说明：  两维图像旋转以及双线性灰度差值算法的实现,章毓晋. 图像工程（上册）——图像处理. 清华大学出版社此书算法实现
(Two-dimensional gray scale image rotation and bilinear difference algorithm, Zhang Yu-Jin. Image Engineering (on)- Image Processing. Tsinghua University Press book algorithm)