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, A9Kt^HR 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, ?
R!Pf: t 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? wNvq['P 那些系数是通过对29525*10阶的矩阵每列的值算出来的嘛? *{x8@|K8 zt!)7HBo sU7fVke1 q8SHFKE gkhmQd function z = zernfun(n,m,r,theta,nflag) BK]5g[
%ZERNFUN Zernike functions of order N and frequency M on the unit circle. aO&!Y\=@ % Z = ZERNFUN(N,M,R,THETA) returns the Zernike functions of order N aE(DNeG-H % and angular frequency M, evaluated at positions (R,THETA) on the {Ri6975 % unit circle. N is a vector of positive integers (including 0), and jI/#NCKE % M is a vector with the same number of elements as N. Each element t9~Y
? % k of M must be a positive integer, with possible values M(k) = -N(k) cB0"vbdO % to +N(k) in steps of 2. R is a vector of numbers between 0 and 1, fL(_V/p^ % and THETA is a vector of angles. R and THETA must have the same w5<&b1: % length. The output Z is a matrix with one column for every (N,M) k5g vo % pair, and one row for every (R,THETA) pair. Rt.2]eZEJ % W
%<,GV % Z = ZERNFUN(N,M,R,THETA,'norm') returns the normalized Zernike y/Ui6D % functions. The normalization factor sqrt((2-delta(m,0))*(n+1)/pi), `|p8zV % with delta(m,0) the Kronecker delta, is chosen so that the integral C23Gp3_0/ % of (r * [Znm(r,theta)]^2) over the unit circle (from r=0 to r=1, Lky T4HC8n % and theta=0 to theta=2*pi) is unity. For the non-normalized %6Y\4Fe % polynomials, max(Znm(r=1,theta))=1 for all [n,m]. QCJf % E3V_qT8 % The Zernike functions are an orthogonal basis on the unit circle. R+# g_"1@p % They are used in disciplines such as astronomy, optics, and ]u|5ZCv0 % optometry to describe functions on a circular domain. tq=7HM % >)t-Zh:n % The following table lists the first 15 Zernike functions. 9}T(m(WQVu % ]|QA`5=$ % n m Zernike function Normalization &SMM<^P. % -------------------------------------------------- RPw1i* % 0 0 1 1 +2#pP % 1 1 r * cos(theta) 2 8a;;MJ) % 1 -1 r * sin(theta) 2 $C
t(M) % 2 -2 r^2 * cos(2*theta) sqrt(6) ra
F+Bt` % 2 0 (2*r^2 - 1) sqrt(3) 6m0-he~ % 2 2 r^2 * sin(2*theta) sqrt(6) R^6]v`j; % 3 -3 r^3 * cos(3*theta) sqrt(8) xf3;:soC % 3 -1 (3*r^3 - 2*r) * cos(theta) sqrt(8) ~? n)/i(" % 3 1 (3*r^3 - 2*r) * sin(theta) sqrt(8) k $E{'Dv % 3 3 r^3 * sin(3*theta) sqrt(8) _iH:>2p 5R % 4 -4 r^4 * cos(4*theta) sqrt(10) :gM_v?sy % 4 -2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) Ssd7]G+n: % 4 0 6*r^4 - 6*r^2 + 1 sqrt(5) UYH&x:WEd % 4 2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) {#N,&?[ % 4 4 r^4 * sin(4*theta) sqrt(10) Mk/ZEy q^ % -------------------------------------------------- 5Z_aN|Xn % `svOPB4C' % Example 1: 0Wb3M"#9< % mW)C=X% % % Display the Zernike function Z(n=5,m=1) PEMuIYm$ % x = -1:0.01:1; u vyvy % [X,Y] = meshgrid(x,x); ;y.<I& % [theta,r] = cart2pol(X,Y); <3 I0$?xL % idx = r<=1; i9^m;Y)^I % z = nan(size(X)); }g"K\x:Z % z(idx) = zernfun(5,1,r(idx),theta(idx)); ;HmQRiCg % figure K7},X01^ % pcolor(x,x,z), shading interp
z:d+RMA % axis square, colorbar /mQ9}E4X % title('Zernike function Z_5^1(r,\theta)') ^,#MfF6 % 6oLZH6fG % Example 2: s x) x7 % @rlL'|&X* % % Display the first 10 Zernike functions -^,wQW:o) % x = -1:0.01:1;
WYW@%t % [X,Y] = meshgrid(x,x); Fv3:J~Yf % [theta,r] = cart2pol(X,Y); ?m h0^G % idx = r<=1; kOV6O?h % z = nan(size(X)); =UV=F/Af^ % n = [0 1 1 2 2 2 3 3 3 3]; 71G00@&w9D % m = [0 -1 1 -2 0 2 -3 -1 1 3]; :Oc&{z?q % Nplot = [4 10 12 16 18 20 22 24 26 28]; 5wI j:s % y = zernfun(n,m,r(idx),theta(idx)); h5ZxxtGU % figure('Units','normalized') S%7%@Qs"% % for k = 1:10 3&Fqd % z(idx) = y(:,k); M7gM#bv>L % subplot(4,7,Nplot(k)) An=Q`Uxt/ % pcolor(x,x,z), shading interp u\@L|rh % set(gca,'XTick',[],'YTick',[]) A[ N>T\ % axis square z1LY|8$G % title(['Z_{' num2str(n(k)) '}^{' num2str(m(k)) '}']) ]*\<k % end :snn-e0l % UpqDGd7M % See also ZERNPOL, ZERNFUN2. y0
