KR100437755B1 - Image outline enhancer - Google Patents

Abstract

PURPOSE: An image outline enhancing circuit is provided to amplify a certain frequency band to be enhanced among input image signals according to levels of the input image signals, and to properly process the amplified image signals, thereby enhancing image outlines at more than a certain level. CONSTITUTION: A level controller(30) detects levels of image signals having a certain frequency band to compare the levels with a reference level, generates a control signal to maintain outline enhancement levels of image signals whose levels are less than the reference level, and maintains outline enhancement levels of image signals whose levels are more than the reference level at more than a certain level by controlling amplifying gains. A selective input unit(10) selectively inputs image signals having the same frequency band as the image signals detected from the level controller(30) among plural frequency bands. A selective output unit(40) amplifies and processes the image signals inputted through the input unit(10) as many as the amplifying gains, and selectively outputs either maximum values or minimum values of original image signals delayed for a certain time and the image signals whose outlines are enhanced.

Description

Image outline enhancer

The present invention relates to an image signal processing apparatus, and in particular, an image contour enhancement apparatus for amplifying a certain frequency band to be emphasized among the image signals according to the level of an input image signal and processing the signal appropriately to emphasize the image contour. It is about.

Hereinafter, an image contour enhancement apparatus according to the related art will be described with reference to the accompanying drawings.

1 is a block diagram illustrating a configuration of an image contour enhancement apparatus according to the related art, and FIGS. 2A to 2D are waveform diagrams illustrating an image contour enhancement process of the image contour enhancement apparatus of FIG. 1.

As shown in FIG. 1, the image contour enhancement apparatus according to the related art includes an amplifier for amplifying the output of the bandpass filter 11 and the bandpass filter 11 that pass only a predetermined band among the input image signals. 12) a first delay unit 13 and a first delay unit 13 for delaying a signal processing time of the video signal while the first input video signal passes through the band pass filter 11 and the amplifier 12; Samples of the video signal via the adder 14 and the first delayer 13 which add the video signal via the band pass filter 11 and the amplification unit 12 are taken as samples. The video signal output from the highest value detector 16 for detecting the highest value, the lowest value detector 15 for detecting the lowest value, and the adder 14 by sampling a predetermined section of the video signal via the first delay unit 13. Of the video signal via the highest value detector 16 and the lowest value detector 15 A first comparator which compares the image signal output from the second delay unit 17 and the second delay unit 17 to delay the call processing time with the detection value of the minimum value detector 15 and generates a corresponding signal ( 18) a second comparator 19, a first comparator and a second comparator 18 which compare the video signal output from the second delay unit 17 with the detected values of the peak detector 16 and generate a signal accordingly; A multiplexer 20 for outputting a predetermined video signal according to the output of the (19).

In the conventional image contour enhancement apparatus configured as described above, when an image signal is input from a TV or a VTR, the bandpass filter 11 passes only a frequency band of a transition region of which the contour image is to be emphasized, as shown in FIG. The amplifier 12 amplifies to a predetermined level and outputs a waveform as shown in FIG. 2B. On the other hand, the original video signal is delayed by the delay time of the video signal via the band pass filter 11 and the amplifier 12 by the first delay unit 13. The video signal passed through the band pass filter 11 and the amplifier 12 and the video signal delayed by the first delay unit 13 for a predetermined time are added by the adder 14. At this time, the video signal added by the adder 14 is amplified to a certain level as shown in FIG. 2C and the width of the transition area is reduced so that its outline is emphasized, but the overshoot and undershoot are It may need to be removed as it may be generated and thereby cause distortion of the playback screen. In this case, the overshoot means the portion where the waveform exceeds the maximum value due to the transient response when the stair wave or the rectangular wave is input, and the undershoot means the portion that exceeds the minimum value when the switching waveform falls as opposed to the overshoot. Accordingly, the lowest value detector 15 and the highest value detector 16 receive the output of the first delay unit 13 and detect a minimum value and a maximum value among them by sampling a predetermined signal section. Subsequently, the first comparator 18 receives and compares the output signal of the second delay unit 17 and the output signal of the lowest value detector 15, and outputs a predetermined signal to the multiplexer 20 so that a larger value can be output. Apply. In addition, the second comparator 19 receives and compares the output signal of the second delay unit 17 and the output signal of the peak detector 16, and outputs a predetermined signal to the multiplexer 20 so that a smaller value can be output. Apply. In addition, the multiplexer 20 reduces the transition region width as shown in FIG. 2D according to the output signals of the first and second comparators 18 and 19 among the input signals, thereby emphasizing the contour and removing the overshoot and undershoot. Select and output the video signal.

Since the image contour enhancement apparatus according to the prior art emphasizes the image contour at a constant level irrespective of the level of the input signal, there is a problem that the contour enhancement for the low level image signal is not well performed in the actual image.

