JPH10200788A - Contour correction circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the contour correction circuit with a simpler structure without causing deterioration in the contour correction effect. SOLUTION: The circuit 200 includes a tilt sensing circuit 210 that senses amplitude transition of a video signal received through an input terminal and generates a tilt sensing signal corresponding to a degree and a time of the amplitude transition. A comparator circuit 220 compares the tilt sensing signal with a prescribed reference signal to generate a control signal based on the comparison result. A delay means delays the input signal by a prescribed time to generate a delay signal. A selective feedback circuit 230 gives selectively the delay signal from the delay means to a delay circuit as its input terminal based on a control signal so as to feed back the delay signal to the circuit. Moreover, a selective output circuit 240 selectively outputs the video signal received from the input terminal or the delay signal depending on the control signal to generate a contour correction signal. Thus, the circuit 200 emphasizes external contour of a video image reproduced by the video signal without causing preshoot, overshoot and deterioration in the contour correction effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video projector, a video tape recorder, and a video tape recorder.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for enhancing an outline of an image used in an image display device such as V, and more particularly, to a contour correction circuit for enhancing an outline of an image for improving the outline of an image displayed by a video signal.

[0002]

2. Description of the Related Art FIG. 1 is a block diagram showing a conventional contour correction circuit.

In FIG. 1, a contour correction circuit includes a first delay unit 121, a second delay unit 122, a third delay unit 123, a first adder 131, a second adder 132, a subtractor 141, and 1
/ 2 amplifier 151.

[0004] The first and second delay units 121 and 122
Delays a video signal input through the input terminal 101 by a certain time T, respectively. The delay signals generated by the first and second delay units 121 and 122 are output to the first adder 131 and the subtractor 141, respectively. The third delay unit 132 is connected to the second delay unit 122
Is delayed by T time to generate a video signal delayed by 2T time. The second adder 132 outputs the video signal delayed by the 2T time to the input terminal 1.
01 is added to the current video signal input through the O.D.01 to continuously generate an addition signal, and the added signal is provided to the 増 幅 器 amplifier 151. The 増 幅 器 amplifier 151 amplifies the added signal from the second adder 132 by １ ／ to generate a 増 幅 amplified signal, and outputs the generated 増 幅 amplified signal to the subtractor 141. Output. The subtractor 14
1 from the video signal delayed by the T time from the second delay unit 122,
A subtraction signal is generated by subtracting the / 2 amplified signal, and the subtraction signal is provided to the first adder 131 as a peaking signal. The first adder 131 is connected to the first delay unit 121.
From the video signal delayed by T time from
The peaking signals from 41 are summed to produce a contour enhanced video signal.

According to the contour correction circuit 100, the circuit generates a peaking signal in response to a continuously input video signal, and adds the generated peaking signal to the video signal. The outline of the formed image is emphasized.

However, in the contour correction circuit, preshoots before and after the amplitude transition of the video signal are used.
The occurrence of t) and overshoot can result in dark, distorted, and unnatural contour correction at the edges of the reproduced image.

An example of a contour correction circuit for improving the outline of an image without the preshoot and overshoot is disclosed in US Pat. No. 5,293,541. The circuit disclosed in U.S. Pat. No. 5,293,541 modulates the amplitude transition time of a video signal to improve the outline of an image. The circuit includes a control signal generation circuit, a number of subtracters, a number of delay circuits, a synthesis circuit, and a signal selection circuit. The control signal generation circuit generates a control signal by combining the subtraction signals generated by the plurality of subtracters. The plurality of subtracters subtract the plurality of delay signals generated by the plurality of delay units from each other to generate the subtraction signal. The combining circuit interconnects the multiple delayed signals to generate multiple combined signals. Then, the signal selection circuit selectively outputs one signal from the plurality of combined signals according to the control signal, thereby generating a video signal whose contour has been corrected.

[0008] However, although the above circuit can improve the outline of an image without preshoot and overshoot, the circuit must generate a large number of delay signals and control signals, so that a large number of delay circuits and There is a problem that a subtractor is required and the circuit is complicated by a large number of delay circuits and subtractors.

