JP2830587B2 - Video signal processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing device for correcting a contour portion of a video signal in a color television receiver.

[0002]

2. Description of the Related Art Conventionally, in a transmission system of a color television signal, the sharpness of an image reproduced by a receiver is reduced due to a limited transmission band. For example,
In the NTSC system, the band of the luminance signal is 0 to 4.2M.
Hz. For this reason, even when an image is taken with an ideal image pickup tube, the signal at the time of the change in the luminance signal between black and white is not sharp at a receiver at a certain rising or falling slope, and the contour portion on the screen is not sharp. Somewhat blurry. In recent years, in order to improve such blurring of an image, in a video signal processing apparatus, contour correction has been performed by creating a secondary differential signal using a delay line and adding the signal to an original signal.

[0003] A conventional video signal processing apparatus will be described below. FIG. 6 shows a configuration diagram of a conventional video signal processing device. In FIG. 6, 1 is an input terminal of a video signal,
Reference numerals 11 and 12 denote delay lines for delaying a predetermined time, reference numerals 13, 14, and 15 denote multipliers, reference numeral 16 denotes an adder, reference numeral 17 denotes a gain controller for changing a contour correction level, reference numeral 18 denotes an adder, and reference numeral 2 denotes an output terminal. FIG.
7 shows operation waveforms at points a to i shown in FIG.

[0004] The operation of the video signal processing device configured as described above will be described below with reference to FIGS. First, in FIG. 6, the video signal input from the input terminal 1 is supplied to the delay line 11 and the multiplier 13. The output signal of the delay line 11 is a delay line 12, a multiplier 14, and an adder 18.
Supplied to The output signal of the delay line 12 is supplied to the multiplier 15. For example, if a video signal having a waveform as shown in FIG. 7A is input to the input terminal 1 (point a), the waveforms of the signals at points b and c are shown in FIGS. 7B and 7C. become that way. The signals at points a, b, and c are given by multipliers 13, 14,
Supplied to 15. The coefficients of each multiplier are Ka = -1, Kb =
2, Kc = −1, at points d, e and f, FIG.
(D), the waveforms shown in FIGS. 7 (e) and 7 (f) are obtained.

[0005] These three signals are applied to an adder 16,
As a result, at point g, the original signal as shown in FIG.
The next differentiated signal waveform is obtained. The output signal of the adder 16 is adjusted in amplitude by an arbitrary gain by a gain controller 17 and is applied to the adder 18. For example, if the gain is １ ／, the signal waveform at the point h is as shown in FIG. The output of the gain controller 17 is applied to the adder 18 together with the output of the delay line 11, and at point i, a signal having the waveform shown in FIG. 7 (i) is obtained and output from the output terminal 2.
In the conventional video signal processing device configured as described above, a signal having a contour portion is obtained, and the contour is corrected.

[0006]

However, in the above-mentioned conventional configuration, there is a problem that the effect of contour correction is small in a gentle contour portion.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a video signal processing device capable of obtaining a sufficient contour correction effect even in a gentle contour portion.

[0008]

According to the first aspect of the present invention,
Inputting a plurality of image signal of the target pixel neighborhood of the input video signal signal
A maximum value detection circuit for detecting the maximum value of those amplitude values as a signal, and a plurality of image signals near the pixel of interest as input signals.
<br/> the minimum value detection circuit for detecting a minimum value of their amplitude values, the detection signal by detecting an average value from the output signal of the output signal and the minimum value detecting circuit of said maximum value detecting circuit as An arithmetic processing circuit for performing arithmetic processing for subtracting from the input video signal; an output signal of the arithmetic processing circuit and the input video signal;
And an adder for adding the signals .

According to a second aspect of the present invention, there is provided a maximum value detection circuit for detecting a plurality of image signals in the vicinity of a target pixel of an input video signal as input signals and detecting a maximum value of amplitude values thereof, and a plurality of image signals in the vicinity of the target pixel. a minimum value detection circuit for detecting a minimum value of these amplitude values an image signal as an input signal, an output signal of said maximum value detection circuit and the output signal of the minimum value detection circuit and
From the input video signal
An arithmetic processing circuit for performing arithmetic processing for subtracting the input signal from the arithmetic processing circuit; an adder for adding the output signal of the arithmetic processing circuit to the input video signal; and an output signal of the adder as an input signal.
Signal level is larger than the output signal of the maximum value detection circuit.
Not smaller than the output signal of the minimum value detection circuit.
And a non-linear processing circuit controlled so as not to decrease .

