| jssylttc |
2012-04-23 19:23 |
如何从zernike矩中提取出zernike系数啊
下面这个函数大家都不会陌生,计算zernike函数值的,并根据此可以还原出图像来, xV
2C4K 我输入10阶的n、m,r,theta为38025*1向量,最后得到的z是29525*10阶的矩阵, 0!7p5 这个,跟我们用zygo干涉仪直接拟合出的36项zernike系数,有何关系呢? ODhq
`?(N 那些系数是通过对29525*10阶的矩阵每列的值算出来的嘛? +jyGRSo 44|tCB` B?- poB& bLAHVi<. )%3T1
D/ function z = zernfun(n,m,r,theta,nflag) 7 )rL<+ %ZERNFUN Zernike functions of order N and frequency M on the unit circle.
E)ZL+( % Z = ZERNFUN(N,M,R,THETA) returns the Zernike functions of order N X8R`C0
% and angular frequency M, evaluated at positions (R,THETA) on the ,&qC
R
sw % unit circle. N is a vector of positive integers (including 0), and i7e6l C % M is a vector with the same number of elements as N. Each element u3GBAjPsIk % k of M must be a positive integer, with possible values M(k) = -N(k) PMV,*`"9"A % to +N(k) in steps of 2. R is a vector of numbers between 0 and 1, \C h01LR" % and THETA is a vector of angles. R and THETA must have the same |ns?c0rM % length. The output Z is a matrix with one column for every (N,M) !!H"B('m % pair, and one row for every (R,THETA) pair. TlRc8r| % 7.6L1srV % Z = ZERNFUN(N,M,R,THETA,'norm') returns the normalized Zernike q!?*M?Oz % functions. The normalization factor sqrt((2-delta(m,0))*(n+1)/pi), dRnf % with delta(m,0) the Kronecker delta, is chosen so that the integral 9 fYNSr % of (r * [Znm(r,theta)]^2) over the unit circle (from r=0 to r=1, upL3M` % and theta=0 to theta=2*pi) is unity. For the non-normalized CgrQ"N5 % polynomials, max(Znm(r=1,theta))=1 for all [n,m]. $|.8@
nj % P(TBFu % The Zernike functions are an orthogonal basis on the unit circle. +38R#2JV % They are used in disciplines such as astronomy, optics, and ?1a9k@[t % optometry to describe functions on a circular domain. m<#12#D % AyOibnoZ2E % The following table lists the first 15 Zernike functions. vIbM@Y4
'? % ~IS8DW$; % n m Zernike function Normalization DQm%=ON7 % -------------------------------------------------- FutS % 0 0 1 1 NX.xEW@ % 1 1 r * cos(theta) 2 >[,eK= % 1 -1 r * sin(theta) 2 bAGKi. % 2 -2 r^2 * cos(2*theta) sqrt(6) z+yIP ?s}( % 2 0 (2*r^2 - 1) sqrt(3) \/o$io,kV % 2 2 r^2 * sin(2*theta) sqrt(6) tmooS7\a % 3 -3 r^3 * cos(3*theta) sqrt(8) U/QgO % 3 -1 (3*r^3 - 2*r) * cos(theta) sqrt(8) PD-&(ka. % 3 1 (3*r^3 - 2*r) * sin(theta) sqrt(8) J5I@*f)l % 3 3 r^3 * sin(3*theta) sqrt(8) JHt
U" % 4 -4 r^4 * cos(4*theta) sqrt(10) Z,A $h>Z % 4 -2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) e12QYoh % 4 0 6*r^4 - 6*r^2 + 1 sqrt(5) &|~7` % 4 2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) hEQyaDD; % 4 4 r^4 * sin(4*theta) sqrt(10) (^m]
7l % -------------------------------------------------- K+F"V W*? % 7MLLx#U % Example 1: aQtd6L+ J % MMs~f* % % Display the Zernike function Z(n=5,m=1) !S#3mT- % x = -1:0.01:1; hx$61E= % [X,Y] = meshgrid(x,x); |JxVfX8^ % [theta,r] = cart2pol(X,Y); ehr-o7]( % idx = r<=1; Wye* ~t % z = nan(size(X)); Cp6S2v I % z(idx) = zernfun(5,1,r(idx),theta(idx)); VAz4@r7hkq % figure LV^^Bd8Ct % pcolor(x,x,z), shading interp q[,p#uJ] % axis square, colorbar gwRB6m$ % title('Zernike function Z_5^1(r,\theta)') m-vn5OX % H@=oVyn/ % Example 2: ctZ,qg*N % 25$_tZPAI % % Display the first 10 Zernike functions HcsVq+ % x = -1:0.01:1; w`)5(~b % [X,Y] = meshgrid(x,x); U]=yCEb8p % [theta,r] = cart2pol(X,Y); 3' i6<
% idx = r<=1; (Xh<F % z = nan(size(X)); +[!S[KE % n = [0 1 1 2 2 2 3 3 3 3]; vW1^ % m = [0 -1 1 -2 0 2 -3 -1 1 3]; rPaJ<>Kz % Nplot = [4 10 12 16 18 20 22 24 26 28]; OlOOg % y = zernfun(n,m,r(idx),theta(idx)); ](w)e
p~;3 % figure('Units','normalized') rx1u*L % for k = 1:10 CUu
Owx6% % z(idx) = y(:,k); _x,X0ncv]@ % subplot(4,7,Nplot(k)) hG?y)g\A % pcolor(x,x,z), shading interp 9|1msg4 % set(gca,'XTick',[],'YTick',[]) P}v
;d] % axis square .gx^L=O: % title(['Z_{' num2str(n(k)) '}^{' num2str(m(k)) '}']) G%
tlV&In % end {EoYU\x % /iU<\+ H % See also ZERNPOL, ZERNFUN2. *#T:
_ DM^0[3XuV5 A@}5'LzL % Paul Fricker 11/13/2006
'"B WNGX`V,d 3^7+fxYWo )QE6X67i ,8@<sFB' % Check and prepare the inputs: q]?qeF[ % ----------------------------- 7g\v (P if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) 6e-ME3!<l error('zernfun:NMvectors','N and M must be vectors.') FEjO}lTK end ~T_|?lU`R LZV- E=` 0cS$S Mn{ if length(n)~=length(m) {r_HcI(h error('zernfun:NMlength','N and M must be the same length.') qUJ"* )S end I%5vI} Y)sB]!hx tvI<Why\p n = n(:); w2
Y%yjCV m = m(:); "ko*-FrQ if any(mod(n-m,2)) ip-X r|Bq error('zernfun:NMmultiplesof2', ... CvU$Fsb 'All N and M must differ by multiples of 2 (including 0).') C+NN.5No end W=+n|1 yB UQ!4e }Va((X w if any(m>n) [c,V=:Cq error('zernfun:MlessthanN', ... gi!_Nz 'Each M must be less than or equal to its corresponding N.') \zBi-GI7 end `K{} >(RkoExO/ 3``JrkPI if any( r>1 | r<0 ) 32ki ?\P error('zernfun:Rlessthan1','All R must be between 0 and 1.') .LDZqWr- end iB)\*) $JY\q2 6>]_H(z7 if ( ~any(size(r)==1) ) || ( ~any(size(theta)==1) ) wH~A>
4*( error('zernfun:RTHvector','R and THETA must be vectors.') Nc\DXc-N
end ~B;}jI]d[ p1UloG\ !n-Sh<8 r = r(:);
|vs5N2_ theta = theta(:); =yod length_r = length(r); )L b` 4B if length_r~=length(theta) r2RJb6 error('zernfun:RTHlength', ... M/o?D <' 'The number of R- and THETA-values must be equal.') rI$NNk'A end P]Fb0X |Hf|N$ :!aLa}`@ % Check normalization: v2;E W p % -------------------- 1/-3m Po if nargin==5 && ischar(nflag) YS|Dw'%g / isnorm = strcmpi(nflag,'norm'); ]9YA~n\ if ~isnorm IW\^-LI. error('zernfun:normalization','Unrecognized normalization flag.') BE0l2[i? end SJiQg-+<Uf else 1V2]@VQF isnorm = false; 7!J-/#! end +R*DE5dz -Lq+FTezE -64lf-< %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% (.#nl}fA % Compute the Zernike Polynomials ~R|9|k %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% n-9xfn0U~# #L.,aTA< 'l'3&.{Yfk % Determine the required powers of r: ](JrEg$K % ----------------------------------- ]
2
`%i5 m_abs = abs(m); 6:8s,a3&[k rpowers = []; `CWhjL8^ for j = 1:length(n) z6`0Uv~ rpowers = [rpowers m_abs(j):2:n(j)]; i]Mem M- end `KZV@t rpowers = unique(rpowers); QT c{7& GQ1/pys b+~_/;Y9 % Pre-compute the values of r raised to the required powers, ZUS-4'"$ % and compile them in a matrix: !.UE} ^TV % ----------------------------- Z#.d7B" if rpowers(1)==0 utmJ>GWSI rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); xKu#OH rpowern = cat(2,rpowern{:}); Ey7zb#/<! rpowern = [ones(length_r,1) rpowern]; D9+qT<ojN else /l<(i+0 rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); =2$(
tXL rpowern = cat(2,rpowern{:}); HGYTh"R end )%^l+w+& uGZGI;9f4 5 tKgm / % Compute the values of the polynomials: e 6mZ;y5_ % -------------------------------------- ^}P94( oz y = zeros(length_r,length(n)); D?dBm for j = 1:length(n) zTc;-, s = 0:(n(j)-m_abs(j))/2; AFi_P\X pows = n(j):-2:m_abs(j); AUD)=a> for k = length(s):-1:1 lrJV"H p = (1-2*mod(s(k),2))* ... VJ\qp% prod(2:(n(j)-s(k)))/ ... O7 ;=g!j prod(2:s(k))/ ... NFTv4$5d prod(2:((n(j)-m_abs(j))/2-s(k)))/ ... @aQ:3/ prod(2:((n(j)+m_abs(j))/2-s(k))); _#V&rY&@ idx = (pows(k)==rpowers); kl]V_ 7[ y(:,j) = y(:,j) + p*rpowern(:,idx); AE:(:U\ end 9D14/9*(dU {^1O if isnorm |tAkv y(:,j) = y(:,j)*sqrt((1+(m(j)~=0))*(n(j)+1)/pi); g(pr.Dw6 end =@d#@ end yP7b))AW9 % END: Compute the Zernike Polynomials vD8pVR+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% .F,l>wUNe (9`dLw5 Z}t;:yhR % Compute the Zernike functions: +.~K=.O) % ------------------------------ kSV(T'#x idx_pos = m>0; }K?b2 6` idx_neg = m<0; v7pu ou-#+Sdd GeJ}myD O z = y; 85!]NF if any(idx_pos) :m`D z(:,idx_pos) = y(:,idx_pos).*sin(theta*m(idx_pos)'); f$FO 1B) end dm}1"BU< if any(idx_neg) $9?:P}$v z(:,idx_neg) = y(:,idx_neg).*cos(theta*m(idx_neg)'); ueJ^Q,-t end OH06{I>; .I>rX#aNt q;#AlquY @ % EOF zernfun 'ge$}L}4
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