KR102489905B1 - Apparatus and method for excessive dimming of backlight unit based on perceptual image analisys - Google Patents

Abstract

The present invention relates to a control of a backlight unit of a liquid crystal display, and an apparatus and method for excessively dimming a backlight according to the present invention perform excessive dimming of a backlight according to sensitivity of brightness perceived by a person rather than numerical brightness of an image. It has the effect of reducing power consumption by reducing the brightness of the backlight while minimizing the deterioration of image quality perceived by humans.

Description

Backlight unit transient dimming device and method based on recognition image analysis

[0001] The present invention relates to a liquid crystal display, and more particularly to a control of a backlight unit of a liquid crystal display.

A liquid crystal display (LCD) still has a high share in the large display market because it can implement a large display.

Since the liquid crystal display cannot generate light by itself, a light source called a backlight unit (BLU) is essential. When the backlight unit provides a light source, the liquid crystal display panel can express an image by expressing color by adjusting transmittance of light.

Conventionally, the backlight unit was always on regardless of the image and the liquid crystal display panel controlled the transmission of light. However, due to the nature of the liquid crystal display, this method prevents light leakage due to the inability to completely block the light of the backlight unit. As a result, the expression of black color is not sufficient, and the image quality is adversely affected, such as lowering the contrast.

To solve this problem, a backlight dimming technology that adjusts the brightness of the backlight unit is applied. Backlight dimming technology is a technology that can improve contrast while reducing power consumption and light leakage by adjusting the brightness of the backlight according to the brightness of the image. Such a backlight dimming technique includes a method using a max pixel, a method using a histogram, and a method using a pixel count. The method of using max pixels is to dim the backlight based on the brightest pixel in the image. Even if there are only one or two bright pixels in the entire image, backlight dimming is not sufficiently performed, so power consumption cannot be reduced, and light leakage or contrast problems etc., there is still a problem that exists. The method using the histogram has a disadvantage in that if the overall image is dark, the bright part becomes dark, and the image quality deteriorates. The method using the pixel count is a method of determining the gray level as the backlight brightness by summing the number of pixels starting from the dark area and making the sum equal to a certain percentage of the total number of pixels. However, since only a certain percentage of pixels are considered, there is a problem of inefficiency in power reduction and contrast enhancement.

The inventors of the present invention have made research efforts to solve the problems of the backlight dimming method of the prior art. Unlike most conventional backlight dimming technologies, which have used optimization methods based on mathematical quality indicators such as algorithms based on pixel values of images or Gaussian distribution, After much effort to complete a backlight dimming device and method, the present invention has been completed.

An object of the present invention is to provide a method for excessive backlight dimming according to an image quality judged by human emotion considering the human visual system.

Another object of the present invention is to reduce power consumption by the backlight and improve image quality such as contrast by over-dimming the backlight.

Meanwhile, other unspecified objects of the present invention will be additionally considered within the scope that can be easily inferred from the following detailed description and effects thereof.

Backlight transient dimming method according to the present invention,

(a) obtaining luminance or contrast of an image composed of a plurality of pixels; and (b) controlling the degree of over-dimming of the backlight based on the criterion of image quality deterioration felt by humans due to the change in luminance or contrast during over-dimming of the backlight.

In the step (b), pixels in which saturation occurs by Backlight Compensation are obtained when excessive backlight dimming is performed, and the ratio of the pixels in which saturation occurs to all pixels is smaller. It is characterized in that the degree of excessive dimming of the backlight for the image is increased.

In the step (b), considering the relationship between the luminance of the image and the brightness perceived by humans, the degree of over-dimming of the backlight for the image is reduced as the sensitivity of the brightness perceived by humans is lower than the luminance of the image. characterized by enlargement.

In step (b), the degree of excessive dimming of the backlight is adjusted by a contrast response function representing a relationship between a change in contrast of the image caused by excessive dimming of the backlight unit and a change in contrast perceived by humans.

