KR20130026257A - Method for improving the sharpness and display apparatus using the same - Google Patents

Abstract

PURPOSE: A definition improving method and a display device using the same are provided to improve image quality while minimizing the degradation of the image quality by changing a definition level of an input image according to an edge level of each input image. CONSTITUTION: A calculating unit(431) of an image data processing unit(430) calculates a WAEL(Weighted Average Edge Level) according to each frame of an input image. The calculating unit extracts a definition level matched with the calculated WAEL from a storage unit(433) to determine the definition level to be applied to each frame. A converting unit(432) of the image data processing unit changes the definition of the input image according to the calculated definition level. [Reference numerals] (410) Receiving unit; (421,422) Data control signal generating unit; (431) Calculating unit; (432) Converting unit; (433) Storage unit

Description

METHOOD FOR IMPROVING THE SHARPNESS AND DISPLAY APPARATUS USING THE SAME}

The present invention relates to a method for improving the sharpness of an image output from the display device and a display device using the same.

Display devices such as TVs are being developed toward higher resolution and higher definition in accordance with user requirements.

1 is an exemplary view showing an image made according to a conventional method of improving sharpness, (a) shows a menu for changing the sharpness level in the display device, (b) shows an image with high definition, ( c) shows an image of a state in which the high-definition image shown in (b) is changed to a state where the horizontal brightness level is increased by a menu as shown in (a).

The display apparatus is provided to the user in a state of being set at a sharpness level at which high definition can be achieved according to the user's request as described above.

In addition, since the sharpness may be different for each user, the user who purchases the display device may change the sharpness level according to a menu provided by the display device in order to obtain a clearer picture quality according to the sensitivity felt by the user.

Such sharpness may be divided into horizontal sharpness representing horizontal sharpness and vertical sharpness representing vertical sharpness, and the user may obtain a desired sharpness by resetting the horizontal sharpness or vertical sharpness level.

However, the conventional method for improving sharpness as described above adjusts the sharpness constantly to the sharpness level preset by the manufacturer or the user for all images, and thus, in the case of an image that already has high sharpness, Defects may occur.

For example, FIG. 1A illustrates a menu for allowing a user to set a horizontal brightness on a display device.

When the manufacturer or the user sets the level of the horizontal brightness higher, the horizontal brightness output through the display device may be improved. Here, the horizontal line brightness means the sharpness of the left and right sides of the vertical line as shown in (a).

Therefore, as the horizontal line brightness increases, the sharpness in the left and right directions of the vertical line increases.

However, in the above case, the sharpness of the image such as the vertical line may be increased, but rather, the sharpness of the image such as the horizontal line may be reduced.

In particular, in the case of a horizontal line made of high definition for testing or the like as shown in (b), an artificial defect (A) as shown in (c) is rather increased according to an increase in the horizontal brightness set in (a). ) May be generated.

In other words, the conventional method of improving sharpness applies fixed sharpness according to a predetermined sharpness level (viewing mode) regardless of the edge level of the image, and thus, in the case of a high-definition image, Defects may occur.

In detail, the conventional method for improving sharpness applies a constant fixed sharpness level regardless of edge level characteristics of an image. Therefore, in a high definition image having a high edge level, which is output from a display device in which the sharpness is set to a high level, artifacts may occur rather.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and calculates an edge level for each input image, so that the sharpness level of the input image can be varied according to the degree of the edge level, and a display device using the same. To provide a technical problem.

According to an aspect of the present invention, there is provided a method of improving sharpness, the method including: calculating an edge value E for each pixel for each frame of an input image; Calculating a cumulative frequency histogram (H) using the edge values; Calculating a weighted average edge level (WAEL) using the cumulative frequency histogram; Extracting a sharpness level matched with the calculated weighted average edge level WAEL; And converting the sharpness of the input image by using the extracted sharpness level.

According to an aspect of the present invention, there is provided a display apparatus using a method for improving sharpness, comprising: a storage unit configured to store a sharpness level set for each weighted average edge level WAEL; A calculator for calculating a weighted average edge level (WAEL) for each frame of the input image, and extracting a sharpness level matched with the calculated weighted average edge level from the storage unit; And a converter for converting the sharpness of the input image by using the extracted sharpness level.

According to the above solution, the present invention provides the following effects.

