应用于VA-LCD Mura补偿的图像预处理算法

Image preprocessing algorithm of VA-LCD Mura compensation

为了消除VA-LCD的Mura缺陷,采用图像处理技术,需要通过相机对显示器数据进行采集,从而捕捉到显示器像素亮度,本文对相机数据的预处理算法进行了深入研究。首先,通过对相机的固定模式噪声和时变噪声进行了降噪,通过标准光源对相机和镜头进行了平面场校正。接着,以圆形点阵图案作为辅助标定图,采用双线性关系建立校正模型,初步获得像素亮度矩阵。然后,根据VA-LCD的视角特性建立起不同灰阶下亮度-视角的特性曲线,采用4次多项式对大量数据进行拟合提升视角模型稳定性,从而消除了像素亮度矩阵的影响。最后,结合补偿值计算及芯片实时补偿技术对算法进行了效果验证,从主观及客观两种指标进行了评定。实验结果表明采用此Mura消除技术后,显示器的JND指标从2.7降低至1.8,面内9点均一性从53.4%提升至82.9%。本文的算法效果可以满足产品最高等规格的需求,在自适应校正上具有良好的鲁棒性,满足工厂的大批量生产。

In order to eliminate the Mura defect of VA-LCD,the image processing technology is adopted to collect display data through camera,so as to capture display pixel brightness.In-depth research is conducted on the algorithm of camera data correction.Firstly,the fixed mode noise and time-varying noise of the camera are reduced,and the plane field of the camera and lens is corrected by the standard light source.Then,the circular dot matrix pattern is used as the auxiliary calibration diagram,and the correction model is established by using the two-line relation,and the pixel brightness matrix is obtained preliminarily.According to the visual angle characteristics of VA-LCD,the characteristic curve of luminance-visual angle under different grey levels is established,and a large number of data are fitted with a fourth-order polynomial to improve the stability of the visual angle model.Finally,the effectiveness of the algorithm is verified by combining the compensation value calculation and chip real-time compensation technology,and the evaluation is carried out from the subjective and objective indicators.The experimental results show that the JND index of the display decreases from 2.7 to 1.8,and the in-plane 9-point uniformity increases from 53.4%to 82.9%after the application of this Mura elimination technique.The algorithm proposed can meet the requirements of the highest specifications of products and has good robustness in adaptive correction to meet the requirements of mass production in factories.