CN104065959A - LED based display screen luminance uniformity assessment method - Google Patents
LED based display screen luminance uniformity assessment method Download PDFInfo
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- CN104065959A CN104065959A CN201410279364.8A CN201410279364A CN104065959A CN 104065959 A CN104065959 A CN 104065959A CN 201410279364 A CN201410279364 A CN 201410279364A CN 104065959 A CN104065959 A CN 104065959A
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Abstract
The invention discloses an LED based display screen luminance uniformity assessment method. A CCD image sensor acquires LED display screen pixel brightness information, stores acquired pixel luminance information to a computer through a digital interface card in an image mode, an image processing system is used for processing the images stored in the computer and sends processed information to an error correction system, the error correction system perform correction, and LED display screen luminance uniformity can be effectively assessed by adopting the systems.
Description
Technical field
The present invention relates to LED display technical field, relate in particular to a kind of based on LED display brightness uniformity appraisal procedure.
Background technology
LED display is as the display terminal of multimedia facility, and its final goal has been that high-quality dynamic video image shows.As self-luminous body show establish, LED pixel has the feature such as discreteness and high brightness, the brightness of LED display and uniformity of chromaticity are the key factors that affects display screen quality, wherein brightness uniformity to people's visual impact much larger than uniformity of chromaticity.Therefore, be necessary the brightness uniformity of LED display to propose objective and accurate appraisal procedure, thereby provide guidance for research and development and the production of LED.Existing appraisal procedure mainly adopts brightness instrument to test the some modules of whole screen and associated area thereof, obtains assessment data through simple computation.This appraisal procedure not only speed is slow, and requires high to test environment.In addition, because image data is limited, therefore to the assessment result of data with very large randomness.
Summary of the invention
The present invention is exactly in order to solve the problems of the technologies described above, a kind of LED display brightness acquisition system is provided, obtain LED pixel intensity information by ccd image sensor, in conjunction with digital image processing techniques and statistics rule, LED pixel grey scale histogram-fitting is become to normal distribution curve, utilize standard deviation to assess LED brightness of display screen uniformity.
Technical scheme of the present invention is as follows:
A kind of based on LED display brightness uniformity appraisal procedure, it is characterized in that comprising:
A, ccd image sensor gather LED display pixel intensity information;
B, ccd image sensor are crossed digital interface card by the pixel intensity information exchange collecting and are saved in computer in the mode of image;
C, image processing system processing are kept at the image in computer, and information after treatment is sent to error correction systems;
D, error correction systems receive the information data that image processing system sends, and this information data are revised.
Further, described ccd image sensor is positioned at LED display screen dead ahead, and makes ccd image sensor camera lens and display screen edge maximum angle within the scope of 2 °.
Further, described image processing system is that the LED pixel intensity characteristic in image is extracted, and generates gray scale pictures.
Further, described error correction systems is revised the sensitization error of angular error and ccd image sensor in described gray scale pictures, obtains approaching the LED display relative brightness information that true brightness distributes.
The present invention's beneficial effect is compared with prior art:
1, utilize CCD collected by camera data, real-time is good, contain much information;
2, image processing system employing image grey level histogram has represented the statistic information of each pixel brightness contribution, can effectively determine the brightness range of display screen;
3, normal distribution standard deviation can simply and effectively represent the uniformity of Luminance Distribution;
4, ccd image sensor camera lens and display screen edge maximum angle, within the scope of 2 °, can reduce LED display pixel visual angle luminance errors like this.
Brief description of the drawings
Fig. 1 system configuration schematic diagram of the present invention.
The intensity map of Fig. 2 LED bearing member, image of the present invention.
Fig. 3 LED display module of the present invention grey level histogram.
Fig. 4 grey level histogram assessment data of the present invention comparison diagram.
Embodiment
Below in conjunction with accompanying drawing, a kind of LED display brightness acquisition system the present invention relates to is described further.
LED display is made up of ten hundreds of LED pixels, and in the bearing member, image being collected by ccd image sensor, the value of each photosensitive unit represents certain gray scale.The information such as the locus that bearing member, image comprises LED pixel, luminous shape and luminous intensity, each LED pixel in bearing member, image by several CCD
Photosensitive unit composition.
