KR19990004749A - Contour correction method and contour correction circuit for performing the same - Google Patents

Abstract

Disclosed is a contour correction method for correcting an inclination of an image signal to impart an outline correction signal to a luminance signal to improve the contour of an image displayed on a television screen, and a contour correction circuit for performing the same. The second luminance signal is separated by subtracting the first luminance signal passed low pass from the luminance signal. A second derivative of the first luminance signal is generated to generate a contour correction signal, a noise is detected from the second luminance signal, and a control signal is output. An amplification correction signal is amplified according to the control signal, and a signal obtained by delaying the luminance signal input from the input terminal and the amplified correction signal are added and output to generate a contour correction signal. By correcting the contour of the luminance signal by adjusting the propagation time of the luminance signal without emphasizing the high frequency portion of the luminance signal, the luminance signal is prevented from being over-corrected.

Description

Contour correction method and contour correction circuit for performing the same

The present invention relates to a contour correction method and a contour correction circuit for performing the same, and more particularly, to a contour correction method for correcting the contour of an image displayed on a television screen by applying a contour correction signal to a luminance signal and performing the same. It relates to a contour correction circuit for.

1 is a view showing a conventional contour correction circuit.

As shown in FIG. 1, the conventional contour correction circuit includes a first delayer 121, a first adder 131, and a second derivative circuit 100. The second differential circuit 100 performs second derivative of the luminance signal input from the luminance signal input terminal 101 to generate the contour correction signal 142. ), A second adder 132, a subtractor 141, and a half amplifier 151.

The first and second delayers 121 and 122 delay the luminance signal input through the input terminal 101 for a predetermined time T, respectively. The second delayer 122 outputs the luminance signal delayed by the T time to the third delayer 123 and the subtractor 141, respectively. The third delayer 123 further delays the luminance signal delayed by the second delayer 122 for T time by T time and outputs the luminance signal delayed by 2T time to the second adder 132. The second adder 132 adds the luminance signal delayed by 2T time by the third delayer 123 to the current luminance signal input through the input terminal 101 and outputs the luminance signal to the 1/2 amplifier 151. . The 1/2 amplifier 151 amplifies 1/2 the added luminance signal input from the second adder 132 and outputs the amplified signal to the subtractor 141. The subtractor 141 subtracts the 1/2 amplified signal from the 1/2 amplifier 151 from the T time delayed luminance signal from the second delayer 122 to generate a contour correction signal 142. The generated contour correction signal 142 is provided to the first adder 131. The first adder 131 generates the contour corrected luminance signal by adding the generated contour correction signal 142 from the subtractor 141 to the luminance time delayed from the first delayer 121. And outputs to a matrix circuit (not shown) through the output terminal 103.

Therefore, in the outline correction circuit, the high frequency portion of the luminance signal is simply emphasized, and there is a problem of over-correction or low-correction at the portion of the high or low level of the luminance signal.

Accordingly, the present invention has been made in view of the foregoing, and a first object of the present invention is to provide an outline correction method capable of preventing overcorrection of a luminance signal during contour correction of the luminance signal.

It is a second object of the present invention to provide an outline correction circuit suitable for performing the above outline correction method.

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

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

FIG. 3 is a flowchart for explaining an operation principle of the contour correction circuit shown in FIG. 2.

<Explanation of symbols for main parts of drawing>

121, 122, 123, 310, 320, 610: delay

131, 132, 330, 620: adder 151, 340, 510: 1/2 amplifier

141, 220, 350: Subtractor

210: Low Pass Filter (LPF)

410: noise detector 520: amplifier

In order to realize the first object of the present invention, the present invention includes the steps of separating the second luminance signal by subtracting the low pass first luminance signal from the luminance signal input through the input terminal; Second-order differentiating the first luminance signal to generate an outline correction signal; Detecting noise from the second luminance signal and outputting a control signal; Amplifying a correction signal according to the control signal; And generating a contour correction signal by adding the delayed signal and the amplified correction signal to the luminance signal inputted from the input terminal.

