KR20100048391A - An image display device - Google Patents

Abstract

PURPOSE: An image display device is provided to form a local dimming differently according to the average luminance level of an image signal by determining the brightness of a light emitting diode at each divided region according to a look-up table. CONSTITUTION: An image analysis part(110) measures an average luminance level of an image from an RBG image signal. An LED brightness decision unit(120) uses the average luminance level of the image and the average luminance level of the first divided region. The LED brightness decision unit decides the brightness of the LED element corresponding to the first divided region. An LED driver(140) drives the LED element according to the brightness of the LED element. The liquid crystal panel displays the RGB image signal.

Description

An image display device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device having a light emitting diode, and more particularly, to an image display device capable of improving contrast ratio through local dimming of a light emitting diode and reducing power consumption thereof.

In general, the liquid crystal display is one of flat panel displays that display an image using liquid crystal. Since the liquid crystal display device is a light receiving device that does not emit light by the liquid crystal display panel, a configuration of a backlight assembly for supplying additional light is required, and a cold cathode fluorescent lamp (CCFL) is mainly used as the light source. It was used.

In recent years, light emitting diodes having excellent color reproducibility compared to the CCFL have been used as light sources of various backlight assemblies.

In connection with the driving device of the light emitting diode, a device for obtaining a high contrast screen through local dimming of the light emitting diode has been developed. In particular, a device for detecting light and dark areas through an input signal of a screen and using the information to control the brightness of the light emitting diode using pulse width modulation is developed. Pulse width modulation is widely used to control large amounts of light emitting diodes at many levels at once.

According to the conventional patent document, contents for driving the backlight device in units of a plurality of divided regions and controlling the brightness of the backlight according to an image signal applied to the backlight device are disclosed.

In the related art, only image data of a divided area is analyzed for an image signal provided by a backlight, and the brightness of the light emitting diode for the corresponding area is determined. Therefore, in the case where the light quantity balance is shifted for each divided region, there is a problem that the light quantity balance misalignment appears as color unevenness in the display image.

That is, as the luminance level of the light emitting diode is determined by the brightness of each region of the division target, the dark image may be darker, but there is a problem in that the gray level is to be darkened in the image.

The present invention detects an average luminance level of an image signal and determines the brightness of a light emitting diode for each divided area according to a look-up table corresponding to the detected average luminance level, thereby local dimming according to the average luminance level of the image signal. An object of the present invention is to propose an image display apparatus and an image display method in which the degree of the difference is different.

In addition, an object of the present invention is to propose an image display apparatus and an image display method that can improve the amount of light balance by using the luminance level of other regions adjacent to the divided region in the process of determining the brightness of the light emitting diode. do.

In addition, the present invention provides a video display device that can reduce the variation in the amount of light for the same area by using the brightness level for the corresponding region of the previous frame or the next frame when determining the brightness of the light emitting diode for the divided region in the current frame; An object of the present invention is to propose a video display method.

An image display apparatus according to the present embodiment includes an image analyzer which measures an average luminance level of an image from an RGB image signal; Determining the LED brightness to determine the brightness of the LED element corresponding to the first divided region using the average luminance level of the image measured by the image analyzer and the average luminance level of the first divided region constituting the image part; An LED driver for driving the LED device according to the brightness of the LED device determined by the LED brightness determining unit; And a liquid crystal panel in which the RGB image signal is displayed.

In addition, the image display apparatus of the embodiment includes a liquid crystal panel in which an image is displayed; An LED element for providing light to the liquid crystal panel; And an LED brightness determiner for dividing the image into a plurality of regions and adjusting brightness of the LED elements corresponding to the divided regions, wherein the brightness of the LED elements is an average luminance of the divided regions. The level and the LED brightness of the average luminance level for the entire area of the image is determined by the recorded look-up table.

