KR880000304B1 - Image outline forced circuit of a television - Google Patents

Abstract

The circuit is constructed that the output of the first image amplifier (1) connects in common to the inverting inputs of reduction amplifier (5a), (5b) and also connects with non-inverting inputs of the reduction aplifiers (5a), (5b) via delays (4a), (4b) having time delays different from each other's, the outputs of the reduction amplifiers commonly connecting with the non-inverting input of the addition amplifier (7) via wave regulators (6a), (6b) and the output of the addition amplifier (7) connecting to the control input of the variable gain image amplifier (8) connecting to the output of the 1st image amplifier (1). The control of the high region frequency gain of the image signal enhances the clarity of screen displays.

Description

TV's Screen Outline Emphasis Circuit

1 is a block diagram of an image amplification unit of a television according to a conventional method.

2 is a frequency characteristic diagram of the high frequency emphasis circuit of FIG.

3 is a block diagram of a screen outline enhancement circuit of the present invention.

4 is an explanatory diagram showing pixel relationships on a two-dimensional plane, and FIG. 4 (a) is an explanatory diagram by an approximate differential method. 4 (b) is an explanatory diagram based on the Robert inclination method.

FIG. 5 is a detailed circuit diagram of one embodiment of FIG. 3, and FIG. 5 (a) is a detailed circuit diagram by an approximate differential method. 5 (b) is a detailed circuit diagram by the Robert gradient method.

* Explanation of symbols for main parts of the drawings

1: first video amplifier 4a, 4a ', 4b: time delay

5a, 5b: Subtractive amplifier 6a, 6b: Full-wave rectifier

7 addition amplifier 8 variable gain image amplifier

[0001] The present invention relates to a screen outline enhancement circuit of a television that can improve the lateral and vertical clarity of a screen at the same time by controlling the gain of a high frequency portion of a frequency characteristic of a video signal. will be.

In the conventional tele edge, as shown in FIG. 1, the gain of the high frequency part which is mainly related to the clarity of the screen among the frequency characteristics of the video signal output from the first image amplifier 1 is obtained by the high frequency frequency emphasis circuit part 2; It is designed to increase and decrease the brightness of the screen.

That is, as shown in FIG. 2 in the high frequency emphasis circuit section 2, when the gain of the high portion of the frequency characteristic is increased, the fine portion of the screen is emphasized to increase the sharpness, and the sharpness when the gain of the high frequency portion is decreased. Will decrease. However, in such a conventional apparatus, a video signal is scanned in the transverse direction of the screen according to the communication method of the television. Therefore, varying the sharpness of the screen by increasing or decreasing the gain in the high range is only related to the transverse sharpness. In other words, there is a drawback that the correlation between several consecutive pixels on one scan line is used only so that the longitudinal sharpness is not affected at all.

In view of the above, the present invention obtains a derivative value using two-dimensional correlation considering not only adjacent pixel components on the same scan line of a specific pixel but also pixel components on adjacent scan lines, and controls the gain of the image signal amplifier by using the derivatives. In order to greatly improve the sharpness of the transverse direction and the longitudinal direction on the screen described in detail by the accompanying drawings as follows.

As shown in FIG. 3, time delays 4a and 4b for outputting the output signal of the first image amplifier 1 with a predetermined time delay, respectively, and the time delays 4a and 4b. Full-wave rectifiers 6a and 6b for rectifying the output signals of the subtracting amplifiers 5a and 5b to subtract the output signals of the first image amplifier 1 to the output signals of the first image amplifier 1, respectively; A variable gain controlling the gain of the output signal of the first image amplifier 1 by the addition amplifier 7 which adds the output signals of the rectifiers 6a, 6b and the output signal of the adder amplifier 7; It is composed of an image amplifier 8, the operation of which is described as follows.