In order to realize the above-described second object of the present invention, the present invention subtracts a low pass first luminance signal from a luminance signal input through an input terminal to obtain a first luminance signal from the first luminance signal and the input luminance signal. A first signal separator for separating the subtracted luminance signal; A second differential circuit unit for generating a differential luminance signal by second-ordering the first luminance signal; A noise detector for detecting noise from the subtracted luminance signal and outputting a control signal; An outline correction unit for amplifying the differentiated luminance signal according to the control signal; And an output section for adding and outputting the delayed signal and the amplified brightness signal inputted from the input terminal.

According to the present invention, a first signal separation unit separates the first luminance signal and the second luminance signal, and secondly differentiates the separated first luminance signal to generate a correction signal, and detects the second luminance signal. The amplification factor of the generated correction signal is determined according to the noise, and the correction signal is added to the luminance signal input from the input terminal to output the contour corrected luminance signal. Therefore, by correcting the contour of the luminance signal by adjusting the propagation time of the luminance signal without emphasizing the high frequency portion of the luminance signal, the luminance signal is prevented from being over-corrected.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

2 is a diagram illustrating a contour correction circuit according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the contour correction circuit 600 includes a first signal separation unit 200, a second differential circuit unit 300, a noise detector 400, a contour correction unit 500, and an output unit 600. It consists of.

The first signal separator 200 includes a low pass filter (LPF) 210 and a first subtractor 220.

After the low pass filter 210 low-pass filters the luminance signal Y input through the input terminal 201, the low-pass filter 210 subtracts the low-pass filtered first luminance signal Y1 from the first subtractor 220 and the second. Output to difference differential circuit 300.

The first subtractor 220 subtracts the first luminance signal Y1 output from the low pass filter 210 from the luminance signal Y input through the input terminal 201 to the second luminance signal Y2. Is generated and the generated second luminance signal Y2 is output to the noise detector 400.

The secondary differential circuit unit 300 has the same configuration as that of the conventional secondary differential circuit 100 shown in FIG. 1. As shown, the second derivative circuit 300 includes a first delayer 310, a second delayer 320, a first adder 330, a first 1/2 amplifier 340, and a second subtractor. It consists of 350.

The first luminance signal Y1 low-passed from the low pass filter 210 is input to the first retarder 310 and the first adder 330. The first delayer 310 outputs the first luminance signal 312 delayed by a T time to the second delayer 320 and the second subtractor 350, respectively.

The second delayer 320 further delays the luminance signal 312 delayed for the T time by the first delayer 310 by T time, thereby adding the 2T time delayed luminance signal 322 to the first adder 330. Will output

The first adder 330 adds the luminance signal 322 delayed by the second delayer 320 by the second delayer 320 to the first luminance signal Y1 input from the low pass filter 210. Output to the 1 1/2 amplifier 340.

The first 1/2 amplifier 340 amplifies the added luminance signal 332 input from the first adder 330 by 1/2 and outputs the amplified luminance signal 332 to the second subtractor 350.

The second subtractor 350 subtracts the half amplified luminance signal 342 from the first half amplifier 340 in the T time delayed luminance signal 312 from the first delayer 312. Subtraction is performed to generate a correction signal 352, and provides the generated correction signal 352 to the contour correction unit 500.

The noise detector 400 includes a noise detector 410. The noise detector 410 receives the second luminance signal Y2 input from the first subtractor 220, detects the noise included in the second luminance signal Y2, and according to the detection value. The generated control signal is output to the contour correction unit 500.

The contour correction unit 500 includes a second 1/2 amplifier 510 and an amplifier 520.

The second half amplifier 510 half amplifies the correction signal 352 output from the second subtractor 350 of the second derivative circuit 300, and then corrects the half amplified correction signal. Is provided to the amplifier 520.

The amplifier 520 amplifies the correction signal amplified 1/2 by the second 1/2 amplifier 510 by α according to the detected value detected by the noise detector 410, and then the α-amplified correction signal ( 522 is provided to the output unit 600.

The output unit 600 includes a third delayer 610 and a second adder 620.

The third delayer 610 delays the luminance signal input from the input terminal 201 for T time, and then outputs the luminance signal 612 delayed by the T time to the second adder 620.

The second adder 620 adds the correction signal 522 amplified by α from the amplifier 520 to the luminance signal 612 delayed by the T delay time from the third delayer 610 to add the contour corrected luminance signal. Is generated and output through the output terminal (Y ').