Controlling the degree of excessive dimming of the backlight by the contrast response function may increase the degree of excessive dimming of the backlight as the slope of the contrast response function of an area to which pixels of the image are included decreases.

Controlling the degree of excessive dimming of the backlight by the contrast response function may include adjusting the degree of excessive dimming of the backlight by applying the contrast response function to only pixels existing in a saturated region among pixels of the image. .

It is characterized in that the above steps are performed in units of local blocks divided into predetermined areas in the image.

The above steps are characterized in that they are applied to each of the red, green, and blue LEDs of the backlight unit.

A backlight transient dimming device for a liquid crystal display according to another embodiment of the present invention,

Liquid Crystal Display (LCD); Backlight Unit; and a controller including at least one processor and memory and controlling dimming of the liquid crystal display and the backlight unit, wherein the controller controls the luminance or contrast of an image composed of a plurality of pixels displayed on the liquid crystal display. It is characterized in that the degree of over-dimming of the backlight is adjusted based on the criterion of image quality damage felt by humans due to the change in luminance or contrast during over-dimming of the backlight.

The control unit obtains pixels in which saturation occurs by Backlight Compensation when performing Excessive Backlight Dimming, and as the ratio of the pixels in which saturation occurs to all pixels is smaller, the backlight unit It is characterized in that the degree of backlight transient dimming is increased.

The control unit increases the degree of excessive dimming of the backlight for the image as the sensitivity of the brightness perceived by the human being is lower than the luminance of the image in consideration of the relationship between the luminance of the image and the brightness perceived by the human. to be characterized

The control unit may adjust the degree of excessive dimming of the backlight by a contrast response function representing a relationship between a change in contrast of the image caused by excessive dimming of the backlight unit and a change in contrast perceived by a human.

The control unit increases the degree of excessive dimming of the backlight as the slope of the contrast response function of an area to which the pixels of the image belong is smaller to adjust the degree of excessive dimming of the backlight by the contrast response function.

The control unit adjusting the degree of excessive dimming of the backlight by the contrast response function applies the contrast response function to only pixels existing in a saturated region among pixels of the image to adjust the degree of excessive dimming of the backlight. to be characterized

According to the present invention, by performing backlight dimming in consideration of human emotions according to the human visual system, there is an advantage in that excessive backlight dimming can be applied while less affecting the image quality of human emotions.

Since the brightness of the backlight can be lowered by excessive backlight dimming, power consumption can be lowered, and image quality such as contrast can be improved while reducing light leakage.

On the other hand, even if the effects are not explicitly mentioned here, it is added that the effects described in the following specification expected by the technical features of the present invention and their provisional effects are treated as described in the specification of the present invention.

1 is a flowchart of a backlight transient dimming method according to a preferred embodiment of the present invention.
2 shows the relationship between backlight transient dimming and pixel brightness.
3 shows a relationship between a theoretical pixel value and luminance and a relationship between a pixel value and luminance perceived by humans.
4 shows a difference in a change perceived by humans according to a change in contrast.
FIG. 5 shows the degree of image quality loss according to the average luminance and contrast when over-dimming the backlight.
6 is a schematic structural diagram of a backlight transient dimming device according to another preferred embodiment of the present invention.
※ It is revealed that the accompanying drawings are exemplified as references for understanding the technical idea of the present invention, and thereby the scope of the present invention is not limited.

Hereinafter, with reference to the drawings, look at the configuration of the present invention guided by various embodiments of the present invention and the effects resulting from the configuration. In the description of the present invention, if it is determined that a related known function may unnecessarily obscure the subject matter of the present invention as an obvious matter to those skilled in the art, the detailed description thereof will be omitted.

Terms such as 'first' and 'second' may be used to describe various elements, but the elements should not be limited by the above terms. The above terms may only be used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a 'first element' may be named a 'second element', and similarly, a 'second element' may also be named a 'first element'. can Also, singular expressions include plural expressions unless the context clearly indicates otherwise. Terms used in the embodiments of the present invention may be interpreted as meanings commonly known to those skilled in the art unless otherwise defined.

