JP2007288534A - Waveform shaping apparatus and waveform shaping method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waveform shaping apparatus and a waveform shaping method for impartially obtaining good results from a thick line including many low frequency components to a thin line including many high frequency components in the case of applying LTI correction to a video signal of characters comprising a combination of thin longitudinal lines and thin lateral lines. <P>SOLUTION: The waveform shaping apparatus in a digital processing system for processing the video signal includes: means (11 to 14) for obtaining a maximum value and a minimum value from a plurality of data including present data and within a predetermined range before and after the present data; means (15 to 17) that obtain a difference between an average of the maximum value and the minimum value and the present data, amplify the difference and summate the amplified difference to the present data; and a means (18) that places a limit on the summated data within a range between the maximum value and the minimum value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a waveform shaping device and a waveform shaping method for performing waveform shaping by emphasis in a digital processing system for processing a video signal.

  Video recording / playback equipment such as TVs, VTRs, DVDs, and hard disk recorders that project video signals. Image quality improvement function that compensates for signal degradation that occurs in the transmission system and signal processing when signals are sent from broadcast stations. Is installed. In particular, the waveform shaping process that raises the inclination of the edge portion that has become dull due to the attenuation of the high frequency component is an effective function for improving the image quality that makes a blurred image clear.

FIG. 7 is a diagram showing a waveform shaping device according to the prior art.
The waveform shaping device 40 shown in FIG. 7 includes a filter 41 for extracting a high-frequency component attenuated from an input video signal, an amplifier 42 for amplifying the high-frequency component extracted by the filter 41, and a group delay amount of the filter 41. A delay circuit 43 for delaying the input video signal only, an adder 44 for adding the high frequency component amplified by the amplifier 42 to the video signal from the delay circuit 43, and the video signal obtained by adding the high frequency component by the adder 44 A limiter 45 for suppressing an excessively emphasized portion and extracting an output signal.

FIG. 8 is a diagram showing signal waveforms at various parts in FIG. 7, and shows a waveform shaping process in which the dull video signal waveform is brought close to the original waveform.
In FIG. 8, (a) is the original waveform, (b) is the input video signal waveform in which the high frequency component is attenuated by signal processing in the transmission system and the previous stage, and (c) is attenuated from the input video signal. The waveform obtained by extracting the high frequency component that has been extracted, the waveform obtained by amplifying the high frequency component extracted by (d) and adding it to the input video signal, and the output waveform obtained by suppressing the portion emphasized by (e) by the limiter process It is.

  As shown in FIG. 8, the high frequency component (c) of the band determined in advance by the filter 41 is extracted from the input video signal waveform (b) that has become dull with respect to the original waveform (a), and the extracted height After the frequency component (c) is amplified by the amplifier 42, the amplified high frequency component and the video signal (b) delayed by the delay circuit 43 are added at the same timing by the adder 44, and the added signal In (d), the limiter 45 limits the overshoot (dotted line portion in (e)) that occurs before and after the edge portion because the enhancement amount is too large.

  In this case, if the frequency band extracted by the filter 41 is set high (that is, the cutoff frequency is high), a thin vertical line with many high-frequency components has an emphasis effect, but a thick line containing many low-frequency components (for example, a horizontal line) ) Will not work, so the overall effect will be small. Also, if the frequency band of the filter 41 is set low (that is, the cut-off frequency is low), the emphasis is effective even for a thick line with many low frequency components, and the overall effect seems to be improved. Since the low-frequency component originally included in the low-frequency component is emphasized, the disadvantage that the thin line becomes thick occurs.

  By the way, the waveform shaping device in FIG. 7 becomes dull by amplifying the high frequency component extracted from the input waveform, adding it to the input waveform, emphasizing the edge portion, and then cutting off the overshoot before and after the edge portion. The slope of the edge portion of the input waveform is shaped.

  Such processing for improving the rise (or fall) of the video signal (luminance signal) is called LTI (luminance signal rise improvement processing). LTI seeks to improve only the waveform response without overshoot correction.

