| 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, GtI6[ :1t 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, :_dICxaLZT 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? bNzqls$ 那些系数是通过对29525*10阶的矩阵每列的值算出来的嘛? Yig0/" msTB'0 9 |:^k. FY;+PY@I{ (hZ:X)E> function z = zernfun(n,m,r,theta,nflag) JSMPyj %ZERNFUN Zernike functions of order N and frequency M on the unit circle. yDd[e]zS` % Z = ZERNFUN(N,M,R,THETA) returns the Zernike functions of order N V/#v\*JHFc % and angular frequency M, evaluated at positions (R,THETA) on the E%k7wM { % unit circle. N is a vector of positive integers (including 0), and 4B O %{ % M is a vector with the same number of elements as N. Each element *crw^e % k of M must be a positive integer, with possible values M(k) = -N(k) !)H*r|*[ % to +N(k) in steps of 2. R is a vector of numbers between 0 and 1, @]
.VQ<X|0 % and THETA is a vector of angles. R and THETA must have the same r)l` % length. The output Z is a matrix with one column for every (N,M) H"YL
k % pair, and one row for every (R,THETA) pair. ?s{C// % ?AsDk ~3 % Z = ZERNFUN(N,M,R,THETA,'norm') returns the normalized Zernike D,W\ gP/h% % functions. The normalization factor sqrt((2-delta(m,0))*(n+1)/pi), mb\t/p % with delta(m,0) the Kronecker delta, is chosen so that the integral $-pbw@7 % of (r * [Znm(r,theta)]^2) over the unit circle (from r=0 to r=1, 0g(6r-2)7 % and theta=0 to theta=2*pi) is unity. For the non-normalized (ppoW % polynomials, max(Znm(r=1,theta))=1 for all [n,m]. /#q")4Mf % bejGfc % The Zernike functions are an orthogonal basis on the unit circle. hH4o;0rqJ % They are used in disciplines such as astronomy, optics, and =Lw3
\5l % optometry to describe functions on a circular domain. ,?b78_,2 % -Ds|qzrN% % The following table lists the first 15 Zernike functions. ;~tsF.= % _-a|VTM % n m Zernike function Normalization Yw"P)Zp % -------------------------------------------------- ; h+ q % 0 0 1 1 @W9H9PWv& % 1 1 r * cos(theta) 2 D9,!
%7i % 1 -1 r * sin(theta) 2 zHFTCL>" % 2 -2 r^2 * cos(2*theta) sqrt(6) h(:<(o@< % 2 0 (2*r^2 - 1) sqrt(3) P>htQ % 2 2 r^2 * sin(2*theta) sqrt(6) i,OKfXp % 3 -3 r^3 * cos(3*theta) sqrt(8) !k h{9I>M % 3 -1 (3*r^3 - 2*r) * cos(theta) sqrt(8) _g6wQdxT % 3 1 (3*r^3 - 2*r) * sin(theta) sqrt(8) ~/c5hyTx % 3 3 r^3 * sin(3*theta) sqrt(8) KS! iL=i % 4 -4 r^4 * cos(4*theta) sqrt(10) lP0k: % 4 -2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) r{ "uv=,` % 4 0 6*r^4 - 6*r^2 + 1 sqrt(5) 9s
$PrF % 4 2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) 0eA5zFU7 % 4 4 r^4 * sin(4*theta) sqrt(10) .~<]HAwq % -------------------------------------------------- &:auB:b % u9>6|w+ % Example 1: SI_?~Pf3k % a/e\vwHLv % % Display the Zernike function Z(n=5,m=1) ?'+8[OHiF^ % x = -1:0.01:1; #:W%,$9\P % [X,Y] = meshgrid(x,x); AF[>fMI % [theta,r] = cart2pol(X,Y); +u#Sl)F % idx = r<=1; q!2<=:f
% z = nan(size(X)); YX `%A6 % z(idx) = zernfun(5,1,r(idx),theta(idx)); 0^iJlR2 % figure .;Z.F7{q % pcolor(x,x,z), shading interp uHrb:X!q % axis square, colorbar q]ZSjJ % title('Zernike function Z_5^1(r,\theta)') b A+[{ % nt`<y0ta % Example 2: ?H0m<jO8~ % | XLFV % % Display the first 10 Zernike functions [D9 :A % x = -1:0.01:1; |$Xf;N37t % [X,Y] = meshgrid(x,x); P' FKk< % [theta,r] = cart2pol(X,Y); x~(y "^ph % idx = r<=1; @Y NGxg~*g % z = nan(size(X)); kpT>G$s~gy % n = [0 1 1 2 2 2 3 3 3 3]; iE+6UK % m = [0 -1 1 -2 0 2 -3 -1 1 3]; /fC\K_<N % Nplot = [4 10 12 16 18 20 22 24 26 28]; H
oS|f0 % y = zernfun(n,m,r(idx),theta(idx)); =VCQ* % figure('Units','normalized') w=$'Lt! % for k = 1:10 q-uLA&4 % z(idx) = y(:,k); x!`KhTu`_A % subplot(4,7,Nplot(k)) TRCI\ % pcolor(x,x,z), shading interp j #es2; % set(gca,'XTick',[],'YTick',[]) 777rE[\@b % axis square X=#It&m%s % title(['Z_{' num2str(n(k)) '}^{' num2str(m(k)) '}']) P09,P % end f:FpyCo=9 % G)4SWu0<t % See also ZERNPOL, ZERNFUN2. ytob/tc F b2p(. ip674'bq7R % Paul Fricker 11/13/2006 VB's :OX$LCi lkN'uZ [DL|Ht> +qZc}
