| 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, 8qYGlew, 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, $HCAC4 这个,跟我们用zygo干涉仪直接拟合出的36项zernike系数,有何关系呢? jc~*#\N 那些系数是通过对29525*10阶的矩阵每列的值算出来的嘛? [W\atmd" iXS-EB/ I4X+'fW, XoQk'7"f Jq<`j<'9 function z = zernfun(n,m,r,theta,nflag) KY34 'Di %ZERNFUN Zernike functions of order N and frequency M on the unit circle. S9#N%{8P % Z = ZERNFUN(N,M,R,THETA) returns the Zernike functions of order N o^"3C1j % and angular frequency M, evaluated at positions (R,THETA) on the {s'_zSz % unit circle. N is a vector of positive integers (including 0), and Qg$Nj=Cw % M is a vector with the same number of elements as N. Each element }'0Xz9/ l % k of M must be a positive integer, with possible values M(k) = -N(k) A*U'SCg(G % to +N(k) in steps of 2. R is a vector of numbers between 0 and 1, ~
2oP, % and THETA is a vector of angles. R and THETA must have the same 18tQWI$ % length. The output Z is a matrix with one column for every (N,M) Zy3&Zt % pair, and one row for every (R,THETA) pair. ]`H.qV % <Jrb"H[T" % Z = ZERNFUN(N,M,R,THETA,'norm') returns the normalized Zernike TY[d%rMm % functions. The normalization factor sqrt((2-delta(m,0))*(n+1)/pi), EAE\Xv % with delta(m,0) the Kronecker delta, is chosen so that the integral >^GCSPe % of (r * [Znm(r,theta)]^2) over the unit circle (from r=0 to r=1, Cj9O[ % and theta=0 to theta=2*pi) is unity. For the non-normalized &b")`p&K % polynomials, max(Znm(r=1,theta))=1 for all [n,m]. v!hs~DnUZ % RW^ v {'o % The Zernike functions are an orthogonal basis on the unit circle. 9<c4y4#y % They are used in disciplines such as astronomy, optics, and XJ/kB8 % optometry to describe functions on a circular domain. vK7,O%!S % 5T3>fw2G % The following table lists the first 15 Zernike functions. Y]Vc}-a(h % W@C tF U9 % n m Zernike function Normalization .p~;U|h" % -------------------------------------------------- na:^7:I % 0 0 1 1 >:E-^t% % 1 1 r * cos(theta) 2 Qf(e'e % 1 -1 r * sin(theta) 2 Z9~Wlt'? % 2 -2 r^2 * cos(2*theta) sqrt(6) n<&R"89 % 2 0 (2*r^2 - 1) sqrt(3) TN aff % 2 2 r^2 * sin(2*theta) sqrt(6) <X&:tZ#/ % 3 -3 r^3 * cos(3*theta) sqrt(8) JlGD.!` % 3 -1 (3*r^3 - 2*r) * cos(theta) sqrt(8) qk1D#1vl % 3 1 (3*r^3 - 2*r) * sin(theta) sqrt(8) bXL a~r4\ % 3 3 r^3 * sin(3*theta) sqrt(8) >*xzSd?\ % 4 -4 r^4 * cos(4*theta) sqrt(10) f_XCO=8'v % 4 -2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) }AYSQ~: % 4 0 6*r^4 - 6*r^2 + 1 sqrt(5) wh+ibH}@! % 4 2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) XPTB,1g+f % 4 4 r^4 * sin(4*theta) sqrt(10) B4Oa7$M/U % -------------------------------------------------- |T"q,i9% % ]%hI- % Example 1: gg_(%.> % ur7a%NH % % Display the Zernike function Z(n=5,m=1) l= S_#
% x = -1:0.01:1; Kp;o?5H % [X,Y] = meshgrid(x,x); h1)\.F4G % [theta,r] = cart2pol(X,Y); _'a4I; % idx = r<=1; -~ Q3T9+ % z = nan(size(X)); $,42h % z(idx) = zernfun(5,1,r(idx),theta(idx)); HX*U2<^ % figure *E_= 8OV % pcolor(x,x,z), shading interp {v(|_j&:o % axis square, colorbar Big-)7?
% title('Zernike function Z_5^1(r,\theta)') SoIMf tX % MWf%Lh;R % Example 2: W#\4"'=I % c[q3O** % % Display the first 10 Zernike functions v8N1fuP} % x = -1:0.01:1; GssoT<Y)Z % [X,Y] = meshgrid(x,x); / KM+PeO % [theta,r] = cart2pol(X,Y); 4R6 .GO % idx = r<=1; PnvLXE}F % z = nan(size(X)); #*@Yil=1 % n = [0 1 1 2 2 2 3 3 3 3]; \g/E4U.+ % m = [0 -1 1 -2 0 2 -3 -1 1 3]; 4r$t}t
gX % Nplot = [4 10 12 16 18 20 22 24 26 28]; q 9^r2OO % y = zernfun(n,m,r(idx),theta(idx)); `h#JDcT;a % figure('Units','normalized') _qfdk@@g % for k = 1:10 d1N&J`R\1 % z(idx) = y(:,k); (?(ahtT4T % subplot(4,7,Nplot(k)) $[e*0!e % pcolor(x,x,z), shading interp @ *dA<N.9 % set(gca,'XTick',[],'YTick',[]) gnt[l0m % axis square f,*e?9@;s % title(['Z_{' num2str(n(k)) '}^{' num2str(m(k)) '}']) = 8n*%NC % end 8dfx _kY`/ % 6O?O6Ub % See also ZERNPOL, ZERNFUN2. ;|c, aqlYB7 fO+;%B % Paul Fricker 11/13/2006 &o(?