For these reasons, a contour correction circuit having a simpler structure without reducing the contour correction effect is required.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a contour correction circuit having a simpler structure without lowering the contour correction effect. Is to do.

[0011]

According to a first aspect of the present invention, there is provided a contour correcting circuit for detecting an amplitude transition of a video signal input through an input terminal, and determining a degree and a degree of the amplitude transition. Sensing means for generating a tilt sensing signal corresponding to time; comparing means for comparing the tilt sensing signal with a predetermined reference signal and generating a control signal based on the comparison result; delaying the input signal by a predetermined time Delay means for generating a delay signal in response to the control signal; selectively providing the delay signal of the delay means as the input signal of the delay means to the delay means to feed back the delay signal. Selective feedback means; and selectively outputting one of the video signal and the delay signal input through the input terminal in response to the control signal to output the contour. Selective output means for generating a positive signal; consisting of.

According to the circuit of the present invention, the outline of an image can be enhanced with a very simple configuration without causing a preshoot, an overshoot, and a decrease in the contour correction effect.

A contour correction circuit according to a second aspect of the present invention senses an amplitude transition of a video signal input through an input terminal and generates a tilt sensing signal corresponding to the degree and time of the amplitude transition. Means for comparing the tilt sensing signal with a first reference signal and generating a first control signal based on the comparison result; comparing and comparing the tilt sensing signal with a second reference signal; Second comparing means for generating a second control signal based on the result; first delay means for generating a first delayed signal by delaying the video signal by a predetermined time; in response to the first control signal First selecting means for selectively outputting one of the first delay signal and the video signal to generate a first selection signal;
Second delay means for delaying the selection signal by the predetermined time to generate a second delay signal; in order to synchronize the first selection signal and the second control signal, the second control signal is shifted by the predetermined time Third delay means for generating a delay control signal with a delay; and selecting one of the first selection signal and the second delay signal in response to the delay control signal to generate a second delay signal as a contour correction signal. Second selection means for generating a selection signal.

According to the circuit of the present invention, the outline of an image can be enhanced with a very simple configuration without causing a preshoot, an overshoot, and a decrease in the contour correction effect.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

Embodiment 1 FIG. 2 is a diagram showing a contour correction circuit according to Embodiment 1 of the present invention.

In FIG. 1, the contour correction circuit 200 includes a tilt sensing circuit 210, a comparison circuit 220, a selective feedback circuit 230, and a selective output circuit 240.

The tilt sensing circuit 210 detects the amplitude transition of the video signal continuously input through the video signal input terminal 201, and detects the amplitude transition of the video signal Y and the tilt detection signal SU corresponding to the time. Occurs.
Further, the tilt sensing circuit 210 is provided with the tilt sensing signal SU.
Is provided to the comparison circuit 220.

The slope sensing circuit 210 includes a first delay unit 211 and a subtractor 2 for sensing the slope of the video signal Y.
22. The first delay unit 211 generates the first delay signal DY1 by delaying the video signal Y by a predetermined time. The subtracter 222 generates the first delay signal DY1.
To generate the subtraction signal SU, and provide the subtraction signal SU to the comparison circuit 220 as the tilt sensing signal SU.

The comparison circuit 220 includes the tilt sensing circuit 2
The control signal SC is generated by comparing the tilt sensing signal SU provided by the control unit 10 with a predetermined reference signal α. Here, it is preferable that the comparing circuit 220 compares the absolute value AS of the tilt sensing signal SU with the magnitude of the reference signal α, and generates a control signal SC according to the comparison result.

The comparison circuit 220 generates an absolute value circuit (hereinafter referred to as an ABS circuit) for generating the control signal SC.
221 and a comparator 222.

The ABS circuit 221 generates an absolute value signal AS of the tilt sensing signal SU, and outputs the absolute value signal AS to the comparator 222.

