JPH04262689A - Nonlinear signal processor - Google Patents

Abstract

PURPOSE:To improve the waveform reproducibility of a transmission waveform and to reduce the noise of the edge part in a picture by digitizing a vertical nonlinear signal processing circuit and making a horizontal nonlinear signal processing circuit into a phase straight line. CONSTITUTION:A video signal inputted from an input terminal 1 is inputted to a digital vertical nonlinear emphasis circuit 2 and a vertical direction high band component receives nonlinear emphasis. The vertical-nonlinear-emphasized video signal is inputted to a horizontal nonlinear phase straight line emphasis circuit 3 and a horizontal direction high band component receives nonlinear emphasis. A signal transmitted through a transmission line 4 is inputted to a horizontal nonlinear phase straight line de-emphasis circuit 5 and the horizontal direction high band component is de-emphasized. The horizontal-nonlinear- phase-strainght-line-de-emphasized video signal is inputted to a digital vertical nonlinear de-emphasis circuit 6 and the vertical direction high band component receives de-emphasis.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonlinear signal processing device used for transmitting video signals.

0002

2. Description of the Related Art Conventionally, two-dimensional nonlinear processing of images has been carried out by, for example, National Technical Rep.
ort DEC. As shown in 1988, analog signal processing was performed by cascade-connecting a circuit that performs vertical nonlinear signal processing and a circuit that performs horizontal nonlinear processing.

An example of a conventional nonlinear signal processing device will be described below with reference to the drawings.

FIG. 4 shows a block diagram of a conventional nonlinear processing device. In FIG. 4, 23 is an input terminal to which a video signal is input. The video signal input from the input terminal 23 is first subjected to processing by a vertical nonlinear emphasis circuit 24 such that the smaller the amplitude of the vertical high frequency component, the greater the amount of emphasis. For example, the vertical nonlinear emphasis circuit has an input terminal 3 as shown in FIG.
0, first adder 31, analog vertical delay element 32, subtracter 33, first amplifier circuit 36, first nonlinear processing circuit 37, second amplifier circuit 34, second nonlinear processing circuit 35
, a second adder 38, and an output terminal 39.

In FIG. 5, for example, when the amplification factor of the amplifier circuit 36 is set to 0, the video signal input from the input terminal 30 is input to the analog vertical delay element 32. The analog vertical delay element 32 is composed of, for example, a CCD, and is normally delayed by one line of the video signal. The output of the delay element 32 is then subtracted from the input video signal using a subtracter 33. Thereafter, the signal is amplified by the necessary amount in the amplifier circuit 34, and then limited in amplitude by the nonlinear processing circuit 35, and added to the input signal using the adder 38. The signal obtained in this manner is output from the output terminal 39. At this time, the characteristics of the nonlinear processing circuit are such that, as shown in FIG. 8, the output signal is proportional to the input signal until the input value reaches a certain value, and when it becomes larger than a certain value, it outputs a constant value th. It has become. Usually, the amplification factor K=1.

The output of the subtracter 34 is amplified by an amplifier circuit 36 if necessary, subjected to amplitude limitation by a nonlinear processing circuit 37, and then fed back to the input signal using an adder 31. On the other hand, the amplification factor of the amplifier circuit 36 is usually 0, that is, the amplification factor is often set to 0, that is, the structure does not provide feedback.

The vertically nonlinearly emphasized video signal is then input to a horizontally nonlinearly emphasized circuit 25.
Horizontal high-frequency components undergo nonlinear emphasis.

FIG. 6 shows the configuration of a normal nonlinear emphasis circuit, which includes an input terminal 40, a phase nonlinear high-pass filter 41, an amplifier circuit 42, a nonlinear processing circuit 43,
It consists of an adder 44 and an output terminal 45. The horizontal high frequency components of the video signal inputted from the input terminal 40 are separated by a phase nonlinear high pass filter 41 . The phase non-linear high-pass filter is composed of a capacitor 59 and a resistor 60, for example, as shown in FIG. ing. After being amplified by the necessary amount in the amplifier circuit 42, the nonlinear processing circuit 4
3, and is added to the input signal by an adder 44. The nonlinear processing circuit 43 operates in the same manner as that used in the vertical nonlinear processing circuit. In this manner, a video signal subjected to vertical nonlinear emphasis and horizontal nonlinear emphasis is output to the output terminal 45.

This emphasized signal is then input to a horizontal nonlinear de-emphasis circuit through a transmission line 26. The horizontal nonlinear emphasis circuit includes, for example, an input terminal 46, a subtracter 47, a phase nonlinear high-pass filter 50, an amplifier circuit 49, and a nonlinear processing circuit 48, as shown in FIG. The input video signal is
The feedback signal is subtracted and output from the output terminal 51 as an output signal. Further, the output of the subtracter 47 passes through a phase nonlinear high-pass filter 50, an amplifier circuit 49, and a nonlinear processing circuit 48, and becomes a feedback signal. The phase nonlinear high-pass filter 50, the amplifier circuit 49, and the nonlinear processing circuit 48 may have the same characteristics as those used in the horizontal nonlinear emphasis circuit.

