说明：  带通滤波器（Butterworth、椭圆、窗函数），采样率fs＝2000Hz, 通带范围为300 -600Hz，阶数自选, 画出频率响应并分析比较， 对cameraman.tif图像分别添加椒盐噪声（密度为0.03）和高斯白噪声（均值为0，方差为0.02）的图像，利用三种方法进行去噪，显示原始图像、加噪图像和去噪图像并对实验结果进行分析
(Band pass filter (Butterworth, ellipse, window function), sampling rate FS = 2000Hz, passband range of 300 -600Hz, order optional, draw frequency response, and analysis and comparison, Respectively, add salt and pepper noise of the cameraman.tif image (density of 0.03) and Gauss white noise (mean 0 and variance 0.02) image denoising using three methods, shows the original image, noise image and image denoising and analysis of experimental results)