JPH03112281A - Video signal processing unit - Google Patents

Abstract

PURPOSE:To control the mode as to whether it is the resolution improvement or the noise suppression by applying gain control complementarily an output signal of an interpolation means and an put signal of a replacement signal forming means in response to the content of a control code and adding low frequency components. CONSTITUTION:A control code discrimination device 14 identifies noise quantity based on 14th, 15th bits and medium based on 12th, 13th bits to discriminate the quantity of noise and gives a gain control signal to control a ratio of low frequency original signal replacement to gain variable amplifiers 18A, 18B of a replacement quantity control circuit 18. When the noise discriminated by the control code is small, the gain of the amplifier 18A is controlled to be decreased and the gain of the amplifier 18B is controlled to be increased to increase the replacement quantity of the low frequency original signal thereby improving the vertical resolution. When the noise discriminated by the control code is large, the gain of the amplifier 18A is controlled to be increased and the gain of the amplifier 18B is controlled to be decreased to decrease the replacement quantity of the low frequency original signal thereby suppressing noise.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a video signal processing device, and particularly to a video signal processing device that performs interpolation processing on an input video signal obtained by, for example, offset sampling.

B0 Summary of the Invention The present invention provides interpolation means for performing interpolation based on N fields of video signals among input video signals, and an arbitrary pixel in one field of the video signal and the next pixel horizontally adjacent to the pixel. and a replacement signal forming circuit for forming a replacement signal for replacing the pixel with the pixel by the arbitrary pixel, and the output signal of the interpolation means and the output signal of the replacement signal formation means are each a low-frequency signal component. is input to a gain control means for controlling the gain of the video signal, and the gain control means complementarily outputs the output signal of the interpolation means and the output signal of the replacement signal forming means based on the content of the control code included in the video signal. By controlling the gain and then adding the low-frequency components of each output signal to each other, it suppresses deterioration of vertical resolution, and also determines whether the S/N of the input signal is good or bad from the control code and reduces noise. This prevents harmful effects on many input signals.

C1 Conventional technology Generally, when sampling and transmitting a signal with a predetermined bandwidth, it is necessary to use a sampling frequency that is twice the frequency of the bandwidth (the so-called Nyquist frequency) or higher in order to completely restore the original signal. However, it is necessary for
In the case of a video signal such as a television signal, it is possible to sample it at a frequency lower than the Nyquist frequency (so-called sub-Nyquist sampling) by focusing on its two-dimensional or even three-dimensional structure. be.

This is offset sampling 48 from the shape of the sample point.
No. 9 discloses a sub-sampled image reproducing device of a system that performs multiple offset sampling at a four-field period.

FIG. 4 shows an example of such an offset sampling system in which one screen is composed of four fields. In FIG. 4, the circles in the figure indicate sample data sent to the first field, la and lb, respectively.

lc,... Similarly, the x mark in the figure indicates the second
The mark indicates the sample data sent to the field, the mark indicates the sample data sent to the third field, the Δ mark indicates the sample data sent to the fourth field, and the numbers 2, 3, and 4 indicate the field. The order is indicated by lowercase letters a, b, c, . . . to distinguish each sample point. Note that the marks "." in the figure indicate sample points that are not transmitted in this 4-field multiplex offset sampling system.

In such an offset sampling system,
When transmitting a still image, from the data of each sample point obtained from 4 fields as shown in Figure 4, the above
By interpolating (interpolation processing) the data marked with j, the original (
The image information (before transmission) is played back. Also,
When transmitting a video, since the image for each field changes, only the information of the current field [゛] is used, and all other data is interpolated from this one field's worth of information (within the field). (interpolation processing) to reproduce the original image information.

In this way, although the resolutions of still images and moving images are different, interpolation is performed for each to obtain data of sample points that are not sent. During the interpolation, a filter is applied to prevent so-called aliasing (aliasing noise), but the horizontal and vertical resolutions deteriorate accordingly.

D. Regarding the problem to be solved by the invention, one method of suppressing the deterioration of vertical resolution is a method of low-frequency original signal replacement. This outputs the low frequency components of the video signal as they are without interpolating them. For example, as shown in FIG. 5A. ．． As shown in B, using the data of each sample point in each field, for example Ia', 1b, lc, ..., replace the pixels between horizontally adjacent sample points with these sample data. The same sample data is output repeatedly (four times in the figure). In this case, so-called aliasing occurs, but it appears on the screen that the vertical resolution has increased accordingly.

