CN101075412A - Liquid crystal display dynamic contrast enhancement method and device - Google Patents

Abstract

The invention provides a method and a device for enhancing dynamic contrast of a liquid crystal display, wherein when an image signal is processed, the intensity and the distribution condition of the signal are analyzed, the analysis result is used for controlling the backlight intensity of a backlight module of the liquid crystal display through a processing unit, and the dynamic distribution adjusting and dynamic signal enhancing unit can dynamically adjust the contrast distribution and the contrast dynamic enhancing effect of the signal, and simultaneously, the defects that the brightness contrast of the liquid crystal display is too low and the brightness of a black picture is too high are improved.

Description

Liquid crystal display dynamic contrast enhancement method and device

technical field

The invention relates to a dynamic contrast enhancement method applied to video images, in particular to a liquid crystal display dynamic contrast adjustment method that can dynamically utilize a backlight adjustment unit and a dynamic signal intensity adjustment unit to change the intensity of an input signal.

Background technique

The hardware equipment of flat display (Flat Display) has approached a mature and stable stage, such as: backlight module, panel or driving circuit, etc., the degree of influence on image quality has gradually decreased, and the improvement of image display quality is the direction of everyone's efforts .

In the past, the part of the quality that users were most concerned about was the brightness (cd/m ² ) of the flat-panel display. At present, there are two ways to improve the brightness. One is to increase the light transmission rate of the LCD panel; the other is to increase the background The brightness of the light, however, a brighter product is not necessarily a better product. Too bright a display screen often makes people feel uncomfortable. On the one hand, it is easy to cause visual fatigue, and it also reduces the contrast between pure black and pure white. The performance of color scale and gray scale.

The luminance ratio measured by the screen under two conditions of full white and full black is called contrast (Contrast). In order to enhance the illuminance of the lighting unit (cold cathode fluorescent lamp, CCFL) used in the LCD backlight (as mentioned above Increase the brightness of the background light) to improve the contrast, usually with high current continuous driving, so as to increase the contrast value marked on the LCD screen specification to attract consumers, but the life cycle of the lighting unit in the high current state will decrease relatively. If a low current is used to drive the lighting unit in order to prolong the life of the lighting unit, it will not be possible to obtain a good illuminance, and it will also lose the willingness to attract consumers to purchase initially.

In addition, the light tube in the backlight module provides a certain value for the brightness of the light source for all display images. The contrast enhancement technology currently used is only a static enhancement technology, which only enlarges the contrast relationship between the signal and the fixed gray scale, or transparent. Through the arrangement of liquid crystal molecules, the luminous flux is affected to produce a darker tone. However, the opening and closing time of each liquid crystal molecule will cause the problem of light leakage in the surrounding area, so the problem of light leakage is still one of the issues that need to be solved urgently, and when the light leakage occurs, it will produce dark or even gray when the screen displays a darker picture. state.

In view of the above-mentioned problems, how to enhance the distribution relationship between signals and adjust the light source in an appropriate state for image displays to make the image quality more perfect, a technology of "dynamic contrast enhancement method and device for liquid crystal displays" is proposed .

Contents of the invention

The primary purpose of the present invention is to dynamically adjust and strengthen the contrast relationship between signals through the input video signal, and also dynamically control the brightness of the backlight of the display. In this way, the shortcomings of low brightness contrast and too bright black screen brightness of the liquid crystal display can be improved at the same time. .

The second object of the present invention is to increase or decrease the brightness level by dynamically adjusting and strengthening the contrast relationship between the signals, so that the brightness level is shifted to the positive side or the negative side, so that the input image can be based on The new probability distribution relationship and the adjustment of the backlight range improve the overall picture quality of the LCD.

Another object of the present invention is to redistribute the distribution probability of signal strength (signal average gray scale value) to generate a new transfer function (transfer function), by converting the original input signal through the transfer function to generate an adjusted output signal , so that the liquid crystal display can obtain a better display effect.

