JPH11308484A - Signal processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a signal processor capable of suppressing the excessive overshoot of video signals and the degradation of images and performing effective enhancement. SOLUTION: This signal processor is provided with a filter 3 for passing through the specified frequency band of input signals, a level detection means 5 for detecting the amplitude level of the output signals of the filter 3, a level control means 6 for controlling the amplitude level of the output signals of the filter 3 corresponding to the detected amplitude level and an addition means 4 for adding the output signals of the level control means 6 and the input signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal processing device for enhancing the outline of a video signal and enhancing an image.

[0002]

2. Description of the Related Art A conventional signal processing apparatus for enhancing the contour of a video signal and enhancing an image is disclosed in, for example, Japanese Patent Application Laid-Open No.
There is an outline correction circuit disclosed in JP-150971A. As shown in FIG. 7, the contour correction circuit extracts a specific frequency component of a video signal input from an input terminal 1 by a filter 3 and adds the specific frequency component to an adder 4.
By adding to the input signal, the amplitude of a signal in a specific frequency band is increased, thereby obtaining a clear image in which contour enhancement or a specific band is enhanced.

[0003]

However, in the conventional signal processing apparatus described above, if the amplitude of the input video signal is large, the overshoot of the contour emphasis effect becomes too large, and the contour of the white portion appears to shine. There was a problem. Further, if the overshoot is too large, there is a problem that image deterioration occurs in which the focus becomes poor in a direct viewing tube. Furthermore, if the input video signal S / N is poor, noise is also emphasized, and thus noise in the white direction in particular causes image quality degradation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide a signal processing apparatus capable of performing effective enhancement without excessively increasing overshoot. And

[0005]

According to the present invention, there is provided a signal processing apparatus comprising: a filter for passing an input signal through a specific frequency band; a level detecting means for detecting an amplitude level of an output signal of the filter; Level control means for controlling the amplitude level of the output signal of the filter according to the amplitude level, and addition means for adding the output signal of the level control means and the input signal.

Further, the apparatus is provided with coring means for removing an amplitude component of the output signal of the filter which is equal to or smaller than a threshold value.

Also, a plurality of filters that allow input signals to pass through different frequency bands, first adding means for adding output signals of these filters, and an amplitude of an output signal of the first adding means equal to or smaller than a threshold value Coring means for removing components, level detecting means for detecting the amplitude level of the output signal of the coring means, and level for controlling the amplitude level of the output signal of the coring means according to the detected amplitude level Control means; and second adding means for adding the output signal of the level control means and the input signal.

Also, a plurality of filters that allow input signals to pass through different frequency bands, amplitude level comparing means for comparing the amplitude levels of output signals of these filters, and outputting a signal having the largest amplitude level, Coring means for removing an amplitude component equal to or smaller than a threshold value of an output signal of the value comparing means; level detecting means for detecting an amplitude level of an output signal of the coring means; and coring means according to the detected amplitude level. And level control means for controlling the amplitude level of the output signal, and addition means for adding the output signal of the level control means and the input signal.

In addition, the apparatus has a plurality of multiplying means for multiplying the amplitudes of the output signals of the plurality of filters by constants of arbitrary magnitudes.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be specifically described with reference to the drawings showing the embodiments. Embodiment 1 FIG. FIG. 1 is a block diagram showing a signal processing apparatus according to Embodiment 1 of the present invention. In the figure, 1 is an input terminal of a video signal, 2 is an output terminal, 3 is a filter,
Is an adder, 5 is a level detector, and 6 is a level controller.

Next, the operation will be described. The video signal input from the input terminal 1 is input to the filter 3, and a signal in a specific frequency band passes. The frequency band of the filter 3 is set to a frequency band in which an enhancement effect can be expected by increasing the amplitude of the video signal. Filter 3
Is input to the level detector 5 and the level controller 6. The level detector 5 detects the amplitude level of the input signal, and the detected amplitude level is input to the level controller 6. The level controller 6 controls the amplitude of the signal input from the filter 3 according to the input amplitude level to an optimum amplitude for enhancement and outputs the signal to the adder 4. The adder 4 adds the signal input from the level controller 6 and the video signal input from the input terminal 1 and outputs the result to the output terminal 2. As a result, a video signal in which only a specific frequency band is amplified to an optimum amplitude is obtained.

FIG. 2 is a block diagram showing a detailed configuration of the level detector 5 and the level controller 6 according to the first embodiment. The level detector 5 includes an amplitude value detector 5a and an amplitude direction detector 5b.
It is composed of The level detector 5 outputs two detection values detected by the amplitude value detector 5a and the amplitude direction detector 5b from the signal f (t) input from the filter 3. The first detection value | a | is the absolute value (= | f (t) |) of the amplitude of the input signal that is the AC wave detected by the amplitude value detector 5a, and the second detection value b is the amplitude. This is binary data (f (t)> 0 or f (t) <0) indicating whether the direction of the amplitude of the input signal detected by the direction detector 5b is convex in the positive direction or convex in the negative direction.
Two detection values obtained by the level detector 5 |
a |, b are output to the level controller 6.