Hereinafter, with reference to the drawings, look at the configuration of the present invention guided by various embodiments of the present invention and the effects resulting from the configuration.

1 is a flowchart of a backlight unit transient dimming method according to an exemplary embodiment of the present invention. Please note that the steps below do not necessarily have to be executed in the following order and the order of execution can be changed if necessary.

In order to over-dimming the backlight, first, it is necessary to find a Max Pixel having a maximum pixel value as a reference in the entire image (S10).

Afterwards, it is necessary to find pixels that become saturated due to excessive dimming of the backlight (S20).

Backlight brightness is reduced by backlight dimming and image quality deteriorates accordingly. To compensate for this, image brightness is compensated by Backlight Compensation, which increases the transmittance of the LCD panel, that is, pixel value, to prevent image quality damage. will compensate

2 shows the relationship between input pixels and output pixels before and after backlight dimming.

Backlight dimming is performed based on various standards, but in general, dimming can be performed without deterioration of image quality by obtaining a max pixel value among pixels of an input image and then performing dimming up to the max pixel value. In FIG. 2 , if the value of the max pixel is the second dotted line 2 , dimming based on the max pixel is to reduce the brightness of the backlight from the uppermost dotted line 1 to the second dotted line 2 .

Since the brightness of the image is darkened by backlight dimming, backlight dimming pixel compensation, which increases the pixel value, is required to compensate for the brightness, and the input/output pixel relationship before compensation (4) changes to the input/output pixel relationship after compensation (5). That is, the max pixel is increased to 255, which is the maximum value of the input pixel, to express the maximum value of backlight brightness, and the pixel value of pixels smaller than the max pixel also increases according to the ratio.

However, when excessive dimming of the backlight is performed, the maximum value of the backlight brightness is lowered to the third dotted line (3), and not only the max pixels but also the pixels having a value greater than bed' are converted to the maximum brightness by backlight dimming pixel compensation, that is, A phenomenon of saturation occurs.

Therefore, after compensation, all pixels having a value of bed' or more are changed to the maximum value, so the contrast of input pixels having a value of bed' or more becomes 0, resulting in distortion and deterioration of image quality. However, since the actual picture quality perceived by humans is involved in cognitive characteristics, if the picture quality damage caused by pixel saturation caused by over-dimming of the backlight is at a level that humans cannot perceive or is acceptable depending on the application field, over-dimming of the backlight is not recommended. Through this, it is possible to maximize the effect of dimming, such as reducing power consumption, without deteriorating image quality.

3 illustrates a relationship between a display output luminance (luminance) and a change in an input pixel value during excessive dimming of a backlight.

3(a) shows a change in luminance according to a change in a theoretical input pixel value. An input pixel value and luminance show a linear relationship.

Figure 3(b) shows the relationship between brightness and pixel values substantially perceived by humans.

In (a) of FIG. 3, the difference in luminance according to the difference in pixel value is the same in the bright part (A) and the dark part (B), but in (b) of FIG. 3, the difference in brightness (pixel value) actually perceived by humans It can be seen that is different in the bright part (A') and the dark part (B'). That is, it can be seen that the difference in brightness recognized by the human eye is reduced from the bright portion (A') to the dark portion (B') even with the same luminance difference. That is, the human eye is less sensitive in a region of high luminance.

Therefore, considering the relationship between max pixels and saturated pixels as described above, and the difference in brightness perceived by humans, the image quality perceived by humans is impaired in areas with high luminance, that is, in brighter images or in brighter areas of the image. The degree of over-dimming of the backlight can be made larger without it.

A brightness sensitivity slope (BSS: Brightness Sensitivity Slope) can be obtained from the previously obtained max pixels and saturated pixels (S30).