In the method and device for dynamic contrast enhancement of a liquid crystal display of the present invention, when a signal is provided for display on a liquid crystal panel, the brightness of the backlight of the liquid crystal display and the signal strength are adjusted in advance to achieve displaying a picture provided by the processed signal, which includes: A signal distribution analysis unit, a backlight module adjustment unit, and a signal dynamic adjustment unit. First, the signal distribution analysis unit analyzes the input signal to obtain an average gray scale distribution probability value of the input signal. The obtained value is obtained by the backlight The module adjustment unit judges the output backlight control signal to control the display light source emitted by the backlight module within a predetermined range; at the same time, the distribution probability value obtained by the signal distribution analysis unit is used by the signal dynamic adjustment unit to judge the signal strength. Whether the highest value of the bright level and the lowest value of the dark level are within a predetermined range, so as to extend the signal scale to display a more detailed display image.

The implementation steps of the present invention will be described below in conjunction with the accompanying drawings. The following examples are used to illustrate the present invention and are not intended to limit the scope of the present invention. Any person familiar with the art may make some changes and modifications , so the protection scope of the present invention shall prevail as defined by the claims.

Description of drawings

Fig. 1 is a circuit block diagram of the present invention;

Figures 2A and B are comparison diagrams of signal strength and backlight range distribution before and after adjustment when a darker picture is to be presented;

Figure 3A and B compare the distribution of signal strength and backlight range before and after adjustment when a brighter picture is to be presented; and

FIG. 4 is a flow chart of the distribution and adjustment of the dynamic signal.

Symbol Description

1 input signal

1a Input signal

10 Signal analysis unit

20 Backlight module adjustment unit

30 Signal dynamic adjustment unit

Step 1~Step 5

Detailed ways

Please refer to the circuit block diagram shown in FIG. 1 to illustrate the architecture of contrast enhancement proposed by the present invention. The architecture includes a signal analysis unit 10, a backlight module adjustment unit 20 and a signal dynamic adjustment unit 30, wherein the input signal 1 is input from the front-stage input terminal of the signal analysis unit 10, and the output signal 1a can provide the backlight The module adjustment unit 20 and the signal dynamic adjustment unit 30 are used as a reference, and further output terminals of the backlight module adjustment unit 20 and the signal dynamic adjustment unit 30 output adjusted signals. The input signal 1 can be a composite signal (Composite Video Signal), a component signal, an S terminal signal, or a Y/C processed signal of other digital signals.

The signal analysis unit 10 receives an external continuous signal 1 input and is electrically connected to the backlight module adjustment unit 10 and the signal dynamic adjustment unit 20. Its main function is to analyze the input signal 1 to obtain an intensity distribution probability of the input signal. value, and the distribution probability value can be used for subsequent reference adjustment of the input signal of the backlight module adjustment unit 20 and the signal dynamic adjustment unit 30 . Further speaking, the probability value of the intensity distribution is a proportional relationship of the gray scale value of the signal.

Here, please refer to Fig. 2A, B and Fig. 3A, B at the same time for comparison and correspondence. For the backlight module adjustment unit 20, the input signal 1a will first be adjusted according to the intensity distribution probability value generated by the signal analysis unit 10, for example: the input signal is in the state shown in Figure 2A at the beginning, and the liquid crystal display needs to display When it is necessary to enhance the black level of the dark picture, or it is in the state shown in Figure 3A, if the liquid crystal display needs to display a bright picture and the white level needs to be strengthened, the expected displayed high and low gray scale value picture is not within the predetermined range In this method, a signal will be output according to the distribution probability state analyzed by the signal analysis unit 10 to indicate that the light source output of the backlight module for display is dynamically adjusted within a range, so that the light output is reduced when a dark picture is required, otherwise a bright picture is required When enhancing its light output, the light source can provide dynamic adjustment of brightness to increase the contrast of the picture.