In addition, the projection display device of the embodiment includes a liquid crystal panel in which the previous frame and the image of the current frame are sequentially displayed; An LED element for providing light to the liquid crystal panel; An average luminance level APL ^t of a first divided region, and an average luminance level APL of a second divided region corresponding to the first divided region in the previous frame. an image analyzer measuring ^t-1 ); An LED brightness determiner configured to adjust brightness of the LED element corresponding to the first divided area by using the result measured by the image analyzer; A filtering unit for correcting the LED brightness determined by the LED brightness determining unit by using an average luminance level of the previous frame and the current frame; And an LED driver for driving the LED device according to the LED brightness output through the filtering unit.

According to the proposed embodiment, local dimming of the LED is performed by using the average luminance level of another area adjacent to the entire or divided area of the image screen, thereby enabling the display of a more natural image.

In addition, according to an exemplary embodiment of the present invention, local dimming is performed on the divided region by using an average luminance level value of brightness of the entire image, and pixel compensation is performed on the RGB signal, so that even in the divided region on which local dimming is performed. There is an advantage that color reproduction is performed.

Hereinafter, with reference to the accompanying drawings for the present embodiment will be described in detail. However, the scope of the idea of the present invention may be determined from the matters disclosed by the present embodiment, and the idea of the invention of the present embodiment may be performed by adding, deleting, or modifying components to the proposed embodiment. It will be said to include variations.

In the following description, the word 'comprising' does not exclude the presence of other elements or steps than those listed.

1 is a diagram illustrating a part of a configuration of an image display apparatus according to a first embodiment of the present invention.

The configuration of the disclosed embodiment is provided between an output terminal of a color space converter (CSC) for outputting a YUV signal as an RGB signal and an input terminal of the LED driver 140, and a driving signal output from the LED driver 140. This is for local dimming of LEDs operating according to.

Referring to FIG. 1, an image display apparatus according to an embodiment receives an RGB image signal and determines an luminance level of an entire image or a partial region, and an image determined by the image analyzer 110. LED brightness determination unit 120 for determining the LED brightness corresponding to the brightness level, and LED driver 140 for driving the LED of the backlight according to the LED brightness level determined by the LED brightness determination unit 120.

In addition, the image display apparatus includes a pixel compensator 150 for changing the luminance level of the RGB image signal by reflecting the luminance level of the image analyzed by the image analyzer 110, and the pixel compensator 150. And a driver IC 160 which outputs a control signal to the liquid crystal panel so that the image output according to the R'G'B 'signal compensated by the PDP is performed.

The image analyzer 110 divides a region of an image into a plurality of regions of the received RGB image signal, and the LED brightness determiner 120 determines the brightness of an LED element corresponding to each region. The brightness determiner 120 provides information about image brightness.

Here, the information on the image brightness includes not only the target segment to which the LED brightness is to be determined, but also an average picture level of another adjacent segment or the entire region of the image.

In addition, the LED brightness determining unit 120 determines the brightness of the LED device corresponding to each divided region by using the information determined by the image analyzing unit 110.

That is, the image analyzer 110 divides the image of one frame into a plurality of regions, and not only an average luminance level of the divided first region but also an average luminance level of other divided regions adjacent to the first region. Provides information about the LED brightness determining unit 110. The image analyzer 110 provides corresponding information so that the LED brightness determiner 120 uses information on the average brightness level of the entire image when the LED brightness determiner 120 determines the LED brightness for a specific segmented area.

The average luminance level of the entire image region determined by the image analyzer 110 or the average luminance level of another region adjacent to the divided region will be described with reference to FIG. 2.

FIG. 2 schematically shows a liquid crystal panel 200 displaying an image and an LED backlight 300 providing light to the liquid crystal panel 200. For local dimming of the LED for the specific first partitioned area 201 among the images displayed on the liquid crystal panel 200, the image analyzer 110 may have an average brightness level for the first partitioned area 201. In addition, the average luminance level of the other divided regions adjacent to the first divided region 201 is also measured.

