JPS60199270A - Profile correcting device of video signal - Google Patents

Abstract

PURPOSE:To avoid unpleasant pattern even when an integrated value per unit time of a profile correction signal is comparatively large by providing a smoothing means receiving the profile correction signal and smoothing it, an amplitude change means changing the amplitude of the profile correction signal in response to the output of the smoothing means and a synthesis means synthesizing the output of the amplitude change means into a video signal. CONSTITUTION:A voltage control system gain variable circuit 9 has an input terminal 8a connected to a profile correction signal generating circuit 6, an output terminal 8b connected to an adder circuit 3 and a control terminal 8c. The profile correction signal E1 obtained from the profile correction signal generating circuit 6 is shown in Fig. B. The profile correction signal E1 is given to a detection circuit 11 in a control signal generating circuit 10, detected and outputted as 2N-set of positive pulses P1 as shown in Fig. C. The pulse P1 is given to the smoothing circuit 12, smoothed and outputted as an output voltage V1 to control the gain of a voltage controlled gain variable circuit 9. Further, the profile correction signal E1 shown in Fig. B is given to the voltage controlled gain vatiable circuit 9, the amplitude is changed and outputted as an output signal E2 shown in Fig. D.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to an improvement in a contour correction device for a video signal.

[Prior Art] FIG. 1 shows a conventional image signal contour correction device. In the figure, an original video signal S1 from video signal 1!1 is applied to one input of an adder circuit 3 via an amplifier circuit 2 as required. This original video signal S1 is also given to the contour correction signal generation circuit 6.

The contour correction signal generation circuit 6 consists of two differentiating circuits 4 and 5 connected in series. The differentiating circuit 4 receives the original video signal S
The differentiating circuit 5 differentiates the component during one picture period, and the differentiating circuit 5 differentiates the output again. Therefore, the contour correction signal @E1, which is the output of the contour correction signal generation circuit 6, is the second-order differential of the component during the video period of the original video signal S1. Contour correction signal E1
is applied to the other input of the adder circuit 3, and is combined with the original video signal $1 applied from the other input. In this way, from the adder circuit 3, the ring IlX? The corrected video signal S2 is output.

Next, the operation of the conventional device shown in FIG. 1 will be explained with reference to the waveform diagram in FIG. Now, the original video signal S1 from the video signal source 1 is as shown in FIG. 2A, for example.
It is assumed that a pulse wave is obtained in each horizontal synchronization section. In this case, the contour correction signal @E1 obtained from the contour correction signal generation circuit 6 is obtained as a second-order differential wave at the rising and falling positions of the original video signal S1, which is a pulse wave, as shown in FIG. 2B. . The original video signal S1 (waveform A) and the contour correction signal E1 (waveform B) are combined in the adder circuit 3 to produce the contour-corrected video signal J! with a waveform as shown in FIG. 2C. S2 is obtained. As is clear from FIG. 2C, this contour-corrected video S signal 8
2 is a signal in which the second-order differential wave is synthesized at the rising and falling positions of the original video signal S1, which is a pulse wave.

If an image is obtained on a display Ml (not shown) using the contour-corrected video signal S2 obtained in this way, the contour of the image will change when the image is obtained using the original video signal S1 as it is. It will be much clearer than if it were.

However, in such conventional devices, the original video signal S
Depending on the contents of item 1, performing contour correction may actually make the screen harder to see.

This is especially true when the integral value per unit time of a pulsed wave of positive or negative polarity (hereinafter simply referred to as pulse) included in the second-order differential wave is relatively large. In that case, the screen on the display device obtained using the contour-corrected video signal S2 becomes so-called "stirly" and becomes difficult to see.

[Summary of the Invention] Therefore, an object of the present invention is to provide a video signal contour correction device that eliminates the above-mentioned drawbacks of the conventional system and does not make the screen difficult to view due to contour correction. That's true.

The contour correction@quality of a video signal according to the present invention includes contour correction signal generation means for receiving a video signal and generating a contour correction signal for contour correction of the video signal. The contour correction signal generated by the contour correction signal generating means is smoothed, and the amplitude of the contour correction signal is changed in response to the smoothed signal. The signal changed by ff1llll is combined with the Ili image signal, thereby producing a video signal subjected to contour correction according to the present invention.

[Embodiment of the Invention] FIG. 143 is a block diagram showing a preferred embodiment of a video signal contour correction device according to the present invention.

The same parts as in FIG. 1 are given the same reference numerals, and their explanation will be omitted. The conventional @Den and Konari shown in Figure 1,
The image signal contour correction apparatus according to the present invention includes a voltage-controlled variable gain circuit 9 between the contour correction signal generation port 116 and the addition circuit 3. The voltage ll11wg1 variable gain circuit 9 has an input terminal 8 connected to the contour correction signal generation circuit 6.
a, an output terminal 8b connected to the adder circuit 3, and a control terminal 8C. A control signal from the control signal generation circuit 10 is applied to the MITI terminal 8C. control 111i
The contour correction signal E1 from the contour correction signal generation circuit 6 is supplied to the signal generation circuit 10. The control signal generation circuit 10 generates a contour correction signal E1, which is a two-way split of the original video signal S1.
A detection circuit 11 detects only pulses of one polarity (for example, positive polarity) among the pulses included in the detection circuit 1;
1, and a smoothing circuit 12 that smoothes the pulse P1 obtained from 1 and outputs a voltage of value 1.

