The results show that Fourier Series Smoothing method is not only an efficient method, but also is easy to estimate image quality using modulation transfer function.
试验结果表明：付立叶级数滤波法是一种行之有效的方法，并便利于用调制传递函数评价影象质量。
2
Filling missing values, smoothing noise data and removing inconsistent data were all adopted to get high quality data.
通过补全缺失数据、平滑噪声数据、消除不一致数据等技术，得到高质量的数据。
3
Image preprocessing: the image is processed by several algorithms including gray level stretch, homomorphic processing and image smoothing, and then the quality of image gets better.