That is, the present invention calculates an edge level for each input image and varies the sharpness level of the input image according to the degree of the edge level, thereby providing an effect of improving image quality while minimizing image quality deterioration. .

In detail, the present invention provides an effect of providing a clearer image by minimizing artificial defects by differently applying a gain of an image according to an edge level of an input image. .

1 is an exemplary view showing an image made according to a conventional method of improving sharpness.
2 is an exemplary view showing a configuration of a display apparatus using a method for improving sharpness according to the present invention.
3 is an exemplary view showing an internal configuration of a timing controller applied to a display device using a method for improving sharpness according to the present invention.
4 is an exemplary view showing an input image and a horizontal edge and a vertical edge applied to a method for improving sharpness according to the present invention.
5 is an exemplary view showing a cumulative frequency histogram of horizontal and vertical edges calculated through a method for improving sharpness according to the present invention.
6 is an exemplary view showing a cumulative frequency histogram of a general image and a pattern image calculated by the method for improving sharpness according to the present invention.
7 is a graph showing the relationship between the sharpness level and WAEL applied to the sharpness improvement method according to the present invention.

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

2 is an exemplary view showing a configuration of a display apparatus using a method for improving sharpness according to the present invention.

As shown in FIG. 2, the display apparatus using the sharpness improving method according to the present invention includes a data driver 300 for driving the data lines DL1 to DLm and a gate driver 200 for driving the gate lines GL1 to GLn. ), A panel 100 driven by the data driver and the gate driver, and a timing controller 400 controlling the data driver 300 and the gate driver 200.

The display device using the sharpness improvement method according to the present invention is a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), an electroluminescent device ( Although it may be implemented as a flat panel display device such as an electroluminescence device (EL), an electrophoretic display device (EPD), etc., for convenience of description, a liquid crystal display (LCD) is described as an example of the present invention.

First, the panel 100 may be formed in various forms according to what kind of flat panel display device the display device using the method for improving clarity according to the present invention is used. As described above, the liquid crystal display device is an example of the present invention. If so, the panel 100 may be configured such that a liquid crystal layer is formed between two glass substrates.

In this case, as shown in FIG. 2, the lower glass substrate of the panel 100 includes a plurality of data lines DL1 to DLm, a plurality of gate lines GL1 to GLn intersecting the data lines, and a data line. Thin film transistors (TFTs) formed at intersections of the gates DL1 to DLm and the gate lines GL1 to GLn, and a plurality of pixel electrodes for charging data voltages to the liquid crystal cells Clc. And a storage capacitor (Cst) connected to the pixel electrode to maintain the voltage of the liquid crystal cell Clc. Meanwhile, liquid crystal cells (called pixels or pixels) are arranged in a matrix form by the cross structure of the data lines DL1 to DLm and the gate lines GL1 to GLn.

Here, the storage capacitor Clc is composed of a liquid crystal positioned between the pixel electrode and the common electrode connected to the thin film transistor TFT. The thin film transistor TFT is turned on by the gate-on voltages from the gate lines GL1 to GLn to supply the data voltages from the data lines DL1 to DLm to the pixel electrodes to supply the data voltage, the common voltage Vcom, and the differential voltage. The liquid crystal capacitor Clc is charged.

The thin film transistor TFT is turned off by the gate-off voltage Voff applied from the gate lines GL1 to GLn to maintain the voltage charged in the liquid crystal capacitor Clc. In this case, the storage capacitor Cst keeps the voltage charged in the liquid crystal capacitor Clc stable.

A black matrix BM, a color filter CF, a common electrode, and the like are formed on the upper glass substrate of the panel 100. The common electrode is formed on the upper glass substrate in the vertical electric field driving method such as twisted nematic (TN) mode and vertical alignment (VA) mode, and the horizontal electric field driving method such as IPS (In Plane Switching) mode and FFS (Fringe Field Switching) mode. Is formed on the lower glass substrate together with the pixel electrode. A polarizing plate is attached to each of the upper and lower glass substrates of the panel 100, and an alignment layer for setting the pretilt angle of the liquid crystal is formed on an inner surface of the panel 100 in contact with the liquid crystal. A column spacer CS may be formed between the upper glass substrate and the lower glass substrate of the panel 100 to maintain a cell gap of the liquid crystal cell.