은 다음 식과 같이 나타낼 수 있다.Let b _i be the pixel value of any pixel in the image, f(b _i ) is the probability of a pixel having pixel value b _i in the entire image, and the lower limit value of the input pixel saturated by backlight over-dimming is bed', Max If the pixel value of a pixel is Max, the ratio of the number of saturated pixels to the total number of pixels in the image

can be expressed as the following equation.

은 0이 될 수 없다.Backlight transient dimming is due to additional dimming at max pixels.

cannot be 0.

As shown in FIG. 3, brightness sensitivity varies depending on the area, and since humans feel less deterioration in image quality due to pixel saturation in areas with lower brightness sensitivity, more over-dimming can be performed. Therefore, in the present invention, the higher the average luminance of the image, the greater the degree of over-dimming.

The following is an example of over-dimming using brightness sensitivity. If PB(b _i ) is the perceived brightness felt by humans for an arbitrary pixel value b _i , the brightness sensitivity slope BSS, which is the difference in brightness perceived by humans versus the difference in luminance by the input pixel value, can be calculated as follows: there is.

The smaller the BSS, the smaller the difference in brightness felt by humans when over-dimming the backlight, so it is difficult to feel the luminance saturation by pixel saturation. Therefore, the smaller the BSS, the more backlight transient dimming is possible.

Since the pixels that affect picture quality by backlight excessive dimming are pixels in the saturation area, the more pixels in the saturation area, the greater the effect on picture quality and the degree of backlight excessive dimming inevitably decreases.

Accordingly, a Saturated Pixel Brightness Sensitivity Slope (SPBSS) may be calculated by considering the BSS and the pixels in the saturated region together (S40).

가 커질수록 SPBSS도 커지게 되므로 SPBSS가 작을수록 과도 디밍의 정도를 크게 할 수 있다.Here, a, b, and c are added as fitting parameters to optimize SPBSS according to the characteristics and application fields of the display panel. That is, from bed' to max pixels

Since SPBSS also increases as is increased, the degree of excessive dimming can be increased as SPBSS is decreased.

4 is a contrast response function showing the degree of perception of a difference in contrast that changes due to excessive dimming of the backlight.

It can be seen that the recognition sensitivity of the contrast change is small even by dimming in the high-contrast area (A) or the low-contrast area (C), whereas the recognition sensitivity is higher in the medium-contrast area (B).

Therefore, in backlight transient dimming, considering the contrast response function, the overall saturated pixel slope (SPS _overall : Overall Saturated Pixel Slope) can be obtained (S50), and the saturated pixel region saturated pixel slope (SPS _sat : Saturated Pixel Region Saturated Pixel Slope) It can also be calculated (S60).

Backlight over-dimming causes pixel saturation, which inevitably results in contrast degradation. Therefore, as the slope of the graph in the contrast response function of FIG. 4 is smaller, it is less sensitive to changes in contrast, and thus more backlight transient dimming is possible. Therefore, according to the present invention, according to the slope of the contrast response function of FIG. 4, the backlight excessive dimming can be increased as the slope is smaller.

It goes without saying that the above transient dimming method according to the present invention may be independently performed depending on luminance or contrast, or may be performed in parallel or sequentially by simultaneously considering luminance and contrast.

5 shows how the degree of image quality damage due to excessive dimming varies according to average luminance and contrast.

Pixel values between 0 and 255 In each region, the dotted line represents the saturation region and the solid line represents the region where saturation does not occur. The center of the arrow represents the average luminance, and the arrow represents the pixel distribution, so the longer the arrow, the greater the contrast.

Cases 1, 2, and 3 all represent cases in which the average luminance, that is, the average pixel value is low. Even if the contrast is increased, since the pixels are not located in the saturated region, the pixels are not affected even if excessive dimming is performed. Therefore, there is no effect on image quality perceived by humans (No damage).

