| 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, F2N"aQ& 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, G5}_NS/ 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? 7-744wV}Z 那些系数是通过对29525*10阶的矩阵每列的值算出来的嘛? UmR)L!QT8 <Lb LMV *!QmYH5r0 ,6^<Vg KuR]X``2 function z = zernfun(n,m,r,theta,nflag) )!8qJQD %ZERNFUN Zernike functions of order N and frequency M on the unit circle. ?C|'GkT % Z = ZERNFUN(N,M,R,THETA) returns the Zernike functions of order N '2^}de!E % and angular frequency M, evaluated at positions (R,THETA) on the -.D?Z8e % unit circle. N is a vector of positive integers (including 0), and }B0[S_mw % M is a vector with the same number of elements as N. Each element +XWTu! % k of M must be a positive integer, with possible values M(k) = -N(k) lR?y
tIY % to +N(k) in steps of 2. R is a vector of numbers between 0 and 1, ChiIQWFE % and THETA is a vector of angles. R and THETA must have the same wB)y@w4k % length. The output Z is a matrix with one column for every (N,M) IdmP!(u % pair, and one row for every (R,THETA) pair. g QBS#NY % e{x>u( % Z = ZERNFUN(N,M,R,THETA,'norm') returns the normalized Zernike oCT,v 0+4O % functions. The normalization factor sqrt((2-delta(m,0))*(n+1)/pi), a6Vfd& % with delta(m,0) the Kronecker delta, is chosen so that the integral 72l:[5ccR % of (r * [Znm(r,theta)]^2) over the unit circle (from r=0 to r=1, PzJ(Q % and theta=0 to theta=2*pi) is unity. For the non-normalized Ii0\Skb % polynomials, max(Znm(r=1,theta))=1 for all [n,m]. j2G^sj"| % "51/,D % The Zernike functions are an orthogonal basis on the unit circle. bF _]j/ % They are used in disciplines such as astronomy, optics, and kFjv'[Y1N % optometry to describe functions on a circular domain. _hY6NMw % sc*R:" % The following table lists the first 15 Zernike functions. S)hDsf.I % Zh8\B)0unn % n m Zernike function Normalization []>rYZ9bv % -------------------------------------------------- N82 6xvA % 0 0 1 1 k|OM?\ % 1 1 r * cos(theta) 2 f0P,j~] % 1 -1 r * sin(theta) 2 ULK]' Rn % 2 -2 r^2 * cos(2*theta) sqrt(6) > TYDkEs0 % 2 0 (2*r^2 - 1) sqrt(3) (BY 0b%^ % 2 2 r^2 * sin(2*theta) sqrt(6) HzM\<YD % 3 -3 r^3 * cos(3*theta) sqrt(8) "G%S
m") % 3 -1 (3*r^3 - 2*r) * cos(theta) sqrt(8) cW^LmA % 3 1 (3*r^3 - 2*r) * sin(theta) sqrt(8) `)cI^! % 3 3 r^3 * sin(3*theta) sqrt(8) )f3A\^ % 4 -4 r^4 * cos(4*theta) sqrt(10) \PS]c9@,rc % 4 -2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) )M;~j % 4 0 6*r^4 - 6*r^2 + 1 sqrt(5) 3$"V,_TBZ % 4 2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) #`y[75<n % 4 4 r^4 * sin(4*theta) sqrt(10) n[>hJ6 % -------------------------------------------------- QPm[4Fd{G % faOiNR7;h % Example 1: b'pwRKpx % i6yA>#^ % % Display the Zernike function Z(n=5,m=1) z#gebr~_\ % x = -1:0.01:1; bIm4s % [X,Y] = meshgrid(x,x); 5QqU.9M % [theta,r] = cart2pol(X,Y); |kZ!-?9Z % idx = r<=1; 2#NnA3l]x% % z = nan(size(X)); k2eKs*WLC % z(idx) = zernfun(5,1,r(idx),theta(idx)); @7}XBg[pI % figure !,ODczWvh % pcolor(x,x,z), shading interp TDw~sxtv& % axis square, colorbar ~Bl,_?CBr % title('Zernike function Z_5^1(r,\theta)') cq>J]35 % q25p3 % Example 2: ,q%X`F
rc % %3dc_YPS % % Display the first 10 Zernike functions r.)n>
% x = -1:0.01:1; 50 w$PW % [X,Y] = meshgrid(x,x); :.=:N%3[ % [theta,r] = cart2pol(X,Y); l!}gWd,H % idx = r<=1; H,
3Bf % z = nan(size(X)); ([<{RjPb % n = [0 1 1 2 2 2 3 3 3 3]; -W6@[5 c % m = [0 -1 1 -2 0 2 -3 -1 1 3]; 6<@mBZ % Nplot = [4 10 12 16 18 20 22 24 26 28]; Mxw-f4j % y = zernfun(n,m,r(idx),theta(idx)); R@grY:h % figure('Units','normalized') xJ<RQCW$ % for k = 1:10 N5)H(<} % z(idx) = y(:,k); l\0PwD % subplot(4,7,Nplot(k)) 6 wd % pcolor(x,x,z), shading interp psvc,V_* % set(gca,'XTick',[],'YTick',[]) L[PqEN\i % axis square BHp>(7, % title(['Z_{' num2str(n(k)) '}^{' num2str(m(k)) '}']) m\*ca3$ % end o#"yFP1 % G8]{pbX % See also ZERNPOL, ZERNFUN2. /V0Put D(Z#um8n \RDqW+, % Paul Fricker 11/13/2006 -hfDf{QN rhzI*nwOT 5Bq;Vb ug{sQyLN [Cd#<Te3 % Check and prepare the inputs: dH0>lV % ----------------------------- wY8Vc" if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) p]X+#I< error('zernfun:NMvectors','N and M must be vectors.') Uf_mwEE end E_30)"] rc:UG "[ B^M