[0010]

According to the first aspect of the present invention, a sufficient contour correction effect can be obtained even with a gentle contour portion. According to the second aspect of the present invention, a sufficient contour correction effect can be obtained even with a gentle contour portion, and further, since undershoot and overshoot are not added, unnatural white and black portions are formed in the contour portion of the image. Contour correction can be performed without borders.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of a video signal processing device according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an input terminal of a video signal, 30a, 30b, 30
c and 30d are one pixel delay devices, 40 is a maximum value detection circuit, 50 is a minimum value detection circuit, 60 is an arithmetic processing circuit, 70 is a gain adjuster,
80 is an adder and 2 is an output terminal. Also, an arithmetic processing circuit
In 60, 61 is an average value circuit, and 62 is a subtractor. In the video signal processing device configured as described above, the video signal input from the input terminal 1
The output signal and the input video signal of each delay device are supplied to the maximum value detection circuit 40 and the minimum value detection circuit 50, respectively, after being delayed by a, 30b, 30c, and 30d. The output signal of the maximum value detection circuit 40, the output signal of the minimum value detection circuit 50, and the output signal of the one-pixel delay unit 30b are supplied to the arithmetic processing circuit 60.

The output signal of the maximum value detection circuit 40 and the output signal of the minimum value detection circuit 50 supplied to the arithmetic processing circuit 60 are
The average value is supplied to the average value circuit 61 and output. The output signal of the averaging circuit 61 is supplied to one input terminal of the subtractor 62, and the output signal of the one-pixel delay unit 30b is supplied to the other input terminal. The output signal of the subtractor 62 is a gain adjuster
Supplied to 70. The output signal of the gain adjuster 70 is
To one input terminal, and the other input terminal is supplied with the output signal of the one-pixel delay unit 30b. The added output of the adder 80 is output from the output terminal 2 as a video signal whose contour has been corrected.

The operation of each circuit of this embodiment will be described with reference to FIG. First, for example, if a video signal as shown in FIG. 2A is input to the input terminal 1, this video signal is successively delayed by one-pixel delay units 30a, 30b, 30c, 30d, and b, c, d , E at FIG. 2 (b),
The signals are as shown in (c), (d), and (e). a,
The maximum value of the video signal at points b, c, d, and e is detected by the maximum value detection circuit 40, and at point f, it becomes a signal as shown in FIG. Similarly, the minimum value of the video signal at points a, b, c, d, and e is detected by the minimum value detection circuit 50.
A signal as shown in FIG. The signals at the points f and g are supplied to the arithmetic processing circuit 60, and the average value is obtained by the average value circuit 61. At the point h, the signal is as shown in FIG. In the subtracter 62, the output signal of the one-pixel delay unit 30b (FIG. 2)
The signal at point h is subtracted from (i)), and at point j
A signal as shown in (j) is obtained. The amplitude of this output signal is adjusted by an arbitrary gain by a gain adjuster 70, and is added to the signal at the point i by an adder 80. For example, when the gain is set to 1 by the gain adjuster 70, a signal as shown in FIG. 2 (k) is obtained at a point k, which is output from the output terminal 2 as a video signal whose contour has been corrected.

FIG. 3 shows the outline correction method (FIG. 3 (A)) described in the conventional example and the outline correction method (FIG. 3 (B)) according to the first embodiment of the present invention. This is a comparison of the situation. FIG. 3 (A), FIG.
In (B), a correction signal (b) is added to an input video signal (a).
Are added to obtain a signal (c) whose contour has been corrected.
Here, both the gains of the correction system are 1. Focusing on the signal (c) whose contour has been corrected, and comparing the two,
In particular, in the central part of the contour, the contour correction effect of FIG. 3A does not appear at all as compared with FIG. On the other hand, FIG. 3B clearly shows a sufficient contour correction effect as compared with FIG.

As described above, according to the first embodiment of the present invention, the average value of the maximum value and the minimum value is detected from the image signal near the target pixel, and the detected signal is subtracted from the image signal of the target pixel. By using the corrected signal as a correction signal, a sufficient contour correction effect can be obtained even in a gentle contour portion.

FIG. 4 shows the configuration of a video signal processing device according to a second embodiment of the present invention. The configuration is basically the same as that of the first embodiment of the present invention shown in FIG. 1 except that the output signal of the adder 80 is used as an input and the maximum value detection circuit is used.
This is the addition of a non-linear processing circuit 90 that performs control using the output signal of 40 and the output signal of the minimum value detection circuit 50. The operation of the circuit will be described with reference to FIG. The detailed operation up to obtaining the output signal (FIG. 5 (k)) of the adder 80 at k points is the same as that described in the first embodiment of the present invention. Adder
The output signal of 80 is supplied to the non-linear processing circuit 90. Also,
The signals at the points f and g (FIG. 5 (f),
(G)) is supplied as a control signal. With these control signals, the nonlinear processing circuit 90 performs nonlinear control on the signal at point k. That is, the nonlinear processing circuit 90
Using the output signal of the adder 80 as the input signal, the level of that signal
Is larger than the output signal of the maximum value detection circuit 40?
The output signal of the minimum value detection circuit 50
Is controlled. For example, when the signal at the point k is larger than the signal at the point f, the signal at the point f is output. When the signal at the point g is smaller than the signal at the point g, the signal at the point g is output.
In other cases, assuming that a signal at point k is output, at point 1, a video signal whose contour is corrected as shown in FIG. 5 (l) is obtained and output from output terminal 2.