Next, the gate driver 200 sequentially shifts the gate start pulse GSP transmitted from the timing controller 400 according to the gate shift clock GSC, and sequentially shifts the gate lines GL1 to GLn. The scan pulse having the gate-on voltage Von is supplied. The gate driver 200 supplies the gate-off voltage Voff to the gate lines GL1 through GLn in the remaining periods in which the scan pulse of the gate-on voltage Von is not supplied.

Meanwhile, the gate driver 200 applied to the present invention may be configured to be independent from the panel and be electrically connected to the panel in various ways. However, the gate driver 200, which is a gate in panel : GIP) method.

In this case, control signals for controlling the gate driver 200 may be a start signal VST and a gate clock GCLK.

Next, the data driver 300 converts the input image data into an analog pixel signal (image data signal) and supplies one horizontal line of image data signal to the data lines every one horizontal period during which the scan signal is supplied to the gate line. do. That is, the data driver 300 converts the image data into an image data signal using the gamma voltages supplied from the gamma voltage generator (not shown) and outputs the image data to the data line.

That is, the data driver 300 generates a sampling signal by shifting a source start pulse (SSP) from the timing controller 400 according to a source shift clock (SSC). The data driver 300 latches the pixel data RGB (image data) input according to the source shift clock SSC according to the sampling signal and then responds to the source output enable signal. Supply in horizontal lines.

To this end, the data driver 300 may include a data sampling unit, a latch unit, a digital analog converter, an output buffer, and the like.

Finally, the timing controller 400 uses timing signals such as vertical and horizontal synchronization signals Vsync and Hsync, data enable DE, and dot clock DCLK input from an external system. The data control signal DCS for controlling the control signal is generated, and the gate control signal GCS for controlling the gate driver 200 is generated.

The data control signal DCS includes a source shift clock SSC, a source start pulse SSP, a polarity control signal POL, a source output enable signal SOE, and the like.

As described above, the gate control signal GCS becomes a gate start pulse GSP, a gate shift clock GSC, a gate output enable signal GOE, or the start signal VST depending on the configuration of the gate driver. And the gate clock GCLK.

On the other hand, the timing controller 400 applied to the present invention is characterized by improving the sharpness of the input image based on the weighted average edge level (WAEL).

That is, the timing controller calculates the weighted average edge level WAEL for each frame of the image data input from the external system, and then controls the sharpness to a level that matches the calculated weighted average edge level. This function is to make the output more clear.

Detailed configurations and functions of the timing controller for performing such a function will be described below in detail with reference to FIGS. 3 to 6.

On the other hand, when the display device using the method of improving the sharpness according to the present invention is composed of liquid crystal display devices as described above, the display device using the sharpness improving method according to the present invention may further include a backlight unit.

In addition, when the display device using the sharpness improvement method according to the present invention is configured as a flat panel display device other than the liquid crystal display device, the display device using the sharpness improvement method according to the present invention may have various components for each flat panel display device. The panel 100, the gate driver 200, the data driver 300, and the timing controller 400 may be basically included as described above.

3 is an exemplary view showing an internal configuration of a timing controller applied to a display device using a method for improving sharpness according to the present invention. 4 is an exemplary view illustrating an input image and a horizontal edge and a vertical edge thereof applied to a method for improving sharpness according to the present invention. In addition, Figure 5 shows the cumulative frequency histogram of the horizontal edge and the vertical edge calculated through the sharpness improvement method according to the present invention, (a) shows a cumulative frequency histogram for the horizontal edge (edge), (b) Is the cumulative frequency histogram of the vertical edge. 6 shows a cumulative frequency histogram of the general image and the pattern image calculated by the method for improving sharpness according to the present invention, (a) shows the cumulative frequency histogram of the general image, and (b) the pattern image. The cumulative frequency histogram is shown. 7 is an exemplary graph showing the relationship between the sharpness level and WAEL applied to the sharpness improving method according to the present invention.

The timing controller 400 applied to the present invention includes a gate for controlling the gate drive driver 200 by using the vertical / horizontal synchronization signals Vsync and Hsync and a dot clock DCLK supplied from an external system (not shown). The control signal GCS and the data control signal DCS for controlling the data driver 300 are output, and the image data received from the external system is rearranged and output to the data driver.

On the other hand, the timing controller 400 calculates the weighted average edge level WAEL for each frame with respect to the image data input from the external system as described above, and then reaches a level matching the calculated weighted average edge level. By controlling the sharpness, the input image is output more clearly.

