从这个答案,我知道如何创建一个高通巴特沃斯滤波器。
从这个视频中,我知道,lowpasskernel = 1 - highpasskernel
。
因此,我创建了以下低通巴特沃斯滤波器,
function [out, kernel] = butterworth_lp(I, Dl, n)
height = size(I, 1);
width = size(I, 2);
[u, v] = meshgrid(-floor(width/2):floor(width/2)-1,-floor(height/2):floor(height/2)-1);
% lp_kernel = 1 - hp_kernel
kernel = 1 - butter_hp_kernel(u, v, Dl, n);
% fft the image
I_fft_shifted = fftshift(fft2(double(I)));
% apply lowpass filter
I_fft_shift_filtered = I_fft_shifted .* kernel;
% inverse FFT, get real components
out = real(ifft2(ifftshift(I_fft_shift_filtered)));
% normalize and cast
out = (out - min(out(:))) / (max(out(:)) - min(out(:)));
out = uint8(255*out);
function k = butter_hp_kernel(u, v, Dh, n)
uv = u.^2+v.^2;
D = sqrt(uv);
frac = Dh./D;
p = 2*n;
denom = frac.^p;
k = 1./denom;
输出
这不是低通滤波器输出。
那么,我的代码有什么问题?