The comparator 222 compares the magnitude of the reference signal α provided from an external signal source (not shown) with the absolute value signal AS to generate a control signal SC corresponding to the comparison result. . The comparator 222 outputs the control signal S
A logic signal is generated as C. The comparator 222 generates a low logic signal when the absolute value signal AS is smaller than the reference signal α, and generates a high logic signal when the absolute value signal AS is larger than or equal to the reference signal α. A signal is generated as the control signal.

In response to the control signal SC, the selective feedback circuit 230 feeds back an output signal output through its output terminal to its input terminal,
The same signal is output during feedback.

The selective feedback circuit 230 includes a first switch 231 and a second delay 232.
The first switch 231 is connected to the video signal input terminal 2
01, the first input terminal S1 connected to the second delay unit 2
32, a second input terminal S2 connected to the output terminal of the second delay unit 232, and an output terminal connected to the input terminal of the second delay unit 232. The first switch 231 is connected to the first input terminal S1 or the second input terminal S2 according to the control signal SC. When the first switch 231 is connected to the second input terminal S2, the first switch 231 and the second delay are connected. The unit 232 forms a feedback loop. The second delay unit 232 delays the input signal provided by the first switch 231 for a predetermined time to generate a second delay signal DY2, and
The delay signal DY2 is output to the selective output circuit 240.

The selective output circuit 240 includes a second switch 24 having a first input terminal S3 and a second input terminal S4.
0. The first input terminal S3 of the second switch 240
Is connected to the video signal input terminal 201 and the second
The input terminal S4 is connected to the output terminal of the second delay unit 232 of the selective feedback circuit 230. The second switch 240 is selectively connected to one of the first input terminal S3 and the second input terminal S4 according to a control signal from the comparator 222, and generates a contour-corrected video signal PS. I do.

Hereinafter, the operation of the contour correction circuit 200 configured as described above will be described in more detail with reference to the accompanying drawings.

FIGS. 3A to 3F are signal waveform diagrams for each part of the circuit shown in FIG.

A video signal Y having a waveform as shown in FIG.
Is input to the video signal input terminal 201, the video signal Y is supplied to the first delay unit 21 of the tilt sensing circuit 210.
1, the first input terminal S1 of the first switch 231 of the selective feedback circuit 230, and the second switch 2
The signals are input to the 40 first input terminals S3.

The first delay unit 21 of the tilt sensing circuit 210
1 delays the input video signal Y by a predetermined time to generate a first delay signal DY1 as shown in FIG.
The generated first delay signal DY1 is subtracted from the subtractor 212.
Output to As a result, the subtractor 212 performs the first
The video signal Y is subtracted from the first delay signal DY1 provided from the delay unit 211 to generate a subtraction signal SU as shown in FIG. The subtraction signal SU is used as the tilt sensing signal SU as described above, and is provided to the ABS circuit 221 of the comparison circuit 220.

The ABS circuit 221 of the comparison circuit 220
Converts the tilt sensing signal SU into an absolute value, and
, The absolute value signal AS is generated, and the generated absolute value signal AS is output to the comparator 222. The comparator 222 compares the absolute value signal AS with the magnitude of the reference signal α to generate a control signal SC as shown in FIG. 3E, and converts the generated control signal SC to the first signal. This is provided to the switch 231 and the second switch 240, respectively.
The comparator 222 generates a low logic signal when the absolute value is smaller than the magnitude of the reference signal α, and a high logic signal when the absolute value is greater than or equal to the magnitude of the reference signal α. With the control signal SC
Occurs as

The first switch 231 of the selective feedback signal 230 is connected to the first input terminal S1 when the control signal SC is a low logic signal, and is input through the first input terminal S1. The output video signal is output to the second delay unit 232.

At the same time, when the control signal SC is a low logic signal, the second switch 240 is connected to the first input terminal S3, and the second switch 240 is connected to the first input terminal S3.
3 is output as a contour correction signal having no signal deformation, as shown in FIG.

When the control signal SU is a high logic signal, the first switch 231 and the second switch 240 are connected to respective second input terminals S2 and S4.

