CN102903340B

CN102903340B - Liquid crystal display is based on the LED dynamic backlight control method of dynamic threshold

Info

Publication number: CN102903340B
Application number: CN201210448094.XA
Authority: CN
Inventors: 章小兵; 刘波; 朱标; 陈文明; 赵小珍
Original assignee: AVIC Huadong Photoelectric Co Ltd
Current assignee: AVIC Huadong Photoelectric Co Ltd
Priority date: 2012-11-12
Filing date: 2012-11-12
Publication date: 2015-11-04
Anticipated expiration: 2032-11-12
Also published as: CN102903340A

Abstract

The invention provides the LED dynamic backlight control method of a kind of liquid crystal display based on dynamic threshold, comprise the steps: first to adopt threshold value dichotomy to obtain the threshold value T making the inter-class variance between background and target maximum; Calculate each region backlight illumination variation factor; Backlight illumination variation factor K (m, n) is substituted into formula BL _{(m, n)}=average _{(m, n)}+ K _{(m, n)}× (max _{(m, n)}-average _{(m, n)}) obtain the backlight illumination in each region.The invention has the advantages that: this algorithm is on the basis of mean picture brightness, ratio shared by image detail increases backlight illumination dynamically, and the ratio shared by image detail is obtained by Da-Jin algorithm, and algorithm is simple, improve LCD picture quality, reduce power consumption.

Description

Liquid crystal display is based on the LED dynamic backlight control method of dynamic threshold

Technical field

The present invention relates to a kind of LED-backlit control method, specifically a kind of LED dynamic backlight control method.

Background technology

Along with improving constantly of people's quality of the life, LCD TV is towards future developments such as large scale, ultra-thin, wide colour gamut, high-contrasts.LED-backlit LCD TV is just along with demand progressively routing study field and the application market of people, and in the middle of LED-backlit liquid crystal tv technology, LED region dynamic backlight LCD TV is then the emphasis of current field of liquid crystals research.Dynamic backlight subjective brightness extraction algorithm reduces backlight power consumption because relating to the full extent while guarantee display frame quality, becomes the important object that each LCD TV production firm and mechanism are studied gradually.

The meaning of this technical research: (1) improving picture display quality.We know, LCD TV backlight colour gamut is close to NTSC colour gamut, and display frame color is access expansion look.But traditional LCD TV is CCFL backlight, and colour gamut can only reach 70% ~ 80% of NTSC colour gamut.Adopt white light LEDs (W-LED) although the more traditional CCFL backlight liquid crystal television color gamut of backlight liquid crystal TV colour gamut promotes very few, the advantage such as contrast raising, lower power consumption realized after W-LED backlight liquid crystal TV can adopt dynamic backlight control technology is that traditional C CFL backlight liquid crystal TV is incomparable.Moreover, adopt RGB-LED backlight easily can reach the NTSC gamut range of 100%, if adopt the LED component that performance is more powerful, then can realize the NTSC gamut range of more than 120%.The raising of colour gamut, contributes to promoting the LCD TV picture color degree of depth.(2) power consumption is reduced.Because LCD TV power consumption mainly concentrates in backlight power consumption, and during traditional CCFL backlight liquid crystal television operations, backlight is all opened, and backlight illumination can not change according to picture material, result in LCD TV power consumption higher.Along with the living standard of people improves constantly, LCD TV is towards development in large size.And due to the continuous increase of LCD TV size, power problems is more and more obvious.Investigation display main product 40 inches in the market, 42 inch liquid crystal TV power consumptions are between 200W-240W, and 46-52 inch power consumption is between 250W-310W, and 65 inch liquid crystal TV power consumptions reach more than 500W.Obviously, power problems can not meet design requirement, and also runs in the opposite direction with the national policy of current energy-saving and emission-reduction.Adopt dynamic backlight control technology LCD TV backlight in good time according to display frame Content adaptation, LCD TV lower power consumption 30%-50% can be made.

Summary of the invention

The technical problem to be solved in the present invention is to provide the LED dynamic backlight control method of a kind of liquid crystal display based on dynamic threshold, and the image both having obtained high-quality again reduces power consumption.

The present invention solves the problems of the technologies described above by the following technical solutions: a kind of liquid crystal display, based on the LED dynamic backlight control method of dynamic threshold, comprises the steps:

Step 1: calculated threshold: maximum kind variance method is a kind of adaptive Threshold, is again Da-Jin algorithm (OTSU).It is, by the gamma characteristic of image, image is divided into background and target (details) two parts.Inter-class variance between background and target is larger, illustrates that the two-part difference of composing images is larger.When partial target mistake is divided into background or part background mistake to be divided into target that two-part difference all can be caused to diminish.Therefore, the segmentation making inter-class variance maximum means that the probability of wrong point is minimum.Adopt threshold value dichotomy to obtain the threshold value T making inter-class variance maximum herein, its formula is as follows:

\{\begin{matrix} w_{0} = N_{0} / (M \times N) \\ w_{1} = N_{1} / (M \times N) \\ g = w_{0} \times w_{1} \times {(u_{0} - u_{1})}^{2} \end{matrix}

Wherein: the ratio that the pixel number belonging to details accounts for entire image is designated as w ₀, average gray is designated as u ₀; The ratio that the pixel number belonging to background accounts for entire image is w ₁, average gray is designated as u ₁; Inter-class variance is designated as g; Image size is M × N; The pixel number that in image, gray-scale value is less than threshold value T is designated as N ₀, the pixel number being greater than T is designated as N ₁.