The LED brightness determiner 120 determines the brightness of the LED device corresponding to the first divided area 201 (located below the first divided area), and the first divided area. In addition to the average luminance level of 201, information on the average luminance level of another divided region adjacent to the first divided region 201 is used.

That is, the LED brightness determiner 120 determines the LED brightness value for the corresponding divided region in consideration of the brightness of the entire image or the brightness of other adjacent areas.

And, according to the LED brightness value determined by the LED brightness determining unit 120, the LED driver 140 is to adjust the brightness of the LED device for transmitting the light to the first partition 201. As a result, local dimming of the LED device is performed in consideration of luminance levels of all or some regions of the image.

In summary, in order to determine the LED brightness of the first divided region 201 in the image, the average luminance level of the entire image or the other luminance region adjacent to the first divided region 201 is measured, The brightness of the LED device corresponding to the first divided area 201 is determined using the measured average brightness level.

To this end, it is necessary to have a look-up table for determining the LED brightness according to the average brightness level of all or a part of the measured image, the LED brightness determiner 120 stores the look-up table The LED brightness corresponding to the average brightness level measured by the image analyzer 110 is read from the look-up table and output.

An example of a look-up table for the LED brightness determined by the LED brightness determiner 120 is shown in FIG. 3.

3 is an illustration of a look-up table for determining LED brightness according to average brightness levels measured in accordance with an embodiment of the invention.

In the description of FIG. 3, an example in which the average luminance level of the first divided region of the LED brightness determination target and the average luminance level of the entire input image are measured by the image analyzer 110 is taken as an example. Let's look at it. That is, the configuration using the average luminance level of the other divided regions adjacent to the first divided region will be replaced with the contents using the average luminance level of the entire image.

The x-axis of the graph shown is the average brightness level for each partition, and the y-axis represents the LED brightness for that partition.

3 shows three graphs, wherein the graph is a first graph 3A used when the average luminance level of the entire image is less than an 'A' value, and the average luminance level of the entire image is 'A'. The second graph 3B used when the value is greater than the value 'B' and the third graph 3C used when the average luminance level of the entire image is greater than or equal to the 'B' value.

That is, when the average luminance level of the entire image is greater than or equal to the preset 'B' value and the entire image is to be expressed in bright gray, local driving of the LED elements corresponding to each of the average luminance levels of the divided regions is performed as shown in the 3C graph. do. In this case, since the image to be displayed on the liquid crystal panel is overall brightness, the phenomenon that the screen is dark while maximizing the effect of local dimming of the LED device is not a big problem.

In other words, when the image is to be expressed in bright gradation as a whole, the larger the average luminance level of the divided region measured for each divided region of the image is, the higher the LED brightness is determined, and the smaller the average luminance level of the divided region is. LED brightness is determined low. For reference, the LED brightness graph for the average brightness level for each partition is shown as a graph having a single slope.

On the other hand, when the image is to be represented with a dark gradation as a whole, that is, when the average luminance level of the entire image is less than the 'A' value, local dimming is performed only on the divided region having an average luminance level smaller than the preset luminance value. .

That is, the proposed look-up table allows local dimming in which the LED brightness is changed only for the partition having an average luminance level smaller than the predetermined luminance value. This is because, when the image is entirely dark, when the LED brightness is determined according to a local dimming graph such as the 3C graph, the brightness of the image is too dark and color reproducibility is rather deteriorated.

Therefore, when the luminance level of the entire image is low, local dimming of the LED element is not performed on the divided regions having the average luminance level of the predetermined brightness or more.

When the average luminance level of the entire image is located between the 'A' value and the 'B' value, if the average luminance level of the divided region to be measured is larger than the preset value, the brightness change of the LED element is reduced. If the average luminance level of the divided region is smaller than the predetermined value, the brightness change of the LED element is large. That is, the local dimming degree of the LED device is reduced for the divided regions having bright gray levels, and the information of the local dimming of the LED elements is relatively increased for the divided regions having lower gray levels.