At this time, the output terminal of the first switch 231 is connected to the output terminal of the second delay unit 232,
The first switch 231 and the second delay unit 232 form a feedback loop. The first switch 23
If a feedback loop is formed by the operation 1, the output terminal and the input terminal of the second delay unit are connected to each other, and the second delay unit 232 is connected to the first switch 23.
Before the first input terminal S2 is connected to the second input terminal S2.
1 continuously outputs the same feedback signal DY2 as the video signal input last. At the same time, the second switch 240 is connected to the first switch 231.
And outputs the feedback signal DY2 as the contour correction signal PS as shown in FIG. 3 (F).

Therefore, according to the circuit 200, the outline of an image can be enhanced with a very simple configuration without causing a preshoot, an overshoot, and a decrease in the contour correction effect.

Embodiment 2 FIG. 4 is a block diagram showing an outline correction circuit according to Embodiment 2 of the present invention.

In the figure, the contour correction circuit 400 includes an inclination sensing circuit 500, a first comparator 610, and a second comparator 62.
0, a first delay unit 711, a first switch 712, a second switch 722, and a third delay unit 630.

The tilt sensing circuit 500 senses the amplitude transition of the video signal Y input through the video signal input terminal 401, and generates a tilt sensing signal DFF corresponding to the degree of the amplitude transition of the video signal and its time. .

Here, the tilt sensing circuit 500 generates the tilt sensing signal DFF in order to generate the tilt sensing signal DFF.
0, subtractor 520, absolute value circuit 530, and differentiating circuit 5
Preferably, it is composed of 40.

The fourth delay unit 510 outputs the video signal Y
Is delayed by a predetermined time to generate a first delay signal DY1,
The first delay signal DY1 is provided to the subtractor 520.

The subtracter 520 converts the video signal Y input through the video signal input terminal 401 into the first signal.
The delay signal DY1 is subtracted to generate a subtraction signal SU, and the subtraction signal SU is provided to the absolute value circuit 530.

The absolute value circuit 530 outputs the subtraction signal SU
Is converted to an absolute value signal AB, and the absolute value signal AB is provided to a differentiating circuit 540.

The differentiating circuit 540 provides the absolute value signal AB
Is differentiated to generate a differential signal DFF.
F as the tilt detection signal DFF, the first comparator 61
0 and the second comparator 620 respectively.

The first comparator 610 compares the tilt detection signal DFF with a first reference signal α, generates a first control signal C1 according to the first comparison result, and generates the first control signal C1.
The control signal C1 is provided to the first switch 710.

The second comparator 620 compares the tilt sensing signal DFF with a second reference signal -α, generates a second control signal C2 according to the second comparison result, and outputs the second control signal C2. Provided to the third delay unit 630.

The third delay unit 630 delays the second control signal C2 by the predetermined time to generate a delay control signal DC2, and outputs the delay control signal DC2 to the second switch 7
22.

The first delay unit 711 delays the video signal Y input through the video signal input terminal 401 to generate a second delay signal DY2, and outputs the generated second delay signal DY2 to the first switch 712. To the second input terminal S2.

The first switch 712 includes a first input terminal S1 connected to the video signal input terminal 401, a second input terminal S2 connected to an output terminal of the first delay unit 711, and a second switch 722. And an output terminal connected to the input terminal of the second delay unit 721. The first switch 712 is connected to the first input terminal S1 or the second input terminal S2 according to a first control signal C1 from the first comparator 610, generates a first selection signal SEL1, and generates a first selection signal SEL1. The selection signal SEL1 is provided to the first input terminal S3 of the second switch 722 and the second delay unit 721.

The second delay unit 721 delays the first selection signal SEL1 by the predetermined time to generate a second delay signal DS.
E, and outputs the second delay signal DSE to the second switch 7.
22 to a second input terminal S4.

The second switch 722 is connected to the first input terminal S3 or the second input terminal S4 according to the delay control signal DC2 provided from the third delay unit 630, and generates the second selection signal SEL2. Then, the second selection signal SEL2 is output as the contour correction signal SEL2.

Hereinafter, the operation of the contour correction circuit 400 configured as described above will be described in more detail with reference to the accompanying drawings.