To this end, the timing controller, as shown in FIG. 3, receives a receiver 410 and an image data (Data) for receiving image data (Data) and timing signals (Vsync, Hsync, DE, DCLK, etc.) from an external system. A weighted average edge level WAEL is calculated for each frame of the input image using the image data processor 430 and the gate driver for varying the clarity of the image data according to the calculated weighted average edge level WAEL. And a control signal generator 420 for generating a gate control signal GCS for controlling the data and a data control signal DCS for controlling the data driver. In addition, although not shown in the drawing, the timing controller 400 may further include an internal clock generator VCO for generating a necessary internal clock inside the timing controller.

First, the receiver 410 is a timing signal and image data (RGB) such as a vertical synchronization signal (Vsync), a horizontal synchronization signal (Hsync), a dot clock (DCLK), a data enable (DE) signal from an external system (not shown). ), And, in particular, may be configured through the LVDS interface.

Here, LVDS is a high-speed digital interface. In LVDS, two signals having opposite polarities are generated, and the two signals are referred to each other to transmit data. Therefore, LVDS is capable of realizing data transmission at low voltage, and thus has low power consumption, high transmission speed, and excellent resistance to noise.

The receiver 410 is connected to an LVDS transmitter (not shown) of an external system, and includes a PLL therein. The PLL may perform a function of maintaining a constant frequency (phase) of an input signal (image data and timing signal) transmitted from an external system and an output signal output from the receiver 410.

Next, as shown in FIG. 3, the control signal generator 420 may include a gate control signal generator 421 and a data control signal generator 422.

Here, the gate control signal generator 421 inputs a timing signal (vertical / horizontal synchronization signals Vsync and Hsync), a data enable signal (Data Enable), and a dot clock (CLK) input from the receiver 410. In response, the gate control signal GCS generates and outputs a gate control signal GCS for controlling an operation timing of the gate driver 200. As described above, the gate control signal GCS may be GSP, GSC, GOE, or the like, or may be VST, GCKL, or the like, depending on the configuration of the gate driver.

In addition, the data control signal generator 422 receives the timing signal as described above, and generates and outputs a data control signal DCS for controlling the operation timing of the data driver 300.

Finally, the image data processor 430 calculates the weighted average edge level WAEL for each frame of the input image using the image data Data received from the external system through the receiver 410, and the calculated weighted average. This function performs the function of changing the sharpness of the image data according to the edge level WAEL and outputting it. Meanwhile, hereinafter, the input image may be used as a meaning of an image continuously received through the receiver, but may also be used as a meaning of an image corresponding to one frame. That is, the present invention calculates the weighted average edge level WAEL for each frame of the input image received through the receiver, and converts the input image for each frame according to the weighted average edge level WAEL. The input image that is converted into is an input image corresponding to one frame among input images continuously received.

To this end, as illustrated in FIG. 3, the image data processor 430 receives from an external system through a storage unit 433 and a receiver 410 for storing a sharpness level set for each weighted average edge level WAEL. The weighted average edge level WAEL is calculated for each frame of the input image using the extracted image data, while the sharpness level matching the calculated weighted average edge level WAEL is extracted from the storage unit every frame. And a converter 431 for determining a sharpness level to be applied to the image and a converter 432 for varying and outputting the sharpness of the input image according to the sharpness level calculated by the calculator. That is, the image data processing unit 430 largely calculates the weighted average edge level WAEL of the input image and determines the sharpness level matched therewith, and the calculated weighted average edge level WAEL ( Hereinafter, the image may be divided into a conversion unit 432 for changing the sharpness of the input image according to simply referred to as 'WAEL'.

Here, the storage unit 433 stores a sharpness level set for each weighted average edge level WAEL. That is, the storage unit 433 stores information corresponding to the graph illustrated in FIG. 7 in the form of a lookup table.

For example, if the present invention improves the sharpness of the input image using the graph as shown in FIG. 7, the sharpness level is set to 85 when the WAEL is 40, and the sharpness when the WAEL is 70. The level is set to 20. In addition, for WAELs having other values, matching sharpness levels are set according to a graph as shown in FIG.

In addition, the calculator 431 calculates a WAEL for each frame of the input image, and determines a sharpness level to be applied to each frame by using the calculated WAEL.