The graph showing the LED brightness for each average brightness level according to the look-up table is stored for the case where the average brightness level of the entire image is maximum (MAX) and the case where the average brightness level of the entire image is minimum (MIN). The table corresponding to the average luminance level of the whole image to be measured may be determined between the maximum and minimum (MIN) graphs of the average luminance level.

This will be described with reference to FIG. 4.

4 is another example of a look-up table for determining LED brightness according to an average brightness level measured according to an embodiment of the present invention.

4 shows a graph 4C applied when the average luminance level of the entire image is maximum (MAX) and a graph 4A applied when the level is minimum (MIN). That is, when the average brightness level of the entire image is the maximum, since the image brightness is the maximum, even if local dimming is performed for each divided region, color reproduction does not fall and power consumption according to driving of the LED can be considerably reduced.

When the average luminance level of the entire image is minimum, the image brightness is minimal. In this case, if local dimming is performed on the entire image, color reproducibility of the image is rather impaired. Therefore, in this case, when the average luminance level of the divided region is smaller than the preset value 4AA, local dimming is performed on the divided region, thereby reducing power consumption due to LED driving while not significantly reducing color reproducibility. You can do it.

When the average luminance level of the entire image is not the maximum or the minimum, the look-up table (graph) to be applied may be generated by interpolating the graphs 4A and 4C. That is, the LED brightness determiner 120 may generate a new graph located in an area formed by the 4A and 4C graphs by using a look-up table at the maximum and the minimum of the average luminance level of the entire image. Can be.

Meanwhile, the method of improving color reproducibility by the pixel compensation unit 150 described above will be described.

According to an exemplary embodiment of the present invention, a correction operation for the RGB signal provided to the liquid crystal panel may be performed along with local dimming of the LED device that provides light to the liquid crystal panel.

That is, when local dimming is performed on the divided region of the image, there may be a region (or a pixel) in which color is to be expressed in the divided region. In this case, gain is applied to the RGB signal provided to the driver IC 160 according to the brightness level of the entire image, so that incomplete color reproduction due to local dimming of the LED device is not performed.

For example, when local dimming is performed on a specific divided region in an image, even if the average luminance level of the divided region is low and there is a large degree of local dimming, there may be a character or an image to be displayed in the divided region. In this case, the effect of reducing power consumption due to local dimming is maintained, but the luminance level of the RGB signal provided to the liquid crystal panel is improved to enable color reproduction of the character or image.

Compensation of the RGB signal by the pixel compensator 150 may be performed by multiplying the luminance level of the RGB signal by a gain. A look-up table for gain applied to the RGB signal is shown in FIG. 5. Accordingly, the pixel compensator 150 calculates a gain using an average luminance level of the entire image measured by the image analyzer 110, and the look-up table used is the pixel compensator 150. It may be stored in or provided with a separate storage means.

5 is an example of a look-up table for determining an RGB signal gain according to an average luminance level measured according to an embodiment of the present invention.

Referring to FIG. 5, using the look-up table as shown in FIG. 5, the degree of pixel (or image area) compensation may be adjusted according to screen brightness, so that relatively large compensation may be performed when the screen is dark. In the case of bright images, the saturation frequency of RGB values can be reduced by making the compensation value smaller, thereby enabling more natural pixel compensation.

The x-axis of the graph shown represents an average luminance level of the entire image measured by the image analyzer 110, and the y-axis represents an RGB signal gain value corresponding thereto.

That is, when the value of the average luminance level of the entire image is larger than the preset value 5A, the RGB gain value is kept at a specific value smaller than 1, and when the average luminance level of the entire image is smaller than the preset value 5A. Gradually increase the gain value.

