为降低LED背光源的功耗，提高LCD的图像显示质量，提出了一种LED背光源动态调光二次修正算法。采用平均值法得到分区的初始背光灰度值；为了解决灰度截断问题，根据分区灰度最大值与平均值的差值进行第一次修正；为了抑制调光带来的光晕效应，采用空间滤波法进行第二次修正。采用侧入式LED背光源的1168 cm(46 in)LCD实验结果表明，采用该算法后，LED背光源平均功耗降低至7302%，灰度截断率为049%，平均PSNR值为6721 dB；典型图像对比度最大达到28 600∶1，显示图像的光晕效应有了明显的改善。二次修正算法能够有效降低背光功耗，增强图像显示质量。

In order to reduce power consumption of LED backlit and improve image quality of LCD, the dynamic dimming algorithm with twice-correction is proposed. Firstly, the values of initial backlight of all LED blocks are calculated with averaging method. Then the first correction values are calculated to resolve grayscale clipping according to the difference between the maximum and average grayscale values in each LED block. Lastly, the second correction values are calculated with spatial filtering method to suppress halo effect caused by dimming. The experiment results on a 1168 cm(46 in) edge-type LED backlit show that the mean power consumption can be reduced to 73.02% and the grayscale clipping is only 0.49% for the typical pictures. Also the mean PSNR (Peak Signal to Noise Ratio) is 67.21 dB, the maximum contrast ratio can reach to 28 600∶1, and halo effect can be suppressed obviously. The dynamic dimming algorithm with twice-correction can improve image quality significantly with a significant reduction in power consumption.