However, in this low-frequency original signal replacement, interpolation between fields and frames is not performed, so when a noisy video signal is input, the noise is output as is, and since it is a low frequency component, it is noticeable. easy.

The present invention has been made in view of these circumstances, and aims to improve vertical resolution by replacing low-frequency original signals, while reducing the amount of replacement for noisy input signals to make them less noticeable. The purpose of the present invention is to provide a video signal processing device that provides a high quality video signal processing device.

81 Means for Solving the Problems In order to solve the above-mentioned problems, the video signal processing device according to the present invention processes the above video of N fields (N is a natural number of 2 or more) out of the input video signals. an interpolation means (interpolation circuit 12) that performs interpolation based on the signal; It has a replacement signal forming circuit (rate converter 17) that forms a replacement signal for replacement, and the output signal of the interpolation means and the output signal of the replacement signal formation means respectively control the gain of the low frequency signal valve. The input signal is input to gain control means (gain control amplifiers 18A, 18B), and the gain control means outputs the output signal of the interpolation means and the output signal of the replacement signal formation means based on the content of the control code included in the video signal. The above problem is solved by performing complementary gain control and then adding the low frequency components of the respective output signals to each other (adder 19).

The noise state of the F1 effect input video signal is known from the control code, and by controlling the gain and adding the low-frequency components according to this control code, the amount of replacement of the low-frequency components changes, and low-frequency replacement according to the noise is performed. Amount can be controlled.

G. Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a video signal processing device according to a first embodiment of the present invention. The input terminal 11 in FIG. 1 is connected to a video signal that generally constitutes one screen with N field signals (N is a natural number of 2 or more), for example, a video signal consisting of 4 fields as described in conjunction with FIG. 4 above. A video signal sampled (at frequency f) by an offset sampling system that forms the screen is supplied. This video signal is, for example, a broadcast signal from a BS (broadcasting satellite),
It is obtained as a reproduction signal from a VTR (video tape recorder), a disc player, etc., and as a standard, a control code as described later is included in the video signal.

The input video signal offset-sampled at this frequency f is processed by the interfield and interframe interpolation circuit 12, L
The signal is sent to a PF (low pass filter) 13 and a control code discriminator 14.

In the inter-field and inter-frame interpolation circuit 12, inter-field and inter-frame interpolation is performed based on sample data signals for four fields of the input video signal, and an aliasing component suppression filter is applied to produce a signal with a rate of 4r, which is 4 times higher. Therefore, HPF (bypass filter) 15 and LPF 16
sent to. Regarding the low frequency components obtained through the LPFI 3 of the above-mentioned input video signal, only the rate is multiplied by 4 in the rate converter 17 without applying a double aliasing component suppression filter, as described above. Figure 5A
, B, resulting in a low frequency replacement signal as shown in FIG.

The low frequency component obtained through LPFlG of the interpolated signal is sent to the gain control amplifier 18A of the replacement amount control circuit 18, and the low frequency replacement signal from the rate converter 17 is sent to the replacement amount control circuit 18. The signal is sent to the gain control amplifier 18B of the quantity control circuit 18. These gain control amplifiers 18A, 18B are
In accordance with a gain control signal from a control code discriminator 14, which will be described later, the gain is controlled in a complementary manner under the condition that the sum of each gain becomes 1, and each gain control amplifier 18A, 1
The output from 8B is sent to an adder 19 and added. As a result, the ratio of the low-frequency component of the interpolated output signal to the low-frequency replacement signal or the amount of replacement changes. The output from the adder 19 is sent to the adder 20, where it is added to the high frequency component of the interpolated signal obtained via the HPF 15, and taken out via the output terminal 21.

Here, the control code included in the input video signal is placed at a predetermined position, for example, in a vertical synchronization signal section, and is made up of several H by repeating 32-bit information several times.
This is what is overwritten. Of this 32-bit control code, for example, the 12th and 13th bits may be used for media identification.
When the 1st bit is 1, it is a VTR, and the 13th bit is 1.