FIG. 9 and FIG. 10 show processing when a thin vertical line and a thick vertical line, which are problems in the prior art, are mixed.
In particular, as shown in FIG. 10A, when waveform shaping processing is performed by emphasizing the image of the letter “H” of the alphabet, the horizontal scanning line 2 corresponding to the middle position in the vertical direction of the letter “H” is displayed. When there is an image having a thin vertical line → thick line (horizontal line) → thin vertical line, if the band of the filter 41 is set slightly lower, the low-frequency component at a small level of the thin vertical line is emphasized. The vertical line becomes thicker. In the horizontal scanning lines 1 and 2 on the video “H”, the video signal on the line 1 is a short-width pulse signal corresponding to a thin vertical line containing a lot of high-frequency components, and the video signal on the line 2 is This is a long-width pulse signal corresponding to a horizontal line containing many low frequency components. That is, even if the filter 41 is set to a low band, the horizontal line including a large amount of low frequency components with a large level is less emphasized, but a low level component with a low level is also included in the band of the filter 41. The thin vertical line is thickened as a result of the low-frequency component being emphasized. For this reason, as shown in FIG. 10B, the vertical lines are thick and the horizontal lines are hardly thick in the horizontal direction, so that both ends of the horizontal lines are recessed, and the image quality appears to be deteriorated. . As countermeasures, complex processing such as suppressing the emphasis effect in the low frequency band to reduce the adverse effect of FIG. 10B or complicating the filter configuration and combining the high frequency and low frequency band characteristics. Was necessary.

9 is a diagram showing signal waveforms of the video “H” of each part of the waveform response improvement in the apparatus of FIG. 7, and FIG. 10 is a diagram showing an example of the video “H” before and after the waveform response improvement corresponding to the signal waveforms of FIG. It is.
Here, the relationship between the waveform of FIG. 9 and the image of FIG. 10 will be described.
9A shows the input waveform of line 1 in FIG. 10A, FIG. 9B shows the input waveform of line 2 in FIG. 10A, and FIGS. 9C and 9D. 9 (a) and 9 (b) are filter output waveforms when the filter 41 of FIG. 7 is set so as to emphasize low frequency components, and FIGS. 9 (e) and 9 (f) are subjected to limiter processing. The output waveforms of lines 1 and 2 are shown.

  FIG. 10A shows an image “H” before enhancement processing, which is an input image of the apparatus of FIG. FIG. 10B is an image obtained as a result of emphasis.

FIGS. 9A and 9B show the input waveforms at the portions surrounded by circles (indicated by symbol G) on the two horizontal scanning lines 1 and 2 in the video “H” of FIG. ing.
Assume that the input waveforms on lines 1 and 2 are dull with respect to the original waveform (broken line) as shown by the solid lines in FIGS. FIGS. 9C and 9D show filter outputs obtained by passing the input signals on the lines 1 and 2 through the filter 41, respectively.

  FIG. 10B shows an image “H” after enhancement processing, which is an output image of the apparatus of FIG. FIGS. 9E and 9F respectively show output waveforms on the two horizontal scanning lines 1 and 2 in a portion (reference symbol G) surrounded by a circle in the video “H” of FIG. 10B. 9 (e) and 9 (f) show the output of the limiter 45 on the lines 1 and 2, respectively.

  As for the thin vertical line in the video “H” before the enhancement processing in FIG. 10A, the output after the enhancement processing in FIG. 10B shows that the video on the line 1 has a thick width indicated by hatching (hatching). It becomes a vertical line. 9 (e) and 9 (f), the output waveform of line 1 shown in FIG. 9 (e) is black and gray close to that of the input waveform of line 1 shown in FIG. 9 (a). The width of the line becomes thicker by ΔL on the left and right. On the other hand, since the video of the horizontal line on the line 2 is hardly thick as described above, it has a shape in which both ends of the horizontal line are recessed.

By the way, as a prior art of the above LTI, there is, for example, Patent Document 1. Patent Document 1 discloses a correction for strengthening coring, a correction for reducing peaking, and a signal rise for a component signal (YCbCr) of a digital SD (Standard Definition) broadcast 480i as compared with image quality correction for other component signals. It is described that the digital noise of the digital SD broadcast 480i is reduced by performing at least one of the correction (LTI) for making the image steep, or making the correction characteristics different.
However, in Patent Document 1, when image quality correction is performed on a video signal such as a character in which thin vertical lines and horizontal lines are combined, many high frequency components are included from thick lines that include many low frequency components. There is no mention of making improvements so that even thin lines are effective.
JP-A-2005-65326

  Therefore, in view of the above problems, the present invention, when performing LTI correction on a video signal such as a character in which thin vertical lines and horizontal lines are combined, causes a high frequency component from a thick line containing many low frequency components. An object of the present invention is to provide a waveform shaping device and a waveform shaping method that are effective even for thin lines containing a large amount of.

