CN100411008C - Method and device for controlling brightness of display - Google Patents

Abstract

The invention provides a method and a device for controlling the brightness of a display, which firstly count the brightness distribution of a received partial picture image, then judge whether the partial picture image is dark or bright, and then compare the backlight brightness with a default value according to the dark partial picture image or the bright partial picture image so as to adjust the backlight brightness of the display.

Description

Method and device for controlling display brightness

technical field

The invention relates to the technical field of flat-panel displays, in particular to a method and device for controlling the brightness of a display.

Background technique

With the development of the electronic industry, portable electronic products such as mobile phones, personal digital assistants (PDAs), MP3 players, etc. have gradually flooded our daily life. These portable electronic products usually have a small display panel, and its panel may be a liquid crystal display (LCD), an organic light emitting flat panel display (OLED) or other common flat panel displays. However, the battery power of these portable electronic products is usually limited. In order to increase the service life of the battery, the brightness of the display is usually adjusted appropriately to increase the overall system service time.

Generally speaking, the stronger the brightness displayed by the flat panel display, the greater the current consumption. Taking a liquid crystal display as an example, if the brightness is higher at the same gray scale, the current consumed by the backlight will be greater; and for an organic light-emitting flat panel display, if it is a single display pixel, the required current consumption will increase.

At present, the common display brightness control methods are as follows: (a) automatically reduce or turn off the brightness of the backlight after counting a certain interruption of use time to save power, but this method will directly affect the overall brightness of the screen, and only in the It can save power only when it is not in operation; and (b) count the brightness distribution of the screen during the operation period, for example: when playing an image, if most of the grayscale values of the entire image are concentrated in the darker area of the image (for example: grayscale If most of the values are less than the grayscale value (50), the brightness of the backlight will be reduced; on the contrary, if the grayscale value of the playback screen is concentrated in the brighter area of the image, the brightness of the backlight will remain normal, so that the human eye will not feel easily affected by the brightness reduction. The resulting image quality is degraded. However, in addition to statistical brightness distribution, the current method also needs to store the entire picture through a frame buffer, which will make the circuit design relatively complicated and the system cost high.

Contents of the invention

The object of the present invention is to provide a method and device for controlling the brightness of a display, so as to dynamically adjust image contrast and brightness according to the brightness distribution of an input image.

The purpose of the present invention is to provide a method and device for controlling the brightness of a display, which can gradually adjust the brightness to avoid brightness flickering caused by discontinuous scenes.

The object of the present invention is to provide a method and device for controlling the brightness of a display, so that the entire frame can be stored without using a frame buffer, so that the circuit design is relatively simple and the system cost can be reduced.

According to a feature of the present invention, it is to propose a method for controlling the brightness of a display, comprising the following steps: a receiving step, which is to receive a part of the picture image; a statistical step, which is to count the brightness distribution of the part of the picture image; The comparing step is to obtain a comparison result according to the brightness distribution of the part of the picture image and the backlight brightness; and the adjusting backlight brightness step is to adjust the backlight brightness of the display according to the comparison result.

According to another feature of the present invention, a device for controlling the brightness of a display is proposed, including: an image data flow statistics unit, which receives a part of the picture image, and counts the brightness distribution of the part of the picture image; a dynamic area calculation unit A module for judging the brightness of the part of the screen image according to the brightness distribution of the part of the screen image, and judging whether the brightness of the backlight conforms to the part of the screen image to obtain a control signal; and a backlight pulse width modulation signal control unit to adjust the brightness of the backlight of the display according to the control signal.

Because the present invention is novel in design, can provide industrial utilization, and has indeed enhanced effect, so apply for the invention patent according to law.

Description of drawings

Fig. 1 is a functional block diagram of a preferred embodiment of the present invention.

Fig. 2 is a flowchart of a preferred embodiment of the present invention.

Fig. 3 is a flowchart of another preferred embodiment of the present invention.

Description of figure number

Image data flow statistics unit 110 Dynamic area calculation module 120

Backlight Pulse Width Modulation Signal Control Unit 130

Digital to Analog Converter 140 Backlight Module 150

Contrast enhancement unit 160

Detailed ways

The present invention is achieved by counting the proportion of the high-brightness area of a partial image. That is, when the number of pixels in the high-brightness portion of the continuous horizontal scanning line is less than a set value, the brightness of the backlight is gradually reduced to save power consumption of the backlight.

Regarding the description of the preferred embodiment of the present invention, please refer to the functional block diagram shown in FIG. 1, which includes a video stream histogram unit 110, a dynamic range calculation module 120, a backlight A PWM signal control unit 130 , a digital-to-analog converter (DAC) 140 , a backlight module 150 and a contrast enhancement unit 160 .