The video signal output from the first video amplifier 1 is delayed and differentiated by the time delays 4a and 45b, respectively, and then applied to the subtraction amplifiers 5a and 5b. The video signal output from the amplifier 1 is also applied to the subtraction amplifiers 5a and 5b and added to the video signals output from the time delays 4a and 4b. However, the derivative value G [f (x, y)] of the image signal f (x, y) on the two-dimensional plane output from the first image amplifier 1 is shown in FIG. 4 (a) of FIG. Given by the approximate differential method

G [f (x, y)] = [{f (x, y) -f (x + 1, y)} ² +

{f (x, y) -f (x, y + 1)} ² ] ^1/2 ... (One)

It becomes

If equation (1) is expressed using an absolute value,

G [f (x, y)] = │ f (x, y) -f (x + 1, y) │ +

F (x, y) -f (x, y + 1) … (2)

It becomes

As can be seen from Equation (1), the time delays 4a and 4b output video signals of f (x, y) and f (x + 1, y), f (x, y + 1). Where f (x + 1, y) and f (x, y + 1) are signals with a time delay of one pixel and one scan line for f (x, y), respectively.

In this way, the video signals f (x + 1, y) and f (x, y + 1) delayed and output from the time delays 4a and 4b are respectively applied to the subtracting amplifiers 5a and 5b, respectively. The video signals f (X, y) output from the video amplifier 1 are respectively subtracted. That is, the subtraction of the first and second terms as shown in equation (2) is executed in the subtracting amplifiers 5a and 5b, respectively, and the output signals are respectively absolute in the full-wave rectifiers 6a and 6b. Since it is propagated to a value and then added in the addition amplifier 7, it is proportional to the addition signal f (x, y), which represents a high frequency component on the two-dimensional plane.

In this way, the gain of the variable gain image amplifier 8 is controlled by the differential image signal G [f (x, y) output from the addition amplifier 7, that is, the differential image signal G [f (x, y)] is increased. In this case, when the gain of the variable image amplifier 8 is controlled to increase, the fine image signal is emphasized on the two-dimensional plane, thereby greatly improving the clarity in the horizontal and vertical directions on the screen.

FIG. 5 (a) is a detailed circuit diagram of an exemplary embodiment of the present invention operated as described above, wherein the output side of the first image amplifier ₁ includes a subtractor 5a including resistors R ₁ -R ₄ and operational amplifiers OP ₁ . ) And a common connection to the inverting input terminal side of the subtracting amplifier 5b composed of resistors R ₅ -R ₈ and operational amplifier OP ₂ , and the output side of the first image amplifier 1 is connected to each other. Through the time delays 4a and 4b having different time delays, respectively, to the non-inverting input terminal sides of the subtraction amplifiers 5a and 5b, respectively, of the subtraction amplifiers 5a and 5b. The output side is a full-wave rectifier 6a composed of resistors (R ₉ -R ₁₃ ), diodes (D ₁ , D ₂ ), operational amplifiers (OP ₃ , OP ₄ ), resistors (R ₁₄ -R ₁₈ ), and diode (D). ₃ , D ₄ ) and the non-inverting of the addition amplifier 7 composed of the resistors R _19- R ₂₂ and the operational amplifier OP ₇ through the full-wave rectifier 6b composed of the operational amplifiers OP ₅ and OP ₆ , respectively. Common connection to the input terminal side Resistance of the output side of the amplifier _{(7) (R 23 -R 25} ) and a field effect transistor (FEF _1, FEF _2), consists of an operational amplifier (OP ₈₎ first and second video amplifier (1), (3) It is configured by connecting to the control input side of the variable gain video amplifier 8 connected therebetween.