Accordingly, an object of the present invention is to provide an image contour enhancement device that can achieve a certain level or more image contour enhancement effect on all image signals regardless of the level of the input image signal. .

1 is a block diagram showing the configuration of the image contour enhancement apparatus according to the prior art

2A to 2D are waveform diagrams illustrating an image contour enhancement signal processing process of the image contour enhancement apparatus of FIG. 1.

3 is a block diagram showing the configuration of the first embodiment of the image contour emphasis apparatus according to the present invention;

4 is a block diagram showing the configuration of a second embodiment of an image contour enhancement apparatus according to the present invention;

Explanation of symbols for main parts of the drawings

10: selection input section 21: first bandpass filter

22: second bandpass filter 23: first multiplexer

30: level control unit 31: transition area detection unit

32: level detector 33: third comparator

34: gain control section 40: selective output section

41: second multiplexer 42: third multiplexer

In order to achieve the above object, the image contour emphasis apparatus according to the present invention detects a level of a video signal of a predetermined frequency band among input video signals, and then highlights the contour of a video signal below the reference level by comparing with a reference level. A level control unit generating a selection signal to maintain the level above a predetermined level, and outputting a gain control signal for adjusting amplification gain according to the level of the video signal; A selection input unit which selects and outputs an image signal having the same frequency band as the image signal of a predetermined frequency band detected by the level controller among the plurality of frequency band band-pass filtered image signals according to the frequency characteristic of the input image signal; The gain of the image signal input through the selection input unit is amplified by the amplification gain determined by the level control unit, and then added to the original image signal to generate a contour-enhanced image signal, and simultaneously detect the lowest and highest values from the original image signal. A signal processor; And a selection output unit configured to selectively output one of the image signal, the maximum value, and the minimum value of the outline, using the comparison result of the contour-enhanced signal, the lowest value, the highest value, and the selection signal of the level controller. .

Hereinafter, a first embodiment of an image contour enhancement apparatus according to the present invention will be described with reference to the accompanying drawings.

3 is a block diagram showing the configuration of the first embodiment of the image contour enhancement apparatus according to the present invention.

Prior to describing the present invention, since the basic components for emphasizing the image contour are the same as in the prior art, description thereof will be omitted.

As shown in FIG. 3, the first embodiment of the image contour enhancement apparatus according to the present invention detects a level of a video signal of a predetermined frequency band among input video signals, compares the level with a reference level, and then outlines the video signal below the reference level. A level control unit 30 for generating a control signal to maintain the emphasis level above a certain level, and controlling the amplification gain according to the level of the video signal to maintain the outline emphasis level of the video signal above the reference level above a certain level; A selection input unit 10 for selectively inputting an image signal of the same frequency band as the image signal of a predetermined frequency band detected by the level controller 30 among the plurality of frequency bands detected according to the frequency characteristic of the image signal to be detected; Amplifying the video signal input through the selection input unit 10 according to the signal of the 30 by the amplification gain of the level control unit 30 And a selection output unit 40 which selectively outputs one of the highest value and the lowest value of the contour-enhanced video signal and the predetermined time delayed original video signal by signal processing.

In this case, between the selection input unit 10, the level control unit 30, and the selection output unit 40, as illustrated in FIG. 1, the amplifier 12, the adder 14, the first delay unit 13, The lowest value detector 15, the highest value detector 16, the second delay unit 17, the first comparator 18, and the second comparator 19 are further included in the present invention. The operation is omitted since it may refer to FIG. 1.

The selection input unit 10 has a conventional frequency band to emphasize in accordance with the frequency characteristics of the video signal (TV signal, VCR signal) in addition to the band pass filter (first band pass filter 21) already provided in the prior art The first and the second bandpass filters 22 having different frequency bands from the bandpass filter 21 and the transition region detection unit 31 in the level control unit 30 according to the signals of the first and second bandpass filters 21 are selected for accurate selection. The first multiplexer 23 is further provided to select and output the same frequency band as the output of the transition region detector 31 among the outputs of the two band pass filters 21 and 22.

The level controller 30 includes a transition region detector 31 for detecting a transition region of a frequency band to be emphasized among the input image signals, a level detector 32 for detecting a voltage level of the detected transition region, and the level detector ( A third comparator 33 which compares the voltage level of the transition region detected in 32 with the reference voltage level and generates a signal according to the voltage level of the transition region detected by the level detector 32; And a gain controller 34 for adjusting the amplification gain of (12).

The selection output unit 40 outputs one of an output signal of the second delay unit 17 and an output signal of the lowest value detection unit 15 according to the signal of the third comparator 33. And a third multiplexer 42 which outputs one of the output signal of the second delay unit 17 and the output signal of the peak detector 16 according to the signal of the third comparator 33.