FIGS. 5A to 5K are waveform diagrams for explaining the operation of each part of the contour correction circuit shown in FIG.

In FIG. 4, when a video signal Y as shown in FIG. 5A is input to an input terminal 201, the video signal Y is input to a first delay unit 711 and a fourth delay unit 510, respectively. .

The first delay unit 711 and the fourth delay unit 51
0 delays the video signal Y by a predetermined time to generate first and second delay signals DY1 as shown in FIG. 5B.

The first subtractor 520 converts the video signal Y into a first delay signal DY1 from the fourth delay unit 510.
Is subtracted to generate a subtraction signal SU as shown in FIG. 5C, and outputs the subtraction signal SU to the absolute value circuit 530.

The absolute value circuit 530 outputs the subtraction signal SU
Is converted into an absolute value signal ABS as shown in FIG. 5D, and the absolute value signal ABS is provided to the differentiating circuit 540.

The differentiating circuit 540 outputs the absolute value signal AB.
S is differentiated to obtain a differentiated signal DFF as shown in FIG.
And the differential signal DFF is converted to the first comparator 610.
And the second comparator 620.

The first comparator 610 outputs the differential signal DF
F with a first reference signal α, and as a result generates a first control signal C1. The first comparator 610 preferably generates a logic signal as the first control signal C1, as shown in FIG. That is, the differential signal D
If the FF is smaller than the first reference signal α, a low logic signal is generated as the first control signal C1, while if the differential signal DFF is larger than or equal to the first reference signal α, the second control signal C1 is generated. A high logic signal is generated as one control signal C1.

The second comparator 620 outputs the differential signal DF
Comparing F with a second reference signal-[alpha], resulting in a second control signal C2. The second comparator 620 is configured as shown in FIG.
It is desirable to generate a logic signal as the second control signal C2 as shown in FIG. That is, the second comparator 620 outputs the differential signal DFF to the second reference signal −α.
If the difference is larger than the second control signal C2, a low logic signal is generated. If the differential signal DFF is smaller than or equal to the second reference signal -α, the second control signal C2 is set as a high logic signal. Generates a signal.

The first switch 712 is controlled by the first control signal C1. When the first control signal C1 is a low logic signal, the first switch 712
Is connected to the first input terminal S1, and the first control signal C1
Is a high logic signal.
2 is connected to the second input terminal S2 to generate a first selection signal SEL1 as shown in FIG. Further, the first switch 712 outputs the first selection signal SEL1 to the second
The first input terminal S of the delay unit 721 and the second switch 722
3 respectively.

The second delay unit 721 delays the first selection signal SEL1 from the first switch 712 by the predetermined time to generate a second delay signal DSE as shown in FIG. The second delay signal DSE is supplied to the second switch 722.
To the second input terminal S4.

On the other hand, the second control signal C2 is provided to the third delay unit 630 and is delayed by the third delay unit 630. The third delay unit 630 generates a delay control signal DC2 as shown in FIG.
C2 is provided to the second switch 722.

The second switch 722 is connected to the first input terminal S3 when the delay control signal DC2 is a low logic signal, and is connected when the delay control signal DC2 is a high logic signal. It is connected to the second input terminal S4 to generate a second selection signal SEL2 as a contour correction signal as shown in FIG.

Therefore, according to the circuit 400, it is possible to enhance the outline of the video reproduced by the video signal without causing the preshoot, the overshoot, and the effect of the contour correction.

As described above, the present invention has been specifically described based on the above embodiments. However, the present invention is not limited to these embodiments, and can be changed and improved without departing from the gist of the present invention. Of course.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a conventional contour correction circuit.

FIG. 2 is a block diagram illustrating a contour correction circuit according to the first embodiment of the present invention.

3 (A) to 3 (F) are signal waveform diagrams for respective portions of the circuit shown in FIG. 2;

FIG. 4 is a block diagram illustrating a contour correction circuit according to a second embodiment of the present invention.

