自己写的针对低对比度图像的增强方法，在CIELAB空间处理，可用于处理沙尘、水下、雾天等图像.简单但有效-Enhance the low contrast image, such as dust/sand, underwater, haze/fog images. Performed in CIELAB color space, with contrast stretch, sharpen and color correction. Sample but effective.