As described above, according to the second embodiment of the present invention, a sufficient contour correction effect can be obtained even with a gentle contour portion, and undershoot and overshoot are not added, and the contour portion of the image is not added. No unnatural white or black borders.

In the first and second embodiments of the present invention, the image signal near the target pixel to be extracted has two points before and after the target pixel in the horizontal direction with the target pixel as the center of symmetry. However, the present invention is not limited to this. Pixels may be extracted in the vertical direction, or any number of points may be taken. Also, there is no need to use all the extracted points to detect the maximum and minimum values,
For example, every other one may be selected.

[0019]

As described above, according to the first aspect of the present invention, a plurality of image signals in the vicinity of a target pixel of an input video signal are input to the input signal.
A maximum value detection circuit that detects the maximum value of those amplitude values, and a plurality of image signals near the pixel of interest as an input signal.
Before the minimum value detecting circuit, a detection signal by detecting a mean value from the output signal of the output signal and the minimum value detecting circuit of said maximum value detecting circuit for detecting a minimum value of their amplitudes and <br An arithmetic processing circuit for performing arithmetic processing for subtracting from the input video signal, an output signal of the arithmetic processing circuit, and the input video signal
Are those in which an adder for adding the door, the arithmetic processing
The average value of the maximum value and the minimum value is detected from the image signal near the target pixel by the logical circuit, and a signal obtained by subtracting the detected signal from the image signal of the target pixel is used as a correction signal.
A sufficient contour correction effect can be obtained even with gentle contours,
An optimal video signal processing image can be obtained. Also bill
The invention described in claim 2 is an addition to the invention described in claim 1,
The level of the signal is maximum when the output signal of the
Not smaller than the output signal of the value detection circuit and the minimum value
Control so that it does not become smaller than the output signal of the detection circuit.
2. A non-linear processing circuit according to claim 1, wherein
Undershoot and over in addition to the effects of the invention of
No shoots added, unnatural white or black on the outline of the image
Video signal processing image that can perform contour correction without adding borders
Can be obtained.

[Brief description of the drawings]

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

FIG. 2 is an operation waveform diagram of the first embodiment of the present invention.

FIG. 3 is a waveform chart showing an outline correction effect according to the first embodiment of the present invention.

FIG. 4 is a configuration diagram of a video signal processing device according to a second embodiment of the present invention.

FIG. 5 is an operation waveform diagram of the second embodiment of the present invention.

FIG. 6 is a configuration diagram of a conventional video signal processing device.

FIG. 7 is an operation waveform diagram of a conventional example.

[Explanation of symbols]

 30 One pixel delay unit 40 Maximum value detection circuit 50 Minimum value detection circuit 60 Arithmetic processing circuit 61 Average value circuit 62 Subtractor 70 Gain adjuster 80 Adder 90 Nonlinear processing circuit

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hideaki Yamauchi 1006 Kazuma Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-62-222777 (JP, A) 108285 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) H04N 5/14-5/217

Claims (3)

(57) [Claims] 1. A maximum value detection circuit for detecting a maximum value of amplitude values of a plurality of image signals near a pixel of interest of an input video signal as an input signal, and a plurality of image signals near the pixel of interest as an input signal. A minimum value detection circuit for detecting the minimum value of the amplitude values, and an average value detected from the output signal of the maximum value detection circuit and the output signal of the minimum value detection circuit.
An arithmetic processing circuit for performing an arithmetic process of subtracting the detection signal from the input video signal, and an output signal of the arithmetic processing circuit;
A video signal processing device comprising: an adder for adding the input video signal . 2. A maximum value detection circuit for detecting a maximum value of amplitude values of a plurality of image signals near a pixel of interest of an input video signal as an input signal, and a plurality of image signals near the pixel of interest as an input signal. A minimum value detection circuit for detecting the minimum value of the amplitude values, and an average value detected from the output signal of the maximum value detection circuit and the output signal of the minimum value detection circuit.
An arithmetic processing circuit that performs arithmetic processing of subtracting the detection signal from the input video signal , an adder that adds an output signal of the arithmetic processing circuit and the input video signal, and an output signal of the adder as an input signal. The signal level is at the maximum
Output signal of the value detection circuit and
Control so that it does not become smaller than the output signal of the small value detection circuit.
And a non-linear processing circuit controlled. 3. The arithmetic processing circuit receives the output signal of the maximum value detection circuit and the output signal of the minimum value detection circuit as input signals.
Claim wherein the average value circuit for calculating an average value of the signal, the more becomes this <br/> a subtractor for subtracting the output signal of the previous <br/> Symbol averaging circuit from the input video signal 1 or 2 The video signal processing device according to the above.