| 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, xaSiG 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, 1\,wV, 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? <_Po/a!c3 那些系数是通过对29525*10阶的矩阵每列的值算出来的嘛? b WZX dNs<`2m z?_5fte` V:4($ ~hA;ji|I function z = zernfun(n,m,r,theta,nflag) 5adB5)` %ZERNFUN Zernike functions of order N and frequency M on the unit circle. A832z` % Z = ZERNFUN(N,M,R,THETA) returns the Zernike functions of order N Uefw % and angular frequency M, evaluated at positions (R,THETA) on the VrRBwvp-K % unit circle. N is a vector of positive integers (including 0), and k{$Mlt?&- % M is a vector with the same number of elements as N. Each element Riz!HtyR % k of M must be a positive integer, with possible values M(k) = -N(k) ;6zp,t0 % to +N(k) in steps of 2. R is a vector of numbers between 0 and 1, (V~PYf% % and THETA is a vector of angles. R and THETA must have the same .We"j_
} % length. The output Z is a matrix with one column for every (N,M) x~O_v % pair, and one row for every (R,THETA) pair. &5wM` % OK9D4
7X % Z = ZERNFUN(N,M,R,THETA,'norm') returns the normalized Zernike *(@[E % functions. The normalization factor sqrt((2-delta(m,0))*(n+1)/pi), b<rJ@1qtJ % with delta(m,0) the Kronecker delta, is chosen so that the integral v:]
AS: % of (r * [Znm(r,theta)]^2) over the unit circle (from r=0 to r=1, =l9H]`T/ % and theta=0 to theta=2*pi) is unity. For the non-normalized 80ms7 B % polynomials, max(Znm(r=1,theta))=1 for all [n,m]. vV9q5Bj: % SA$1rqU= % The Zernike functions are an orthogonal basis on the unit circle. cS1BB#N0 % They are used in disciplines such as astronomy, optics, and wq&TU'O % optometry to describe functions on a circular domain. ~v<,6BS<$Z % nM)H2'%kL& % The following table lists the first 15 Zernike functions. ~cx/>Hu % sh"\ kk9 % n m Zernike function Normalization pn~$u % -------------------------------------------------- H0B"?81 % 0 0 1 1 DV/P/1E % 1 1 r * cos(theta) 2 $.@)4Nu!_ % 1 -1 r * sin(theta) 2 0SziTM % 2 -2 r^2 * cos(2*theta) sqrt(6) N^.!l_ % 2 0 (2*r^2 - 1) sqrt(3) xcYYo'U % 2 2 r^2 * sin(2*theta) sqrt(6) [0e}%!%M % 3 -3 r^3 * cos(3*theta) sqrt(8) L);kwx7{LW % 3 -1 (3*r^3 - 2*r) * cos(theta) sqrt(8) f&ym'S % 3 1 (3*r^3 - 2*r) * sin(theta) sqrt(8) Gv}h/zu- % 3 3 r^3 * sin(3*theta) sqrt(8) DNaU
mz % 4 -4 r^4 * cos(4*theta) sqrt(10) "8"7AoE % 4 -2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) 7MT[fA8^ % 4 0 6*r^4 - 6*r^2 + 1 sqrt(5) i'%:z]hp9 % 4 2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) yVM
1W"Q % 4 4 r^4 * sin(4*theta) sqrt(10) s],+]<qX % -------------------------------------------------- n300kpv % ,Mwj`fgh % Example 1: <3>Ou(F % cwxO|
.m % % Display the Zernike function Z(n=5,m=1) `?VB) % x = -1:0.01:1; { LJRdV % [X,Y] = meshgrid(x,x); bg)yliX % [theta,r] = cart2pol(X,Y); 'I_\ELb_ % idx = r<=1; ?8X+)nU@ % z = nan(size(X)); t$Z#zxX % z(idx) = zernfun(5,1,r(idx),theta(idx)); M+ gYKPP % figure Q[y75 [ % pcolor(x,x,z), shading interp `1KZ14K % axis square, colorbar ,g$N % title('Zernike function Z_5^1(r,\theta)') KPUc+`cN% % :R<n{%~ % Example 2: 4PEJ}BW % #$Z|)i]w % % Display the first 10 Zernike functions @"H+QVJ@ % x = -1:0.01:1; !58-3F%P % [X,Y] = meshgrid(x,x); 16YJQ ue % [theta,r] = cart2pol(X,Y); @fbB3 % idx = r<=1; .Tdl'y:.. % z = nan(size(X)); 4y+]V~p % n = [0 1 1 2 2 2 3 3 3 3]; E#T-2^nD % m = [0 -1 1 -2 0 2 -3 -1 1 3]; U&/Jh^Yy % Nplot = [4 10 12 16 18 20 22 24 26 28]; o=2y`Eq % y = zernfun(n,m,r(idx),theta(idx)); xgt dmv% % figure('Units','normalized') _~DFZt@T % for k = 1:10 %