Cases 4, 5, and 6 represent cases in which the average luminance is medium. The higher the contrast, the more pixels are located in the saturated area. Eventually, the average luminance is similar, but the pixels in the case 4 area, which have the highest contrast, suffer from excessive dimming, and the pixels in the case 6 area, where the contrast is low, suffer relatively poor picture quality. less by

Cases 7, 8, and 9 represent cases in which the average luminance is large, but since the pixels belong to the saturated region, image quality is inevitably deteriorated. However, in the case of Case 9, if the contrast is small, the sensitivity to contrast change in the contrast response function is small, so the degree of image quality damage is only moderate.

The following are examples of performing excessive dimming using such a contrast response function or contrast and average luminance.

로 나눈 값을 이미지 슬로프(Image Slope)라 하고, 이를 통해 콘트라스트를 평가한 다음 이를 바탕으로 콘트라스트 응답 함수를 고려할 수 있다.Since the contrast between pixels is proportional to the difference in brightness of pixels per unit length, the contrast between any two pixels b _m and b _n must consider the distance between the two pixels and the difference in pixel values. That is, for all two pixels b _m and b _n in the pixel saturated area, the pixel value difference between the two pixels is the physical distance between the two pixels (

The value divided by is called an image slope, and the contrast can be evaluated through this, and then the contrast response function can be considered based on this.

)를 다음 식과 같이 구할 수 있고, 이는 콘트라스트 응답 함수에서 콘트라스트의 위치를 나타낸다.The larger the contrast and the larger the P(b _ed ', Max), which is the pixel distribution ratio from b _ed ' where saturation begins to the Max pixel, the more the backlight over-dimmable range decreases. Saturated pixel slope (

) can be obtained by the following equation, which represents the position of contrast in the contrast response function.

함수를 최적화하기 위해 사용될 수 있다. 콘트라스트가 작을수록, 포화 픽셀 수가 적을수록 더 많은 백라이트 과도 디밍이 가능하므로 전체 포화 픽셀 슬로프가 작을수록 더 많은 백라이트 과도 디밍이 가능하다.An image slope (CRS) function means a contrast response function slope, and two pixels b _m and b _n mean two arbitrary pixels greater than 0 and less than a max pixel. The constants d, e, and f depend on the characteristics or application of the contrast response function.

Can be used to optimize functions. The lower the contrast, the lower the number of saturated pixels, the more backlight over-dimming, and the smaller the overall saturated-pixel slope, the more backlight over-dimming.

Considering the contrast of an image, since all pixels in the saturated pixel area are saturated and the contrast becomes 0, the smaller the contrast between the pixels before saturation, the less the contrast change is felt, and more backlight excessive dimming is possible. Therefore, in order to additionally consider a phenomenon in which the contrast of the input image is degraded (to be zero) due to excessive dimming of the backlight, the saturation pixel slope SPS _sat can be obtained as follows. Based on the contrast response function, the perceived amount of reduction in the input image contrast can be determined as the saturated pixel area saturated pixel slope as:

이다. 앞서의 식들과 마찬가지로 식을 최적화 하기 위해 상수 g, h, i가 추가될 수 있다. 이 때 포화되는 비율이 일정 이하면 영향이 있다고 보기 어려우므로 포화되는 비율이

이상인 경우로 적용 범위를 한정할 수 있다. 앞의 전체 포화 픽셀 슬로프와 마찬가지로 포화 픽셀 구역 포화 픽셀 슬로프 역시 그 값이 작을수록 백라이트 과도 디밍은 크게 할 수 있다.Any two pixels b _m , b _n are pixels in the saturation region and

to be. As in the previous equations, the constants g, h, and i can be added to optimize the equation. At this time, if the saturation rate is below a certain level, it is difficult to see that there is an effect, so the saturation rate is

The scope of application can be limited to the above cases. Similar to the previous entire saturated pixel slope, the smaller the value of the saturated pixel area saturated pixel slope, the greater the backlight transient dimming.

Since the picture quality degradation tolerance may be different depending on the application field, Optimum Excessive Global Dimming (Opt.EGD) according to the tolerance may be expressed as the following equation.

α, β, γ, and δ are used as constants to adjust the degree of influence of each function.

