α of the coefficient unit 38, but this coefficient α is not a constant value, but is changed according to the motion signal supplied to the mix circuit 18.

 That is, the coefficient unit 39 operates as follows.

In the mixing circuit 18, at least during the period when the mixing ratio of the signal of the moving area signal processing system 22 is larger than the mixing ratio of the signal of the still area signal processing system 20, the moving area signal processing system
Conversely, as the mixing ratio of the 22 signals decreases, the amplitude of the contour signal increases. That is, the coefficient α of the coefficient unit 39
Increase. Since the motion signal used in the mix circuit 18 is used as it is as the control signal for changing the coefficient α, there is no need to prepare a special control signal.

FIG. 3 is a characteristic diagram for explaining the circuit operation of FIG. 1 in detail.

FIG. 3A shows the case where the mixing ratio of the signal of the static region signal processing system 20 is 0 and the mixing ratio of the signal of the dynamic region signal processing system 22 is 1, that is, the signal of the dynamic region signal processing system 22. 3 illustrates the band of the mix circuit 18 when only the band is used. The sloping portion in the figure is a boost (enhancement) portion of the band due to the addition of the contour signal by the contour signal adding circuit 25.

FIG. 3B shows that the mixing ratio of the signal of the static region signal processing system 20 is 1/4 and the mixing ratio of the signal of the moving region signal processing system 22 is 3/4.
3 shows the band of the mix circuit 18 in the case of FIG. In this case, the additional weight of the contour signal in the moving area is the same as that in the case (a), and the amplitude of the contour signal is not changed by the motion signal and is set to a constant value.

In the case of (b), the boosting of the band due to the addition of the contour signal is also increased by 3/4 by the mixing circuit 18, and as a result, the boosting of the band is Decrease.

In order to prevent this drawback, in this embodiment, as shown in FIG. 3 (c), the amount of boost by adding a contour signal is increased. Therefore, the amount of increase in the band in the mix circuit 18 can be set to the same amount as (a).

However, even if the mixing ratio of the signals of the moving area signal processing system 22 is reduced, if the amplitude of the contour signal is always increased, the noise component of the contour signal increases to adversely affect the contour signal. Therefore, as described above, boosting is performed only when the mixing ratio of the signals of the static region signal processing system 20 is large.

Therefore, it is preferable that the characteristic of the coefficient α of the coefficient unit 39 be determined in consideration of the noise increase and the relationship with the signal in the still area (whether or not there is a sense of discomfort when viewing the reproduced image).

[Effects of the Invention] According to the present invention, a contour signal adding circuit is provided in a signal processing system corresponding to a moving region at a stage preceding the mix circuit, and
Since the contour signal adding circuit changes the amplitude of the contour signal according to the motion signal representing the motion amount,
With a relatively simple circuit configuration, it is possible to further clarify the outline of the displayed image as compared with the conventional case, it is possible to reduce the blur of the visual moving region, and to improve the image quality of the entire reproduced image. .

[Brief description of the drawings]

1 is a block diagram of a preferred embodiment of the present invention, FIG. 2 is a detailed block diagram of a contour signal adding circuit used in FIG. 1, FIG. 3 is an operation characteristic diagram for explaining the operation, and FIG. Is MUSE
FIG. 5 is a two-dimensional region display characteristic diagram of the static region bandwidth of the MUSE system, and FIG. 5 is a two-dimensional region display characteristic diagram of the moving region bandwidth of the MUSE system. 12 ... Blem interpolating circuit 14 ... Two-dimensional interpolating filter circuit 16 ... Field interpolating circuit 18 ... Mix circuit 20 ... Static area signal processing system 22 ... Moving area signal processing system 25 ... Contour Signal addition circuit 26, 30 1H delay circuit 28, 34 Adder 32 Subtractor 36 Multiplier 39 Coefficient unit

Claims (1)

(57) [Claims] 1. A decoder for a broadcasting system using a multiplex sub-sampling transmission system, wherein a still image processing system and a moving image processing system are provided in parallel, and the output of both processing systems is provided at the subsequent stage of both processing systems. The moving image processing system includes a two-dimensional interpolation filter and a contour signal addition unit that adds a contour signal to an output signal from the filter. And a contour signal adding circuit configured to change a coefficient for determining an amplitude of the contour signal in accordance with a motion amount.