利用双线性插值和最近邻插值实现RGB图像的缩放，利用MATLAB编写-The use of bilinear interpolation and nearest neighbor interpolation to achieve RGB image scaling, using MATLAB to prepare

灰度图像转换为索引图像，索引图像转换为灰度图像，索引图像转换为RGB图像。-Grayscale image is converted to indexed image, the index image is converted to grayscale, indexed images to RGB images.