}W
TG($l2 |<S9nZg%p );C !:? ax$0J|}7 % Check and prepare the inputs: w t}a`hxu % ----------------------------- rYT3oqpfT if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) =+u$ZZ0+]o error('zernfun:NMvectors','N and M must be vectors.') /3fo=7G6 end sfH|sp 8d]=
+n! V%+KJ}S!Z if length(n)~=length(m) SYyH_0N error('zernfun:NMlength','N and M must be the same length.') +IU]=qS end b'G4KNW mu(S9 15870xS n = n(:); StE4n0V m = m(:); TJCoID7a8 if any(mod(n-m,2)) 4Hu.o 7 error('zernfun:NMmultiplesof2', ... *Owq_)_(| 'All N and M must differ by multiples of 2 (including 0).') U*zjEY:A end :Y"f.> K@hv[4 7;Wj ^# if any(m>n) %H:!/'45 error('zernfun:MlessthanN', ... H>VuUH| 'Each M must be less than or equal to its corresponding N.') o zv><e# end D:%v((Ccw *@/!h2 >RRb8=[J if any( r>1 | r<0 ) nF05p2Mh error('zernfun:Rlessthan1','All R must be between 0 and 1.') $ U<xrN>O end ,!c. "= HCP, poeKY[]. if ( ~any(size(r)==1) ) || ( ~any(size(theta)==1) ) b{9q error('zernfun:RTHvector','R and THETA must be vectors.') )Nk^;[ end 1}9@aKM +
6O5hZ 1S <V,9( r = r(:); <kt,aMw[* theta = theta(:); *l^h;RSx length_r = length(r); 2\W[ ItxL0 if length_r~=length(theta) On#RYy^} error('zernfun:RTHlength', ... Uk5jZ| 'The number of R- and THETA-values must be equal.') 0d~>zKho end -Y{P"!p0 NFv9%$l- $s$z"< % Check normalization: \-gZ_>) % -------------------- XX#YiG4|J if nargin==5 && ischar(nflag) r1]shb%J? isnorm = strcmpi(nflag,'norm'); Y[#i(5w if ~isnorm s9?klJg error('zernfun:normalization','Unrecognized normalization flag.') :VX?j3qW end x/ lW=EQ else $d'GCzYvZ isnorm = false; L]I)E`s end MPhO#;v x!"S`AM /{#1w\ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 4Bsx[~ u& % Compute the Zernike Polynomials <p;cR` %uE %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% tT>~;l%' P33x/#VVE |t5K!?{i % Determine the required powers of r: CXwDG_e % ----------------------------------- wM8Gz.9, m_abs = abs(m); `}Ssc-A rpowers = []; >vF=}1_L for j = 1:length(n) rZm|7A)i rpowers = [rpowers m_abs(j):2:n(j)]; * _ {w0U) end ?{ns1nW: rpowers = unique(rpowers); }%Dsy2:y }@>=,A4Y #Y6'Q8gf % Pre-compute the values of r raised to the required powers, (P&~PJH % and compile them in a matrix: 1'@/jR % ----------------------------- h)2W}p{a4= if rpowers(1)==0 r*'a-2Au rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); ~Q}JC3f> rpowern = cat(2,rpowern{:}); vs}_1o rpowern = [ones(length_r,1) rpowern]; _PUgK\ else b.V\EOk rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); `&]<_Jc1 rpowern = cat(2,rpowern{:}); MM8@0t'E end JsAl;w .4P5tIn\ Qvo(2( % Compute the values of the polynomials: PEqO<a1Z8 % -------------------------------------- #~<cp)!3 y = zeros(length_r,length(n)); IO3`/R- for j = 1:length(n) U"\$k& s = 0:(n(j)-m_abs(j))/2; KZ_d..l*W pows = n(j):-2:m_abs(j); xDv5'IGBb for k = length(s):-1:1 W3K&C[f p = (1-2*mod(s(k),2))* ... I!'PvIyO prod(2:(n(j)-s(k)))/ ... pd2Lc
$O@ prod(2:s(k))/ ... >b9nc\~ prod(2:((n(j)-m_abs(j))/2-s(k)))/ ... P>q"P1&{ prod(2:((n(j)+m_abs(j))/2-s(k))); IRy!8A=X idx = (pows(k)==rpowers); wX dtY y(:,j) = y(:,j) + p*rpowern(:,idx); 8/ lv, m# end pdCn98}%- my+y<C-o` if isnorm pe(31%(h y(:,j) = y(:,j)*sqrt((1+(m(j)~=0))*(n(j)+1)/pi); Np$peT[ end P%HvL4R end 9e^HTUFbG % END: Compute the Zernike Polynomials Lbb{ z %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% NR3]MGBKv wkSIQL )nJo\HFXv % Compute the Zernike functions: *5KV DOd
% ------------------------------ 0Vu&UD idx_pos = m>0; ^H]q[XFR idx_neg = m<0; qf7:Q?+.| s"1:#.u QiDf,$t|, z = y; \)H} if any(idx_pos) -9Iz$(>a z(:,idx_pos) = y(:,idx_pos).*sin(theta*m(idx_pos)'); c,WRgXL end {a>a?fVU if any(idx_neg) b-sbR R z(:,idx_neg) = y(:,idx_neg).*cos(theta*m(idx_neg)'); '2`MT- end ?$rSbw q:OSQ~U_ +(>!nsf % EOF zernfun \5g7_3,3W
|
|