When this is the case, it is considered a disc, and when the 12th and 13th bits are all "0", it is considered a normal broadcast. Also, 14.1
The 2nd bit of the 5th bit is assigned to identify the amount of noise, and the numbers are assigned from “”oo” to “11” in order from the smallest noise to the largest noise.
Let it be °°. Note that the absolute amount of noise in this case may be different for each media, with VTR having the highest noise, discs and broadcasting decreasing in that order, and VTR having the lowest noise of "00'". The amount of noise may be larger than the amount of noise when the maximum noise is "'11" in broadcasting.

The control code discriminator 14 in FIG.
．． By identifying the amount of noise based on the 15th bit, the (absolute) amount of noise is determined, and the gain control signal for controlling the ratio of low frequency original signal replacement is applied to the replacement amount control circuit 18. The output signal is sent to variable amplifiers 18A and 18B. When the noise determined by this control code is small, the gain of the variable gain amplifier 18A is reduced, and the gain of the variable gain amplifier 18A is reduced.
By greatly controlling the gain of B, the amount of replacement of the low-frequency original signal is increased, and the vertical resolution is improved. On the other hand, when the noise is large, the gain of the variable gain amplifier 18A is controlled to be large and the gain of the variable gain amplifier 18B is controlled to be small, thereby reducing the amount of replacement of the low-frequency original signal, thereby suppressing the noise. In other words, even if the input contains noise such as side-scanning and beats, these noises are rapidly reduced by performing inter-field and inter-frame interpolation in the interpolation circuit 12. This is because the filter is applied not only in the axial direction but also in the horizontal and vertical directions.

As mentioned above, the amount of noise (or S/
N) is determined using a control code, the amount of replacement of the low frequency original signal is controlled according to the result, and when the input signal has a good S/N, the amount of replacement of the low frequency original signal is increased to bring out the effect of improving vertical resolution. When the input signal has a poor S/2N, deterioration of the S/N can be prevented by reducing the replacement ratio of the low-frequency original signal. Further, since the amount of replacement of the low-frequency original signal is continuously controlled according to the amount of noise, switching noise and the like do not occur. Furthermore, since the control code is determined, noise detection times.

Since no circuit is required, the circuit configuration can be simplified accordingly.

By the way, the above LPF for outputting the low frequency replacement signal
The order of the rate converter 13 and the rate converter 17 can be interchanged, and a second embodiment in which these are interchanged is shown in FIG. That is, the input video signal from the input terminal 11 is directly sent to the rate converter 17.

In this FIG. 2, parts corresponding to those in FIG. The output signal from the rate converter 17 is input to the input terminal a of the low-frequency original signal replacement circuit 23, and the output signal from the control code discriminator 14 is input to the control input terminal of the low-frequency original signal replacement circuit 23. Each is sent to C. In the low frequency original signal replacement circuit 23, the interpolated video signal from the input terminal a is supplied to the HPF 24 and the LPF 25, the rate-converted video signal from the input terminal a is supplied to the LPF 26, and each LPF 25. The low frequency output signals from 26 are sent to gain control amplifiers 27A and 27B of a replacement amount control circuit 27, respectively. The output signals from each gain control amplifier 27A, 27B are sent to an adder 28
The output from the adder 28 is sent to the adder 29 and added to the signal from the HPF 24. The output from the adder 29 is sent to the low frequency original signal replacement circuit 23.
The signal is sent to the output terminal 21 via the output terminal d. HPF 24 and LPF 25 in this low frequency original signal replacement circuit 23
．． 26, replacement amount control circuit 27 and adders 28 and 29,
They correspond to the HPF 15, LPF 16.13, replacement amount control circuit 18, and adder 19.20 in FIG. 1, respectively, and perform similar operations. The second embodiment shown in FIG. 2 differs only in that an LPF 26 is arranged behind the rate converter 17 as a configuration for obtaining a low-frequency replacement signal, as described above, and the second embodiment shown in FIG. Almost the same operation is performed, and the same effects can be obtained.

Next, FIG. 3 shows a main part of a third embodiment of the present invention, and shows a specific example of a low-frequency original signal replacement circuit that can be used in place of the low-frequency original signal replacement circuit 23 in FIG. ing. That is, the terminals a to d in FIG. 3 are respectively connected to the terminals a to d in FIG. Become.