To apply the above equations per block rather than the entire image (Global), obtain the SPS _sat and SPS _overall within the local block and optimize the amount of dimming according to the image characteristics of the local block (Opt.ELD : Optimum Excessive Local Dimming) can be obtained as follows.

In local dimming, the smaller the size of the local block, the more uniform (homogeneous) characteristics compared to the entire image. Considering these characteristics, transient local dimming can be maximized. When local dimming is applied, blocking artifacts may occur when a difference in dimming values is large compared to neighboring blocks, so this must be taken into consideration.

If the backlight unit is implemented by being divided into red, green, and blue colors, applying dimming to each of the RGB LEDs can maximize backlight over-dimming and is more advantageous for optimizing power and picture quality. Since pixel saturation and deterioration in image quality can be applied to each of R, G, and B, the following equation can be obtained by applying the previous equations to R, G, and B, respectively.

Where c is R, G or B. In the case of performing backlight transient dimming in whole image units, local block units, or R, G, and B units, a criterion for performing backlight excessive dimming may be set to a lower value by comparing max pixel and RGB values. Since dimming can be performed up to the lower of the two values without deterioration in picture quality, the following equation can be applied to perform backlight transient dimming up to the lower of the two values.

6 is a structural diagram of a backlight transient dimming device according to another embodiment of the present invention.

A backlight transient dimming device 10 according to the present invention includes a backlight unit 12, an LCD panel 14 and a controller 16.

Since the LCD panel 14 cannot emit light by itself, the backlight unit 12 must provide a light source for displaying images.

The controller 16 may include one or more processors and memories, and controls the backlight unit 12 and the LCD panel 14 . Program codes and setting data for driving a processor for controlling the backlight unit 12 and the LCD panel 14 may be stored in the memory of the controller 16 .

The controller 16 may obtain a max pixel, which is a pixel having the largest pixel value, in the entire image to be subjected to backlight over-dimming, and obtain pixels saturated by backlight compensation when performing backlight over-dimming based on this.

Since the present invention will be implemented based on the brightness perceived by humans rather than the mathematical pixel values of these pixels, the difference between the perceived brightness of the max pixel obtained above and the perceived brightness of the saturated pixel is obtained, and then the value of the max pixel and the saturated pixel The brightness sensitivity slope (BSS) can be obtained by dividing the value by the difference value. Since the brightness sensitivity is the sensitivity of brightness actually perceived by humans, excessive dimming of the backlight unit 120 can be increased as the brightness sensitivity slope decreases.

Here, the more pixels saturated by backlight over-dimming, the smaller the backlight over-dimming should be, so the ratio of saturated pixels should be considered. Accordingly, a saturated pixel brightness sensitivity slope (SPBSS) considering the ratio of saturated pixels can be obtained.

Backlight transient dimming must take into account not only the brightness of a pixel, but also the difference in contrast between pixels. Therefore, considering the contrast response function, the overall saturated pixel slope (SPS _overall ) and the saturated pixel slope (SPS _sat ) of the saturated pixel area can be obtained and reflected in backlight transient dimming.

The overall saturated pixel slope is obtained by considering the contrast between two pixels of the entire image, and the saturated pixel area saturated pixel slope is obtained by considering only the contrast of pixels in the saturated region. The higher the contrast, the more severe the deterioration in image quality due to the over-dimming of the backlight. Therefore, the lower the overall saturated pixel slope or the saturated-pixel area saturated pixel slope, the greater the over-dimming of the backlight.

Even if picture quality is degraded due to backlight over-dimming, the optimal value of backlight over-dimming may be different because the tolerance is different depending on the application field. Therefore, considering the previously obtained saturated pixel brightness sensitivity slope, saturated pixel slope, and saturated pixel area saturated pixel slope, the optimal transient global dimming (Opt.EGD) value, which is the optimal amount of backlight transient dimming, can be obtained.