The video signal f (x, y) output from the first video amplifier 1 is applied to the inverting input terminal side of the subtraction amplifiers 5a, 5b, and the video signal f (x, y) is time delayed. The non-inverting input terminals of the subtraction amplifiers 5a and 5b after being delayed and output to the video signals f (x + 1, y) and f (x, Y + 1) respectively in the groups 4a and 4b. Since each is applied to the side, the subtraction amplifiers 5a and 5b perform a subtraction operation as in Equation (2) and output them, and these output signals are full-wave rectified by the full-wave rectifiers 6a and 6b, respectively. Since the common input is made to the non-inverting input terminal side of the addition amplifier 7, the full-wave rectified signals output from the full-wave rectifiers 6a and 6b are added by the addition amplifier 7 and output. The output signal of the add amplifier 7 is proportional to the derivative of the video signal as described above, and represents the high frequency component of the video signal on the two-dimensional plane.

As described above, the differential image signal output from the addition amplifier 7 controls the gate currents of the field effect transistors FET ₁ and FEF ₂ of the variable gain control amplifier 8 to output the image from the first image amplifier 1. Since the gain of the signal is controlled, the fine image signal is emphasized on the two-dimensional plane, thereby greatly improving the lateral ice direction and the sharpness of the longitudinal direction on the desired screen. The same effect can also be obtained by directly controlling the contrast control circuit built in the television receiver with the output signal of the add amplifier 7. In addition, another method of obtaining a derivative value of an image signal output from the first image amplifier 1 is a method using the Robert Gradient method as shown in FIG. 4 (b). The signal G [f (x, y)] is

G [f (x, y)] "t-1" [{f (x, y) -f (x + 1, y + 1)} ² +... … … … … … … … (3)

{f (x + 1, y) -f (x, y + 1)} ² ] ^1/2

Appears.

If the above expression (3) is expressed as an absolute value

G [f (x, y)] ˜ = {f (x, y) −f (x + 1, y + 1)} +... … … … … … … … … … … (4)

{f (x + 1, y) -f (x, y + 1)}

It becomes

Therefore, in order to implement Equation (4), the delay time of FIG. 3 is considered to be delayed by one scanning line and one pixel than the video signal f (x, y). It is only necessary to modify the configuration of the groups 4a and 4b. That is, as shown in FIG. 5 (b), the output side of the first image amplifier 1 is connected to the inverting input terminal side of the subtractive amplifier 5b, and the time delay units 4a and 4b are respectively connected. A time delay unit connected to the inverting input terminal and the non-inverting input terminal side of the subtracting amplifier 5b, and having the same delay time as the time delay unit 4a having the same delay time as the time delay unit 4a. When connected to the non-inverting input terminal side of the subtraction amplifier 5a via 4a ', the operation is performed as described in FIGS. 3 and 5 (a) to control the variable gain image amplifier 8. do.

As described above, the present invention controls the high frequency gain of the video signal in consideration of the two-dimensional correlation of the video signal, so that the sharpness of the screen can be greatly improved simultaneously in the horizontal and vertical directions.

Claims (3)

The output side of the first image amplifier 1 is commonly connected to the inverting input terminals of the subtraction amplifiers 5a and 5b, and the time delays 4a and 4b each have different time delays. The sub amplifiers 5a and 6b are connected to the non-inverting input terminals, respectively, and the output amplifiers of the sub amplifiers 5a and 5b are respectively supplied through the full-wave rectifiers 6a and 6b. After the common connection to the non-inverting input terminal side, the output side of the television is characterized by connecting to the control input side of the variable gain image amplifier 8 connected to the output side of the first image amplifier 1. Circuit. 2. The television screen outline enhancement circuit according to claim 1, wherein the variable gain image amplifier (8) is removed and the output side of the addition amplifier (7) is connected to a control terminal of a contrast circuit built in the television receiver. 3. The first image amplifier 1 according to claim 1 or 2, wherein the output side of the time delay unit 4b is connected to the input side of the time delay unit 4a 'having the same delay time as the time delay unit 4a. Is connected to the inverting and non-inverting input terminals of the subtractor 5a and the inputs of the time delays 4a and 4b are respectively connected to the inverting and non-inverting input terminals of the subtractor 5a. A screen outline enhancement circuit of a television, which is connected to the inverting and non-inverting input terminals, respectively.

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