The video signal that has undergone horizontal nonlinear de-emphasis is then input to a vertical non-linear de-emphasis circuit 28, where vertical high-frequency components are de-emphasized.
The restored signal is obtained at the output terminal 29.

The vertical nonlinear de-emphasis circuit 28 is
This can be obtained by inverting the polarities of the two amplifier circuits of the vertical nonlinear emphasis circuit (FIG. 5) and setting the amplification factor to an appropriate value, so a description thereof will be omitted.

The horizontal and vertical de-emphasis reduces the noise and distortion components added in the transmission line 26 and improves the signal-to-noise ratio (SNR).

[0013]

[Problems to be Solved by the Invention] Such conventional nonlinear signal processing devices use analog signal processing for vertical nonlinear emphasis (de-emphasis), so they suffer from problems such as a narrow video signal band and poor waveform reproducibility. Regarding horizontal nonlinear emphasis (de-emphasis), since it is a phase non-linear emphasis, there is a problem that a lot of noise that is not de-emphasized is left at the edge of the image during de-emphasis. ing. Therefore, there is a problem in that the waveform of the video signal is significantly degraded as a whole, and a lot of noise remains at the edge portions of the image.

The present invention solves the above-mentioned problems, and aims to provide a nonlinear signal processing device with good waveform reproducibility and with less noise at the edge of an image than in the past.

[0015]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention has a configuration in which a vertical nonlinear signal processing circuit is digitized and a horizontal nonlinear signal processing circuit is phase linearized. It has a configuration in which emphasis is applied and transmitted in the order of non-linear phase linear emphasis, and de-emphasis is performed in the order of horizontal non-linear phase linear de-emphasis and digital vertical non-linear de-emphasis.

[0016]

According to the present invention, with the above-described configuration, the waveform reproducibility of the video signal can be improved, and noise in the edge portion left behind by de-emphasis can also be reduced.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an input terminal, 2 is a digital vertical nonlinear emphasis circuit, 3 is a horizontal nonlinear phase linear emphasis circuit, 4 is a transmission line, 5 is a horizontal nonlinear phase linear emphasis circuit, 6 is a digital vertical nonlinear deemphasis circuit, 7 is the output terminal.

The configuration of the block diagram is the same as the conventional example shown in FIG. 4, except that the vertical nonlinear emphasis circuit and vertical nonlinear deemphasis circuit of the conventional example are digitized, and the horizontal nonlinear emphasis circuit and horizontal This is greatly different from the conventional example in that the de-emphasis circuit is a phase linear emphasis.

The video signal inputted from the input terminal 1 is first inputted to a digital vertical nonlinear emphasis circuit, and the vertical high frequency components are subjected to nonlinear emphasis. Figure 2 shows a block diagram of the digital nonlinear emphasis circuit.
It is shown in The operation is the same as that shown in the conventional example, so a description thereof will be omitted, but the vertical delay element 10 is constituted by a digital memory. This results in a vertical nonlinear emphasis circuit that is superior in waveform reproducibility and transmission band compared to analog delay elements. The digital vertical delay element 10 transmits the video signal for one horizontal scanning period (referred to as 1H).
It is an element that delays in units of 1H, and the delay time is usually 1H, but it may be 2H or an integral multiple of 1H.

The vertically nonlinearly emphasized video signal is then input to a horizontally nonlinear phase linear emphasis circuit 3, where the horizontal high frequency components are subjected to nonlinear emphasis. The horizontal nonlinear phase line emphasis is configured as shown in FIG. 3, and the video signal input from the input terminal 18 is first input to the phase line high pass filter 19. The phase linear high-pass filter is configured as shown in FIG. 10, for example. In FIG. 10, 62 is an input terminal, 63, 64, 65, 66 are horizontal unit delay elements,
67, 68, 69, 70, and 71 are multipliers, 72 is an adder, and 73 is an output terminal. The video signal input from the input terminal 62 is delayed by unit delay elements 63 to 66, and then
The input signal and the output of each unit delay element are multiplied by an appropriate constant by multipliers 67 to 71, and added by an adder 72. The output of the adder is then output from the output terminal 73 as the output of the phase linear high-pass filter.

The separated horizontal high-frequency components are amplified by an appropriate amount in the amplifier circuit 20, amplitude limited in the nonlinear processing circuit 21, added to the input signal in the adder 74, and outputted from the output terminal 22. . As explained in the conventional example, the nonlinear processing circuit 21 is a circuit having limiter characteristics as shown in FIG.

In this way, the vertically nonlinearly emphasized and horizontally nonlinearly emphasized signals are transmitted along the transmission line 4 with various noises and distortions.