qq7Dmu lPn&,\9@~ n$jf($* % Paul Fricker 11/13/2006 )}SiM{g MKr:a]-'f~ f/e2td*A }9>X M {-,^3PI\ % Check and prepare the inputs: 3bMUsyJ 2 % ----------------------------- Clzz!v if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) -1 _7z{. error('zernfun:NMvectors','N and M must be vectors.') \:-N<[ end J9`[Qy\ "6P- 0CJ 2O)2#N if length(n)~=length(m) f n'N^ error('zernfun:NMlength','N and M must be the same length.') 2s8(r8 AI end Y\ G^W8 TkV$h(#!f& l%9nA.M' n = n(:); 8Zvh"Z? m = m(:); Y$6W~j if any(mod(n-m,2)) da53XEF& error('zernfun:NMmultiplesof2', ... Abf=b<bu 'All N and M must differ by multiples of 2 (including 0).') 9{5 c}bX end Ow7I`#P rFR2c?j8 _\2^s&iJh if any(m>n) *oz=k error('zernfun:MlessthanN', ... 7Om)uUjU4 'Each M must be less than or equal to its corresponding N.') |A@Gch fd end ;t}ux 05m/iQ blA]z!FU if any( r>1 | r<0 ) 7&9'=G error('zernfun:Rlessthan1','All R must be between 0 and 1.') r.;(Kx/M end IWcYa.=tZ `)R@\@jt ~+Da`Wp if ( ~any(size(r)==1) ) || ( ~any(size(theta)==1) ) to*<W,I error('zernfun:RTHvector','R and THETA must be vectors.') rKys:is end IRQ3> 4hI er0ClvB ]]Da/^K=Z r = r(:); SAGLLk07G theta = theta(:); `g iCytv length_r = length(r); o$r]Z1 if length_r~=length(theta) c{t[iXDG error('zernfun:RTHlength', ... @Q atgYu 'The number of R- and THETA-values must be equal.') nNff~u)I end W[3)B(Vq<E __V6TDehJ$ d/ OIc){tD % Check normalization: ;DKwv} % -------------------- =}~hbPJM if nargin==5 && ischar(nflag) gaJIc^O isnorm = strcmpi(nflag,'norm'); E$[\Fk}S if ~isnorm 8_tMiIE-pS error('zernfun:normalization','Unrecognized normalization flag.') :22IY>p end ZR'q.y[k) else Tl3{)(ezx isnorm = false; :[N[D#/z end a".uS4x z,oqYU\: >9g` 9hB %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% e+F5FAMR68 % Compute the Zernike Polynomials RfB""b8]= %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 3EcmNwr y6o^ Knl tH"SOGfSt % Determine the required powers of r: v=|BqG` % ----------------------------------- Mf&W<n^j m_abs = abs(m); 8E Y<^: rpowers = []; aM9St!i for j = 1:length(n) %Ys>PzM rpowers = [rpowers m_abs(j):2:n(j)]; [lA[wCw end 5@Q4[+5&_ rpowers = unique(rpowers); !DCJ2h%E[_ bhSpSul <5(8LMF % Pre-compute the values of r raised to the required powers, :u{0M& % and compile them in a matrix: iEki<e/ % ----------------------------- |7/B20 if rpowers(1)==0 .VmI4V?}h rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); Rhx7eU#& rpowern = cat(2,rpowern{:}); *ftJ( rpowern = [ones(length_r,1) rpowern]; }FMl4 _}u else vd /_`l.D rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); ZZE rpowern = cat(2,rpowern{:}); $#@4i4TN- end Z=!*7@QY _:'m/K3Ee 2>O2#53ls0 % Compute the values of the polynomials: BPrA*u}T % -------------------------------------- {7eKv+30 y = zeros(length_r,length(n)); @\!wW-:A for j = 1:length(n) DcbL$9UI s = 0:(n(j)-m_abs(j))/2; ^^?DYC
pows = n(j):-2:m_abs(j); MQY1he2M for k = length(s):-1:1 Bd O$ p = (1-2*mod(s(k),2))* ... &,."=G prod(2:(n(j)-s(k)))/ ... 2c%}p0<;|? prod(2:s(k))/ ... B0z.s+. prod(2:((n(j)-m_abs(j))/2-s(k)))/ ...
OV8b~k4= prod(2:((n(j)+m_abs(j))/2-s(k))); ;*W]]4fy idx = (pows(k)==rpowers); qW7"qw= y(:,j) = y(:,j) + p*rpowern(:,idx); Z{p6Q1u end B@zJ\Ir[ f/;\/Q[Z7 if isnorm F` I-G~e y(:,j) = y(:,j)*sqrt((1+(m(j)~=0))*(n(j)+1)/pi); "}SERC7 end 4rM77Uw> end <YeF?$S} % END: Compute the Zernike Polynomials 38q@4U=aiw %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% N@MeaO pXFNK"jm qfSoF| % Compute the Zernike functions: FOk @W& % ------------------------------ k) v[/#I idx_pos = m>0; &vMH
AZd idx_neg = m<0; 4(aesZ8h o@>c[knJ ($S{td; z = y; BRD'5 1]| if any(idx_pos) '-i
tn z(:,idx_pos) = y(:,idx_pos).*sin(theta*m(idx_pos)'); 5&X end "]_|c\98 if any(idx_neg) ImV54h' z(:,idx_neg) = y(:,idx_neg).*cos(theta*m(idx_neg)'); =H,cwSE+% end Ar<OP'C Ox~'w0c,f ~o/^=:* % EOF zernfun Yip9K[
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