The output of the second delay unit 17, the output of the second multiplexer 41 of the selective output unit 40, and the output of the third multiplexer 42 are input to the multiplexer 20, and the multiplexer 20 is provided. Is an image of which one of the output signals of the second delay unit 17 and the second and third multiplexers 41 and 42 is contour-enhanced by using the comparison result of the first and second comparators 18 and 19 as a selection signal. Select and output as a signal.

In the image contour enhancement device configured as described above, the video signal such as the TV signal or the VCR signal is transferred to the first and second band pass filters 21 and 22 of the selection input unit 10 and the transition region detection unit 31 of the level control unit 30. And it inputs into the 1st delay part 13 simultaneously.

Then, the transition region detector 31 of the level controller 30 detects the transition region of the predetermined frequency band to be emphasized from the input image signal, and thus the first multiplexer 23 of the level detector 32 and the selection input unit 10. Will output The level detector 32 detects the voltage level of the transition region detected by the transition region detector 31 and outputs the voltage to the third comparator 33 and the gain controller 34, and the gain controller 34 is a level detector. The amplification gain of the amplifier 12 is determined according to the voltage level detected at 32, and then output to the amplifier 12.

Meanwhile, the first and second band pass filters 21 and 22 of the input selector 10 filter only the video signals of the frequency band set in each of the input video signals and output the filtered video signals to the first multiplexer 23. The first multiplexer 23 corresponds to a frequency band of the transition region detected by the transition region detector 31 among the outputs of the first and second band pass filters 21 and 22 according to a signal from the transition region detector 31. The same output is selected and output to the amplifier 12. The amplifier 12 variably amplifies the input video signal according to the gain determined by the gain controller 34 and outputs the amplified part 14 to the adder 14. The adder 14 adds the amplified video signal and the original video signal output through the first delay unit 13 and outputs the added video signal to the second delay unit 17. Then, since the width of the transition region is reduced and the image outline is emphasized, the image outline enhancement level is varied according to the voltage level of the input image signal, thereby maintaining the image outline enhancement level for all the image signals above a certain level.

In addition, the third comparator 33 compares the self-configured reference voltage level with the transition region voltage level detected by the level detector 32 and selects a signal according to the selected signal when the voltage level of the transition region is greater than the reference voltage level. And output to the second and third multiplexers 41 and 42 of 40). Then, the second and third multiplexers 41 and 42 select the outputs of the lowest value detector 15 and the highest value detector 16 and apply them to the multiplexer 20 so that overshoot and undershoot can be eliminated. .

At this time, the first comparator 18 compares the output signal of the second delay unit 17 with the output signal of the lowest value detector 15 and outputs a predetermined signal to the multiplexer 20 so that a larger value can be output. Apply. In addition, the second comparator 19 compares the output signal of the second delay unit 17 with the output signal of the peak detector 16. The second comparator 19 supplies a predetermined signal to the multiplexer 20 so that a smaller value can be output. Is authorized.

The multiplexer 20 selects one of the outputs of the second delay unit 17 and the second and third multiplexers 41 and 42 according to the output signals of the first and second comparators 18 and 19. To print. Therefore, the image signal is emphasized and the overshoot and undershoot are eliminated. At this time, if the input video signal is a level higher than the reference voltage level, that is, a high level signal, as shown in the description of FIG. 2, overshoot and undershoot may be distorted because the reproduction screen may be distorted.

On the other hand, when the voltage level of the transition region detected by the level detector 32 is smaller than the reference voltage level set in the third comparator 33, the second and third multiplexers 41 and 42 are configured to perform the third comparator. Under the control of (33), the video signal whose outline is emphasized is selected via the second delay unit 17 and output to the multiplexer 20. In this case, the multiplexer 20 receives an overshooting signal regardless of the signals of the first and second comparators 18 and 19 since only the image contour is emphasized through the second delay unit 17. The undershoot is not removed and only the outline of the image is output. In this case, when the input video signal is a signal having a lower level than the reference voltage level, the overshoot and undershoot do not affect the playback screen, and the image outline may be emphasized due to the presence of the overshoot and undershoot. Therefore, if the voltage level of the input video signal is smaller than the reference voltage level set in the third comparator 33, the overshoot and undershoot are not eliminated because the emphasis level of the signal cannot be obtained even if the video contour of the signal is emphasized. By outputting without additional image contour enhancement effect, even image contour enhancement of a certain level or more may be performed on the entire image signal regardless of the input level of the input image signal.

Hereinafter, a second embodiment of an image contour enhancement apparatus according to the present invention will be described with reference to the accompanying drawings.

4 is a block diagram showing the configuration of the second embodiment of the image contour enhancement apparatus according to the present invention.

