JPH03235487A - Low frequency displacement device - Google Patents

Abstract

PURPOSE:To obtain a satisfactory picture quality by detecting a noise quantity in the low frequency of a multiplex sub-sample transmission signal in a noise detection means and changing a displacement rate between a decoding signal and respective low frequencies of the multiplex sub-sample transmission signal in accordance with the noise quantity in a displacement variable means. CONSTITUTION:The noise detection part 7 generates a control signal as against a variable coefficient unit 4. The inputted multiplex sub-sample transmission signal is given to the noise detection part 7 and it detects the noise quantity of the transmission signal. It outputs a smaller coefficient as the noise quantity increases much more, and outputs the larger coefficient as the noise quantity decreases. Namely, the rate of displacement by the inputted multiplex sub-sample transmission signal is reduced and the rate of a decoding signal is improved as the noise quantity increases much more. Since the rate of displacement is deteriorated when the quantity of noise components is much, the picture quality based on a low frequency displacement signal can be maintained in a satisfactory state even if the noise components of the low frequency is included in the transmission signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a low-frequency replacement circuit, and is particularly applicable to a reproducing device (decoder) for multiple subsampled transmission signals.

[Prior Art] As one of the methods for band-compressing and transmitting a television signal, there is a multiplex sub-sampling transmission method using offset I sampling between frames and between fields. This multiplex subsample transmission method is also used as a transmission method for high-definition television signals, and the method for high-definition television signals proposed by the Japan Broadcasting Corporation is MtJS.
It is called the E method.

Therefore, the playback device of transmission No. 18 according to the MUSE method, that is, the MUSE decoder, performs decoding processing such as interframe interpolation processing, interfield interpolation processing, intrafield interpolation processing, noise reduction processing, etc. as appropriate to produce high-definition television. Play the signal.

By the way, the transmission signal according to the MUSE method has a low frequency range (0
~4MHz) does not include aliasing components between frames, so there is no problem even if the low frequency range of the signal obtained by such decoding processing (hereinafter referred to as the decoded signal) is replaced with the low frequency range of the input transmission signal. This does not occur; rather, by replacing it, an increase in vertical resolution and an improvement in dynamic resolution can be expected, and replacing the low frequency range has already been proposed (Japanese Patent Laid-Open No. 172875/1983).

[Problems to be Solved by the Invention] When an input transmission signal is compared with a decoded signal, the transmission signal has more noise components than the decoded signal because it has not been subjected to decoding processing (including noise reduction processing).

As described above, various effects can be obtained by low frequency replacement, but if the input transmission signal is replaced with an input transmission signal containing many noise components, the image quality of the reproduced image may be degraded on the contrary. Since the low-frequency noise component becomes a wide noise on the displayed image, it is easily noticeable and tends to cause the above-mentioned image quality deterioration.

The present invention has been made in consideration of the above points, and it is an object of the present invention to provide a low-frequency replacement circuit that can obtain good image quality even if the input transmission signal contains low-frequency noise components. It is something.

[Means for solving the problem] In order to solve the problem, in the first invention,
Low-frequency replacement that replaces the low frequency range of a decoded signal obtained by decoding a multiplex subsampled transmission signal that does not include aliasing components between frames in the low frequency range with the low frequency range of a multiplexed subsampled transmission signal that has not been decoded. In the circuit, noise detection means detects the amount of noise in at least a low frequency range of the multiplex subsampled transmission signal, and replaces the low frequency range of the decoded signal with the low frequency range of the multiplexed subsampled transmission signal according to the detected amount of noise. A replacement variable means for varying the ratio is provided.

In the second aspect of the invention, the low frequency of a decoded signal obtained by decoding a multiplexed subsampled transmission signal that does not include inter-frame aliasing components in the low frequency range is replaced by a multiplexed subsampled signal that has not been decoded. In the low frequency replacement circuit that replaces the low frequency range of the transmission signal, a noise reduction means is provided which performs coring processing to reduce noise components by compressing the small level portion of the low frequency range of the multiple subsampled transmission signal to be replaced.

A third aspect of the present invention is that the noise reduction means in the second aspect of the present invention varies the amount of compression depending on the amount of noise detected by the newly provided noise detection means.

The fourth invention includes a component according to the first invention and a second invention.
Both components according to the present invention are provided.