The transmitted signal is first input to the horizontal nonlinear phase linear de-emphasis circuit 5, where the horizontal high-frequency components are de-emphasized and at the same time the horizontal high-frequency components of the noise are reduced. The configuration of horizontal nonlinear phase straight line de-emphasis is shown in FIG. 3 as in the case of emphasis. However, the transfer function of the filter on the emphasis side is H
e(ω) (ω is the angular frequency), the amplification factor of the amplifier circuit 20 is A
e, the transfer function Hd on the de-emphasis side (
ω)=He(ω)/(1+Ae·He(ω)), and the amplification factor Ad=−Ae.

The video signal subjected to the horizontal nonlinear phase linear deemphasis is input to the digital vertical nonlinear deemphasis circuit 6, where the vertical high frequency component is deemphasized and at the same time, the vertical high frequency component of the noise is reduced. The configuration of the digital vertical nonlinear de-emphasis circuit 61 is shown in FIG. 2 similarly to the digital vertical non-linear emphasis circuit 2. However, during emphasis, when the amplification factor of the amplifier circuit 12 is Ve and the amplification factor of the amplifier circuit 14 is 0, on the de-emphasis side, the amplification factor of both the amplifier circuits 12 and 14 must be set to Vd=-Ve/(1+Ve). It won't happen. The operation is the same as for emphasis, so it will be omitted.

In this manner, a de-emphasized signal with reduced noise and distortion components added during transmission is output to the output terminal 7.

Furthermore, if the image sampling frequency is not high enough, aliasing interference from diagonal sampling carriers may occur because the nonlinear processing circuit in the vertical nonlinear emphasis (de-emphasis) section is a digital process. Conceivable. However, on the emphasis side, vertical nonlinear processing is performed before emphasizing the high-frequency diagonal components of the image using horizontal emphasis.
Furthermore, on the de-emphasis side, since vertical non-linear processing is performed after horizontal de-emphasis, the diagonal components of the image subjected to vertical non-linear emphasis (de-emphasis) do not have a very large amplitude. For this reason, aliasing interference of oblique components in the vertical nonlinear processing section does not pose a problem.

In order to further improve waveform reproduction, horizontal nonlinear emphasis (de-emphasis) processing may also be digitally processed.

As described above, the nonlinear signal processing circuit according to the embodiment of the present invention achieves good waveform reproducibility and the effect of reducing edge noise by digitizing the vertical processing and linearizing the phase of the horizontal processing.

[0029]

Effects of the Invention As is clear from the above embodiment, according to the present invention, the vertical nonlinear emphasis, which was conventionally processed by analog processing, is digitized, and the horizontal nonlinear emphasis, which was phase nonlinear, is now converted to a phase linear On the emphasis side, emphasis and de-emphasis are applied in vertical and horizontal order, and on the de-emphasis side, in horizontal and vertical order, respectively, resulting in good waveform reproducibility and reduction of noise at the edge of the image. It is possible to provide a nonlinear signal processing device that is effective.

[Brief explanation of the drawing]

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

FIG. 2 is a block diagram of a digital vertical nonlinear emphasis circuit.

FIG. 3 is a block diagram of horizontal nonlinear phase linear emphasis.

FIG. 4 is a block diagram showing a conventional example.

FIG. 5 is a block diagram showing a conventional vertical nonlinear emphasis system.

FIG. 6 is a block diagram showing a conventional horizontal nonlinear emphasis system.

FIG. 7 is a block diagram showing conventional horizontal nonlinear de-emphasis.

FIG. 8 is a diagram showing input/output characteristics of a nonlinear signal processing circuit.

FIG. 9 is a circuit diagram of a phase nonlinear high-pass filter.

FIG. 10 is a block diagram of a phase linear high-pass filter.

[Explanation of symbols]

1, 8, 18, 23, 30, 40, 46, 58, 62
Input terminals 7, 17, 22, 29, 39, 45, 51, 61, 73
Output terminals 9, 16, 74, 31, 38, 44, 72 Adder 1
1, 33, 47 subtractor

Claims (4)

[Claims] Claim 1: After applying non-linear processing to the vertical high frequency components of the input video signal using digital signal processing such that the amplitude amplification factor is larger as the amplitude signal becomes smaller, the horizontal high frequency components are A nonlinear signal processing device characterized by performing nonlinear processing such that the amplitude of the signal is increased by a larger amplification factor. 2. The nonlinear signal processing device according to claim 1, wherein the nonlinear processing for the horizontal high range is phase linear processing. 3. After applying non-linear processing to the horizontal high frequency range of the input video signal to attenuate the amplitude to a greater extent as the smaller the amplitude signal is, digital signal processing is applied to the vertical high frequency component to reduce the amplitude for the smaller amplitude signal. A nonlinear signal processing device characterized by performing nonlinear processing that greatly attenuates the signal. 4. The nonlinear signal processing device according to claim 3, wherein the nonlinear processing for the horizontal high range is phase linear processing.