5 (A) to 5 (K) are signal waveform diagrams relating to respective portions of the circuit shown in FIG. 4;

[Explanation of symbols]

 200, 400 Contour correction circuit 210, 500 Tilt sensing circuit 220 Comparison circuit 230 Selective feedback circuit 240 Selective output circuit 510 4th delay unit 610 1st comparator 620 2nd comparator 630 3rd delay unit 711 1st delay unit 712 First switch 722 Second switch

Claims (10)

[Claims] 1. A sensing means for sensing an amplitude transition of a video signal input through an input terminal and generating an inclination detection signal corresponding to the degree and time of the amplitude transition; Comparison means for generating a control signal based on the comparison result; delay means for generating a delay signal by delaying an input signal by a predetermined time; delay of the delay means in response to the control signal Selective feedback means for selectively providing a signal to the delay means as the input signal of the delay means to feed back the delayed signal; and a video signal input through the input terminal in response to the control signal And a selective output means for selectively outputting one of the delay signals to generate a contour correction signal. circuit. 2. The delay means for delaying the video signal to generate a delayed video signal, and the video signal is subtracted from the delayed video signal to generate a subtraction signal as the tilt sensing signal. 2. The contour correction circuit according to claim 1, comprising a subtractor for generating. 3. The selective feedback means is connected to a first input terminal connected to the input terminal, a second input terminal connected to an output terminal of the delay means, and an input terminal of the delay means. A first switch having an output terminal, wherein the first switch is connected to the first or second input terminal in response to the control signal, and the output signal of the delay means is fed back when connected to the second input terminal. The contour correction circuit according to claim 1, wherein: 4. The control device according to claim 1, wherein the selective output means is a second switch having a first input terminal connected to the input terminal and a second input terminal connected to an output terminal of the delay means. 2. The contour correction circuit according to claim 1, wherein said contour correction circuit is connected to said first or second input terminal according to a signal and outputs said contour correction signal. 5. Sensing means for sensing an amplitude transition of a video signal input through an input terminal and generating an inclination detection signal corresponding to a degree and a time of the amplitude transition; the inclination detection signal and a first reference signal. And first comparison means for generating a first control signal based on the comparison result; comparing the tilt sensing signal with a second reference signal; and generating a second control signal based on the comparison result. Second comparing means for generating; first delaying means for delaying the video signal by a predetermined time to generate a first delayed signal; the first delayed signal and the video signal in response to the first control signal One of
First selecting means for selectively outputting one and generating a first selection signal; second delay means for generating a second delay signal by delaying the first selection signal by the predetermined time; Third delay means for generating a delay control signal by delaying the second control signal by the predetermined time in order to synchronize the first selection signal with the second control signal; and in response to the delay control signal, A second selection means for selecting one of the first selection signal and the second delay signal to generate a second selection signal as an outline correction signal; 6. A subtractor for subtracting the first delay signal from the video signal to generate a subtraction signal; an absolute value circuit for converting the subtraction signal into an absolute value; 6. The contour correcting circuit according to claim 5, further comprising a differentiating circuit for differentiating an absolute value from the circuit to generate the tilt sensing signal. 7. The first comparing means, if the voltage of the tilt sensing signal is lower than the voltage of the first reference signal, a low level.
6. The logic circuit according to claim 5, wherein a logic signal is generated as the first control signal when a voltage of the tilt sensing signal is higher than or equal to a voltage of the first reference signal. Contour correction circuit. 8. The first selecting means selects the first delay signal when the first control signal is a low logic signal, and selects the first delay signal when the first control signal is a high logic signal. 8. The contour correction circuit according to claim 7, wherein said first selection signal is generated by selecting said video signal. 9. The second comparing means, when the voltage of the tilt sensing signal is higher than the voltage of the second reference signal, sets a low level.
6. The logic circuit according to claim 5, wherein a logic signal is generated as the second control signal when a voltage of the tilt sensing signal is lower than or equal to a voltage of the second reference signal. Contour correction circuit. 10. The second selection means selects the second delay signal when the delay control signal is a low logic signal, and selects the second delay signal when the delay control signal is a high logic signal. 10. The contour correction circuit according to claim 9, wherein said contour correction signal is generated by selecting a first selection signal.