As shown in Figure 1, described LED display brightness acquisition system, comprises LED display, ccd image sensor, digital interface card, computer, image processing system, error correction systems; Ccd image sensor is used for gathering LED display pixel intensity information, ccd image sensor is crossed digital interface card by the pixel intensity information exchange collecting and is saved in computer in the mode of image, image processing system is for the treatment of the image being kept in computer, and information after treatment is sent to error correction systems, revise by error correction systems.
Described image processing system is that the LED pixel intensity characteristic in image is extracted, and generates brightness data matrix.
Described error correction systems is that angular error when taking pictures and the sensitization error of CCD camera are revised, and obtains approaching the LED display relative brightness information that true brightness distributes.
Fig. 2 is the Luminance Distribution of the CCD bearing member, image of the each pixel of 2 × 2 pixel L ED display panel module.As we can see from the figure, the Luminance Distribution of single led display pixel is not a plane, but a curved surface that radius of curvature is different, and represents that the gray areas that the photosensitive unit of object brightness feature forms is not the circle of rule in ideal yet.In figure, in each target area, the gray value of photosensitive unit is reduced to surrounding gradually by center, and near the gray value maximum of target's center's place's photosensitive unit, and (carry on the back region) around target, gray value is very little.Suppose that whole screen has M*N LED pixel, wherein any one pixel intensity can be expressed as Pmn, is (I*J) mn corresponding to the CCD photosensitive unit number of this pixel, and wherein the gray value of each CCD photosensitive unit is f mn (i, j), the relation between them can be expressed as:
According to above analysis, the brightness data of each LED pixel can be extracted and generate gray scale pictures.Picture is generated by the numerical tabular that represents LED pixel brightness value 0 ~ 255 tonal range.
Grey level histogram in image processing system is a kind of very important utility during image is processed, and it has summarized the gray scale content of piece image.From mathematics, grey level histogram is the function of the each gray value statistical property of image and gradation of image value, number of times and probability that in its statistics piece image, each gray scale occurs.Gray level image f(x, y) histogram may be defined as discrete function: h(rk)=nk, k ∈ [0, L], wherein rk is image f(x, y) k level gray scale, nk is image f(x, y) in, have the number of pixels of gray value rk, n is total number of image pixels, and L is the number of greyscale levels of image.Because h(rk) provided each rk frequency of occurrences statistics, histogram provides the grey value profile situation of image.Grey level histogram can also be expressed as in normalization: P(rk)=h(rk)/n=nk/n, k ∈ [0, L], P (rk) is the frequency that gray scale rk occurs, its all gray scale frequency sums etc. 1.In grey level histogram coordinate system, the gray scale of each pixel in abscissa presentation video, ordinate is number of times or the probability that each pixel of each gray scale epigraph occurs.
Fig. 3 is single gradation histogram of the resolution LED display that is 64*128, its transverse axis list table gray value, the longitudinal axis represents the percentage of certain gray-value pixel frequency, i.e. P(rk) * 100%, highest point is the frequency (peak value) of brightness average.
Normal distribution refers to that the frequency of variable or frequency are at most middle, and reduce gradually symmetrically at two ends, shows as bell a kind of probability distribution.In theory, if the probability density function of stochastic variable x be:
Being called x obedience average is μ, the normal distribution that standard deviation is σ.Standard deviation represents the difference condition between variable and average, the dispersion degree of reflection data set.The feature of normal distribution is that the both sides centered by average are symmetrical, and the frequency of average place variable is the highest.μ mono-timing, the shape of curve determines by σ, and σ is larger, and curve is " short and stout " more, and overall distribution is overstepping the bounds of propriety loose; σ is less, and curve is " tall and thin " more, and overall distribution is more concentrated.
By the information analysis of LED brightness of display screen is found, its grey level histogram is normal distribution trend on a certain numerical value interval, as shown in Figure 3.