j7lLSusX % z(idx) = y(:,k); c|Nv^V*2 % subplot(4,7,Nplot(k)) R/iw#.Yy % pcolor(x,x,z), shading interp X.g")Bt7 % set(gca,'XTick',[],'YTick',[]) ?iUAzM8 % axis square J%;TK6 % title(['Z_{' num2str(n(k)) '}^{' num2str(m(k)) '}']) |_%| % end
#oi4!%*M % g R(*lXm5w % See also ZERNPOL, ZERNFUN2. 5sx-u!7 HT5G HkT >b |l6#% % Paul Fricker 11/13/2006 5Y)!q?#H _#e='~; ]5' Srz.-,2 PF ]`y4n=L. % Check and prepare the inputs:
~-6Kl3Y % ----------------------------- 6pQ#Zg()vp if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) Tfgx>2 error('zernfun:NMvectors','N and M must be vectors.') I, .`w/I+ end >GgX-SZ% %"DEgIP u/cL[_Q if length(n)~=length(m) 6A/Nlk. error('zernfun:NMlength','N and M must be the same length.') ID5?x8o#k end S0g5Ym
ia Lqbu] 3`k1 n = n(:); 7##nY3",^ m = m(:); t[F tIj6 if any(mod(n-m,2)) GOa](oD} error('zernfun:NMmultiplesof2', ... f
7et 'All N and M must differ by multiples of 2 (including 0).') sN7I~ end .7Ys@;>B Y1Bj++?2 Uz\B^"i| if any(m>n) )AqM?FE4R error('zernfun:MlessthanN', ... ,ibI@8;#~' 'Each M must be less than or equal to its corresponding N.') g^^%4Y end EUe2<G `t: 7&$>T <2ffcBv if any( r>1 | r<0 ) 1?)<*[ error('zernfun:Rlessthan1','All R must be between 0 and 1.') -^$CGRE6A end }!& w<wR r['T.yo usR19 _E- if ( ~any(size(r)==1) ) || ( ~any(size(theta)==1) ) B8|=P&L7N error('zernfun:RTHvector','R and THETA must be vectors.') Fkz+Qz end =q^o6{d0" C1|e1 X`:(-3T r = r(:); l?a(= theta = theta(:); A`=ESz length_r = length(r); g;\zD_":l if length_r~=length(theta) R/b)h P~ error('zernfun:RTHlength', ... ).N }x^ 'The number of R- and THETA-values must be equal.') Z,,Da|edH end iyu%o9_0 @*q\$Eg}2 ?9v!UT % Check normalization: c"H4/,F % -------------------- cIja^xD if nargin==5 && ischar(nflag) L`x:Y>C( isnorm = strcmpi(nflag,'norm'); WaN0$66[: if ~isnorm mv SNKS error('zernfun:normalization','Unrecognized normalization flag.') X+P&
up06 end (bH "x else .-`7Av+7 isnorm = false; b\][ x6zJp end .+ai
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'D{{ i{ T0[\4 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% kdQ=% % Compute the Zernike Polynomials =NF},j" %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 6O$OM }N2T/U Kdx?s;i % Determine the required powers of r: ECg/ge2 % ----------------------------------- 4'Vuhqk m_abs = abs(m); _9#4 rpowers = []; z:RwCd1\ for j = 1:length(n) 2y
~]Uo rpowers = [rpowers m_abs(j):2:n(j)]; rA8neO) end ~Rk6@&ZS} rpowers = unique(rpowers); =o{zw+|% % vay_QxB5 @w,-T@nAW % Pre-compute the values of r raised to the required powers, 9j:?s;B % and compile them in a matrix: `B
:Ydf % ----------------------------- exTpy if rpowers(1)==0 O#Xq0o rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); UG&/0{j5XV rpowern = cat(2,rpowern{:}); Z\(+awv rpowern = [ones(length_r,1) rpowern]; G:c)e,pD else 2ztP' rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); !(uyqplTk rpowern = cat(2,rpowern{:}); h+,zfVJu end ?%;7k'0" yFl@z
Rc0OEs%7P % Compute the values of the polynomials: 1f~unb\Gg % -------------------------------------- ud'r?QDM y = zeros(length_r,length(n)); p!|Wp for j = 1:length(n) vs7Hg)F s = 0:(n(j)-m_abs(j))/2; 9N5&N3 pows = n(j):-2:m_abs(j); 3)atqM)i for k = length(s):-1:1 k/j]*~" p = (1-2*mod(s(k),2))* ... mAk)9`f/ prod(2:(n(j)-s(k)))/ ... t$]lK6 prod(2:s(k))/ ... &=<x&4H+ prod(2:((n(j)-m_abs(j))/2-s(k)))/ ... p8%x@%k prod(2:((n(j)+m_abs(j))/2-s(k))); E2LpQNvN%g idx = (pows(k)==rpowers); p r(:99~3 y(:,j) = y(:,j) + p*rpowern(:,idx); G9N6iKP! end 3"6lPUS r*&gd | |