Study On Display Quality Testing Method Of LED Large Screen

Because of the dispersion of the LED emission wavelength and attenuation rate,the display quality of LED large screen gradually becomes worse as usage timeincreases, so regular detection and calibration are needed to ensure the displayqualification. LED large screen display quality indexes include maximum luminance,white color coordinates, main wavelength error of primary colors, display uniformityand the rate of incontrollable pixels. So far, single point photometer and colorimeter iswidely used in LED large screen display quality detection, although this kind ofinstrument can reach a fairly high measuring accuracy, however, its measuringefficiency is rather low in consideration of the huge number of LED pixels of the screen.So the traditional measuring instruments are inappropriate in the LED large screenrelated measurement. Taking account of the LED large screen characteristics, this articleproposed an image photometric measurement and digital image processing technologybased method, and with CCD being the photometric sensor，designed a LED largescreen display quality detection system.Here listed below are the main research contents of this article:1. Based on the analysis of the feasibility of CCD photometric measurement, thisarticle studied the V(λ) matching and luminance calibration of the spectral response ofthe image acquisition module composed by the CCD image sensor and filters.2. The LED large screen image processing methods were explored, includingimage filtering, image segmentation, image morphological processing and so on. Bymeans of the image processing, the precise location of the LED pixels in the image wasobtained, which provided the position reference in the luminance and colormeasurement.3. The representation of LED pixels’ luminance, color and chromatic aberrationwas studied. Those LED pixels of which luminance and color were beyond a certainrange were recorded and corrected.4. The program of the LED large screen display quality testing system, whichconsists of image restoration, threshold segmentation, boundary location, LED pixels’position, display quality detection and correction and so on, was designed. Themethod’s reliability test was conducted on field. Through a number of experiments andby referring the contrastive high-precision photometer and colorimeter, the results showed that the image photometric detection system was effective and reliable.Compared to the conventional testing method, this method greatly improved the testingspeed and efficiency.Finally, the methods yet to be improved and refined in the article were proposedand overviewed.