| 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, ?:9"X$XR 我输入10阶的n、m,r,theta为38025*1向量,最后得到的z是29525*10阶的矩阵, hOK8(U0 这个,跟我们用zygo干涉仪直接拟合出的36项zernike系数,有何关系呢? lH~[f 那些系数是通过对29525*10阶的矩阵每列的值算出来的嘛? G=bCNn< ?+8\.a! 3=V&K- ql~J8G9 +1!ia] function z = zernfun(n,m,r,theta,nflag) cso8xq|b7 %ZERNFUN Zernike functions of order N and frequency M on the unit circle. 3o/[t % Z = ZERNFUN(N,M,R,THETA) returns the Zernike functions of order N + LJ73
! % and angular frequency M, evaluated at positions (R,THETA) on the @>7%qS % unit circle. N is a vector of positive integers (including 0), and Y}KNKO; % M is a vector with the same number of elements as N. Each element <%mRSv % k of M must be a positive integer, with possible values M(k) = -N(k) ;qV>L=a % to +N(k) in steps of 2. R is a vector of numbers between 0 and 1, *qpSXmOz % and THETA is a vector of angles. R and THETA must have the same RPbZ(. % length. The output Z is a matrix with one column for every (N,M) AQ^u % pair, and one row for every (R,THETA) pair. 0<*<$U % :Llb< MY2 % Z = ZERNFUN(N,M,R,THETA,'norm') returns the normalized Zernike /dIzY0<aO % functions. The normalization factor sqrt((2-delta(m,0))*(n+1)/pi), j5h-dK % with delta(m,0) the Kronecker delta, is chosen so that the integral B`sAk
% % of (r * [Znm(r,theta)]^2) over the unit circle (from r=0 to r=1, 62NsJ<#> % and theta=0 to theta=2*pi) is unity. For the non-normalized N6TH}~62} % polynomials, max(Znm(r=1,theta))=1 for all [n,m]. :rP=t , % 9A#i_#[R % The Zernike functions are an orthogonal basis on the unit circle. y|jq?M<A % They are used in disciplines such as astronomy, optics, and tQ601H>o % optometry to describe functions on a circular domain.
Wa~=bH % IAyp 2 % The following table lists the first 15 Zernike functions. ]I6 J7A[ % lNv|M)I % n m Zernike function Normalization 9jGu}Vo % -------------------------------------------------- o#N+Y?O % 0 0 1 1 lmhLM. 2 % 1 1 r * cos(theta) 2 dgP3@`YS % 1 -1 r * sin(theta) 2 @E8+C8' % 2 -2 r^2 * cos(2*theta) sqrt(6) _(zG?]y0P % 2 0 (2*r^2 - 1) sqrt(3) ?r!o~|9| % 2 2 r^2 * sin(2*theta) sqrt(6) 2>59q$| % 3 -3 r^3 * cos(3*theta) sqrt(8) FC4wwzb % 3 -1 (3*r^3 - 2*r) * cos(theta) sqrt(8) CU~PT. % 3 1 (3*r^3 - 2*r) * sin(theta) sqrt(8) [PbOfxxgA % 3 3 r^3 * sin(3*theta) sqrt(8) Fs^Mw
go % 4 -4 r^4 * cos(4*theta) sqrt(10) O.JN ENZf % 4 -2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) fd9k?,zM % 4 0 6*r^4 - 6*r^2 + 1 sqrt(5) o,wUc"CE % 4 2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) T6kdS]4- % 4 4 r^4 * sin(4*theta) sqrt(10) ,iwp,=h= % -------------------------------------------------- ABYcH]m % >C~6\L`c % Example 1: 8JUwf % .o}v#W+st % % Display the Zernike function Z(n=5,m=1) @[v~y"tE} % x = -1:0.01:1; %xt^698&X % [X,Y] = meshgrid(x,x); #Rr%:\* % [theta,r] = cart2pol(X,Y); k|f4Cf, % idx = r<=1; CTA3*Gn % z = nan(size(X)); x$(f7?s] 1 % z(idx) = zernfun(5,1,r(idx),theta(idx)); E<*xx#p % figure J?$,c4;W2 % pcolor(x,x,z), shading interp EB|}fz % axis square, colorbar [1H^3g
' % title('Zernike function Z_5^1(r,\theta)') |vzl. ^"- % {(?4!rh % Example 2: -H-~;EzU % 6-ils3& % % Display the first 10 Zernike functions PTV:IzoW % x = -1:0.01:1; Ef{Vp;] % [X,Y] = meshgrid(x,x); <
FAheE+ % [theta,r] = cart2pol(X,Y); YZJyk:H\ % idx = r<=1; 2I{"XB % z = nan(size(X)); W=4FFl[ % n = [0 1 1 2 2 2 3 3 3 3]; 0Wp|1)ljA % m = [0 -1 1 -2 0 2 -3 -1 1 3]; Srd4))2/0 % Nplot = [4 10 12 16 18 20 22 24 26 28]; kg\>k2h % y = zernfun(n,m,r(idx),theta(idx)); |(^PS8wG % figure('Units','normalized') I1&aM}y{G % for k = 1:10 IO:G1;[/2L % z(idx) = y(:,k); f(7GX3? % subplot(4,7,Nplot(k)) *}W_+qo" % pcolor(x,x,z), shading interp bi;1s'Y<D % set(gca,'XTick',[],'YTick',[]) "tpSg % axis square Ny)X+2Ae % title(['Z_{' num2str(n(k)) '}^{' num2str(m(k)) '}']) Z;)%%V%o % end &PtJ$0%q % ZqO^f*F>h % See also ZERNPOL, ZERNFUN2. R0-j5&^jju y1L,0 ] ENY+^7 % Paul Fricker 11/13/2006 -d:Jta!}{ @pU)_d!pJ \Y}8S/] 8, >P 0#^v{DC % Check and prepare the inputs: ^_mj % ----------------------------- q'MZ R'<@ if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) \1Em`nvOX error('zernfun:NMvectors','N and M must be vectors.') +^T@sa`[I end 7. ;3e@s D.XvG _ |LKXOU
c if length(n)~=length(m) R*r#E{!V; error('zernfun:NMlength','N and M must be the same length.') P7/X|M z end ,s;UfF k"w"hg&e iOO)Q\ n = n(:); Owk |@6! m = m(:); UFuX@Lu0 if any(mod(n-m,2)) uu687|Pm error('zernfun:NMmultiplesof2', ...