Referring now to FIGS. 4 and 5, the operation of the video signal contour correction apparatus shown in FIG. 3, which is a preferred embodiment of the present invention, will be described below.

4 and 5 are waveform diagrams for explaining the operation of one embodiment of the present invention. Here, we will focus on one horizontal synchronization section of the original video signal 81 from the video signal source 1.

As shown in FIG. 14, if the original video signal S1 consists of N pulses in the horizontal synchronization period,
Contour correction signal E1 obtained from the contour correction signal generation circuit 6
As shown in FIG. 6B, the waveform consists of 2N sets of two-several waves of positive polarity and negative polarity. This contour correction signal E1 is applied to the detection circuit 11 in the control signal generation circuit 10, detected, and output as 2N positive pulses P1 as shown in FIG. 6C. The pulse P1 is passed through the smoothing circuit 12
It is smoothed and outputted as an output voltage (I'I) for controlling the gain of the voltage I1IIll type variable gain circuit 9.

FIG. 5 shows an example of fluctuations in the output voltage ■1 of the *+W signal generation circuit 10, focusing on a sufficiently long period compared to the vertical synchronization of the original video signal 81. In the figure, A and A- represent sections where the integral value of pulse P1 per unit time is relatively large, and B represents @darkness where the integral value of pulse P1 per unit time is relatively small.

The contour correction f4@El shown in FIG. 4B is applied to the voltage-controlled variable gain circuit 9 to change its amplitude, and is outputted as an output signal 1iQE2 as shown in the fourth diagram. Contour correction faith! Let the amplitude of E1 be VEI, and a voltage controlled gain variable circuit! When the amplitude of the output signal @E2 of I9 is VH2, the gain A of the voltage-controlled variable gain circuit 9 is expressed as A-VE2/VEI.

The gain A of the voltage 1111-type variable gain circuit 9 is 1I11
It is controlled by the output voltage v1 of the 1II signal generation circuit 10.

FIG. 6 shows the output voltage v1 of the control signal generation circuit 10 and the gain 11! of the voltage-controlled variable gain circuit 9! It is a graph showing a preferable relationship of A. 61st! As shown in FIG. 1, the gain 41A of the voltage-controlled variable gain circuit 9 is
The output voltage v1 is decreased as the output voltage v1 of the output voltage v1 increases. In FIG. 6, the relationship between gain and voltage 1 is shown to be inversely proportional, but this relationship may be changed as appropriate to obtain desired characteristics.

The signal E2 in the fourth diagram is sent to the adder circuit 3 as the original ll! −
As a result, the adder circuit 3 outputs the contour-corrected video signal S2 shown in FIG. 4E.

Now, if the integral time constant of the smoothing circuit j112 is determined appropriately, if the integral value per unit time of the pulse P1 shown in FIG. The gain 1jA of the variable gain circuit 9 becomes smaller. On the contrary, if the integral value of the pulse P1 per unit time becomes smaller, the profit vIA increases in inverse proportion to the integral value. Since the 8 gain A changes in inverse proportion to the integral value per unit time of the pulse P1, the contour correction signal (signal E2) after the amplitude change is independent of the contour correction signal E1 before the amplitude change. The signal is almost constant. Therefore, Fig. 4E
The contour correction according to the present invention shown in FIG.
! It will be understood that the image signal @S2 always undergoes appropriate contour correction.

In the above embodiment, the output of the contour correction signal generation circuit 6 is directly given to the detection circuit 11, but by providing a clip circuit or an amplitude discrimination circuit between the two, only pulses having a certain amplitude or more are sent to the detection circuit 11. 11111. In this case as well, the same effects as in the above-described embodiment can be achieved.

Furthermore, in the above embodiment, the case of contour correction in the horizontal direction was explained, but the present invention can be similarly applied to contour correction in the vertical direction, and in this case as well, the same effects as in the above case can be enjoyed. do. Further, a delay circuit may be inserted between the amplifier circuit 2 and the adder circuit 3, thereby making it possible to perform more appropriate contour correction. The delay may be, for example, one vertical phase period.