Therefore, when the whole image has a bright gray level, the gain value for the RGB signal is set low to prevent the RGB value from becoming more than 255 bits.In the case where the entire image has a dark gray level, a relatively large gain value is used for the RGB signal. In this case, the color is reproduced in the pixel where color reproduction is to be performed even in the area where local dimming is performed.

The embodiment of the present invention as described above has described the LED brightness and pixel compensation for each segment in a single image frame for the input RGB signal. In the following embodiments, a configuration for determining the LED brightness and a configuration for correcting the RGB video signal using the average brightness level of the current video frame and the previous video frame will be described. Briefly, if the first embodiment described above is called spatial compensation, the second embodiment to be described later may be understood as time compensation.

FIG. 6 is a diagram illustrating a partial configuration of an image display apparatus according to a second embodiment of the present invention, and FIG. 7 is a diagram for describing image analysis according to a second embodiment of the present invention.

First, three image frames to be displayed on the liquid crystal panel are shown in FIG. 7. The current frame 710, the previous frame 700 to be displayed before the current frame 710, and the current frame are displayed based on the display time. The next frame 720 to be displayed next to the frame 710 is shown.

In order to implement a more natural local dimming in the display of the image, determining the brightness of the LED element corresponding to the first partition 711 in the current frame 710, and the first partition 711 ), The image of the previous frame 700 or the next frame 720 may be referenced.

That is, in order to determine the LED brightness of the first divided region 711 of the current frame 710, the average luminance level value of the region 701 corresponding to the previous frame or the region 721 corresponding to the next frame is determined. The LED brightness of the first partition 711 of the current frame 710 may be determined using the average value of the average brightness level of these areas.

In addition, in order to determine the LED brightness of the first partition 711 of the current frame 710, it is also possible to use the overall image average luminance level of the previous frame or the next frame.

Referring to FIG. 6, in relation to the LED brightness and RGB signal compensation for the first partition of the current frame, the average brightness level value of the second partition 701 corresponding to the first partition in the previous frame is determined. A case of performing a local dimming process on the first partition of the current frame by using an example will be described.

The average luminance level of the first divided region is illustrated as APL ^t , and the average luminance level of the second divided region is illustrated as APL ^t-1 .

As shown in FIG. 6, the image display apparatus of the second embodiment receives an RGB image signal and inputs the image analyzer 210 and the image analyzer 210 to determine the luminance level of the entire or partial region of the image. LED brightness determination unit 220 for determining the LED brightness corresponding to the image brightness level determined by the LED brightness, and LED brightness determined by the LED brightness determination unit 220 in order to prevent a sudden change in the brightness of the LED device in time Filtering unit 230 that is a means for correcting the level and the LED driver 240 for driving the LED of the backlight according to the signal output through the filtering unit 230.

In addition, the image display apparatus includes a pixel compensator 250 for changing the luminance level of the RGB image signal by reflecting the luminance level of the image analyzed by the image analyzer 210, and the pixel compensator 250. And a driver IC 260 which outputs a control signal to the liquid crystal panel so as to perform an image output according to the R'G'B 'signal compensated for. In the description of the second embodiment, regarding the compensation operation of the RGB signal by the pixel compensation unit 250, the contents described in the first embodiment may be referred to.

The image analyzer 210 measures an average luminance level of an image of a current frame and a previous frame, and transfers the average luminance level APL ^t of the first segment of the target to determine the brightness of the LED device. The average luminance level APL ^t-1 for the second divided region at the position corresponding to the first divided region in the frame is also measured.

In addition, the LED brightness determiner 220 divides each segment by using a look-up table in which the brightness of the LED device is prepared for a plurality of average brightness level values measured by the image analyzer 210. Outputs a signal containing the brightness information of the LED device for the area.

