说明：  利用傅里叶变换实现两幅大小相同的RGB图像的水印嵌入。包含水印的大小处理，水印嵌入和提取，以及对PNSR的计算。
(Fourier transform two of the same size of the RGB image watermark embedding. Contains the size of the watermark processing, the watermark embedding and extraction, as well as on the PNSR the calculation.)