图像中的噪声：高斯噪声、椒盐噪声、乘性噪声产生方法，以及分别利用中值滤波、算术均值滤波、低通滤波对噪声进行处理-Image noise: Gaussian noise, salt and pepper noise, multiplicative noise, and a median filter, respectively, the arithmetic mean filter, low pass filtering the noise processing