The level controller 6 adaptively changes the amplitude of the signal f (t) input from the filter 3 using the two input detection values | a |, b under the following condition. if b = − | f (t) | = α (| a |) × | a | if b = + | f (t) | = β (| a |) × | a | where α (| a |) , Β (| a |) is a function of | a |. That is, when the amplitude direction b is convex in the negative direction, for example, when the video signal is a luminance signal, it is convex in the black signal direction, so the amplitude is increased. However, the deterioration of the image is not noticeable, and the outline can be emphasized. Therefore, there is little need to limit the amplitude according to the magnitude of the amplitude value | a |, and α (| a |), which is a function of the amplitude value | a |, may be a substantially constant value or a constant.

Conversely, when the amplitude direction b is convex in the positive direction, a large amplitude value | a | in the white signal direction may overshoot, deteriorate the focus, or emphasize noise. There is a possibility that the image quality may be degraded. Therefore, the function β (| a |) is adaptively changed with respect to the magnitude of the amplitude value | a |. For example, the larger the amplitude value | a |, the smaller the function β (| a |) becomes. Thus, adaptive processing is performed to limit the magnitude of the small amplitude as it is and the magnitude of the large amplitude.

As described above, the first embodiment
Extracts only a specific frequency band of the input video signal by a filter, detects the amplitude value of the output signal of this filter and the direction of the unevenness of the amplitude by a level detecting means, and detects the amplitude value which is convex in the positive direction. If the value is large, the overshoot in the white direction increases or the image quality deteriorates due to noise, so the level control means adaptively reduces the amplitude according to the magnitude of the amplitude value and adds the amplitude to the input signal, On the other hand, when the amplitude is convex in the negative direction, the image quality is less likely to be degraded even if the amplitude value is large, so that the amplitude is not limited and the input signal is added to the input signal. If the output signal overshoots in the white direction,
Effective enhancement can be performed without deteriorating image quality due to noise.

Embodiment 2 FIG. 3 is a block diagram showing a signal processing device according to a second embodiment of the present invention, and the same reference numerals as those in FIG. 1 denote the same or corresponding parts. In the figure, reference numeral 7 denotes coring means.

Next, the operation will be described. Coring means 7
Has a threshold value determined as a value for removing a noise component of the input signal, and removes an amplitude level below the threshold value from the signal input from the filter 3 and outputs the signal to the level detector 5 and the level controller 6.

According to the second embodiment, the noise component contained in the input signal is removed, and the signal whose amplitude has been adaptively processed by the level controller 6 is added to the input signal by the adder 4. It is possible to prevent a noise component from being added to the input signal and amplified as in the conventional example.

Embodiment 3 FIG. 4 is a block diagram showing a signal processing apparatus according to Embodiment 3 of the present invention, and the same reference numerals as those in FIG. 3 denote the same or corresponding parts. In the figure, reference numeral 8 denotes a filter group having a plurality of filters 8a to 8x, and 41 denotes an adder for adding output signals of the filters 8a to 8x.

Next, the operation will be described. Multiple filters 8
a to 8x are horizontal filters, vertical filters, or two-dimensional filters, each configured to extract a specific frequency band and not to extract signals in overlapping frequency bands. The output signals of the respective frequency components extracted by the filters 8a to 8x are added by the adder 41 and output to the coring means 7. Hereinafter, similarly to the second embodiment, the coring means 7, the level detector 5,
The signal is converted into a signal having an optimum amplitude from which the noise component has been removed by the level controller 6, and is added to the input signal by the adder 4.

According to the third embodiment, more flexible filtering becomes possible, and an arbitrary frequency band can be emphasized individually.

Embodiment 4 FIG. 5 is a block diagram showing a signal processing apparatus according to a fourth embodiment of the present invention. The same reference numerals as those in FIG. 3 denote the same or corresponding parts. In the figure, reference numeral 9 denotes a filter group having a plurality of filters 9a to 9x, and 10 denotes an amplitude value comparing means.

Next, the operation will be described. Multiple filters 9
a to 9x are a horizontal filter, a vertical filter, or a two-dimensional filter, each of which is a specific frequency band so as to extract a signal whose frequency band may overlap with a filter of an adjacent frequency band. It is configured. Output signals of each frequency component extracted by these filters 9a to 9x are input to the amplitude value comparing means 10. The amplitude value comparing means 10 compares the amplitudes of the input signals,
The signal having the largest amplitude is output to the coring means 7.
Thereafter, the signal is changed to a signal having an optimum amplitude from which noise components have been removed by the coring means 7, the level detector 5, and the level controller 6, and is added to the input signal by the adder 4. According to the fourth embodiment, enhancement can be performed with a more optimal amplitude regardless of whether the frequency bands of the plurality of filters 9a to 9x overlap.