To this end, when the input image as shown in FIG. 4 is received, the calculation unit includes a cumulative frequency histogram of a horizontal edge of the input image as shown in FIG. 5A and FIG. 5B. The cumulative frequency histogram H of the vertical edge of the input image as shown in the drawing is obtained.

First, the calculator 431 calculates a horizontal edge E _H and a vertical edge E _V for each frame of the input image by using Equation 1 below.

In Equation 1, the horizontal edge E _H is an absolute value of the difference between the image value I (luminance value) of the reference pixel (x, y) and the image value of the left pixel (x-1, y). (abc) and the absolute value abc of the difference between the image values of the right pixel (x + 1, y) are calculated as half of the sum of the sums.

In addition, the vertical edge E _V is an absolute value of the difference between the image value of the reference pixel (x, y) and the image value of the upper pixel (x, y-1) and the lower pixel (x, y). It is calculated as 1/2 of the sum of the absolute values of the differences between the image values of y + 1).

Second, after calculating the horizontal edge value and the vertical edge value for all the pixels corresponding to one frame, the cumulative frequency histograms for the horizontal edge and the vertical edge are calculated using the same.

The cumulative frequency histogram H for the horizontal edge is expressed as shown in FIG. 5A, and the cumulative frequency histogram H for the vertical edge is expressed as shown in FIG. 5B.

Third, the WAEL is calculated using the cumulative frequency histogram for the horizontal and vertical edges.

By visually checking the cumulative frequency histogram H as described above, it may be determined what type of images the input image of the frame is composed of. However, since the calculation unit 431 itself cannot perform this determination arbitrarily, the present invention calculates the WAEL. Therefore, according to the value of the WAEL, whether the input image is a pattern image having a high definition or a general image is determined. Can be confirmed.

First, a method of determining whether an input image is a pattern image having a high definition or a general image through the cumulative frequency histogram as described above will be described.

For example, the cumulative frequency histogram as shown in (a) of FIG. 6 represents a cumulative frequency histogram of a general image, and it is understood that many pixels are distributed in a region where the difference in luminance value of adjacent pixels is small. Can be.

In the case of a general image, most of the input image (image) corresponding to one frame is occupied by a background (other external regions and other internal regions in FIG. 4), and various types of objects (hereinafter, simply referred to as 'object forms'). (In Fig. 5, the shape of the guitar, the shape of the guitar string, etc.) is only a fraction.

On the other hand, the luminance value of each of the pixels forming the background has a small difference from the luminance value of pixels adjacent to each other up, down, left and right. Therefore, when the vertical edge or horizontal edge as described above is calculated for each of the pixels forming the background, the value has a small value.

That is, the portion indicated by 'B' in FIG. 6 corresponds to a value where the vertical edge or the horizontal edge is less than or equal to 10, and the values less than or equal to L <10 are pixels corresponding to a background area having almost no edges. Able to know.

Also, in general, luminance values of each pixel forming an object have a large difference from luminance values of pixels adjacent to each other vertically or horizontally. Therefore, when the vertical edge or the horizontal edge as described above is calculated for each of the pixels forming various objects, the value has a large value close to 255.

However, as described above, since the number of pixels forming the object shape in the general image is only a part of the total pixels, the cumulative frequency histogram shows that the distribution is very small, as shown in FIG. It is expressed as

On the other hand, the cumulative frequency histogram as shown in (b) of FIG. 6 represents a cumulative frequency histogram of the pattern image, and it can be seen that many pixels are distributed in a region where the luminance values of adjacent pixels have a large difference. .

Here, the pattern image refers to an image arbitrarily generated by the manufacturer of the display apparatus to test the quality of various images and the like, and is formed of complex and various images.

Therefore, in the case of the pattern image, most of the input image (image) corresponding to one frame is occupied by the object form, and the background is only a part. That is, in the pattern image, the number of pixels representing the object form becomes larger than the number of pixels representing the object form in the general image.

On the other hand, as described above, since the luminance value of each pixel of the background is small from the luminance value of pixels adjacent to the top, bottom, left and right of the pixel, the luminance value of each pixel of the background is small. When calculating the vertical edge or the horizontal edge as described above, the value becomes small, and the luminance value of each pixel forming the object is different from the luminance value of pixels adjacent to each other vertically or horizontally. Therefore, when the vertical edge or horizontal edge as described above is calculated for each of the pixels constituting various types of objects, the value has a large value close to 255.