  According to the first aspect of the present invention, there is provided a waveform shaping device in a digital processing system for processing a video signal, wherein a maximum value and a minimum value are determined from a plurality of data within a predetermined range before and after the current data. Means for obtaining the difference between the average of the maximum value and the minimum value and the current data, amplifying the difference value and adding it to the current data as an enhancement component, and adding the added data to the maximum value There is provided a waveform shaping device comprising: means for outputting within a range between the minimum value and the minimum value.

  According to a second aspect of the present invention, there is provided a waveform shaping device in a digital processing system for processing a video signal, wherein a plurality of stages of extracting current data and a plurality of data within a predetermined range before and after the current data. A delay unit having a delay unit; a unit for detecting a maximum value and a minimum value from the current data from the delay unit and a plurality of data before and after the delay unit; and adding the detected maximum value and minimum value to obtain an average. Means for subtracting the average value from the current data and amplifying the difference; means for adding the amplified difference value to the current data as an enhancement component; and adding the added data to the maximum There is provided a waveform shaping device comprising: means for outputting within a range between a value and a minimum value.

  According to a third aspect of the present invention, there is provided a waveform shaping device in a digital processing system for processing a video signal, the magnitude comparison means for judging whether input data is larger or smaller than the previous data, A first delay means having a plurality of delay sections for delaying input data by a predetermined number of stages; and a plurality of stages for delaying a result of size comparison determined by the size comparison means by the predetermined number of stages. A second delay unit having a delay unit, a unit for detecting an inflection point where the result of the magnitude comparison is reversed with reference to outputs of a plurality of stages of the second delay unit, and the inflection point If detected, the data at the inflection point closest to the front and rear from the current data to be processed is output from the first delay means as the maximum value or the minimum value, and the inflection point does not exist If A means for outputting the data at the farthest phase within the range of the predetermined number of stages as the minimum value or the maximum value from the first delay means, the average of the maximum value and the minimum value, and the current data Means for obtaining a difference, amplifying the difference value and adding it to the current data as an emphasis component, and means for outputting the summed data within the range between the maximum value and the minimum value A waveform shaping device is provided.

  According to a fourth aspect of the present invention, there is provided a waveform shaping method in a digital processing system for processing a video signal, wherein a maximum value and a minimum value are determined from current data and a plurality of data within a predetermined range before and after the current data. Determining the difference between the average of the maximum and minimum values and the current data, amplifying the value and adding it to the current data, and adding the added data to the maximum and minimum values. There is provided a waveform shaping method characterized by comprising the step of outputting within the range.

  According to a fifth aspect of the present invention, there is provided a waveform shaping method in a digital processing system for processing a video signal, the step of determining whether input data is larger or smaller than the previous data, and the determination A step of delaying the magnitude comparison result and the input data by a predetermined number of delay stages, a step of detecting an inflection point at which the polarity of the magnitude comparison result is inverted, and a process when the inflection point is detected. The data at the inflection point closest to each of the current data to be performed is output as the maximum value or the minimum value, and when the inflection point does not exist, the range of the predetermined number of delay stages A step of outputting the data at the farthest phase as a minimum value or a maximum value, and a step of outputting the summed data within the range between the maximum value and the minimum value , Waveform shaping method is characterized in that comprising a are provided.

  According to the present invention, when LTI correction is performed on a video signal such as a character in which a thin vertical line and a horizontal line are combined, a thin line that contains many high frequency components from a thick line that contains many low frequency components. It is possible to provide a waveform shaping device that is effective evenly up to the line.

Embodiments of the invention will be described with reference to the drawings.
An embodiment of the present invention is a waveform shaping device that improves the image quality by setting an edge of a luminance signal that has become dull due to attenuation of a high-frequency component that occurs in the transmission system or in the process of signal processing. By detecting the minimum value and emphasizing the difference between the average of the maximum and minimum values and the current data, it is uniform from a thick line containing many low frequency components to a thin line containing many high frequency components. Make an effect.