Step 2: calculate each region backlight illumination variation factor: obtain inter-class variance maximum time threshold value T after, we carry out binaryzation by this threshold value to image.In statistics bianry image single area, pixel value is 1 counts out, and is designated as M ₁; Pixel value is 0 counts out, and is designated as M ₀.Then backlight illumination variation factor is:

K(m,n)＝M ₁/(M ₀+M ₁)

Step 3: K (m, n) is substituted into formula BL _{(m, n)}=average _{(m, n)}+ K _{(m, n)}× (max _(m, _n)-average _{(m, n)}) obtain the backlight illumination in each region.Wherein: BL represents backlight brightness values; Average and max represents the average backlight brightness values in region and maximum backlight brightness values respectively; (m, n) represents the m capable n-th divided and arranges a region.

The invention has the advantages that: this algorithm is on the basis of mean picture brightness, ratio shared by image detail increases backlight illumination dynamically, ratio shared by image detail is obtained by Da-Jin algorithm, algorithm is simple, owing to being increase backlight illumination on the basis of average brightness value, so the backlight modulation plot quality obtained is high, distortion is few, improve LCD picture quality, reduce power consumption.

Embodiment

For each two field picture, first we extract the maximal value (doing the number of pixels that distortion occurs to overflow after can reducing pixel compensation like this) of image each pixel RGB by MATLAB programming, the matrix that maximal value forms is divided into 12 × 16 totally 192 regions; Then, programming obtains maximal value Imax and the mean value Iaverage of each area grayscale value, calculates the high-high brightness max=(Imax/255) in brightness corresponding to gray-scale value and region ^r, mean flow rate average=(Iaverage/255) ^r, r=2.2.MATLAB programming is adopted to obtain the max-thresholds T of inter-class variance, and by image binaryzation, the pixel value being greater than T is 1, the pixel value being less than T is 0, statistics regional in pixel value be 1 number be designated as M1 (details of representative image), pixel value be 0 number be designated as M0 (background of representative image), according to formula K (m, n)=M ₁/ (M ₀+ M ₁) obtain the K (m, n) of regional.Finally, K (m, n) is substituted into BL _{(m, n)}=average _{(m, n)}+ K × (max _{(m, n)}-average _{(m, n)}) obtain the backlight illumination in each region.Adopt the algorithm of dynamic threshold, for the image that details is abundanter, the backlight modulation figure effect that this algorithm process obtains is better, operation time of this algorithm very fast (be approximately 0.9s for the image operation time of one 640 × 480).

The foregoing is only the preferred embodiment of the invention; not in order to limit the invention; the any amendment done within all spirit in the invention and principle, equivalently to replace and improvement etc., within the protection domain that all should be included in the invention.

Claims

1. liquid crystal display is based on a LED dynamic backlight control method for dynamic threshold, it is characterized in that: comprise the steps:

Step 1: calculated threshold: adopt threshold value dichotomy to obtain the threshold value T making the inter-class variance between background and target maximum, its formula is as follows:

\{\begin{matrix} w_{0} = N_{0} / (M \times N) \\ w_{1} = N_{1} / (M \times N) \\ g = w_{0} \times w_{1} \times {(u_{0} - u_{1})}^{2} \end{matrix}

Wherein: the ratio that the pixel number belonging to details accounts for entire image is designated as w ₀, average gray is designated as u ₀; The ratio that the pixel number belonging to background accounts for entire image is w ₁, average gray is designated as u ₁; Inter-class variance is designated as g; Image size is M × N; The pixel number that in image, gray-scale value is less than threshold value T is designated as N ₀, the pixel number being greater than threshold value T is designated as N ₁;

Step 2: calculate each region backlight illumination variation factor: obtain inter-class variance maximum time threshold value T after, carry out binaryzation by this threshold value to image, in statistics bianry image single area, pixel value is 1 counts out, and is designated as M ₁; Pixel value is 0 counts out, and is designated as M ₀, then backlight illumination variation factor is:

K(m,n)＝M ₁/(M ₀+M ₁)；

Step 3: backlight illumination variation factor K (m, n) is substituted into formula BL _{(m, n)}=average _(m, _n)+ K _{(m, n)}× (max _{(m, n)}-average _{(m, n)}) obtain the backlight illumination in each region, wherein: BL represents backlight brightness values; Average and max represents the average backlight brightness values in region and maximum backlight brightness values respectively; (m, n) represents the m capable n-th divided and arranges a region.