Here, as described above, since the number of pixels constituting the object shape of the pattern image is larger than the number of pixels constituting the object form of the general image, the cumulative frequency histogram of the pattern image is illustrated in FIG. As shown, it can be seen that a large number of pixels are distributed even in a region where the horizontal edge or the vertical edge L is large.

That is, it can be seen that the pixels of the pattern image are distributed more than the pixels of the upper and lower or left and right and the pixels having a large difference in luminance value.

Therefore, the user or manufacturer can distinguish the pattern image from the general image by using the difference in the cumulative frequency histogram of the pattern image and the general image.

On the other hand, since the pattern image is generally configured in a state of high sharpness, if the meaning of the pattern image is interpreted differently, the pattern image may be represented as a high sharpness image.

That is, the higher the sharpness of the image, as shown in (b) of FIG. 6, it can be interpreted that many pixels are distributed in a region having a large horizontal edge or a vertical edge on the cumulative frequency histogram.

Accordingly, the present invention distinguishes an input image having a high clarity (hereinafter, simply referred to as a 'pattern image') and an input image having a low clarity (hereinafter simply referred to as a 'general image') into various ranges, such as a pattern image, A different level of sharpness is applied to the input image corresponding to each range.

However, as described above, the manufacturer or the user may visually check the cumulative frequency histogram and then determine whether the cumulative frequency histogram is a pattern image or a general image, but the calculation unit 431 cannot make such a determination. . Therefore, the present invention calculates WAEL in order to mathematically process such a judgment.

That is, the WAEL is for mathematically determining which edge values have a large distribution of pixels on a cumulative frequency histogram, and can be calculated through Equation 2 below.

In Equation 2, L is a number having a value (edge value) of 0 to 255, H (L) represents a cumulative frequency histogram, and N represents the number of pixels of the input image corresponding to one frame. Here, WAEL has a value between '0' and '225'.

That is, the WAEL calculated by Equation 2 has a large value, which means that the input image has a sharpness that is close to the pattern image. The WAEL has a small value that means that the input image has a sharpness that is close to the general image. That means having

Fourth, when the WAEL is calculated as described above, the calculation unit 431 extracts the sharpness level matching the calculated WAEL from the lookup table stored in the storage unit 433 to determine the sharpness level for converting the input image. After the determination, the information about the extracted sharpness level is transmitted to the converter 432.

That is, when the relationship between the sharpness level of the input image and the WAEL is configured in the form of a graph as shown in FIG. 7, the calculator 431 extracts the sharpness level matched with the WAEL calculated through the above process and converts the sharpness level into the transform unit. send.

On the other hand, in the case where WAEL is 40 or less in FIG. 7, the sharpness level is set to 85 consistently, even if the sharpness level is set to 85 or higher, as a result of various tests, the sharpness and difference when the sharpness level is 85 is not large. It is set by.

That is, when comparing the sharpness of the converted image converted by setting the sharpness of the input image to 85 and the sharpness of the converted image converted by setting the sharpness of the input image to 100, the difference cannot be identified by the eyes of the general user. Since it was judged to be only a minute difference, the sharpness level was set to 85 as shown in FIG.

Similarly, when comparing the sharpness of the converted image converted by setting the sharpness of the input image to 20 and the sharpness of the converted image converted by setting the sharpness of the input image to 0, the difference cannot be identified by the eyes of the general user. Since it was judged to be only a minute difference, the sharpness level was set with a minimum value of 20 as shown in FIG.

In addition, when the calculated WAEL is between 40 and 70, the calculator extracts a sharpness level matching the corresponding WAEL value on the graph as shown in FIG. 7, and extracts a sharpness level as 85 when the WAEL is 40 or less. If the WAELd is 70 or more, the sharpness level can be extracted as 20.

That is, in a typical display device (TV set), the sharpness level gain is between 0 and 100, and the viewing mode is divided into a standard mode, a clear mode, a movie mode, and the like. In this case, the graph showing the relationship between the sharpness level and WAEL illustrated in FIG. 7 is a graph calculated on the assumption that the sharpness level (gain) is 85 at maximum based on the clear mode.

However, since the present invention is not limited thereto, the maximum and minimum values of the sharpness level and the slope of the sharpness level to convert the input image may be set to various values.