[First Embodiment]
FIG. 1 shows a block diagram of a waveform shaping device according to a first embodiment of the present invention.
The waveform shaping device 10 shown in FIG. 1 is provided corresponding to each of the delay circuits 11 and 12, with delay means including a delay circuit 11 to which input data is supplied and a delay circuit 12 cascaded to the delay circuit 11. Maximum value / minimum value detection means using the maximum value / minimum value detection circuits 13 and 14, an arithmetic circuit 15 having a differentiation function including a digital filter, an amplifier 16, an adder 17, and an output signal And a limiter 18 for limiting the amplitude of the waveform. Here, the data corresponds to sampling data that is latched every clock, for example, dot data. The dot data is one piece of data constituting the number of display dots (resolution) of the display device, and is usually constituted by a predetermined number of bits (for example, 8 bits).

The delay circuit 11 includes a plurality of stages of delay units and is means for delaying input data by a predetermined number of stages, and extracts a predetermined number of data (hereinafter referred to as subsequent data) after the current data to be processed. This is a delay circuit.
The delay circuit 12 includes a plurality of stages of delay units, and is a means for delaying the data output from the delay circuit 11 by a predetermined number of stages, and a predetermined number of data (hereinafter referred to as the following data) that precedes the current data to be processed. This is a delay circuit for extracting the previous data.

  Each of the delay circuits 11 and 12 is configured by cascading a predetermined number of stages of one-stage delay circuits. The predetermined number of stages in the delay circuits 11 and 12 corresponds to a detection range determined before and after the current data. The one-stage delay circuit is composed of a data latch circuit. Each of the delay circuits 11 and 12 delays data by sequentially shifting the input data to a predetermined number of data latch circuits corresponding to a predetermined number of stages every clock. The data at the connection point of the delay circuits 11 and 12 is the current data.

  The maximum value / minimum value detection circuit 13 is means for detecting and extracting data indicating the maximum value or the minimum value from the current and subsequent data groups. The maximum value / minimum value detection circuit 14 is means for detecting and extracting data indicating the minimum value or the maximum value from the current and previous data groups.

  Therefore, the maximum value / minimum value detection circuits 13 and 14 obtain and extract the maximum value and the minimum value from data within a predetermined range before and after the current data. As a method for detecting the maximum value and the minimum value, the maximum value and the minimum value may be found by comparing the numerical values from a plurality of data within a predetermined range, or a plurality of data within a predetermined range. From this, first, the peak may be detected, and the maximum value or the minimum value may be found from those detected.

  The arithmetic circuit 15 is a differentiation circuit composed of, for example, a digital filter, and adds an adder 151 that adds two data of a maximum value and a minimum value, reverses the polarity of the addition output of the adder 151, and reduces the amplitude to 1 /. 1 and 2 and an adder 153 for adding the inverted output from the 1/2 inversion circuit 152 to the current data, and the average value of the maximum value and the minimum value is determined as the current data. The difference value is obtained by subtracting from the value of. The amplifier 16 amplifies the difference value. The adder 17 adds the signal amplified by the amplifier 16 to the current data, and outputs a signal in which the edge portion of the current data is emphasized.

The limiter 18 limits the output of the adder 17 in a range between a maximum value and a minimum value (limit range). When the result of addition by the adder 17 exceeds the maximum value and the minimum value, the maximum value or Replace with the minimum value and limit it so that it does not exceed that value.
When the current data is the maximum value or the minimum value, the current data is limited by its own data.

Next, the operation of the apparatus shown in FIG. 1 will be described with reference to FIG.
FIG. 2 is a diagram for explaining the signal processing method of FIG. In FIG. 2, the horizontal axis represents time, and the vertical axis represents the data size.
The delay circuits 11 and 12 extract data before and after the current data to be processed within a specified range (detection range), and extract the closest maximum value and minimum value from the current data. The average value of the maximum and minimum values obtained is taken, the difference value subtracted from the current data is amplified and added to the current value, and then limited and output within the limit range between the maximum and minimum values. . As shown in FIG. 1, data at intermediate positions of the delay circuits 11 and 12 are also supplied to the maximum / minimum value detection circuits 13 and 14, respectively, and the maximum and minimum values including the current data are detected. I am doing so.