The operation of the outline correction circuit 700 configured as described above will be described in more detail with reference to the accompanying drawings.

FIG. 3 is a flowchart for explaining an operation principle of the contour correction circuit shown in FIG. 2.

The low pass filter 210 low-pass filters the luminance signal Y input through the input terminal 201 (step S1). The low-pass filtered first luminance signal Y1 is output to the first subtractor 220 and the first delayer 310 of the secondary differential circuit 300. The first subtractor 220 subtracts the first luminance signal Y1 output from the low pass filter 210 from the luminance signal Y input through the input terminal 201 to the second luminance signal Y2. Is generated and the generated second luminance signal Y2 is output to the noise detector 410 (step S2).

The first retarder 310 receives the first luminance signal Y1 low-passed from the low pass filter 210, and receives the first luminance signal 312 delayed by a T time from the second delayer ( 320 and the second subtractor 350, respectively. The second delayer 320 receives the luminance signal 312 delayed for the T time by the first delayer 310, and further delays the luminance signal 322 delayed by 2T after the T time by the first delayer 310. Output to the adder 330.

The first adder 330 adds the luminance signal 322 delayed by the second delayer 320 by the second delayer 320 to the first luminance signal Y1 input from the low pass filter 210, and then adds the luminance. The signal is output to the first half amplifier 340. The first 1/2 amplifier 340 receives the luminance signal 332 added from the first adder 330 and amplifies 1/2 to provide the 1/2 amplified signal to the second subtractor 350. do.

The second subtractor 350 subtracts the 1/2 amplified luminance signal 342 from the first 1/2 amplifier 340 from the T time delayed luminance signal 312 from the first delayer 312. To generate a correction signal 352 and provide it to the second 1/2 amplifier 510 of the contour correction unit 500 (step S3).

The second subtractor 350 receives the second luminance signal Y2 input from the first subtractor 220, detects noise included in the second luminance signal Y2, and according to the detection value. The generated control signal is output to the amplifier 520 of the contour correction unit 500 (step S4).

The second half amplifier 510 half amplifies the correction signal 352 output from the second subtractor 350 of the second derivative circuit 300, and then corrects the half amplified correction signal. Is provided to the amplifier 520, and the amplifier 520 amplifies the correction signal amplified 1/2 by the second half amplifier 510 by α according to the detected value detected by the noise detector 410. ) Provides a correction signal 522 amplified by α to the second adder 620 of the output unit 600 (step S5).

The third delayer 610 delays the luminance signal input from the input terminal 201 for T time, and outputs the luminance signal 612 delayed by the T time to the second adder 620. The second adder 620 adds the correction signal 522 amplified by α from the amplifier 520 and the luminance signal 612 delayed by T time (step S6) to generate the contour corrected luminance signal to generate an output terminal. Output via (Y ') (step S7).

According to the above configuration, the contour of the luminance signal is corrected by adjusting the propagation time of the luminance signal without emphasizing the high frequency portion of the luminance signal, thereby preventing over-correction of the luminance signal.

In other words, to correct the contour, a signal having high pass noise removed through low pass filtering is used, and the contour compensation ratio is determined according to the amount of noise in the luminance signal removed by the high pass noise. This is because as the amount of noise increases, contour compensation is not necessary.

Next, the operation principle of the contour correction circuit 700 having the above-described configuration will be described in connection with the amount of noise detected from the noise detector 410, as shown in Table 1 below.

Edge Compensation According to Detected Noise

Noise component Contour compensation 大 × 中 中 Small 大

When the amount of noise detected from the noise detector 410 is large, the effect of the compensation signal amplified by the second 1/2 amplifier 510 is minimized by decreasing or increasing the amplification factor α of the amplifier 520. . When the amount of detected noise is small, by increasing α, the effect of the compensation signal is maximized to correct the contour of the luminance signal.

Therefore, according to the above configuration, the luminance signal is low-pass filtered to determine the contour compensation signal from the luminance signal from which the high-pass portion is removed, and separated from the luminance signal according to the amount of noise component of the second luminance signal separated from the luminance signal. By determining the correction amount of the contour compensation signal, it is possible to increase the contour correction degree of the luminance signal. By doing so, it is possible to attenuate the difference caused by the back noise.