The backlight transient dimming performed by the controller 16 is performed in local block units, which are smaller units than the entire image, depending on the backlight unit 12, or R and G in the case of the backlight unit 12 that can control RGB, respectively. As described above, it is possible to obtain a greater effect in improving image quality and reducing power consumption by performing each of the , B LEDs.

According to the backlight transient dimming device and method of the present invention as described above, the backlight transient dimming is controlled based on the image quality perceived by humans rather than numerical analysis, thereby reducing the brightness of the backlight while minimizing the deterioration in image quality that can be felt by humans. There are advantages to improving image quality.

The protection scope of the present invention is not limited to the description and expression of the embodiments explicitly described above. In addition, it is added once again that the scope of protection of the present invention cannot be limited due to obvious changes or substitutions in the technical field to which the present invention belongs.

Claims (14)

A method for dimming a backlight unit excessively performed by a control unit including one or more processors:
(a) obtaining luminance or contrast of an image composed of a plurality of pixels; and
(b) adjusting the degree of over-dimming of the backlight based on the quality damage that humans feel due to the change in luminance or contrast during over-dimming of the backlight;
In step (b),
Considering the relationship between the luminance of the image and the brightness perceived by humans, the degree of excessive dimming of the backlight for the image is adjusted as the sensitivity of the brightness perceived by humans is lower than the luminance of the image,
The contrast response function representing the relationship between the contrast change of the image due to the backlight excessive dimming and the contrast change perceived by humans. A method for transient dimming of a backlight unit, characterized in that the degree of is greatly adjusted.
According to claim 1,
In the step (b), pixels in which saturation occurs by Backlight Compensation are obtained when excessive backlight dimming is performed, and the ratio of the pixels in which saturation occurs to all pixels is smaller. A backlight unit transient dimming method characterized by increasing the degree of backlight transient dimming for the image.
delete delete delete According to claim 1,
Controlling the degree of excessive dimming of the backlight by the contrast response function is characterized in that the degree of excessive dimming of the backlight is adjusted by applying the contrast response function to only pixels existing in a saturated region among pixels of the image. , the backlight unit transient dimming method.
The method of any one of claims 1, 2 and 6,
The method of dimming the backlight unit excessively, characterized in that the steps are performed in units of local blocks divided into predetermined areas in the image.
The method of any one of claims 1, 2 and 6,
Characterized in that the steps are applied to each of the red, green and blue LEDs of the backlight unit, the backlight unit transient dimming method.
Liquid Crystal Display (LCD);
Backlight Unit; and
A controller including one or more processors and memories and controlling dimming of the liquid crystal display and the backlight unit; including,
The control unit obtains the luminance or contrast of an image composed of a plurality of pixels displayed on the liquid crystal display, and adjusts the degree of excessive dimming of the backlight based on the quality damage that humans perceive due to the change in the luminance or contrast during excessive dimming of the backlight. characterized in that,
The control unit adjusts the degree of over-dimming of the backlight by considering the relationship between the luminance of the image and the brightness perceived by humans, and the lower the sensitivity of the brightness perceived by humans compared to the luminance of the image, the better the image. The contrast response function of the area to which the pixels of the image belong is determined by greatly adjusting the degree of excessive dimming of the backlight for A backlight transient dimming device for a liquid crystal display, characterized in that the degree of the backlight transient dimming for the image is greatly adjusted as the inclination decreases.
According to claim 9,
The control unit obtains pixels in which saturation occurs by Backlight Compensation when performing Excessive Backlight Dimming, and as the ratio of the pixels in which saturation occurs to all pixels is smaller, the backlight unit A backlight transient dimming device for a liquid crystal display, characterized in that the degree of backlight transient dimming is increased.
delete delete delete According to claim 9,
The control unit adjusting the degree of excessive dimming of the backlight by the contrast response function applies the contrast response function to only pixels existing in a saturated region among pixels of the image to adjust the degree of excessive dimming of the backlight. A device for transient dimming of a backlight of a liquid crystal display, characterized in that:

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