  In the example of FIG. 2, the maximum value / minimum value detection circuits 13 and 14 sequentially compare adjacent data in time from the current data in order to the maximum value and minimum value within the specified range. When a value is detected, the data before the current data is the maximum value, and the data after the third data is the minimum value. Since the average value of the maximum value and the minimum value is smaller than the current data, when the difference value obtained by subtracting the average value from the current data is added to the current data by the adder 17, the current data When the maximum value is exceeded, limit processing is performed to replace the maximum value.

  In the maximum value / minimum value detection circuit 13, the data value decreases as the data (right side in FIG. 2) after the current data (data indicated by hatching in FIG. 2) output from the delay circuit 11 is reached. The data corresponding to one boundary of the detection range (the right end of the detection range) is detected as the minimum value. Further, the maximum value / minimum value detection circuit 14 detects the data value which increases and decreases as it goes to the data (left side in FIG. 2) before the current data (data shown by hatching in FIG. 2). The data at the point where the data is reversed from increase to decrease (inflection point) before the other boundary of the range (the left end of the detection range) is detected as the maximum value.

  As described above, in the example of FIG. 2, when data before and after the current data is searched, there is one peak point where the polarity of the data inverts within the detection range (that is, when there is one maximum value candidate). However, in the first embodiment, even when there are a plurality of maximum values and minimum values in the detection range (when there are a plurality of so-called inflection points), the largest value in the detection range is obtained. The maximum value is detected, and the smallest value is detected as the minimum value.

3 and 4 are diagrams showing the effect of this embodiment. FIG. 3 is a diagram showing a signal waveform of a specific video “H” of each part of the waveform response improvement in the apparatus of FIG. 1, and FIG. 4 is an example of a video “H” before and after the waveform response improvement corresponding to the signal waveform of FIG. FIG.
3 (a) and 3 (b) show the input waveforms of line 1 and line 2 in the horizontal scan of the input video “H” in FIG. It is the figure which showed the average value of the maximum value calculated by the arithmetic circuit 15 when using embodiment of this invention, and the minimum value.

  3 (c) and 3 (d) are waveforms obtained by subtracting the average values shown in FIGS. 3 (a) and 3 (b) from the input waveforms indicated by the solid lines in FIGS. 3 (a) and (b), respectively. The emphasis signal is added for waveform shaping. 3 (e) and 3 (f) are waveforms after the waveform response is improved, and FIG. 4 (B) is an image of the result of the waveform response improvement after passing through the limiter 18.

As shown in FIGS. 3 and 4, in the present invention, regardless of the frequency spectrum of the input waveform, the maximum value and the minimum value of the slope in which the data to be processed are obtained to perform the process of raising the slope. Waveform shaping (waveform response) uniformly from a thick line containing a lot of low frequency components to a thin line containing a lot of high frequency components. Less likely to occur.
According to the first embodiment, when the LTI (waveform response improvement) correction is performed on a video signal such as a character in which a thin vertical line and a horizontal line are combined, a thick line that contains many low frequency components is used. It is possible to obtain an effect uniformly even for a thin line containing many high frequency components.

[Second Embodiment]
FIG. 5 shows a block diagram of a waveform shaping apparatus according to the second embodiment of the present invention.
The waveform shaping device 20 shown in FIG. 5 includes a first delay means including a delay circuit 21 to which input data is supplied, a delay circuit 22 connected in cascade to the delay circuit 21, a magnitude comparison circuit 23, and a second comparison circuit 23. A shift register 24, a polarity inversion detection circuit 25, a selector 26 to which the output of each stage of the delay circuit 21 is input, and a selector 27 to which the output of each stage of the delay circuit 22 is input. And a minimum value output means, an arithmetic circuit 28 having a differentiation function composed of a digital filter or the like, an amplifier 29, an adder 30, and a limiter 31 for limiting the amplitude of the output signal waveform.

  The delay circuit 21 includes a plurality of stages of delay units and is a means for delaying input data by a predetermined number of stages, and is a circuit for extracting current data and a plurality of subsequent data as in FIG. The delay circuit 22 includes a plurality of stages of delay units, and is a means for delaying input data by a predetermined number of stages, and is a circuit for extracting current data and a plurality of previous data. The delay circuit 21 and the delay circuit 22 constitute first delay means for delaying input data by a predetermined number of stages.