7rJF % Check and prepare the inputs: PgTDjEo % -----------------------------
h/{8bC@bi if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) AW62~* error('zernfun:NMvectors','N and M must be vectors.') 8}9Ob~on
end [Q=4P*G}X `L;OY 4 uh1S
7!^ if length(n)~=length(m) e-jw^
error('zernfun:NMlength','N and M must be the same length.') 6VGo>b; end cL
ae=N @,GjeF]! =_uol8v n = n(:); "TUPYFK9 m = m(:); 4xp j< if any(mod(n-m,2)) J/=
+r0c error('zernfun:NMmultiplesof2', ... `fLfT' 'All N and M must differ by multiples of 2 (including 0).') #*\Ry/9Q end a&8l[xe1 cJ2y)` i5Eeg`NMl if any(m>n) i{P%{hVb error('zernfun:MlessthanN', ... cu:-MpE 'Each M must be less than or equal to its corresponding N.') e7h\(`J0lj end w}"!l G |iAEDZn
fHLFeSfH if any( r>1 | r<0 ) S'|lU@PCl error('zernfun:Rlessthan1','All R must be between 0 and 1.') B U'Ki \ end $m{{,&}k oO8]lHS?@ *1i?6$[
" if ( ~any(size(r)==1) ) || ( ~any(size(theta)==1) ) /#@LRN<oCq error('zernfun:RTHvector','R and THETA must be vectors.') ?{?Vy9'B end ]}_p3W "Y9 &^AzIfX}Gw rtcJ=`)0` r = r(:); vi^z5n theta = theta(:); JThk Wx length_r = length(r); D\ n>*x if length_r~=length(theta) <\+Po<)3j error('zernfun:RTHlength', ... 3e#x)H/dr 'The number of R- and THETA-values must be equal.') 1V#0\1sj end Pkj T&e) :fl*w""V@ m=#aHF % Check normalization: RA!x % -------------------- ~WzMK if nargin==5 && ischar(nflag) }<E sS isnorm = strcmpi(nflag,'norm'); loml.e=87 if ~isnorm aeLBaS error('zernfun:normalization','Unrecognized normalization flag.') 5T7_[{ end MacL3f else f S(^["*G isnorm = false; yjeqv-7 end B9%yd*SJ .%|OGl ? kt;}]O2%R %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 7Ntjx(b$"h % Compute the Zernike Polynomials "K9vm^xP %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% rOs)B 21/ /+Wb6{lY y.L|rRe@P % Determine the required powers of r: cpP.7ZR
% ----------------------------------- B)_!F`9 m_abs = abs(m); Pc/.*kOT rpowers = []; "Nk`RsW for j = 1:length(n) ?FkQe~FN{ rpowers = [rpowers m_abs(j):2:n(j)]; #p11D=
@[ end 8:;u
v7p rpowers = unique(rpowers); *?EjYI -U/I'RDLEz f'7d4 % Pre-compute the values of r raised to the required powers, -`<6=[QUO % and compile them in a matrix: 7vB9K _wCI % ----------------------------- SQz$kIZR if rpowers(1)==0 'XC&BWJ rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); p{\qSPK rpowern = cat(2,rpowern{:}); sDz)_;;% rpowern = [ones(length_r,1) rpowern]; l4R<`b\Jt else iKR8^sj7S rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); 3j[w
-Lfp rpowern = cat(2,rpowern{:}); p,_6jdz end O=4ceEmz e<: 4czh8 G}Qk!r % Compute the values of the polynomials: Z<$E.## % -------------------------------------- +35)=Uov y = zeros(length_r,length(n)); Q6s5#7h'"
for j = 1:length(n) E@\d<c. s = 0:(n(j)-m_abs(j))/2; Z7mGC`> pows = n(j):-2:m_abs(j); Mp DdJ, for k = length(s):-1:1
f4A4 p = (1-2*mod(s(k),2))* ... `\WcF7 prod(2:(n(j)-s(k)))/ ... y~4SKv
$ prod(2:s(k))/ ... &deZ prod(2:((n(j)-m_abs(j))/2-s(k)))/ ... oF 1W}DtA prod(2:((n(j)+m_abs(j))/2-s(k))); UIm[DYMS idx = (pows(k)==rpowers); .f?qUg y(:,j) = y(:,j) + p*rpowern(:,idx); $Hl+iF4j< end d~P<M3#> YokZar2a0 if isnorm auyKLT3C y(:,j) = y(:,j)*sqrt((1+(m(j)~=0))*(n(j)+1)/pi); VDb,$i.Z0 end Mo?t[]L end FBwncG$]F* % END: Compute the Zernike Polynomials buxI-wv %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% ,&zjOc_v r=iMo7q `K@df<}%*, % Compute the Zernike functions: ib""Fv7{ % ------------------------------ e!2%k u idx_pos = m>0; 9FIe W[ idx_neg = m<0; R|Q_W X
7am/X. jmk*z(}#: z = y; N.Wdi if any(idx_pos) vS24;:f z(:,idx_pos) = y(:,idx_pos).*sin(theta*m(idx_pos)'); _L `N^I. end ?( dYW7S if any(idx_neg) 3Q!J9t5dc z(:,idx_neg) = y(:,idx_neg).*cos(theta*m(idx_neg)'); q|]0on~] end |)72E[lL 7S~9E2N h3;o!FF % EOF zernfun
6Qzu-
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