| 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, qOVs9'R 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, aT$q1!U`j2 这个,跟我们用zygo干涉仪直接拟合出的36项zernike系数,有何关系呢? "K5n |{# 那些系数是通过对29525*10阶的矩阵每列的值算出来的嘛? % <
D eN fo8xUG PsU.dv[ 7^P!@o$v! $m] ~d6 function z = zernfun(n,m,r,theta,nflag) Qctm"g| %ZERNFUN Zernike functions of order N and frequency M on the unit circle. RbKAB8 % Z = ZERNFUN(N,M,R,THETA) returns the Zernike functions of order N :[z=u % and angular frequency M, evaluated at positions (R,THETA) on the H)(@A W+- % unit circle. N is a vector of positive integers (including 0), and ^o}!=aMr % M is a vector with the same number of elements as N. Each element R|
[mp%Q % k of M must be a positive integer, with possible values M(k) = -N(k) i% 19|an % to +N(k) in steps of 2. R is a vector of numbers between 0 and 1, vi')-1Y
KM % and THETA is a vector of angles. R and THETA must have the same SV}q8z\ % length. The output Z is a matrix with one column for every (N,M) m/gl7+ % pair, and one row for every (R,THETA) pair. *9M 5' % rT9<_< % Z = ZERNFUN(N,M,R,THETA,'norm') returns the normalized Zernike )F4H' % functions. The normalization factor sqrt((2-delta(m,0))*(n+1)/pi), /Aooh~ % with delta(m,0) the Kronecker delta, is chosen so that the integral Q]9H9?}N? % of (r * [Znm(r,theta)]^2) over the unit circle (from r=0 to r=1, i$gm/ZO % and theta=0 to theta=2*pi) is unity. For the non-normalized &;S.1tg % polynomials, max(Znm(r=1,theta))=1 for all [n,m]. OQ;'Xo % `VX]vumG % The Zernike functions are an orthogonal basis on the unit circle. Vui5Z K % They are used in disciplines such as astronomy, optics, and 0l#gS; % optometry to describe functions on a circular domain. e0Cr> I5/e % *jM~VTXwt % The following table lists the first 15 Zernike functions. p!BZTwP % :M)B#@ c= % n m Zernike function Normalization A ^@:Ps % -------------------------------------------------- (dn(:<_$ % 0 0 1 1 5 fY\0 % 1 1 r * cos(theta) 2 _Bm/v^( % 1 -1 r * sin(theta) 2 Se7NF@>9_ % 2 -2 r^2 * cos(2*theta) sqrt(6) ${Cb1|g>j % 2 0 (2*r^2 - 1) sqrt(3) RO?5WJpPj % 2 2 r^2 * sin(2*theta) sqrt(6) :c3}J<Z % 3 -3 r^3 * cos(3*theta) sqrt(8) F* " % 3 -1 (3*r^3 - 2*r) * cos(theta) sqrt(8) %SuEfCM % 3 1 (3*r^3 - 2*r) * sin(theta) sqrt(8) S'm&Ll2i@ % 3 3 r^3 * sin(3*theta) sqrt(8) 8##-fv] % 4 -4 r^4 * cos(4*theta) sqrt(10) t<s:ut)Q! % 4 -2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) o"dX3jd % 4 0 6*r^4 - 6*r^2 + 1 sqrt(5) MT9c:7}[& % 4 2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) EEFM1asJf % 4 4 r^4 * sin(4*theta) sqrt(10) .|`JS?L[ % -------------------------------------------------- +>mbBu!7 % aZEi|\VU % Example 1: +InAK>NZ' % GADb Xp3 % % Display the Zernike function Z(n=5,m=1) )\#w=P % x = -1:0.01:1; Qz/o-W; % [X,Y] = meshgrid(x,x); S~fUR n % [theta,r] = cart2pol(X,Y); KLD)h,] % idx = r<=1; 5>+>=)* % z = nan(size(X)); V)#se"GV % z(idx) = zernfun(5,1,r(idx),theta(idx)); .O!JI"? % figure o&}!bq] % pcolor(x,x,z), shading interp _V\rs{
5 % axis square, colorbar P @N7g`u3} % title('Zernike function Z_5^1(r,\theta)') 1M+o7HO.mG % %&m/e?@%I % Example 2: C5oslP/@ % nI4Kuz`dF % % Display the first 10 Zernike functions 1FCqkwq[ % x = -1:0.01:1; 1%~yb Q % [X,Y] = meshgrid(x,x); HnU; N S3J % [theta,r] = cart2pol(X,Y); ?u.&BP % idx = r<=1; _Kdqa%L
! % z = nan(size(X)); NFq&a i % n = [0 1 1 2 2 2 3 3 3 3]; >xQgCOi % m = [0 -1 1 -2 0 2 -3 -1 1 3]; N>qOiw[ % Nplot = [4 10 12 16 18 20 22 24 26 28]; 8q9HQ4dsL % y = zernfun(n,m,r(idx),theta(idx)); ~ED8]*H|` % figure('Units','normalized') ArWMbT>Zqw % for k = 1:10 -U/"eVM % z(idx) = y(:,k); |hBX" % subplot(4,7,Nplot(k)) h8@8Qw % pcolor(x,x,z), shading interp eF+:w:\h % set(gca,'XTick',[],'YTick',[]) d 7vD % axis square ^uB9EP*P % title(['Z_{' num2str(n(k)) '}^{' num2str(m(k)) '}']) +-tvNX%IJ % end OUCLtn\ % 0kxo % See also ZERNPOL, ZERNFUN2. )p*I(y M#o.$+Uh 7u[U %yd % Paul Fricker 11/13/2006 Y_m/? [: wh4ik`S 1 x\taG.'zX $:IOoS|e ^Ud1 ag!- % Check and prepare the inputs: }uWIF|h~ % ----------------------------- zbQ-l1E if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) AX6z4G error('zernfun:NMvectors','N and M must be vectors.') 7|4t;F! end J2A+x\{< {