  The size comparison circuit 23 is a circuit that performs a size comparison between input data and the previous data. For example, (previous data) − (input data) is positive (the horizontal axis is time, the vertical axis is If the data size is reduced to the right), “1” is output, and if it is negative (upward to the right), “0” is output and input to the shift register 24. The shift register 24 has the number of stages (the number of taps) corresponding to (total number of stages of the delay circuits 21 and 22 as the first delay means) −1, and the magnitude comparison result (the above “1”) of the magnitude comparison circuit 23. , '0' phase) is delayed by a predetermined number of stages.

The shift register 24 includes a plurality of stages of delay units, and constitutes second delay means for delaying the magnitude comparison result determined by the magnitude comparison circuit 23 by the same predetermined number of stages as the first delay means. Yes. Therefore, a number sequence of “1” and “0” corresponding to the lower right and the upper right is output from the tap of each stage of the shift register 24.
The polarity inversion detection circuit 25 is a circuit that detects an inflection point at which the phase “1” or “0” of each tap of the shift register 24 is inverted.
The selector 26 selects and outputs the data corresponding to the inflection point closest to the current data detected by the polarity inversion detection circuit 25 with respect to the subsequent data from the delay circuit 21.
The selector 27 selects and outputs data corresponding to the inflection point closest to the current data of the polarity inversion detection circuit 25 with respect to the previous data from the delay circuit 22.

  The selector 26 and the selector 27 maximize the data corresponding to the inflection point closest to the current data detected by the polarity inversion detection circuit 25 for a plurality of data within the range of the number of stages predetermined by the first delay means. Maximum value and minimum value output means for outputting as a value or minimum value. That is, the selector 26 and the selector 27 search for an inflection point whose polarity is reversed before and after the phase of the current data to be processed, and when there is an inflection point, the data of the inflection point is obtained. The maximum or minimum value is output. If there is no inflection point, the data farthest from the current data is output as the minimum or maximum value within a predetermined number of steps (detection range). To do.

  The arithmetic circuit 28 is an arithmetic circuit that obtains the average of the maximum value and the minimum value output from the maximum value and minimum value output means and subtracts it from the current data to be processed. The arithmetic circuit 28 includes an adder 281 for inputting and adding two data of the maximum value and the minimum value, and a 1/2 inversion circuit for inverting the polarity of the addition output of the adder 281 and reducing the amplitude to ½. 282 and an adder 283 that adds the inverted output from the 1/2 inversion circuit 282 to the current data, and obtains a difference value by subtracting the average value of the maximum value and the minimum value from the value of the current data. Is.

The amplifier 29 amplifies the difference value. The adder 30 adds the signal amplified by the amplifier 29 to the current data as an enhancement component, thereby outputting a signal in which the edge portion of the current data is enhanced.
The limiter 31 limits the output of the adder 30 in a range between a maximum value and a minimum value (limit range). When the result of addition by the adder 30 exceeds the maximum value and the minimum value, the maximum value or Replace with the minimum value and output so that the value is not exceeded.
The amplifier 29, the adder 30 and the limiter 31 are circuits corresponding to the amplifier 16, the adder 17 and the limiter 18 of FIG.

Next, the operation of the apparatus shown in FIG. 5 will be described with reference to FIG.
FIG. 6 is a diagram illustrating a signal processing method. In FIG. 6, the horizontal axis indicates time, and the vertical axis indicates the data size.
In the example of FIG. 6, the individual data of the delay circuits 21 and 22 are not compared, but the input data is compared with the previous data and the result is delayed by the shift register 24, and the predetermined number of stages is determined. When polarity reversal exists in the range of, the data corresponding to the point of inversion closest to the current data (inflection point) is output as the maximum or minimum value, and polarity reversal does not exist In such a case, the farthest data in the range of predetermined number of stages (detection range) is output as the minimum value or the maximum value. That is, the closest inflection point of the current data is output as the maximum value or the minimum value. In this example, there is no polarity reversal on the back side of the current data, so the data that is the third farthest in the predetermined range is output as the minimum value.

The effects of the second embodiment are the same as the effects described in FIGS. 3 and 4 in the first embodiment. As a result of the experiment, an improvement in waveform response similar to that of the first embodiment was obtained.
According to the second embodiment, when correction of LTI (waveform response improvement) is performed on a video signal such as a character in which a thin vertical line and a horizontal line are combined, a thick line containing many low frequency components is used. It is possible to obtain an effect uniformly even for a thin line containing many high frequency components.