The image data flow statistics unit 110 is used to receive image information (R, G, B) for performing statistical processing on some frames, so as to obtain the results of some frames that meet the default values. The dynamic area calculation module 120 receives the statistics result of the image data flow statistics unit 110, and performs processing of whether to adjust the backlight according to the statistics result to obtain a control signal. The backlight pulse width modulation signal control unit 130 adjusts the width (PW) of a pulse modulation signal (PWM) according to the control signal output by the dynamic range calculation module 120 to adjust the brightness of the backlight. The digital-to-analog converter 140 converts the digital pulse modulation signal into an analog signal to control the brightness of the backlight module 150 . The contrast enhancement unit 160 is used to adjust the R, G, and B values of the pixels to enhance the contrast of the picture.

In addition, the contrast enhancement unit 160 is an optional functional unit, and in other embodiments, this functional block may not be added. Moreover, in other embodiments, the digital-to-analog converter 140 can also be replaced by a low pass filter (Low Pass Filter, LPF).

For further description of the present invention, please refer to FIG. 1 and FIG. 2 together, wherein FIG. 2 is a flowchart of a preferred embodiment of the present invention. First, in step S205 , the image data stream statistics unit 110 receives partial frame image information. In this embodiment, part of the frame image information refers to a single horizontal scanning line. In other embodiments, the image information of a part of the frame may be half a horizontal scanning line, several pixels (for example: 200 dots), several consecutive horizontal scanning lines or a segmented frame. In step S210, the image data flow statistics unit 110 will find out the maximum value (L) among R, G, and B of each pixel, for example: the R, G, and B values of a certain pixel are 50, 100, respectively. 160, it means that the maximum R, G, B value (L) of this pixel is 160.

In step S215 , the image data stream statistics unit 110 determines whether the L value is smaller than a first default value (for example: 64), and if the L value is smaller than the first default value, it means that the pixel is dark. In step S220, the number of dark pixels is accumulated to obtain a dark accumulation value SUM. On the contrary, if the value of L is greater than the first default value, proceed to step S210.

In step S225, it is judged whether the statistical processing of the part of the image is completed, if not, then continue to return to step S210 to continue the statistics of the number of dark pixels. On the contrary, if the statistics of this part of the image have been completed, step S230 is executed.

In step S230, the dynamic range calculation module 120 judges whether the accumulated number of dims SUM is greater than the second default value S _TH (for example: 500) and whether the width of the pulse modulation signal is greater than the third default value PWmin (minimum allowable Backlight brightness, eg: 88). If yes, execute step S235; if not, execute step S240.

In step S235, it indicates that the dark pixels of the part of the frame image exceed the second default value S _TH (500), and the width of the pulse modulation signal is greater than the third default value PWmin. That is, the image in this part of the screen is dark, but the brightness of the backlight is relatively bright, so the brightness of the backlight can be slightly lowered. At this time, the width of the pulse modulation signal is reduced to reduce the brightness of the backlight module 150 .

In step S240, it is judged whether the accumulated dim number SUM is smaller than the second default value S _TH (500) and whether the width of the pulse modulation signal is smaller than the fourth default value PWmax. If yes, execute step S245; if not, execute step S250.

In step S245, it means that the dark pixels of the part of the frame image do not exceed the second default value S _TH (500), and the width of the pulse modulation signal is smaller than the fourth default value PWmax. That is, the image in this part of the screen is brighter, but the brightness of the backlight is relatively dark, so the brightness of the backlight can be slightly increased. At this time, the width of the pulse modulation signal is increased to increase the brightness of the backlight module 150 .

Finally, after adjusting the width of the pulse modulation signal, step S250 is executed to output the pulse modulation signal to the digital-to-analog converter 140 to control the brightness of the backlight module 150 . In this way, the brightness of the backlight can be adjusted dynamically according to the influence of the playing picture, and the power consumption of the system can be reduced.

The above-mentioned embodiment is mainly based on counting the number of dark spots in the partial image. Of course, in other embodiments, the counting of the number of bright spots in the partial image can also be used as the basis.

Fig. 3 is a flowchart of another preferred embodiment of the present invention. Most of the steps S305-S325, S350-S360 are similar to the steps S205-S225, S230-S250 in FIG. 2, so no further description is given here. However, in this embodiment, step S330 is to determine whether the L value is greater than the fifth default value (for example: 196), and if the L value is greater than the fifth default value, it means that the pixel is brighter. Therefore, step S330 is to count the number of partial bright spots.