A fifth aspect of the present invention is that the noise reduction means in the fourth aspect of the present invention varies the amount of compression depending on the amount of noise detected by the noise detection means.

[Operation] If many noise components are mixed in the low frequency range of the multiplex sub-sampled transmission signal which is the signal to be replaced, the image quality deterioration due to the replacement will be more severe.

In that case, the replacement should be done to the extent that image quality does not deteriorate due to the replacement. At this time, if the effect of the replacement is also expected, it is preferable to replace it largely when there are few noise components, and to replace it slightly when there are many noise components. Therefore, in the first aspect of the present invention, the noise detection means detects the amount of noise in at least the low frequency range of the multiplex sub-sampled transmission signal, and the variable replacement means detects the amount of noise in the low frequency range of the decoded signal according to the detected amount of noise. We decided to vary the replacement ratio of the multiple sub-sampled transmission signal with the low frequency band.

Since it is required to suppress image quality deterioration due to the mixing of many noise components, in order to satisfy this requirement, it is sufficient to reduce the noise components. Therefore, in the second aspect of the present invention, a noise reduction means is provided to reduce the noise component by compressing the low-frequency, low-level portion of the multiplex sub-sampled transmission signal to be replaced.

If compression processing is performed when there are few noise components, there is a risk of degrading the original signal portion, so it is preferable that the noise reduction processing is also controlled according to the amount of noise. The third aspect of the present invention combines the configuration of the second aspect of the present invention with variable control based on the amount of noise.

The basic inventions for suppressing image quality deterioration due to the mixing of many noise components are the above-mentioned first and second inventions.
As for the (third) invention, further effects can be expected by effectively combining these. The fourth and fifth inventions are combination inventions of these inventions.

[Examples] Hereinafter, first to fifth embodiments of the present invention will be sequentially described in detail with reference to the drawings.

Nail top practice First, a first embodiment will be described using FIG.

In FIG. 1, an input multiple sub-sampled transmission signal is given to a decoding processing section 1. The decoding processing unit 1 performs decoding processing such as interframe interpolation processing, interfield interpolation processing, intrafield interpolation processing, and noise reduction processing (for details, see Ninomiya et al. John Society Journal, Vo
l, 42. No.

5 (1988) Ike).

This decoded signal is given to the low frequency replacement section 2. The input multiplex sub-sampled transmission signal is supplied to the low-pass replacement unit 2 as a signal to be replaced. In the low-pass replacement unit 2, a subtracter 3 obtains a difference signal between the multiplex sub-sampled transmission signal and the decoded signal, this difference signal is multiplied by a coefficient via a variable coefficient unit 4, and then a low-pass filter unit 5 Only the frequency band components (for example, 0 to 4 MHz) are converted into P-waves, and finally, the adder 6 adds the P-wave signal and the decoded signal to replace the low frequency components.

The following describes in detail how replacement is performed through such arithmetic processing. Taking into account that it passes through the low-pass filter section 5, and considering the low frequency range of the multiplex sub-sampled transmission signal,
The low frequency signal passes through a subtracter 3, is multiplied by a coefficient in a coefficient multiplier 4, and is added to the decoded signal in an adder 6. On the other hand, considering the low-frequency range of the decoded signal considering that it passes through the low-pass filter section 5, the low-frequency range passes through the subtracter 3, has its polarity inverted, is multiplied by a coefficient in the coefficient unit 4, and is outputted in the adder 6. Since it will be added to the decoded signal and the polarity is reversed, such an addition effectively means a subtraction.

That is, the low frequency range of the multiple sub-sampled transmission signal is multiplied by a coefficient and added to the decoded signal, and the low frequency range of the decoded signal is multiplied by a coefficient and subtracted from the decoded signal, so that it is replaced by a predetermined ratio (coefficient). It turns out.

In the case of this first embodiment, a control signal for the variable coefficient unit 4 is generated by the noise detection section 7. The noise detection unit 7 is supplied with the input multiple sub-sampled transmission signal, and detects the amount of noise in this transmission signal. The larger the noise amount, the smaller the coefficient is output, and the smaller the noise amount, the larger the output coefficient. In other words, the larger the amount of noise, the smaller the ratio of replacement with the input multiple subsampled transmission signal to increase the ratio of the decoded signal, and the smaller the amount of noise, the smaller the ratio of replacement with the input multiple subsampled transmission signal. Increase the replacement ratio and lower the decoded signal ratio.

