1．对图像进行直方图均衡化，从而达到增强图像的目的，观察图像直方图的前后变化；．2.对图像加入某种噪声（如椒盐噪声等），运用低通滤波和中值滤波分别进行图像平滑。

3．同态图像的增强：对照明分量和反射分量进行同态滤波。-1. The image histogram equalization, so as to achieve the purpose of enhancing the image of change, before and after the image histogram . 2. The image added some noise (such as salt and pepper noise, etc.), the use of low-pass filter and median filter for image smoothing, respectively. 3. Homomorphic image enhancement: lighting component and the reflection component of homomorphic filtering.