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+Hd 'All N and M must differ by multiples of 2 (including 0).') !%0 *z end ,zY$8y] tIgN$BHR> @F*%9LPv if any(m>n) f&
' error('zernfun:MlessthanN', ... VP]% Hni] 'Each M must be less than or equal to its corresponding N.') HyWCMK6b end *;*r8[U}q y'*K|aTG Tnm.A? if any( r>1 | r<0 ) 83q6Sv error('zernfun:Rlessthan1','All R must be between 0 and 1.') #;nYg?d= end yz8jw:d^- u.Dz~$T JaGtsi9%. if ( ~any(size(r)==1) ) || ( ~any(size(theta)==1) ) G'A R`"F error('zernfun:RTHvector','R and THETA must be vectors.') wAW5
Z0D end @MCg%Afw `W*U4?M 9q[oa5INd r = r(:); z' >_Mc6 theta = theta(:); kPLxEwl length_r = length(r); <e</m)j if length_r~=length(theta) Y0-n\| error('zernfun:RTHlength', ... e^D]EA]% 'The number of R- and THETA-values must be equal.') b1?'gn~ end ?.;c$' )P|),S,;Z oM`0y@QCf % Check normalization: 0KOgw*>_ % -------------------- p=}Nn( if nargin==5 && ischar(nflag) @J`"[%U isnorm = strcmpi(nflag,'norm'); ,nDaqQ-C!! if ~isnorm #4 pB@_ error('zernfun:normalization','Unrecognized normalization flag.') B_m8{44zM end OpYY{f else s,&Z=zt0R isnorm = false; pcWPH. end `RL"AH:+ WEi2=3dV z ~/` 1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% *CI#+P % Compute the Zernike Polynomials | h#u^v3 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% ]3.;PWa: '$%l7 Z}Ft:7 % Determine the required powers of r: iqQD{SRt{ % ----------------------------------- %M|hA#04vZ m_abs = abs(m); -C?ZB}` rpowers = []; ?+}_1x` for j = 1:length(n) YglmX"fLf rpowers = [rpowers m_abs(j):2:n(j)]; + @s"zp;F end U|Ta4W`k\ rpowers = unique(rpowers); ;@Y;g(bw: %/ #NK1&M _^%,x % Pre-compute the values of r raised to the required powers, ExL0?FemWV % and compile them in a matrix: Cd}<a?m, % ----------------------------- |H+UOEiv,p if rpowers(1)==0 &Ys<@M7E: rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); IKilr' rpowern = cat(2,rpowern{:}); *mvlb
(' & rpowern = [ones(length_r,1) rpowern]; ={@6{-tl else [j/9neaye rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); hy"\RW rpowern = cat(2,rpowern{:}); Od,qbU4O end pYmk1!]/
57 ,S]7 'UP % Compute the values of the polynomials: =R$u[~Xl2X % -------------------------------------- )W
_v:?A9 y = zeros(length_r,length(n)); Iom'Y@x for j = 1:length(n) +E(L \ s = 0:(n(j)-m_abs(j))/2; <&g,Nc'5C pows = n(j):-2:m_abs(j); EaY?aAuS: for k = length(s):-1:1 >$/>#e~ p = (1-2*mod(s(k),2))* ... N]=q|D prod(2:(n(j)-s(k)))/ ... y(yHt=r prod(2:s(k))/ ... v\%HPMlh prod(2:((n(j)-m_abs(j))/2-s(k)))/ ... . ~~T\rmI prod(2:((n(j)+m_abs(j))/2-s(k))); a fW@T2 idx = (pows(k)==rpowers); 2B& | |