| 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, &v+8RY^F= 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, xf8C$|, 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? cvpcadN[ 那些系数是通过对29525*10阶的矩阵每列的值算出来的嘛? c <[?Z7y <_@ S@t) L Ty[) r'/7kF- 5 X I\zEXO function z = zernfun(n,m,r,theta,nflag) 7FMg6z8~ %ZERNFUN Zernike functions of order N and frequency M on the unit circle. j+:q:6 = % Z = ZERNFUN(N,M,R,THETA) returns the Zernike functions of order N mnM#NT5] % and angular frequency M, evaluated at positions (R,THETA) on the 317Lv
\[ % unit circle. N is a vector of positive integers (including 0), and w!7f* % M is a vector with the same number of elements as N. Each element M0<gea\ = % k of M must be a positive integer, with possible values M(k) = -N(k) F/[vg % to +N(k) in steps of 2. R is a vector of numbers between 0 and 1, o$>A;< % and THETA is a vector of angles. R and THETA must have the same ^$aj,*Aj~ % length. The output Z is a matrix with one column for every (N,M) B*A{@)_ % pair, and one row for every (R,THETA) pair. !o2lB^e8 % QDS=M] % Z = ZERNFUN(N,M,R,THETA,'norm') returns the normalized Zernike NAjK0]SRY % functions. The normalization factor sqrt((2-delta(m,0))*(n+1)/pi), ]<mXf~zg
% with delta(m,0) the Kronecker delta, is chosen so that the integral \?-`?QPux % of (r * [Znm(r,theta)]^2) over the unit circle (from r=0 to r=1, ~xqRCf{8 % and theta=0 to theta=2*pi) is unity. For the non-normalized &[}T41 % polynomials, max(Znm(r=1,theta))=1 for all [n,m]. k9`Bi`wp % Bry\"V"'g % The Zernike functions are an orthogonal basis on the unit circle. [ZS}P % They are used in disciplines such as astronomy, optics, and c *(]pM % optometry to describe functions on a circular domain. 8Letpygm % az~4sx$+} % The following table lists the first 15 Zernike functions. ["}0umt % UUy|/z% % n m Zernike function Normalization m]JZ@ % -------------------------------------------------- R_ojK&% % 0 0 1 1 lL~T@+J~ % 1 1 r * cos(theta) 2 dV<|ztv % 1 -1 r * sin(theta) 2 eLcP.;Z % 2 -2 r^2 * cos(2*theta) sqrt(6) ~WK>+T,% % 2 0 (2*r^2 - 1) sqrt(3) MNNPBE % 2 2 r^2 * sin(2*theta) sqrt(6) ? &ew$% % 3 -3 r^3 * cos(3*theta) sqrt(8) w+bQpIPM % 3 -1 (3*r^3 - 2*r) * cos(theta) sqrt(8) ygr[5Tl % 3 1 (3*r^3 - 2*r) * sin(theta) sqrt(8) _B)LRD+Hj % 3 3 r^3 * sin(3*theta) sqrt(8) LD5n_W % 4 -4 r^4 * cos(4*theta) sqrt(10) [>+(zlK" % 4 -2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) `<2y
[<y % 4 0 6*r^4 - 6*r^2 + 1 sqrt(5) ,x}p1EZ % 4 2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) "; tl>Ot % 4 4 r^4 * sin(4*theta) sqrt(10) S`TP#uzKu] % -------------------------------------------------- MNO T<( % ?y!0QAIXK % Example 1: Ub%+8M % P&C,E E$ % % Display the Zernike function Z(n=5,m=1) t0p^0 % x = -1:0.01:1; #q40 >)] % [X,Y] = meshgrid(x,x); GQoaBO. % [theta,r] = cart2pol(X,Y); ?J,hv'L] % idx = r<=1; -Y%#z'^- % z = nan(size(X)); d paZ6g % z(idx) = zernfun(5,1,r(idx),theta(idx)); sY!PXD0Q % figure /o#!9H % pcolor(x,x,z), shading interp D+d\<": % axis square, colorbar $}r*WZ
% title('Zernike function Z_5^1(r,\theta)') Oz!#);v % n.p6+^ES % Example 2: ZurQr} % 'WkDpa % % Display the first 10 Zernike functions )e|Cd} 2 % x = -1:0.01:1; I{AteL % [X,Y] = meshgrid(x,x); QN:gSS{30 % [theta,r] = cart2pol(X,Y); S#dkJu]]# % idx = r<=1; g
nJe!E % z = nan(size(X)); J6/Mm7R % n = [0 1 1 2 2 2 3 3 3 3]; tpj({
% m = [0 -1 1 -2 0 2 -3 -1 1 3]; $A,fO~ % Nplot = [4 10 12 16 18 20 22 24 26 28]; X*VHi % y = zernfun(n,m,r(idx),theta(idx)); Q[`J= % figure('Units','normalized') &Al9%W % for k = 1:10 M@fUZh
% z(idx) = y(:,k); LGZ5py=xb % subplot(4,7,Nplot(k)) *`[dC,+`. % pcolor(x,x,z), shading interp .j:[R. % set(gca,'XTick',[],'YTick',[]) cZT;VmC % axis square #z 3tSnmp % title(['Z_{' num2str(n(k)) '}^{' num2str(m(k)) '}']) |rkj$s, % end R X:wt % !xyO % See also ZERNPOL, ZERNFUN2. "&%:
9O ~>zml1aJ6 GJW+'-f % Paul Fricker 11/13/2006 W@v@|D@ U.~,Bwb mz;S*ONlV uhvmh \dSMF,E % Check and prepare the inputs: rMAH YH9 % ----------------------------- a(&!{Y1bt if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) 1$oVcDLl error('zernfun:NMvectors','N and M must be vectors.') |9ro&KA end b}4k-hZL evryk,x =A&x
d" if length(n)~=length(m) NKB,D$!~& error('zernfun:NMlength','N and M must be the same length.') WV_y@H_ end d)`XG cx{= mcAg,~"HB ~Fv&z'R n = n(:); sL|lfc'bB m = m(:); 2P`QS@v0a= if any(mod(n-m,2)) -=,%9r error('zernfun:NMmultiplesof2', ... eSf
e
s 'All N and M must differ by multiples of 2 (including 0).') I9P<!#q> end 2MwRjh_ dk~ h l^4[;%*f#l if any(m>n) 'bp*hqG[ error('zernfun:MlessthanN', ... Vzf{gr? 'Each M must be less than or equal to its corresponding N.') CZyOAoc< end ;V]EF 2f(5C*~ /'?Fz*b if any( r>1 | r<0 ) IQ[?ej3W error('zernfun:Rlessthan1','All R must be between 0 and 1.') Q>f^*FyOw< end Q>[*Y/`I } Zu2GU$6 )iadu if ( ~any(size(r)==1) ) || ( ~any(size(theta)==1) ) qR0V\OtgY~ error('zernfun:RTHvector','R and THETA must be vectors.') 2xRb$QF end $+P9@Q$ +F q`I2l| <Ur(< WTV r = r(:); 2h0I1a,7 theta = theta(:); HpXMPHd length_r = length(r); ?z0f5<dL if length_r~=length(theta) a*JM2^,HO error('zernfun:RTHlength', ... d!/@+i 'The number of R- and THETA-values must be equal.') mN3}wJ}J end s mub> V [o8a(oC '8`{u[: % Check normalization: {Pm^G^EP % -------------------- b9%}<w if nargin==5 && ischar(nflag) -a(f- isnorm = strcmpi(nflag,'norm'); '8>h4s4 if ~isnorm Ti`<,TA54 error('zernfun:normalization','Unrecognized normalization flag.') >kOc a end q:sDNj)R\ else e'aKI]>a isnorm = false; |sz`w^# end ])h={gI UI|L;5 }CZ,WJz= %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% j{N;2#.u % Compute the Zernike Polynomials !J!zi %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% p3O%|)yV \V`O-wcJ]S =MO2M~e! % Determine the required powers of r: :7%JD .;W % ----------------------------------- *)"U5A/v) m_abs = abs(m); Yu=4j9e_mG rpowers = []; L^rtypkJ for j = 1:length(n) quk~z};R>\ rpowers = [rpowers m_abs(j):2:n(j)]; 6~GaFmW= end .E!7}O6 rpowers = unique(rpowers); $+Ke$fq.> w=\Lw+X "{;]T % Pre-compute the values of r raised to the required powers, x^_Wfkch] % and compile them in a matrix: 5P{dey! % ----------------------------- xjOy3_Js if rpowers(1)==0 3P Twpq1 rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); @8C^[fDL rpowern = cat(2,rpowern{:}); DrbjqQL+. rpowern = [ones(length_r,1) rpowern]; oQ~Q?o]Ri else k\_>/)g rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); G;615p1 rpowern = cat(2,rpowern{:}); 6"WR}S0o end C- ]H+p Gdnk1_D> 'GQ1;9A57 % Compute the values of the polynomials: [,Ts;Hy6Q % -------------------------------------- R0+v5E y = zeros(length_r,length(n)); eJ)Bs20Q for j = 1:length(n) LfyycC2E s = 0:(n(j)-m_abs(j))/2; !JUXq pows = n(j):-2:m_abs(j); \*6%o0c for k = length(s):-1:1 |DfYH~@( p = (1-2*mod(s(k),2))* ... rgILOtk[ prod(2:(n(j)-s(k)))/ ... C.@R#a' prod(2:s(k))/ ... N J:]jd prod(2:((n(j)-m_abs(j))/2-s(k)))/ ... Tz58@VY V prod(2:((n(j)+m_abs(j))/2-s(k))); =Y|TShKk idx = (pows(k)==rpowers); jEklf0Z y(:,j) = y(:,j) + p*rpowern(:,idx); tr7FV1p end lW'6rat s2g}IZfo if isnorm yXY8 oE y(:,j) = y(:,j)*sqrt((1+(m(j)~=0))*(n(j)+1)/pi); gqNd@tYI end hF+YZU]rT end gj\r>~S % END: Compute the Zernike Polynomials 'mpY2|]\$ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% $y\'j5nk3 kxoJL6IC !l~tBJr*sB % Compute the Zernike functions: t d q;D % ------------------------------ ~FH''}3:3 idx_pos = m>0; &GwBxJ
idx_neg = m<0; 2|tZ xlt- _]1dm)% ywmx6q4MFL z = y; !40{1U&@a` if any(idx_pos) xZtA) Bp z(:,idx_pos) = y(:,idx_pos).*sin(theta*m(idx_pos)'); ;M8N% end r$;DA<<|<c if any(idx_neg) sBS\S z(:,idx_neg) = y(:,idx_neg).*cos(theta*m(idx_neg)'); ckP&N:tC end )HS|pS: m^U\l9LE Slq=;TDp % EOF zernfun
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