FVLH:{U^ >YP6/w,e if length(n)~=length(m) g '2'K error('zernfun:NMlength','N and M must be the same length.') _dOR-< end K_/-mwA v eeKErpj8A VB
53n' n = n(:); nx{_^sK m = m(:); )1 ]P4 if any(mod(n-m,2)) 0($@9k4!/ error('zernfun:NMmultiplesof2', ... >6fc`3*! 'All N and M must differ by multiples of 2 (including 0).') b4NUx)%ln end hcWYz R9=K/ cuv?[M if any(m>n) n~~0iU) error('zernfun:MlessthanN', ... 5=<
y%VF 'Each M must be less than or equal to its corresponding N.') \:>GF-Z( end Ns?qLSN >q W_% XLwmXi if any( r>1 | r<0 ) 5:3%RTLG error('zernfun:Rlessthan1','All R must be between 0 and 1.') -+1_ 1! end tJ:]ne Hn~=O8/2 ]/byz_7] if ( ~any(size(r)==1) ) || ( ~any(size(theta)==1) ) lw/zgR#| error('zernfun:RTHvector','R and THETA must be vectors.') Qsv3`c end 5R^e y3!r;>2k= -nBb -y r = r(:); >%qk2h> theta = theta(:); h7],/? s length_r = length(r); KDx~^OO if length_r~=length(theta) oW0A8_|9 error('zernfun:RTHlength', ... 6yDc4AX 'The number of R- and THETA-values must be equal.') 9 Vn
end )8BGN'jyi %V40I{1 l,z#
:k % Check normalization: SZ/}2_; % -------------------- k7o49Y(# if nargin==5 && ischar(nflag) )C?bb$
G isnorm = strcmpi(nflag,'norm'); PwF
1Pr`r if ~isnorm NO(^P+s error('zernfun:normalization','Unrecognized normalization flag.') q.
i2BoOd end R^_7B( else Pv mmyF isnorm = false; FG-v71!h# end , 7` /D z ^e99dz +sN'Y/- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Yd}Jz % Compute the Zernike Polynomials u\L=nCtLby %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% zDEX `~c KyQO>g{R ;3 N0) % Determine the required powers of r: {2|[7oNT6 % ----------------------------------- [73 \jT m_abs = abs(m); <K^{36h rpowers = []; uc0 1{t0, for j = 1:length(n) HR.^
y$IE rpowers = [rpowers m_abs(j):2:n(j)]; Z%h _g-C end <>gX'te rpowers = unique(rpowers); M
@|n"(P _J|TCm Xv1SRP# % Pre-compute the values of r raised to the required powers, &m=GkK % and compile them in a matrix: 2#<)-Cak % ----------------------------- pQQN8Y~^Y if rpowers(1)==0 O9+Dd%_KS# rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); bc+~g>o rpowern = cat(2,rpowern{:}); _*tU.x|DP rpowern = [ones(length_r,1) rpowern]; goE \C else {6_M$"e. rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); GJu[af rpowern = cat(2,rpowern{:}); >GbCRN~ end 4tQ~Z6Jn; :i{Svb*_' Y/%(4q*' % Compute the values of the polynomials: qocN:Of1 % -------------------------------------- q
<, b y = zeros(length_r,length(n)); 9.:]eL for j = 1:length(n) `l#|][B)g$ s = 0:(n(j)-m_abs(j))/2; =:w]EpH" pows = n(j):-2:m_abs(j); $;4y2?E for k = length(s):-1:1 w5C$39e\G p = (1-2*mod(s(k),2))* ... PRdyc+bf prod(2:(n(j)-s(k)))/ ... &oz^dlw prod(2:s(k))/ ... Z[ NO`!< prod(2:((n(j)-m_abs(j))/2-s(k)))/ ... cuw 7P prod(2:((n(j)+m_abs(j))/2-s(k))); I pp#{'Do idx = (pows(k)==rpowers); xj ?#]GR y(:,j) = y(:,j) + p*rpowern(:,idx); [NxC7p:Lo end <W>T!;4! gwA+%] if isnorm EZ"n3#/ y(:,j) = y(:,j)*sqrt((1+(m(j)~=0))*(n(j)+1)/pi); 3jI
rB% end A^2n i=b end yb-1zF| % END: Compute the Zernike Polynomials c\Z.V*o %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 6YHQ/#'G~ &x": 3P.v#TEst % Compute the Zernike functions: @QN(ouq Q % ------------------------------ ~E8L,h~ idx_pos = m>0; #`HY"-7m_ idx_neg = m<0; &'V1p4' PM?F;mj h7P<3m} z = y; xg^Z. q)d if any(idx_pos) f} !Eu z(:,idx_pos) = y(:,idx_pos).*sin(theta*m(idx_pos)'); <hV%OrBz- end @^2?97i
c if any(idx_neg) FwjmC%iY z(:,idx_neg) = y(:,idx_neg).*cos(theta*m(idx_neg)'); N|rB~
end 1_jd1UT 5r)]o'?s SSAf<44e % EOF zernfun x+;a2yE~
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