As shown in FIG. 4, the configuration and operation of the second embodiment of the image contour enhancement apparatus according to the present invention are the same as those of the first embodiment of the present invention except for the selection output unit, and thus only the configuration and operation of the selection output unit 50 will be described. Let's do it.

The selection output unit 50 according to the second embodiment of the present invention selectively outputs one of a contour-enhanced video signal, a minimum value of the original video signal delayed for a predetermined time, and a maximum value of the original video signal delayed for a predetermined time. And a third multiplexer 52 for outputting one of the output of the second multiplexer 51 and one of the image signals of which the contour is emphasized according to the output signal of the third comparator 33. .

The second multiplexer (3 to 1 multiplexer) 51 of the selective output unit 50 configured as described above is the second and third multiplexers 2to 1 multi of the first embodiment of the present invention shown in FIG. And the operation for removing the overshoot and undershoot of the signal in which the image contour is emphasized, and the third multiplexer 52 performs the operation shown in FIG. The multiplexer 20 according to the first embodiment of the present invention performs an operation performed according to the signal of the third comparator 33, that is, an operation of outputting an input signal having a predetermined level or less without removing overshoot and undershoot. Thus, the second embodiment of the present invention, like the first embodiment of the present invention, reduces the number of multiplexers used in comparison with the first embodiment of the present invention, and evens out the outline of a certain level regardless of the level of the input signal. You can get the effect.

The image contour enhancement apparatus according to the present invention maintains the image contour enhancement level above a certain level for all image signals according to the voltage level of the input signal, and increases the sharpness of the screen by performing additional contour enhancement operation for the low voltage level. There is an effect that can improve the image quality.

Claims (8)

After detecting a level of a video signal of a predetermined frequency band among the input video signals, a selection signal is generated to maintain the contour enhancement level of the video signal below the reference level above a predetermined level by comparing with a preset reference level. A level control unit for outputting a gain control signal for adjusting the amplification gain according to the level of the video signal; A selection input unit which selects and outputs an image signal having the same frequency band as the image signal of a predetermined frequency band detected by the level controller among the plurality of frequency band band-pass filtered image signals according to the frequency characteristics of the input image signal; The gain of the video signal inputted through the selection input unit is amplified by the amplification gain determined by the level control unit, and then added to the original video signal to generate a contour-enhanced video signal, and simultaneously detect the lowest and highest values from the original image signal. A signal processor; And A selection output unit which selects and outputs one of the highest and lowest values of the contour-enhanced image signal and the original image signal by using a result of comparing the minimum and maximum values of the contour-enhanced signal and the original image signal and a selection signal of the level controller; Image contour emphasis device, characterized in that configured to include. The method of claim 1, wherein the level control unit A transition region detector for detecting a transition region of a frequency band to be emphasized among the input image signals; A level detector for detecting a voltage level of the transition region; A third comparing unit which compares the voltage level of the transition region detected by the level detecting unit with a preset reference voltage level and generates a selection signal according thereto; An image contour emphasis device comprising: a gain controller configured to generate and output a control signal for adjusting amplification gain according to the voltage level of the transition region detected by the level detector; The method of claim 2, wherein the selection unit First and second bandpass filters for selectively passing video signals of different frequency bands from among the input video signals; And an image multiplexer configured to select and output an image having the same frequency band as the output of the transition region detector from among the output images passing through the first and second band pass filters by the control of the transition region detector. Emphasis. The method of claim 2, wherein the selection output unit A second multiplexer for selectively outputting one of a minimum value of the original image signal and the contour-enhanced image signal according to the selection signal of the third comparator; And a third multiplexer for selectively outputting one of the highest value of the original image signal and the contour-enhanced image signal according to the selection signal of the third comparator. The method of claim 2, wherein the selection output unit A second multiplexer configured to compare the lowest and highest values of the contour-enhanced image signal and the original image signal, respectively, and selectively output one of the contour-enhanced image signal, the lowest value and the highest value of the original image signal; , And a third multiplexer configured to selectively output one of an output of the second multiplexer and an image signal of which the contour is emphasized according to the selection signal of the third comparator. The method of claim 4, wherein the second multiplexer The image comparator according to the third comparison unit, if it is determined that the voltage level of the transition region is greater than the reference voltage level, the lowest value of the original video signal is selected; . The method of claim 4, wherein the third multiplexer And if the voltage level of the transition region is greater than the reference voltage level, the third comparator selects the highest value of the original video signal, and if it is not large, selects and outputs an image signal whose contour is highlighted. . The method of claim 4, wherein the selection output unit A multiplexer for comparing the contour-enhanced image signal with the lowest and highest values of the original image signal, respectively, and selectively selecting one of the contour-enhanced image signal, the output of the second multiplexer, and the output of the third multiplexer according to the comparison result. Image contour enhancement device characterized in that it further comprises.