Embodiment 5 FIG. 6 is a block diagram showing a signal processing apparatus according to a fifth embodiment of the present invention. The same reference numerals as those in FIG. 5 denote the same or corresponding parts. In the figure, reference numeral 11 denotes a multiplier group having multipliers 11a to 11x.

Next, the operation will be described. Multiple multipliers 11
a to 11x multiply the output signals of the filters 9a to 9x by arbitrary constants a to x to change the magnitude of the amplitude and output the result to the amplitude value comparing means 10. Thereafter, the signal is changed to a signal having an optimum amplitude from which noise components have been removed by the coring means 7, the level detector 5, and the level controller 6, and is added to the input signal by the adder 4.

According to the fifth embodiment, the multiplier 11a
By changing the constants a through x of each filter 9a
The weights of 重 み 9x can be changed, so that each frequency band can be emphasized more flexibly.

In the third embodiment shown in FIG. 4, the same effect can be obtained by adding the multipliers 11a to 11x shown in FIG. 6 between the filters 8a to 8x and the adder 41. be able to.

[0028]

Since the present invention is configured as described above, it has the following effects.

Since the amplitude of a specific frequency band is controlled in accordance with the magnitude and direction of the amplitude, it is possible to prevent the output signal from overshooting in the white direction or being accompanied by deterioration due to noise. Enhancements can be made.

Further, a plurality of filters are provided to pass different frequency bands of the input signal, and an output signal of these filters is added to remove an amplitude component below a threshold value of the signal, and the amplitude of the signal is determined by the magnitude of the amplitude. Since the control is performed in accordance with the direction and the direction, filtering with more flexibility is possible, and it is possible to individually emphasize an arbitrary frequency band, and to perform effective enhancement.

Further, a plurality of filters are provided to pass different frequency bands of the input signal, a signal having the largest amplitude level is selected from the output signals of these filters, and an amplitude component below a threshold value is removed. Since the amplitude is controlled in accordance with the magnitude and direction of the amplitude, the enhancement can be performed with the optimum amplitude without amplifying only the amplitude of the overlapping band.

[Brief description of the drawings]

FIG. 1 is a block diagram of a signal processing device according to a first embodiment of the present invention.

FIG. 2 is a detailed diagram of a level detector and a level controller according to the first embodiment.

FIG. 3 is a block diagram of a signal processing device according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a signal processing device according to a third embodiment of the present invention.

FIG. 5 is a block diagram of a signal processing device according to a fourth embodiment of the present invention.

FIG. 6 is a block diagram of a signal processing device according to a fifth embodiment of the present invention.

FIG. 7 is a block diagram of a conventional signal processing device.

[Explanation of symbols]

3,8a-8x, 9a-9x filter, 4,41 adder, 5 level detector, 5a amplitude value detector, 5b
Amplitude direction detector, 6 level controller, 7 coring means, 10 amplitude value comparing means, 11a to 11x multiplier.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Noriyuki Yamaguchi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation

Claims (5)

[Claims] 1. A filter for passing a specific frequency band of an input signal, a level detecting means for detecting an amplitude level of an output signal of the filter, and an amplitude of an output signal of the filter according to the detected amplitude level A signal processing device comprising: level control means for controlling a level; and addition means for adding an output signal of the level control means and the input signal. 2. The signal processing apparatus according to claim 1, further comprising coring means for removing an amplitude component of the output signal of the filter that is equal to or smaller than a threshold value. 3. A plurality of filters that allow input signals to pass through different frequency bands, first adding means for adding output signals of these filters, and an amplitude of an output signal of the first adding means equal to or smaller than a threshold value. Coring means for removing components; level detecting means for detecting an amplitude level of an output signal of the coring means; and a level for controlling an amplitude level of an output signal of the coring means in accordance with the detected amplitude level. A signal processing apparatus comprising: a control unit; and a second adding unit that adds an output signal of the level control unit and the input signal. 4. A plurality of filters for passing different frequency bands of an input signal, amplitude value comparing means for comparing the amplitude levels of output signals of these filters, and outputting a signal having the largest amplitude level; Coring means for removing an amplitude component equal to or less than a threshold value of an output signal of the value comparing means; level detecting means for detecting an amplitude level of an output signal of the coring means; and coring means according to the detected amplitude level. A signal processing device comprising: level control means for controlling the amplitude level of the output signal of the above; and addition means for adding the output signal of the level control means and the input signal. 5. The signal processing apparatus according to claim 4, further comprising a plurality of multiplying means for multiplying the amplitudes of the output signals of the plurality of filters by constants having arbitrary magnitudes.