In step S340, it is judged whether the accumulated dim number SUM1 is greater than the accumulated bright number SUM2, whether the accumulated dim number SUM is greater than the second default value S _TH (500) and whether the width of the pulse modulation signal is greater than the third default value PWmin. If all are true, it means that the part of the image has a large number of dark spots, and at this time the width of the pulse modulation signal is reduced to reduce the brightness of the backlight module 150 (step S350 ).

In step S345, it is judged whether the accumulated partial bright number SUM2 is greater than the accumulated partial dark number SUM1, whether the accumulated partial bright number SUM2 is greater than the second default value S _TH (500) and whether the width of the pulse modulation signal is If it is smaller than the fourth default value PWmax, if both are true, it means that the part of the image has a large number of bright spots. At this time, increase the width of the pulse modulation signal to increase the brightness of the backlight module 150 (step S355).

From the above description, it can be known that the present invention dynamically adjusts the image contrast and brightness according to the brightness distribution of the input image. In addition, when adjusting the brightness of the backlight, it adopts gradual adjustment, which can avoid the brightness flickering of the screen when the scene is not continuous, and the present invention The above effects can be achieved without using a frame buffer, which not only makes the circuit simpler but also lowers the cost.

The above-mentioned preferred specific embodiments are only examples for convenience of description, and the scope of protection claimed by the present invention should be determined by the claims of the present invention, rather than being limited to the above-mentioned embodiments.

Claims (18)

1. a method of controlling display brightness is characterized in that, comprises following step:

One receiving step receives a part of picture image;

One statistics step, the Luminance Distribution of adding up this part picture image;

One comparison step, Luminance Distribution and backlight illumination according to this part picture image obtain a comparative result, and wherein this backlight illumination is with the width means of a PM signal; And

One adjusts the backlight illumination step, adjusts the backlight illumination of this display according to this comparative result.

2. the method for claim 1 is characterized in that, this part picture image is a plurality of pixels.

3. the method for claim 1 is characterized in that, this part picture image is a section picture.

4. the method for claim 1 is characterized in that, in this statistic procedure, adds up the dim spot number of this part picture image.

5. the method for claim 1 is characterized in that, in this statistic procedure, adds up the bright spot number of this part picture image.

6. the method for claim 1 is characterized in that, in this statistic procedure, also comprises the maximum R that finds out each pixel, G, and the B value then relatively should maximum R, G, B value and one first default value.

7. the method for claim 1 is characterized in that, in this comparison step, comes comparison one second default value according to the Luminance Distribution of this part picture image, to judge the brightness of this part picture image.

8. method as claimed in claim 7 is characterized in that, if the Luminance Distribution of this part picture image is dark partially, and this backlight illumination is then adjusted in backlight illumination step the reduction backlight illumination in this greater than one the 3rd default value.

9. method as claimed in claim 7 is characterized in that, if the Luminance Distribution of this part picture image is bright partially, and this backlight illumination is then adjusted in backlight illumination step the increase backlight illumination in this less than one the 4th default value.

10. a device of controlling display brightness is characterized in that, comprises:

One imaging data stream statistic unit receives a part of picture image, and adds up the Luminance Distribution of this part picture image;

One dynamic area computing module, judge the brightness of this part picture image according to the Luminance Distribution of this part picture image, and judge whether backlight illumination meets this part picture image, to obtain a control signal, wherein this backlight illumination is with the width means of a PM signal; And

One backlight pulse width modulation signaling control unit is adjusted the backlight illumination of this display according to this control signal.

11. device as claimed in claim 10 is characterized in that, this part picture image is a plurality of pixels.

12. device as claimed in claim 10 is characterized in that, this part picture image is a section picture.

13. device as claimed in claim 10 is characterized in that, this imaging data stream statistic unit is added up the dim spot number of this part picture image.

14. device as claimed in claim 10 is characterized in that, this imaging data stream statistic unit is added up the bright spot number of this part picture image.

15. device as claimed in claim 10 is characterized in that, this imaging data stream statistic unit is found out the maximum R of each pixel by this part picture image, G, and the B value then relatively should maximum R, G, B value and one first default value.

16. device as claimed in claim 10 is characterized in that, this dynamic area computing module comes comparison one second default value according to the Luminance Distribution of this part picture image, to judge the brightness of this part picture image.

17. device as claimed in claim 16 is characterized in that, if partly the Luminance Distribution of picture image is dark partially for this, and this backlight illumination is greater than one the 3rd default value, and then this dynamic area computing module output one reduces the control signal of backlight illumination.

18. device as claimed in claim 16 is characterized in that, if partly the Luminance Distribution of picture image is bright partially for this, and this backlight illumination is less than one the 4th default value, and then this dynamic area computing module output one increases the control signal of backlight illumination.

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