Figure 4 shows that the comparison of grey level histogram assessment data, a, b, c, d are respectively with imageing sensor collection and through brightness data and extract the assessment data of the LED display sample block brightness obtaining, in a, available gray-scale distributes approximately 106 gray scales, its peak value is 2. 8 %, and the equal standard deviation after normal distribution matching is 0. 158; In b, available gray-scale distributes approximately 100 gray scales, and its peak value is 3. 5%, and the equal standard deviation after normal distribution matching is 0. 119; In c, available gray-scale distributes approximately 48 gray scales, and its peak value is 9. 1%, and the equal standard deviation after normal distribution matching is 0. 048; In d, available gray-scale distributes approximately 34 gray scales, and its peak value is 13. 1%, and the equal standard deviation after normal distribution matching is 0. 031; As can be seen here, adopt image grey level histogram, and obtain standard deviation by normal distyribution function matching and assess the brightness uniformity of LED display and can reach with human eye vision and feel consistent.
The method is obtained LED pixel intensity information by CCD imageing sensor, in conjunction with digital image processing techniques and statistics rule, LED pixel grey scale histogram-fitting is become to normal distribution curve, utilizes standard deviation to assess LED display brightness uniformity.Experimental results show that the method is consistent with vision subjective assessment result, can Efficient Evaluation L ED brightness of display screen uniformity.
Be only to understand the present invention for helping for the description of the understanding of embodiment, instead of be used for limiting of the present invention.Those skilled in the art all can utilize thought of the present invention to carry out some changes and variation, as long as its technological means does not depart from thought of the present invention and main points, still within protection scope of the present invention.
Claims (4)
1. based on a LED display brightness uniformity appraisal procedure, it is characterized in that comprising:
A, ccd image sensor gather LED display pixel intensity information;
B, ccd image sensor are crossed digital interface card by the pixel intensity information exchange collecting and are saved in computer in the mode of image;
C, image processing system processing are kept at the image in computer, and information after treatment is sent to error correction systems;
D, error correction systems receive the information data that image processing system sends, and this information data are revised.
2. acquisition system according to claim 1, is characterized in that: described ccd image sensor is positioned at LED display screen dead ahead, and makes ccd image sensor camera lens and display screen edge maximum angle within the scope of 2 °.
3. acquisition system according to claim 1, is characterized in that: described image processing system is that the LED pixel intensity characteristic in image is extracted, and generates gray scale pictures.
4. acquisition system according to claim 1, it is characterized in that: described error correction systems is revised the sensitization error of angular error and ccd image sensor in described gray scale pictures, obtain approaching the LED display relative brightness information that true brightness distributes.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107527340A (en) * | 2017-08-25 | 2017-12-29 | 江南大学 | A kind of method of quick judge and optimization light guide plate luminous mass based on image processing techniques |
| CN111599294A (en) * | 2020-05-26 | 2020-08-28 | 昆山国显光电有限公司 | Evaluation method and device for granular sensation of display screen |
| CN111860497A (en) * | 2020-06-30 | 2020-10-30 | 维沃移动通信有限公司 | Information identification method and device |
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| CN103630332A (en) * | 2013-11-15 | 2014-03-12 | 南京中电熊猫照明有限公司 | Backlight brightness uniformity measuring device and method |
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| CN103630332A (en) * | 2013-11-15 | 2014-03-12 | 南京中电熊猫照明有限公司 | Backlight brightness uniformity measuring device and method |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107527340A (en) * | 2017-08-25 | 2017-12-29 | 江南大学 | A kind of method of quick judge and optimization light guide plate luminous mass based on image processing techniques |
| CN107527340B (en) * | 2017-08-25 | 2020-10-09 | 江南大学 | Method for rapidly judging and optimizing light-emitting quality of light guide plate based on image processing technology |
| CN111599294A (en) * | 2020-05-26 | 2020-08-28 | 昆山国显光电有限公司 | Evaluation method and device for granular sensation of display screen |
| CN111860497A (en) * | 2020-06-30 | 2020-10-30 | 维沃移动通信有限公司 | Information identification method and device |
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Application publication date: 20140924 |