数字图像频域滤波处理，分别进行二阶巴特沃斯(Butterworth)高通、低通滤波器。-Digital image processing frequency domain filtering, respectively second-order Butterworth (Butterworth) high pass, low pass filter.

双线性变换法设计巴特沃斯数字低通滤波器。-Bilinear transformation method to design butterworth digital low-pass filter.

使用脉冲响应不变法设计巴特沃斯低通滤波器。-Using the impulse response is not political reform design butterworth low-pass filter.