CN107393485A - Local dimming method applied to Novel backlight - Google Patents

Abstract

The present invention relates to the technical fields of color gamut expansion, image and video display, in order to propose a regional dimming method applied to a new type of backlight source, and apply the method to a system with WE (white LEDs and sapphire blue LEDs) backlight sources, which can achieve improved The purpose of display system contrast enhancement and extended color gamut. The technical solution adopted by the present invention is to apply the regional dimming method of the new backlight source, partition the input image according to the number of backlight module units, and use the minimum power consumption as the limiting condition to determine the white light LED in each regional unit by the formula. The brightness W _LED and the brightness E _LED of the sapphire blue LED and the corresponding liquid crystal compensation values (R _LC , G _LC , B _LC ). The invention is mainly applied to image and video display occasions.

Description

Regional dimming method applied to new backlight

technical field

The present invention relates to the technical field of color gamut extension and image and video display, in particular, relates to an area dimming method applied to a new type of backlight source.

Background technique

In order to improve the display effect, the backlight algorithm generally uses the regional dimming algorithm, because the regional dimming algorithm can well achieve the purpose of high energy saving and high contrast. Regional dimming can be divided into white light regional dimming and multi-primary color regional dimming due to different backlight sources.

1) White light area dimming algorithm

Using white light as the backlight is a relatively common backlight, which can greatly improve the contrast of the display and has a better energy-saving rate. The common regional dimming algorithms include arithmetic method (maximum value method, average value method, root mean square method), IMF (mapping function inversion) method [1], CDF (cumulative distribution function) threshold method [2], error correction Law [3]. Among them, the arithmetic method is simple to implement, but the effect is not good; the IMF algorithm has a good processing effect on high brightness, but is not suitable for scenes with low overall brightness; the error correction method has a wide range of applications and good processing effect, but the energy saving rate is not high; and The energy-saving rate of the CDF threshold method is higher than that of the other two algorithms, but the quality of the processed image has a certain range of distortion.

In order to make the display reproduce more real colors in nature, the multi-primary color shading algorithm has entered the field of vision of researchers.

2) Multi-primary color area dimming algorithm

In addition to improving contrast and saving energy, multi-primary color area dimming can also expand the color gamut. Because of the different backlight sources, different multi-primary color algorithms are derived. Common multi-primary color backlights include RGB LEDs backlight, RGBY LEDs (that is, red, green, blue, and yellow) backlights, and RGBC LEDs (that is, red, green, blue, and blue) backlights. Literature [4] proposed a parallel computing structure algorithm with priority for RGB LEDs backlight. This algorithm can achieve wide color gamut, high contrast, and optimal energy saving effect.

references:

[1] LIN F, LIAO C, LIAO L, et al. Inverse of Mapping Function (IMF) method for image quality enhancement of high dynamic LCD TVs. ISSN/007-0966x/07/382007SID, 1343-1346.

[2]Hyunsuk Cho, Oh-Kyong Kwon. A Backlight Dimming Algorithm for LowPower and High Image Quality LCD Application, 0098 3063/09 2009IEEE, 839-994.

[3] Liu Yanzhong, Zheng Xueren, Chen Jianbin. LCD Dynamic Backlight Main Brightness Extraction Algorithm Based on Image CDF Threshold and Its Hardware Implementation [J]. Liquid Crystal and Display, 2010,25(3):449-453.

[4]Marc Albrecht, Andreas Karrenbauer, Chihao Xu. A Video-Capable Algorithm for Local Dimming RGB Backlight. ISSN/009-0966X/09/3902-0753-$1.00 2009SID. SID 09DIGEST 753-756.

Contents of the invention

In order to overcome the deficiencies in the prior art, the present invention aims to propose a regional dimming method applied to a new type of backlight, and apply the method to a system with a WE (white LEDs and sapphire blue LEDs) backlight, which can improve the contrast of the display system The purpose of improving and expanding the color gamut. The technical solution adopted by the present invention is to apply the regional dimming method of the new backlight source, partition the input image according to the number of backlight module units, and use the minimum power consumption as the limiting condition to determine the white light LED in each regional unit by the formula. The brightness W _LED and the brightness E _LED of the sapphire blue LED and the corresponding liquid crystal compensation values (R _LC , G _LC , B _LC );

The brightness of the white LED and the sapphire blue LED in each area unit are determined by the formula (W _LED and E _LED respectively) specifically:

Among them, (X(i,j), Y(i,j) and Z(i,j)) respectively represent the maximum value of XYZ in each area, (X _WW , Y _WW , Z _WW ) is the full brightness of the white LED The XYZ components of the transparent full white field when the sapphire blue LED is fully bright, (X _WE , Y _WE , Z _WE ) are the XYZ components of the transparent full white field when the sapphire blue LED is fully bright. (X _WW , Y _WW , Z _WW ) and (X _WE , Y _WE , Z _WE ) can be measured by a luminance meter, (W _LED (i, j), E _LED (i, j)) are (i, j ) The luminance value of the area white LED and sapphire blue LED, with the power reaching the minimum as its limiting condition:

P＝P _W W _LED (i,j)+P _E E _LED (i,j)

P _W represents the power consumption when the power of the white light LED is the maximum; _PE represents the power consumption when the power of the sapphire blue LED is the maximum; take the power consumption P as the minimum.