The LED brightness determination unit 220 is the average or those with the average brightness level value (APL ^t-1) and the average brightness level value (APL ^t) for the first partition of the current frame for the second partition of the previous frame Using the difference value APL ^t -APL ^t-1 , the brightness of the LED device with respect to the first partitioned region may be determined. To this end, the LED brightness determining unit 220 may store a look-up table for the LED brightness applied according to the luminance level difference between the first partition and the second partition, and also the first partition and the first partition. The look-up table may be stored in which the value of the LED brightness applied according to the average value of the average brightness levels of the second partition area is recorded.

In addition, the filtering unit 230 is a difference value between the average luminance level of the previous frame arbitrary second partition region measured by the image analyzer 210 and the first partition region of the current frame (APL ^t -APL ^t-1). ) To calibrate the brightness of the LED device.

The (APL ^t -APL ^t-1 ) information is used by the filtering unit 230 to readjust the brightness level of the LED device. That is, when the value of (APL ^t -APL ^t-1 ) is very large, the change in the time axis of a certain block of the screen is very large, for example, a scene change of the screen, and the like. Therefore, even if the brightness change of the LED element for the corresponding block (divided area) is large, the degree of correction for the brightness of the LED element is reduced.

In addition, when the value of (APL ^t -APL ^t-1 ) is relatively small, the change in the brightness of the image is small and the change in the brightness of the LED device is also made small so that the natural image can be expressed. In determining the brightness of the LED device for the first divided area of the current frame, the LED device by the filtering unit 230 may reflect not only the second divided area of the previous frame but also the entire brightness of the current frame image. Correction of brightness is necessary.

As the filtering of the first divided region of the current frame, an operation related to the readjustment of the LED brightness value output from the LED brightness determiner 220 will be described.

Where L ' _t is the modified LED brightness value for the first partition of the current frame, L _t is the LED brightness value determined by the LED brightness determiner for the first partition of the current frame, and L _t-1 Is the LED brightness value determined by the LED brightness determiner for the second partition of the previous frame, and β is a coefficient.

An example of determining the coefficient β will be described with reference to FIG. 8. It can be seen from the above equation that the smaller the value of β, the larger the influence of the previous frame, and the larger the value of β, the larger the influence of the current frame.

In determining the coefficient β, it is advantageous to use the above-mentioned (APL ^t -APL ^t-1 ) information. That is, when the change of the screen (Abs (APL ^t -APL ^t-1 )) is less than or equal to the D value, the β value is used as the fixed value C. When the change of the screen is greater than or equal to the D value, the β value is gradually increased. The weight for the value of the image brightness of the current frame is increased.

That is, in order to reduce the sudden change in screen brightness, the β coefficient as in the example shown in FIG. 8 and the above equation are used. If the screen brightness in the video signal is suddenly changed between the previous frame and the current frame, it is regarded as a scene change of the screen and driven according to the brightness of the LED element determined by the LED brightness determining unit, and the brightness of the current frame compared to the previous frame. If it does not change rapidly, readjust the LED brightness to improve the gradation of the image.

9 is an image illustrating a case where local dimming is performed according to the prior art, and FIG. 10 is an image illustrating a case where local dimming and RGB signal correction is performed according to embodiments of the present invention.

In the related art, as the degree of local dimming is determined by using an average luminance level value for a region to be subjected to local dimming, as illustrated in FIG. 9, the color in the region 9A in which local dimming is performed is performed. Reproduction was not performed at all.

However, according to an exemplary embodiment of the present invention, local dimming of the divided region is performed using the average luminance level value of the brightness of the entire image, and pixel compensation of the RGB signal is performed. Color reproduction is also performed in the partition 10A in which local dimming is performed.

1 is a diagram showing a part of the configuration of an image display device according to a first embodiment of the present invention;

2 is a view for explaining the image analysis method of an embodiment of the present invention.

3 is an illustration of a look-up table for determining LED brightness according to average brightness levels measured in accordance with an embodiment of the invention.

4 is another illustration of a look-up table for determining LED brightness according to average brightness levels measured in accordance with an embodiment of the invention.

5 is an illustration of another look-up table for determining an RGB signal gain according to an average brightness level measured in accordance with an embodiment of the present invention.