[Effects of the Invention] As described above, according to the present invention, even when the integral value per unit time of the contour correction signal is relatively large, the screen obtained by the contour-corrected video signal becomes difficult to see. I am afraid that there will be no such effect.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing a conventional video signal contour correction device, and Fig. 2 is a block diagram showing a conventional video signal contour correction device. 1 is a waveform diagram for explaining the operation of the conventional @ position, 3rd WJ is a block diagram showing a video signal contour correction device which is a preferred embodiment of the present invention, 4th WU and 5 are A waveform diagram for explaining the operation of a preferred embodiment of the present invention shown in FIG. 3, and FIG.
It is a graph showing the relationship between J voltage (1) and gain. In the figure, 1 is a video signal source, 2 is an amplifier circuit, 3 is an adder circuit, 4 and 5 are differentiating circuits, 6 is a contour correction signal generation circuit, 9 is a voltage 1% + 111 type 14J gain variable circuit, and 10 is a control signal 11 is a detection circuit, and 12 is a flat WA circuit. Agent Large Pg Increase Male Figure 1 Figure 2 Figure m3 ■ Figure 5 Figure 4 51 -JhiJt-. Figure 6 Procedural Amendment (Voluntary) Date of 1927 To the Commissioner of the Japan Patent Office 2 Title of the invention Image signal contour correction device 3 Relationship to the person making the amendment Case Patent application Address: 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name:
(601) Mitsubishi Electric Co., Ltd. Representative Hitoshi Katayama 4 Agent Address 2-2-3-5 Marunouchi, Chiyoda-ku, Tokyo 2-2-3-5 Marunouchi, Chiyoda-ku, Tokyo Claims column 6 of the specification to be amended, Description of the contents of the amendment Section 3 + Claim 11 shall be amended as shown in the attached sheet. Above 2, Claim (1) An apparatus for performing contour correction of a video signal, comprising a contour correction M for receiving the video signal and correcting the contour thereof.
contour correction signal generating means for generating a signal; smoothing means for receiving and smoothing the contour correction signal; and receiving the contour correction signal and changing the amplitude of the contour correction signal in response to the output of the smoothing means. A contour correction device for an H image signal, comprising: an amplitude changing means for changing the amplitude; and a combining means for combining the output of the amplitude changing means with the video signal. (2) The contour correction device for a video signal according to claim 1, wherein the amplitude changing means decreases the amplitude of the contour correction signal as the output of the smoothing means increases. (3) The contour correction device for a video signal according to claim 1, wherein the contour correction signal generating means includes a differentiating circuit that differentiates the video signal. (4) The contour correction side L of the video signal according to claim 3, wherein the differentiating circuit includes a second-order differentiating circuit. (5) The output of the differentiating circuit includes positive and negative polarity pulses, and the smoothing The contour correction side L of the isthmus signal according to claim M3, wherein the means smoothes only one polarity of the positive and negative polarity pulses. Image signal contour correction 1 according to claim M5, wherein the smoothing means configured to smooth only pulses includes a detection circuit for selecting the pulses of one polarity. (7) The contour correction device for a video signal according to claim 1, wherein the smoothing means smoothes only those of the contour correction signal having a predetermined amplitude or more. (8) Claim 7, wherein the smoothing means configured to smooth only the contour correction signal having a predetermined amplitude or more includes an amplitude discrimination circuit for discriminating the amplitude of the contour correction signal. Contour correction of the described video signal V41f
. (9) The combining means includes delay means for delaying the one set of signals, and the output of the amplitude changing means is combined with the one set of signals delayed by the delay means. 2. The video signal contour correction device described in 2.

Claims (8)

[Claims] (1) An apparatus for performing contour correction of a video signal, comprising: a contour correction signal generating means for receiving the video signal and generating a contour correction signal for contour correction; and a contour correction signal generating means for receiving the contour correction signal. smoothing means for smoothing the contour correction signal; amplitude changing means for receiving the contour correction signal and changing the amplitude of the contour correction signal in response to the output of the smoothing means; A video signal contour correction device, comprising a combining means for combining into an am signal. (2) The contour correction device for a video signal according to claim 1, wherein the amplitude changing means decreases the amplitude of the contour correction signal as the output of the smoothing means increases. (3) The contour correction device for a video signal according to claim 1, wherein the contour correction signal generating means includes a differentiating circuit for differentiating the video signal. . (4) The image signal contour correction device according to claim 3, wherein the differentiating circuit includes two or more circuits. (5) The output of the differentiating circuit includes pulses of positive and negative polarity, and the smoothing means is adapted to smooth only one polarity of the pulses of positive and negative polarity. A video signal contour correction device according to scope 3. (6) The video signal according to claim 5, wherein the smoothing means configured to smooth only the impulse-like pulses includes a detection circuit for selecting the impulse-like pulses. contour correction device. (7) The contour correction cap L for a video signal according to claim 1, wherein the smoothing means smoothes only those of the contour correction signal that have a predetermined amplitude or more. (8) The flat groove means configured to smooth only the contour correction signal having a predetermined amplitude or more includes an amplitude discrimination circuit for discriminating the amplitude of the contour correction signal. 2. The video signal contour correction device described in 2. (9) The synthesizing means includes a delay means for delaying the contour correction signal, and the output of the amplitude changing means is combined with the contour correction signal delayed by the delay means. 2. The video signal contour correction device described in 2.