LCD compensation algorithm:

Where (X _R (i,j),Y _R (i,j),Z _R (i,j)) is the tristimulus value through the LCD red filter, (X _WR ,Y _WR ,Z _WR ) is the white LED The red tristimulus value is displayed by the LCD, (X _WE , Y _WE , Z _WE ) is the sapphire blue LED The red tristimulus value is displayed by the LCD, (W _DST (i,j), E _DST (i,j)) is The luminance distribution value at coordinates (i, j) can be similarly obtained through the LCD blue filter tristimulus value (X _G (i, j), Y _G (i, j), Z _G (i, j)) , through the LCD green filter tristimulus value (X _B (i,j), Y _B (i,j), Z _B (i,j))

Where (R′ _LC (i,j),G′ _LC (i,j),B′ _LC (i,j)) is the LCD brightness value, (X _in (i,j),Y _in (i,j) ,Z _in (i,j)) input image signal value;

(R′ _LC (i,j),G′ _LC (i,j),B′ _LC (i,j)) is converted into the corresponding liquid crystal compensation value (R _LC (i,j),G _LC (i,j),B _LC (i,j));

Finally, the LCD brightness is determined by the liquid crystal compensation value (R _LC (i,j), G _LC (i,j), B _LC (i,j)), and the backlight brightness is determined by the (i,j) area white LED and sapphire blue LED The brightness value of (W _LED (i, j), E _LED (i, j)) is determined.

Among them, the XYZ component (X _WR , YW _R , Z _WR ) of the white LED at full brightness, the XYZ component (X _WE , Y _WE , Z _WE ) of the transparent full white field of the sapphire blue LED at full brightness, coordinates (i, j ) at the brightness distribution value (W _DST (i, j), E _DST (i, j)) are measured by the luminance meter.

Features and beneficial effects of the present invention are:

Because the present invention adopts it, it can achieve the purpose of improving the contrast of the display system and expanding the color gamut, and can realize the improvement of the contrast of the display system and expanding the color gamut, and also has the characteristics of energy saving and consumption reduction.

Description of drawings:

Fig. 1 Schematic diagram of backlight panel and LCD panel structure.

Figure 2 shows the overall architecture of the system.

detailed description

The present invention comprehensively considers the characteristics of white light and multi-primary color light, adds sapphire blue LEDs on the basis of white LED backlight to expand the color gamut, and proposes an algorithm for the backlight module.

The present invention uses white light LEDs and sapphire blue LEDs as backlight sources, which are arranged in an alternating manner of white light and sapphire blue light, as shown in FIG. 1 .

Backlight area dimming algorithm:

Among them, (X(i,j), Y(i,j) and Z(i,j)) respectively represent the maximum value of XYZ in each area, (X _WW , Y _WW , Z _WW ) is the full brightness of the white LED The XYZ components of the time-transmitting full-white field, (X _WE , Y _WE , Z _WE ) are the XYZ components of the light-transmitting full-white field when the sapphire blue LED is fully bright. Where (X _WW , Y _WW , Z _WW ) and (X _WE , Y _WE , Z _WE ) are measured by a luminance meter. (W _LED (i, j), E _LED (i, j)) are the brightness values of white LED and sapphire blue LED in (i, j) area, respectively. It is limited by the minimum power:

P＝P _W W _LED (i,j)+P _E E _LED (i,j)

P _W represents the power consumption when the power of the white light LED is the maximum; _PE represents the power consumption when the power of the sapphire blue LED is the maximum; take the power consumption P as the minimum.

LCD compensation algorithm:

Where (X _R (i,j),Y _R (i,j),Z _R (i,j)) is the tristimulus value transmitted through the LCD red filter, (X _WR ,Y _WR ,Z _WR ) is the white LED The red tristimulus value is displayed by the LCD, (X _WE , Y _WE , Z _WE ) is the sapphire blue LED The red tristimulus value is displayed by the LCD, (W _DST (i,j), E _DST (i,j)) is Brightness distribution value at coordinate (i,j). Among them (X _WR , Y _WR , Z _WR ), (X _WE , Y _WE , Z _WE ), (W _DST (i,j), E _DST (i,j)) are measured by the luminance meter. Similarly, (X _G (i,j),Y _G (i,j),Z _G (i,j)),(X _B (i,j),Y _B (i,j),Z _B ( i,j))

Where (R′ _LC (i,j),G′ _LC (i,j),B′ _LC (i,j) is the LCD brightness value, (X _in (i,j),Y _in (i,j), Z _in (i, j)) input image signal value.