The reason for controlling the replacement ratio according to the amount of noise in this way is to improve the image quality by improving the vertical resolution and motion resolution by replacing it, and to reduce the image quality by making the noise part more conspicuous by replacing it. This is because the objective was to achieve the best image quality.

Therefore, according to the first embodiment described above, the replacement ratio is reduced when the amount of noise components is large, so even if the transmission signal contains low-frequency noise components, the low-frequency replacement signal It is possible to maintain good image quality based on

Incidentally, it is conceivable to selectively control whether or not to perform low frequency replacement depending on the noise base, but in reality, the amount of noise changes in an analog manner, so this is not sufficient to improve image quality. be.

star lambda side Next, a second embodiment will be described using FIG. 2.

In FIG. 2, the input multiple sub-sampled transmission signal is given to a decoding processing section 11. Decode processing section]
-1 performs decoding processing such as interframe interpolation processing, interfield interpolation processing, intrafield interpolation processing, noise edge reduction processing, etc., and provides a decoded signal to the low frequency replacement section 12.

An input multiplex sub-sampled transmission signal is provided to the low-pass replacement section 12 . In the low frequency substitution section 12, a subtracter 13 obtains a difference signal between the multiplex sub-sampled transmission signal and the decoded signal, and this difference signal is passed through a coring processing section 14 to compress only the low-level portion. Only the low-frequency components are passed through by the low-pass filter section 15, and finally, the filtered signal and the decoded signal are added by the adder 16 to replace the low-frequency components.

Here, the reason why the coring processing section 14 is provided is to reduce noise by compressing the low level part, and even if there is a lot of noise in the input multiple sub-sampled transmission signal, it is replaced by low-frequency conversion. This is because an attempt was made to reduce noise in the signal and prevent deterioration in image quality due to noise while maintaining the effects of vertical resolution and dynamic resolution improvement through replacement.

In this way, the second embodiment can also improve the image quality compared to the prior art.

Next, a third embodiment will be explained using FIG. 3. When this third embodiment is compared with the second embodiment, the difference is that the coring processing amount (noise reduction amount) is varied depending on the amount of noise included in the input multiple sub-sampled transmission signal.

In FIG. 3, the input multiplex sub-sampled transmission signal is applied to a decoding processing section 21, where it is subjected to decoding processing, and the decoded signal is applied to a low frequency replacement section 22.

An input multiplex sub-sampled transmission signal is provided to the low-frequency replacement section 22. In the low frequency substitution section 22, a subtracter 23 obtains a difference signal between the multiplex sub-sampled transmission signal and the decoded signal, and this difference signal is sent to the variable coring processing section 24.
Only a small part of the level is compressed via
The low-pass filter section 25 converts only the low-frequency components into p-waves, and finally, the adder 26 adds the r-wave signal and the decoded signal to replace the low-frequency components.

In the case of this third embodiment, the noise detection section 27 generates the control signal for the variable coring processing section 24. This noise detection section 27 detects the amount of noise in the input multiple sub-sampled transmission signal. A control signal is output such that the larger the amount of noise is, the larger the coring process is performed, and the smaller the amount of noise is, the smaller the coring process is performed.

The reason for controlling the amount of coring processing according to the amount of noise in this way is that when the amount of noise is small, if a large amount of coring processing is performed, the reduction of components other than noise components will also be large, and the image quality will be improved by replacement. This is because the effect may be reduced.

In this way, this third embodiment also makes it possible to improve the image quality compared to the prior art.

Next, a fourth embodiment will be described using FIG. 4. This fourth embodiment differs from the first embodiment in that a coring processing section is inserted between the variable coefficient multiplier and the low-pass filter section.

In FIG. 4, the input multiplex sub-sampled transmission signal is decoded by a decode processing section 31 and then given to a low frequency replacement section 32.

In the low-frequency substitution section 32, a subtracter 33 obtains a difference signal between the multiplex sub-sampled transmission signal and the decoded signal.

The variable coefficient multiplier 34 multiplies this difference signal by a coefficient corresponding to the noise detection signal from the noise detection section 35. After that, the coring processing section 36 performs coring processing, the low-pass filter section 37 passes only the low frequency components, and the adder 3
8 adds the filtered signal and the decoded signal, thereby replacing the low frequency.

