说明：  对纤维类图像进行前期处理，效果较好，包括高通滤波，平滑中值滤波，全局阈值分割，二值化，反相，最后求取骨架
(Image of the fiber pre-processing, better, including high-pass filter, smoothing filter, global thresholding, binarization, RP to get the final frame)