1 is a block diagram of a waveform shaping device according to a first embodiment of the present invention. The figure explaining the signal processing method of FIG. The figure which shows the signal waveform of the specific image | video of each part of the waveform response improvement in the apparatus of FIG. The figure which shows the example of the image | video before and after the waveform response improvement corresponding to the signal waveform of FIG. The block diagram of the waveform shaping apparatus of the 2nd Embodiment of this invention. The figure explaining the signal processing method of FIG. The block diagram of the waveform shaping apparatus of a prior art example. The figure which shows the general signal waveform of each part of the waveform response improvement in the apparatus of FIG. The figure which shows the signal waveform of the specific image | video of each part of the waveform response improvement in the apparatus of FIG. The figure which shows the example of the image | video before and behind the waveform response improvement corresponding to the signal waveform of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Waveform shaping device 11, 12 ... Delay circuit 13, 14 ... Maximum value / minimum value detection circuit 15 ... Operation circuit 16 ... Amplifier 17 ... Adder 18 ... Limiter 20 ... Waveform shaping device 21, 22 ... Delay circuit 23 ... Large and small Comparison circuit 24 ... Shift register 25 ... Polarity inversion circuit 26,27 ... Selector 28 ... Operation circuit 29 ... Amplifier 30 ... Adder 31 ... Limiter

Claims (5)

A waveform shaping device in a digital processing system for processing a video signal,
Means for obtaining maximum and minimum values from current data and a plurality of data within a predetermined range before and after the current data;
A means for obtaining a difference between the average of the maximum value and the minimum value and the current data, amplifying the difference value, and adding it to the current data as an enhancement component;
Means for restricting and outputting the added data within the range between the maximum value and the minimum value;
A waveform shaping device comprising: A waveform shaping device in a digital processing system for processing a video signal,
A delay unit having a plurality of stages of delay units for extracting current data and a plurality of data within a predetermined range before and after the current data;
Means for detecting a maximum value and a minimum value from the current data from the delay means and a plurality of data before and after the data;
Means for adding the detected maximum and minimum values to obtain an average;
Means for subtracting this average value from the current data to obtain a difference and amplifying it;
Means for adding the amplified difference value to the current data as an emphasis component;
Means for restricting and outputting the added data within the range between the maximum value and the minimum value;
A waveform shaping device comprising: A waveform shaping device in a digital processing system for processing a video signal,
A size comparison means for determining whether the input data is larger or smaller than the previous data;
First delay means having a plurality of stages of delay units for delaying the input data by a predetermined number of stages;
A second delay unit having a plurality of delay units for delaying a result of the size comparison determined by the size comparison unit by the predetermined number of stages;
Means for detecting an inflection point where the polarity of the result of the magnitude comparison is reversed with reference to the outputs of the plurality of stages of the second delay means;
When the inflection point is detected, the data at the inflection point closest to the front and rear from the current data to be processed is output from the first delay means as the maximum value or the minimum value, and the inflection point is output. If there is no point, means for outputting the data at the farthest phase within the range of the predetermined number of stages as the minimum value or the maximum value from the first delay means;
Means for obtaining the difference between the average of the maximum and minimum values and the current data, amplifying the difference value and adding it to the current data as an enhancement component;
Means for restricting and outputting the added data within the range between the maximum value and the minimum value;
A waveform shaping device comprising: A waveform shaping method in a digital processing system for processing a video signal,
Obtaining a maximum value and a minimum value from a plurality of data within a predetermined range before and after the current data; and
Calculating the difference between the average of the maximum and minimum values and the current data, amplifying the value and adding it to the current data;
Limiting and outputting the added data within the range between the maximum value and the minimum value; and
A waveform shaping method comprising: A waveform shaping method in a digital processing system for processing a video signal,
Determining whether the input data is larger or smaller than the previous data;
Delaying the determined magnitude comparison result and the input data by a predetermined number of delay stages;
Detecting an inflection point where the result of the magnitude comparison is polarity inversion;
When the inflection point is detected, the current data to be processed is output as the maximum or minimum value of the data at the inflection point closest to the front and rear, and the inflection point does not exist The step of outputting the data at the farthest phase within the range of the predetermined number of delay stages as a minimum value or a maximum value;
Limiting and outputting the added data within the range between the maximum value and the minimum value; and
A waveform shaping method comprising:

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