FIG. 6 is a diagram illustrating a partial configuration of an image display device according to a second embodiment of the present invention. FIG.

7 is a view for explaining image analysis according to a second embodiment of the present invention.

8 is an illustration of a look-up table for determining coefficients for readjusting the brightness of an LED device according to a second embodiment of the present invention.

9 is an image illustrating a case where local dimming is performed according to the prior art.

10 is an image showing a case where local dimming and RGB signal correction is performed according to embodiments of the present invention.

Claims (10)

An image analyzer which measures an average luminance level of the image from the RGB image signal; Determining the LED brightness to determine the brightness of the LED element corresponding to the first divided region using the average luminance level of the image measured by the image analyzer and the average luminance level of the first divided region constituting the image part; An LED driver for driving the LED device according to the brightness of the LED device determined by the LED brightness determining unit; And And a liquid crystal panel in which the RGB image signal is displayed. The method of claim 1, The image analyzer measures an average luminance level of the entire region of the image or another divided region adjacent to the first divided region, together with the average luminance level of the first divided region from the RGB signal. Image display device. The method of claim 2, The LED brightness determiner stores a look-up table in which the brightness of the LED device is written with respect to the average brightness level of the first divided area. The LED brightness determiner reads a look-up table corresponding to an average luminance level of the entire region of the image measured by the image analyzer or another divided region adjacent to the first divided region, and thus the brightness of the LED element. Image display device, characterized in that for determining. The method of claim 2, Further comprising a pixel compensator for compensating the image signal applied to the liquid crystal panel, The pixel compensator is configured to provide a signal to which the predetermined gain is applied to the RGB signal to the liquid crystal panel using a look-up table in which a gain for the average luminance level measured by the image analyzer is prepared. Image display apparatus characterized in that. The method of claim 4, wherein When the average luminance level of the entire image measured by the image analyzer or the average luminance level of another divided region adjacent to the first divided region is larger than a predetermined value 5A, the pixel compensator is configured for the RGB signal. And the gain is set to be smaller than one. A liquid crystal panel displaying an image; An LED element for providing light to the liquid crystal panel; And And a LED brightness determiner for dividing the image into a plurality of regions and adjusting brightness of the LED elements corresponding to the divided regions. The brightness of the LED element is determined by a look-up table in which the average brightness level of the divided area and the LED brightness of the average brightness level of the entire area of the image are recorded. . The method of claim 6, An image display apparatus according to claim 1, wherein the divided region of the image corresponding to the LED element whose brightness is adjusted by the LED brightness determining unit outputs an RGB signal to which a gain value corresponding to an average luminance level of the entire region of the image is applied. . A liquid crystal panel in which a previous frame and an image of the current frame are sequentially displayed; An LED element for providing light to the liquid crystal panel; An average luminance level APL ^t of a first divided region, and an average luminance level APL of a second divided region corresponding to the first divided region in the previous frame. an image analyzer measuring ^t-1 ); An LED brightness determiner configured to adjust brightness of the LED element corresponding to the first divided area by using the result measured by the image analyzer; A filtering unit for correcting the LED brightness determined by the LED brightness determining unit by using an average luminance level of the previous frame and the current frame; And And an LED driver for driving the LED device according to the LED brightness output through the filtering unit. The method of claim 8, The filtering unit may generate a look-up table in which a predetermined coefficient for a difference (APL ^t -APL ^t-1 ) of the average luminance level between the first divided domain and the second divided region, which is a result measured by the image analyzer, is created. And readjust the brightness of the LED element by using the coefficient. The method of claim 8, Further comprising a pixel compensator for compensating the image signal applied to the liquid crystal panel, The pixel compensator uses a look-up table in which a gain for an average luminance level measured by the image analyzer is created, to provide a signal to which the predetermined gain is applied to the RGB signal to the liquid crystal panel. Image display device.

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