问题是frdescp
代码(我使用this code,应该与您所提到的相同)也是为了使傅立叶描述符居中。
如果要以正确的方式描述形状,必须保留一些与表示DC分量的描述符相对称的描述符。
下图总结了概念:
为了解决你的问题(和其他像你),我写了下面两种功能:
function descriptors = fourierdescriptor(boundary)
%I assume that the boundary is a N x 2 matrix
%Also, N must be an even number
np = size(boundary, 1);
s = boundary(:, 1) + i*boundary(:, 2);
descriptors = fft(s);
descriptors = [descriptors((1+(np/2)):end); descriptors(1:np/2)];
end
function significativedescriptors = getsignificativedescriptors(alldescriptors, num)
%num is the number of significative descriptors (in your example, is was 20)
%In the following, I assume that num and size(alldescriptors,1) are even numbers
dim = size(alldescriptors, 1);
if num >= dim
significativedescriptors = alldescriptors;
else
a = (dim/2 - num/2) + 1;
b = dim/2 + num/2;
significativedescriptors = alldescriptors(a : b);
end
end
知道,你可以使用上述功能如下:
im = imread('test.jpg');
im = im2bw(im);
b = bwboundaries(im);
b = b{1};
%force the number of boundary points to be even
if mod(size(b,1), 2) ~= 0
b = [b; b(end, :)];
end
%define the number of significative descriptors I want to extract (it must be even)
numdescr = 20;
%Now, you can extract all fourier descriptors...
f = fourierdescriptor(b);
%...and get only the most significative:
f_sign = getsignificativedescriptors(f, numdescr);
您从哪里得到了frdescp?它可能是问题的根源 – Rasman 2012-04-02 16:38:44
我从冈萨雷斯的数字图像处理MATLAB书中得到它,其实我认为bwboundaries是问题! – 2012-04-09 08:40:03
我编辑了[我以前的答案](http://stackoverflow.com/a/23741097/738017),我希望它对你和其他用户有用。 – 2014-05-22 17:08:13