For the signal dynamic adjustment unit 30, the input signal 1a will redistribute the distribution probability of the signal intensity (signal average gray scale value) according to the distribution probability value, so as to generate a new transfer function (transfer function), by converting the original input The signal is transformed by the transfer equation to produce the adjusted output signal. For example: if the signal is intended to produce a darker (the signal distribution as shown in Figure 2) or a brighter (the signal distribution as shown in Figure 3), if the display area is wider, it will inevitably result in In some cases, the contrast is poor, and the screen becomes foggy. After the signal is redistributed according to the above method through the signal dynamic unit 30, the signal ratio is extended, and the signal with the adjusted gray scale value is output, and the original distribution intensity range is enlarged, so that a more detailed and layered display screen can be obtained. Solve the shortcomings of the liquid crystal display that the brightness of the black screen is too bright and the brightness of the bright screen is not bright enough. The situation after the signal strength adjustment can be seen from the shift of the signal in FIG. 2B to the left (darker scale) and the signal in FIG. 3B to the right (brighter scale).

Through the above relationship, the steps of the dynamic contrast enhancement method of the present invention can be obtained, please refer to FIG. 4 at the same time. First, the input signal is analyzed by the signal distribution analysis unit to obtain an intensity distribution probability value of the input signal (step 1), and the obtained value is judged by the backlight module adjustment unit to output the backlight control signal to control the backlight module The emitted display light source is adjusted in a predetermined range (step 4); at the same time, a new transfer function (transfer function) is generated according to the distribution probability (step 2), and the adjusted transfer function is generated by converting the original input signal through the transfer function. Output a signal (step 3), and make the output signal undergo subsequent processing. If the signal is within a predetermined range and does not need to be adjusted, the input signal is directly turned into an output signal (step 5).

Therefore, the present invention can use the signal analysis unit to obtain an intensity distribution probability relationship, and then control the display light source emitted by the backlight module within a predetermined range according to the relationship, and adjust the signal intensity by extending the signal ratio, so as to obtain a more detailed picture.

Claims (5)

1. A liquid crystal display dynamic contrast enhancement device, by changing the signal distribution relationship, to achieve the effect of improving the contrast of the picture, it is characterized in that, comprising: A signal analysis unit, which receives continuous signal input and is electrically connected to the backlight module adjustment unit and the signal dynamic adjustment unit, which analyzes the input signal to obtain an intensity distribution probability value of the input signal; A backlight module adjustment unit, at least electrically connected to the signal analysis unit, dynamically adjusts the output signal of the light source of the backlight module for display from the distribution probability state obtained by the signal analysis unit, so that the light source can dynamically adjust the brightness; and A signal dynamic adjustment unit, which is at least electrically connected to the signal analysis unit, and judges the highest value of the light level and the lowest value of the dark level of the signal intensity from the distribution probability state obtained by the signal analysis unit, so as to extend the signal ratio to output a signal for display A detailed display screen. 2 . The dynamic contrast enhancement device according to claim 1 , wherein the intensity distribution probability value is an analysis of the gray scale value of the input signal. 3 . 3. A liquid crystal display dynamic contrast enhancement method, by changing the signal distribution relationship, to achieve the effect of improving the contrast of the picture, characterized in that: Firstly, the input signal is analyzed by the signal distribution analysis unit to obtain an intensity distribution probability value of the input signal; The backlight module adjustment unit judges the output backlight control signal to match the intensity distribution probability value, so as to control the display light source emitted by the backlight module to adjust the backlight within a predetermined range. 4. A liquid crystal display dynamic contrast enhancement method, by changing the signal distribution relationship, to achieve the effect of improving the contrast of the picture, characterized in that: Firstly, the input signal is analyzed by the signal distribution analysis unit to obtain an intensity distribution probability value of the input signal; The signal dynamic adjustment unit judges and converts the original input signal through the conversion equation of the intensity distribution probability value to generate an adjusted output signal. 5. The dynamic contrast enhancement method according to claim 3 or 4, wherein if the signal is within a predetermined range and does not need to be adjusted, the input signal is directly converted into an output signal.

Images