As described above, the present invention makes it possible to realize an outline correction circuit which is not over-corrected during contour correction of the luminance signal.

Although this invention was demonstrated concretely by the said Example, this invention is not restrict | limited by this, A deformation | transformation and improvement are possible within the normal knowledge of a person skilled in the art.

Claims (11)

(a) subtracting the low pass first luminance signal from the luminance signal input through the input terminal to separate the second luminance signal; (b) second-order differentiating the first luminance signal to generate an outline correction signal; (c) detecting noise from the second luminance signal and outputting a control signal; (d) amplifying a correction signal according to the control signal; And and (e) generating a contour correction signal by adding the delayed signal and the amplified correction signal to the luminance signal inputted from the input terminal and outputting the amplified correction signal. The method of claim 1, wherein step (a) (a-1) low-passing the luminance signal input through the input terminal and outputting a first luminance signal; And and (a-2) subtracting the first luminance signal low-pass filtered by the step (a-1) from the luminance signal inputted through the input terminal to output the second luminance signal. Way. The method of claim 1, wherein step (b) (b-1) delaying the first luminance signal separated by step (a) by T time; (b-2) delaying the first luminance signal delayed by T time by step Tb by T time; (b-3) adding the first luminance signal separated by step (a) and the first luminance signal delayed by 2T time output by step (b-2); (b-4) half amplifying the signal added by the step (b-3); And and (b-5) subtracting the signal amplified by step (b-4) from the signal delayed by step (b-1) and outputting a contour correction signal. The method of claim 1, wherein step (d) (d-1) half amplifying the contour correction signal separated by step (b); And (d-2) amplifying the contour correction signal by α according to step (c). The method of claim 1, wherein step (e) (e-1) delaying the luminance signal input from the input terminal by T time; And (e-2) adding the correction signal amplified by step (d) to the luminance signal delayed by step (e-1) and outputting the contour correction method. A first signal separation unit for subtracting the first luminance signal passed low pass from the luminance signal input through the input terminal to separate the first luminance signal and the second luminance signal subtracted from the input luminance signal; 200); A second differential circuit unit 300 for second-ordering the first luminance signal to generate a correction signal; A noise detector for detecting noise from the subtracted second luminance signal and outputting a control signal; An outline correction unit 500 for amplifying the differential luminance signal according to the control signal; And And an output unit (600) for adding and outputting the delayed signal and the amplified brightness signal input from the input terminal. The method of claim 6, wherein the first signal separation unit 200 A low pass filter 210 for low-pass filtering the luminance signal input through the input terminal to output a first luminance signal; And And a first subtractor 220 configured to add a first luminance signal output from the low pass filter 210 to a luminance signal input through an input terminal, and output a second luminance signal. . The method of claim 6, wherein the second differential circuit unit 300 A first delayer (310) for delaying the first luminance signal by T time; A second delayer (320) for delaying the first luminance signal delayed by T time output from the first delayer (310) by T time; A first adder (330) for adding a 2T delayed first luminance signal output from the second delayer (320) to the first luminance signal; A first 1/2 amplifier 340 for amplifying the signal output from the first adder 330 1/2; And A second subtractor for outputting a contour correction signal by subtracting a signal amplified 1/2 from the first 1/2 amplifier 340 from the first luminance signal delayed by the first delay 310 by a T time ( And a contour correction circuit. 7. The contour correction circuit according to claim 6, wherein the noise detector (400) comprises a noise detector (410) for detecting noise from the second luminance signal and outputting a control signal. The method of claim 6, wherein the contour correction unit 500 A second half amplifier 510 for half amplifying the contour correction signal output from the second differential circuit unit 300; And And an amplifier (520) for amplifying the contour correction signal according to the amplification factor α determined by the noise detector (410). The method of claim 6, wherein the output unit 600 A third delayer 610 for delaying the luminance signal input through the input terminal by T time; And And a second adder (620) for adding the correction signal output from the output unit (500) to the luminance signal output from the third delayer and outputting the correction signal as a contour correction signal.