In this embodiment, the variable coefficient unit 34 whose coefficients are controlled depending on the amount of noise is provided for the same reason as in the first example, and the coring processing section 36 is provided for the same reason as in the first example. This is due to the same reason as in the second embodiment.

In this way, the fourth embodiment can also improve the image quality compared to the prior art.

Next, a fifth embodiment will be described using FIG. 5. The fifth embodiment differs from the fourth embodiment only in that the coring process is also varied depending on the amount of noise. The reason why the coring process is varied depending on the amount of noise is the same as in the third embodiment.

In FIG. 5, the input multiplex sub-sampled transmission signal is decoded by a decoding processing section 41 and then given to a low frequency replacement section 42. In FIG.

In this low-frequency substitution section 42, a subtracter 43 obtains a difference signal between the multiplex sub-sampled transmission signal and the decoded signal.

The variable coefficient multiplier 44 multiplies this difference signal by a coefficient corresponding to the noise detection signal from the noise detection section 45. Thereafter, the coring processing unit 46 performs coring processing according to the noise detection signal from the noise detection unit 45, the low-pass filter unit 47 passes only low-frequency components, and the adder 48
The wave signal and the decoded signal are added and the low frequency is replaced by this.

This fifth embodiment also makes it possible to improve the image quality compared to the prior art.

(1) In the above embodiment, the amount of noise in the input multiple sub-sampled transmission signal was detected, but at least the amount of noise in the low range, which is the frequency component to be replaced, is detected. Also good. Further, the noise detection section may be provided as an independent component, or may utilize an already existing component. For example, a circuit that performs noise reduction processing may be used.

(2) The present invention can be widely applied not only to MUSE decoders but also to devices for reproducing multiple subsampled transmission signals.

(3) The position of the low-pass filter section is not limited to the stage after the coefficient unit and the coring processing section, but may be provided at the stage before the coefficient unit and the coring processing section.

[Effects of the Invention] As described above, according to the present invention, the coefficient that defines the replacement ratio is varied according to the amount of noise, and/or coring processing is performed to reduce the noise of the low-frequency component to be replaced. Therefore, even if the input transmission signal contains low-frequency noise components, the effect of low-frequency replacement can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of a low frequency replacement circuit according to the present invention, FIG. 2 is a block diagram of a second embodiment of the present invention, and FIG. 3 is a block diagram of a third embodiment of the present invention. , FIG. 4 is a block diagram of a fourth embodiment of the present invention, and FIG. 5 is a block diagram of a fifth embodiment of the present invention. 1.11...Decode processing section, 2.12...Low frequency replacement section, 3.13...Subtractor, 4...Variable coefficient unit, 5
．． 15...Low pass filter unit, 6.16...Adder, 7...Noise detection unit, 14...Coring processing unit.

Claims (5)

[Claims] (1) The low frequency range of the decoded signal obtained by decoding a multiplex subsampled transmission signal that does not include aliasing components between frames in the low frequency range is converted into the low frequency range of the multiplexed subsampled transmission signal that has not been decoded. In the replacement low frequency replacement circuit, noise detection means detects the amount of noise in at least the low frequency range of the multiplex subsample transmission signal; 1. A low-frequency replacement circuit characterized by comprising: replacement variable means for varying the replacement ratio of a signal with a low-frequency range. (2) The low frequency range of the decoded signal obtained by decoding a multiplex subsampled transmission signal that does not include aliasing components between frames in the low frequency range is converted into the low frequency range of the multiplexed subsampled transmission signal that has not been decoded. A low-frequency replacement circuit characterized in that a low-frequency replacement circuit is provided with a noise reduction means for performing a coring process for compressing a low-frequency low-level part of the multiplex subsampled transmission signal to be replaced and reducing noise components. circuit. (3) A claim characterized in that noise detection means is provided for detecting the amount of noise in at least a low frequency range of the multiple sub-sampled transmission signal, and the noise reduction means varies the amount of compression according to the detected amount of noise. The low frequency replacement circuit according to item 2. (4) A noise reduction means is provided which performs a coring process to reduce noise components by compressing a low-frequency, low-level portion of the multiplex sub-sampled transmission signal to be replaced. low frequency replacement circuit. (5) The low frequency replacement circuit according to claim 4, wherein the noise reduction means varies the amount of compression depending on the amount of noise detected by the noise detection means.