Fifth, when a sharpness level for converting the input image is received from the calculator 431, the converter 432 converts the sharpness of the input image using the received sharpness level, and then rearranges the converted converted image (Data). To the data driver 300.

That is, since the input image having a large value of WAEL is expected to have high definition like a pattern image, the conversion unit 432 may convert the input image with a low sharpness level, and the WAEL has a small value. Since the input image is not expected to be as high as a normal image, the converter 432 may convert the input image to a high definition level.

The characteristics of the sharpening method and the display apparatus using the same according to the present invention as described above are summarized as follows.

That is, the present invention is to calculate the WAEL for each frame of the input image, and to change the sharpness level of the input image based on this, and has the feature that the image quality can be improved by changing the application of the sharpness level for each input image. have.

For example, the present invention calculates an edge level for each input image, so that an input image with a large value of edge components is low, and a sharpness level is applied to an input image that is not excessive, thereby minimizing image degradation. You can get a picture quality improvement.

In addition, the present invention can reduce the artifacts by applying an optimized sharpness (gain) according to the edge level of the input image, can lead to the effect that the sharpness of the input image can be improved have.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

400: timing controller 410: receiver
420: control signal generation unit 430: image data processing unit
431 calculation unit 432 conversion unit
433: storage unit

Claims (13)

Calculating an edge value E for each pixel for each frame of the input image;
Calculating a cumulative frequency histogram (H) using the edge values;
Calculating a weighted average edge level (WAEL) using the cumulative frequency histogram;
Extracting a sharpness level matched with the calculated weighted average edge level WAEL; And
And converting the sharpness of the input image by using the extracted sharpness level. The method of claim 1,
The edge value E is represented by the following equation

Sharpness improvement method characterized in that it is calculated using. The method of claim 1,
The weighted average edge level WAEL is represented by the following equation

Calculated using
In the above equation, L is a number having an edge value between 0 and 255, H (L) represents the cumulative frequency histogram, and N represents the number of pixels of the input image corresponding to one frame. Way. The method of claim 1,
The greater the weighted average edge level, the lower the sharpness level,
The sharpness level improving method characterized in that the smaller the weighted average edge level is higher. The method of claim 1,
The sharpness level is
Above the preset weighted average edge level, the same sharpness is set.
The method of improving clarity, characterized in that below the predetermined weighted average edge level is set to another same clarity. The method of claim 1,
By judging a second input image having a higher weighted average edge level as a clearer image than a first input image having a smaller weighted average edge level,
And converting the first input image using a sharpness level having a value higher than the sharpness level assigned to the second input image. A storage unit for storing a sharpness level set for each weighted average edge level WAEL;
A calculator for calculating a weighted average edge level (WAEL) for each frame of the input image, and extracting a sharpness level matched with the calculated weighted average edge level from the storage unit; And
And a converter for converting the sharpness of the input image using the extracted sharpness level. The method of claim 7, wherein
The calculating unit calculates,
The edge value E for each pixel is calculated for every frame of the input image.
A cumulative frequency histogram H is calculated using the edge value,
The weighted average edge level WAEL is calculated using the cumulative frequency histogram,
And a sharpness level matched with the calculated weighted average edge level (WAEL) from the storage unit. The method of claim 8,
The calculation unit, the following equation

Display device using a sharpness improvement method characterized in that for calculating the edge value (E) using. The method of claim 8,
The calculation unit, the following equation

Using the weighted average edge level (WAEL) is calculated,
In the above equation, L is a number having an edge value between 0 and 255, H (L) represents the cumulative frequency histogram, and N represents the number of pixels of the input image corresponding to one frame. Display device using the method. The method of claim 7, wherein
The greater the weighted average edge level, the lower the sharpness level,
The display device using a sharpness improvement method characterized in that the smaller the weighted average edge level, the higher the sharpness level. The method of claim 7, wherein
The sharpness level is
Above the preset weighted average edge level, the same sharpness is set.
A display device using a sharpness improving method, characterized in that the same sharpness is set below another weighted average edge level. The method of claim 7, wherein
The calculating unit calculates,
By judging a second input image having a higher weighted average edge level as a clearer image than a first input image having a smaller weighted average edge level,
The display apparatus using the sharpness improvement method characterized in that for converting the first input image using a sharpness level having a value higher than the sharpness level assigned to the second input image.

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