L}$ if length(n)~=length(m) nzxHd7NIZ error('zernfun:NMlength','N and M must be the same length.') ?!F<xi: end ?mV2|; %iPIgma ~eTp( XG n = n(:); !<h9XccN m = m(:); IecD41% if any(mod(n-m,2)) }x{1{Bw>Y error('zernfun:NMmultiplesof2', ... +R$;LtR 'All N and M must differ by multiples of 2 (including 0).') \{rhHb\|h end 0n X5Vo )jwovS?V CNj |vYj if any(m>n) 6V9r[,n error('zernfun:MlessthanN', ... kyJKai 'Each M must be less than or equal to its corresponding N.') CXu$0DQ( end
j AoI`J y]i}j,e0L ^eoW+OxH if any( r>1 | r<0 ) .2P3 !KCL error('zernfun:Rlessthan1','All R must be between 0 and 1.') tOF8v8Hd end 1A(f_ 0,.Q i5WO)9Us taVK&ohWx if ( ~any(size(r)==1) ) || ( ~any(size(theta)==1) ) |J-tU)|1vl error('zernfun:RTHvector','R and THETA must be vectors.') V LeYO5'L end bQ?Vh@j(M $Y$s*h_-/< lZ"C~B}9:I r = r(:); 7
mA3&<&q theta = theta(:); \(?d2$0m length_r = length(r); /gaC if length_r~=length(theta) KKg\n^ error('zernfun:RTHlength', ... 0aGauG[ 'The number of R- and THETA-values must be equal.') :1UOT'_ end >_\]c-~< D!)h92CIDm ( t"|XSF % Check normalization: %0u5d$b q % -------------------- Z0~,cO8~ if nargin==5 && ischar(nflag) {)Zz4 isnorm = strcmpi(nflag,'norm'); /K,@{__JP if ~isnorm {poTA+i error('zernfun:normalization','Unrecognized normalization flag.') qIy9{LF end bL:+(/: else |<8g 2A{X isnorm = false; -&y&b- end }6__E;h#J #LYx;[D6 3=Xvl 58k %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% ~vZ1.y4 % Compute the Zernike Polynomials 0KZsWlD:L %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% {!4ZRNy(k 'F1<m^ Ac>GF % Determine the required powers of r: P6'0:M@5 % ----------------------------------- `1
Tg8 m_abs = abs(m); )qWO}]F rpowers = []; 4tt=u]: for j = 1:length(n) {X\FS rpowers = [rpowers m_abs(j):2:n(j)]; V2 }.X+u&< end '
b,zE[Q rpowers = unique(rpowers); X=k|SayE8 ~c=*Y=)LG
-,"eN}P^ % Pre-compute the values of r raised to the required powers, Je#3 % and compile them in a matrix: tgrZs8? % ----------------------------- 4Gh%PUV# if rpowers(1)==0 K!G/iz9SB rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); 7ws[Rp8 rpowern = cat(2,rpowern{:}); ;Ac!"_N?7 rpowern = [ones(length_r,1) rpowern]; ub{Yg5{3S\ else Nu}Zsb|{ rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); i:^
8zW rpowern = cat(2,rpowern{:}); <
$rXQ end ( 2KopL Ed"p|5~ .18MMzdN % Compute the values of the polynomials: tH4+S?PI % -------------------------------------- {<Vw55)#0Q y = zeros(length_r,length(n)); 8rjiW# for j = 1:length(n) lHgmljn5u s = 0:(n(j)-m_abs(j))/2; _4t pows = n(j):-2:m_abs(j); Znh<r[p< for k = length(s):-1:1 DM !B@ p = (1-2*mod(s(k),2))* ... YR~)07 prod(2:(n(j)-s(k)))/ ... RM`iOV,Y prod(2:s(k))/ ... OxVe}Fym prod(2:((n(j)-m_abs(j))/2-s(k)))/ ... *2I@_b6& prod(2:((n(j)+m_abs(j))/2-s(k))); n\4sNoFI idx = (pows(k)==rpowers); i"y @Aj!7 y(:,j) = y(:,j) + p*rpowern(:,idx); eq36mIo end /.@"wAw: gs= (h* if isnorm 2o`L^^ y(:,j) = y(:,j)*sqrt((1+(m(j)~=0))*(n(j)+1)/pi); 5SHZRF(. 2 end h\OMWJ~ end
qmGLc~M0 % END: Compute the Zernike Polynomials "[\TL#/ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% HS
1zA <SNu`,/I p!~V@l % Compute the Zernike functions: ywbdV-t/ % ------------------------------ lyyRyFfQ idx_pos = m>0; 0\yA6`}! idx_neg = m<0; kR;Hb3hb (%iCP/E3 ' u4TI=[6 z = y; -|&&lxrwh if any(idx_pos) QetyuhS~ z(:,idx_pos) = y(:,idx_pos).*sin(theta*m(idx_pos)'); Ouc$M2m0! end .0'FW!;FV if any(idx_neg) @L5s.]vg= z(:,idx_neg) = y(:,idx_neg).*cos(theta*m(idx_neg)'); 'C<4{agS end `-82u :" W v!%'IB j.7BoV % EOF zernfun D1f}g
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