In FIG. 3, the interpolated video signal supplied to the input terminal a is sent to a subtracter 31 and a delay circuit 32, and the subtracter 31 converts the rate of the video signal supplied to the input terminal a. The interpolated video signal is subtracted from the interpolated video signal. The output signal from the subtracter 31 is sent to a gain control amplifier 34 via an LPF 33 for gain control, and sent to an adder 35 where it is added to the output signal from the delay circuits 32-5. The delay circuit 32 is an LPF
It has a delay time equal to the signal delay caused by 33 and gain control amplifier 34.

In such a configuration, the interpolated video signal (denoted as M) is subtracted from the rate-converted video signal (denoted as R) by the subtracter 31, and the low frequency component is extracted by the LPF 33. When the signal is (RM)L = RtMt, this is multiplied by 7 in the gain control amplifier 34, sent to the adder 35, and added to the interpolated video signal M, resulting in M+α(RM)L. −M+αRL−αMt is obtained.

Here, if the interpolated video signal M is replaced with the sum of the high-frequency component MH and the low-frequency component M (MmiMu + Mt), the above addition output becomes M, -1-M L + α R, -α ML-M +1
+(1-α)Mt+αRL, and it can be seen that the same output signal as in FIGS. 1 and 2 is obtained.

In this case, when the noise 6 is small, the gain α is largely controlled to increase the amount of low-frequency substitution, and when the noise is large, the gain α is controlled to be small and the amount of low-frequency substitution is not reduced. Of course, the same effects as in the second embodiment can be obtained.

It should be noted that the present invention is not limited to the above embodiments, and for example,
The number N of fields constituting one screen may be a natural number other than 4 in the above example, and various positions of sample points for each field may be considered in addition to the specific example shown in FIG.

H. Effects of the Invention As is clear from the above explanation, the video signal processing device according to the present invention allows the interpolation means output signal and the replacement signal formation means output signal to be complementary to each other according to the content of the control code. Since the gain is controlled and each low frequency component is added to each other, it is possible to perform control to select between resolution improvement or noise suppression depending on the amount of noise, and since this control is continuous control, switching is possible. Noise etc. are not generated, and a circuit for noise detection is not required, so the configuration can be simplified.

Specifically, the control code discrimination means determines the noise amount information of the input video signal, and when there is little noise, the amount of replacement of the low frequency original signal is increased to improve the vertical resolution, and when there is a lot of noise, the amount of replacement of the low frequency original signal is increased. It is possible to improve the S'/N by reducing the amount of signal replacement.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing a schematic configuration of a first embodiment of a video signal processing device according to the present invention, FIG. 2 is a block circuit diagram showing a schematic configuration of a second embodiment, and FIG. 3 is a block circuit diagram showing the configuration of the main parts of the embodiment, FIG. 4 is a schematic plan view showing sample points on the screen for explaining a specific example of 4-field multiple offset sampling, and FIG. 5A
, B are schematic plan views showing sample points on a screen for explaining a specific example of a low-frequency replacement signal. 11...Video signal input terminal 12...Interfield and interframe interpolation circuit 13.16.25.26.33...LPF (low pass filter) 14...
・Control code discriminator 15.24...H
PF (bypass filter) 17...Rate converter 18.27...Replacement amount control circuit 18A, 18B, 27A, 27B, 34,...Gain control amplifier 19.20.28.29.35 ...adder 21
...Video signal output terminal 23 ...Low frequency original signal replacement circuit

Claims (1)

[Claims] An interpolation means for performing interpolation based on N fields (N is a natural number of 2 or more) of the input video signals; a replacement signal forming circuit for forming a replacement signal for replacing a pixel with the next pixel horizontally adjacent to the pixel by the arbitrary pixel, the output signal of the interpolation means and the replacement signal; The output signals of the forming means are respectively input to gain control means for controlling the gain of the low frequency signal, and the gain control means replaces the output signal of the interpolation means with the output signal of the interpolation means based on the content of the control code included in the video signal. A video signal processing device characterized in that the gain of the output signal of the signal forming means is controlled in a complementary manner, and then the low frequency components of the respective output signals are added together.