飞机中液晶显示屏上显示的一般是图形和数据，显示界面上有较大范围是暗场景。若采用传统液晶显示器恒定亮度的面光源，会造成不必要的电能消耗，且存在漏光现象导致图像的对比度下降，因此对液晶显示的背光源采用动态背光的控制。文章通过分析常见的平均值和最大值背光亮度提取方法，提出基于灰阶熵的LCD背光亮度调整方法。该方法既解决平均值法失真严重的问题，保证图像质量，同时相比于最大值法又减少功耗，达到降低功耗和保证图像质量的要求。

The display contents of LCD in airplanes are commonly figures and data. So a large scale of scene is dark. In conventional LCDs, the backlight is set to constant luminance regardless of the image which causes power waste and low contrast ratio. To circumvent this problem, dynamic backlight is investigated. By analyzing the conventional methods, the average method and the max method, a modulation algorithm based on gray entropy is proposed. The method not only solves the problem of serious distortion in the average method, but also reduces power consumption in comparison to the max method. Therefore，the proposed method achieves low power consumption and high image quality simultaneously.