简单的利用硬阈值函数、软阈值函数、半软阈值函数、软硬阈值折中函数、指数型阈值函数对图像进行去噪处理，并求得各自的mse和psnr-Using the hard threshold function, soft thresholding function, semi-soft threshold function, hard and soft threshold tradeoff function, exponential threshold function to denoise, and ca