(R′ _LC (i,j),G′ _LC (i,j),B′ _LC (i,j) are converted into corresponding liquid crystal compensation values through gamma correction (R _LC (i,j),G _LC ( i, j), B _LC (i, j)).

Finally, the LCD brightness is determined by the liquid crystal compensation value (R _LC (i,j), G _LC (i,j), B _LC (i,j)), and the backlight brightness is determined by the brightness value of the area white LED and sapphire blue LED (W _LED (i, j), E _LED (i, j)) determined.

As shown in Figure 2, after the image displayed by the system is input, RGB to XYZ chromaticity space conversion is performed, the brightness information and chromaticity information of the image are taken out, and the backlight area dimming algorithm and corresponding liquid crystal compensation algorithm proposed by the present invention are adopted, That is to calculate the backlight value (white LED and sapphire LED) and panel LCD liquid crystal compensation value corresponding to each image area, so that the display system can achieve the purpose of high contrast and wide color gamut.

In an example of the present invention, at first, the input image is partitioned according to the number of backlight module units, and with the minimum power consumption as the limiting condition, the brightness (W _LED , E _LED ) and the corresponding liquid crystal compensation value (R _LC , G _LC , B _LC ). By adopting the regional dimming algorithm proposed by the present invention, the display system can achieve the goals of improving contrast, expanding color gamut and reducing energy consumption.

Claims (3)

1. a kind of local dimming method applied to Novel backlight, it is characterized in that, according to backlight module element number to input Image carries out subregion, and with the minimum qualifications of power consumption, the brightness W of white light LEDs in each territory element is determined by formula_LEDWith Sapphire blue LED brightness E_LEDAnd corresponding liquid crystal compensation value (R_LC,G_LC,B_LC)；

The brightness W of white light LEDs in each territory element is determined by formula_LEDWith sapphire blue LED brightness E_LED, specifically：

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Wherein, (X (i, j), Y (i, j) and Z (i, j)) represents the maximum of XYZ in each region, (X respectively_WW, Y_WW, Z_WW) it is white The XYZ components of printing opacity white field entirely, (X during light LED all lights_WE, Y_WE, Z_WE) XYZ points of printing opacity white field entirely when being sapphire blue LED all lights Amount.(X_WW, Y_WW, Z_WW) and (X_WE, Y_WE, Z_WE) gained, (W can be measured by luminance meter_LED(i, j), E_LED(i, j)) it is respectively (i, j) The brightness value of region white light LEDs and sapphire blue LED, reach minimum using power and be used as its qualifications：

P=P_WW_LED(i,j)+P_EE_LED(i,j)

P_WRepresent power consumption during white light LEDs power maximum；P_ERepresent power consumption during sapphire blue LED power maximum；Take work( Rate consumption P is minimum.

2. it is applied to the local dimming method of Novel backlight as claimed in claim 1, it is characterized in that, liquid crystal compensation algorithm：

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Wherein (X_R(i,j),Y_R(i,j),Z_R(i, j)) it is through the red filter disc tristimulus values of LCD, (X_WR,Y_WR,Z_WR) it is that white LEDs lead to Cross the red tristimulus values of LCD displays, (X_WE,Y_WE,Z_WE) it is that sapphire blue LED shows red tristimulus values, (W by LCD_DST (i,j),E_DST(i, j)) be coordinate (i, j) place Luminance Distribution value, can must similarly pass through LCD indigo plant filter disc tristimulus values (X_G(i, j),Y_G(i,j),Z_G(i, j)), through the green filter disc tristimulus values (X of LCD_B(i,j),Y_B(i,j),Z_B(i,j))

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Wherein (R '_LC(i,j),G′_LC(i,j),B′_LC(i, j)) it is LCD brightness values, (X_in(i,j),Y_in(i,j),Z_in(i, j)) it is defeated Enter image signal value；

(R′_LC(i,j),G′_LC(i,j),B′_LC(i, j)) by gamma correction be converted to corresponding to liquid crystal compensation value (R_LC(i,j), G_LC(i,j),B_LC(i,j))；

Finally, LCD brightness is by liquid crystal compensation value (R_LC(i,j),G_LC(i,j),B_LC(i, j)) determine, backlight illumination is by (i, j) area Brightness value (the W of domain white light LEDs and sapphire blue LED_LED(i, j), E_LED(i, j)) determine.

3. it is applied to the local dimming method of Novel backlight as claimed in claim 1, it is characterized in that, wherein white light LEDs are complete XYZ components (X when bright_WR,YW_R,Z_WR), the XYZ components (X of printing opacity white field full during sapphire blue LED all lights_WE,Y_WE,Z_WE), coordinate Luminance Distribution value (the W at (i, j) place_DST(i,j),E_DST(i, j)) gained is all measured by luminance meter.