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, !0ly1T 9 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, TU ]Ed*'& 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? a<X8l^Ln 那些系数是通过对29525*10阶的矩阵每列的值算出来的嘛? 49f- u H /Idc,* %bI( '\%c"? `5 py6, function z = zernfun(n,m,r,theta,nflag) (IXiwu %ZERNFUN Zernike functions of order N and frequency M on the unit circle. qW]gp7jK4 % Z = ZERNFUN(N,M,R,THETA) returns the Zernike functions of order N p:M#F: % and angular frequency M, evaluated at positions (R,THETA) on the x_9<&Aj6 % unit circle. N is a vector of positive integers (including 0), and nb(4"|8} % M is a vector with the same number of elements as N. Each element =! v.VF\; % k of M must be a positive integer, with possible values M(k) = -N(k) ?wE@9g A % to +N(k) in steps of 2. R is a vector of numbers between 0 and 1, =PHl|^ % and THETA is a vector of angles. R and THETA must have the same "8K>Yu17 % length. The output Z is a matrix with one column for every (N,M) VM{`CJ2 % pair, and one row for every (R,THETA) pair. vQrce& % 1xK'1g72 % Z = ZERNFUN(N,M,R,THETA,'norm') returns the normalized Zernike xsK{nM6g % functions. The normalization factor sqrt((2-delta(m,0))*(n+1)/pi), TJ(P TB; % with delta(m,0) the Kronecker delta, is chosen so that the integral "%~\kJ(G % of (r * [Znm(r,theta)]^2) over the unit circle (from r=0 to r=1, V~LZ%NZ8 % and theta=0 to theta=2*pi) is unity. For the non-normalized &pwSd % polynomials, max(Znm(r=1,theta))=1 for all [n,m]. $iQ>c6 % t}-[^|)7 % The Zernike functions are an orthogonal basis on the unit circle. yu"Ii-9z % They are used in disciplines such as astronomy, optics, and lhg3
}dW % optometry to describe functions on a circular domain. tf64<j6 % :0o
$qz2 % The following table lists the first 15 Zernike functions. #1R_*
Uh % &{QB}r % n m Zernike function Normalization n<MMO=+bg % -------------------------------------------------- )
Kfk\ % 0 0 1 1 ~`2w
ul % 1 1 r * cos(theta) 2 f uojf+i % 1 -1 r * sin(theta) 2 Vzy]N6QT{ % 2 -2 r^2 * cos(2*theta) sqrt(6) :QgC Zq % 2 0 (2*r^2 - 1) sqrt(3) 3{_A zL % 2 2 r^2 * sin(2*theta) sqrt(6) PpMZ-f@ % 3 -3 r^3 * cos(3*theta) sqrt(8) 8>x.zO_.c> % 3 -1 (3*r^3 - 2*r) * cos(theta) sqrt(8) 2=ZR}8}9Q: % 3 1 (3*r^3 - 2*r) * sin(theta) sqrt(8) Rde_I`Ru % 3 3 r^3 * sin(3*theta) sqrt(8) J*6I@_{/U % 4 -4 r^4 * cos(4*theta) sqrt(10) Ab7hW(/ % 4 -2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) T#Pz_
hAu % 4 0 6*r^4 - 6*r^2 + 1 sqrt(5) }]vj"!?a % 4 2 (4*r^4 - 3*r^2) * cos(2*theta) sqrt(10) O;M_?^'W % 4 4 r^4 * sin(4*theta) sqrt(10) KsYT3 % -------------------------------------------------- IV^LYu % FtN1ZZ"<* % Example 1: j)\g0u6 % O<4i)Lx2 % % Display the Zernike function Z(n=5,m=1) .jMm-vox} % x = -1:0.01:1; _dqjRhu % [X,Y] = meshgrid(x,x); `XYT:' % [theta,r] = cart2pol(X,Y); #1Mk9sxo % idx = r<=1; cJA0$)JP& % z = nan(size(X)); qx
3.oU % z(idx) = zernfun(5,1,r(idx),theta(idx)); :b>Z|7g ? % figure /Nq!^= % pcolor(x,x,z), shading interp ?97MW a % axis square, colorbar _yjM_ALjo % title('Zernike function Z_5^1(r,\theta)') (Br$(XJoK} % Orh5d7+S % Example 2: &n<jpMB % ]SrKe-*:U % % Display the first 10 Zernike functions IcL3.(!]l % x = -1:0.01:1; Td[w<m+p<P % [X,Y] = meshgrid(x,x); qt]QO1pAd % [theta,r] = cart2pol(X,Y); +C;ZO6%w % idx = r<=1; fEs957$ % z = nan(size(X)); 5!#"8|oY % n = [0 1 1 2 2 2 3 3 3 3]; )xQxc. % m = [0 -1 1 -2 0 2 -3 -1 1 3]; J'9&dt % Nplot = [4 10 12 16 18 20 22 24 26 28]; GQqw(2Ub} % y = zernfun(n,m,r(idx),theta(idx)); xy mK| % figure('Units','normalized') |}Mkn4 % for k = 1:10 $Br^c< y % z(idx) = y(:,k); x+B~ t4A % subplot(4,7,Nplot(k)) N=D
Ynz_~ % pcolor(x,x,z), shading interp :'y % set(gca,'XTick',[],'YTick',[]) @usQ*k % axis square ]+0-$t7Y % title(['Z_{' num2str(n(k)) '}^{' num2str(m(k)) '}']) y NV$IN% % end PL~k
`L % Oi
BK % See also ZERNPOL, ZERNFUN2. t)XV'J L:Wy- Z 1@)]+* F*z % Paul Fricker 11/13/2006 ]p'Qk CcY.8|HT } Q1$v~ v{
C]\8 uNd ;;X % Check and prepare the inputs: p5F[( H|9 % ----------------------------- vCH>Fj"7 if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) 9Z*` { error('zernfun:NMvectors','N and M must be vectors.') H'gPGOd end *XH?|SV |D]jdd@!a2 Jr17pu(t if length(n)~=length(m) aS~k.^N error('zernfun:NMlength','N and M must be the same length.') KXw
\N! end tB(Q-c tHoFnPd\| m.K"IXD n = n(:); Rp`}"x9 m = m(:); @Jvw"= if any(mod(n-m,2)) @TgCI`E error('zernfun:NMmultiplesof2', ... 9q* sR1 'All N and M must differ by multiples of 2 (including 0).') }QJE9;<e end Y2<#%@%4 aF'Ik XG d J=zZGd% if any(m>n) nWXI*%m5 error('zernfun:MlessthanN', ... K:'pK1zy 'Each M must be less than or equal to its corresponding N.') |lJXI:GG end =Rb, `% 00;=6q]TA $6y1';A if any( r>1 | r<0 ) ;uoH+`pf error('zernfun:Rlessthan1','All R must be between 0 and 1.') ][G<CO`k end ybS7uo ~-M7 c"O\fX if ( ~any(size(r)==1) ) || ( ~any(size(theta)==1) ) |{9"n<JW error('zernfun:RTHvector','R and THETA must be vectors.') O)9T|,
U end @Wx_4LOhf a S<JsB Z]SCIU @+ r = r(:); HwU \[f theta = theta(:); QyHUuG|g length_r = length(r); + !_^MB kk if length_r~=length(theta) /o|@]SAe. error('zernfun:RTHlength', ... XLmbpEh 'The number of R- and THETA-values must be equal.') j,1,; end v11mu2 PI{sO | a[(n91J0 % Check normalization: '|FM|0~-J % -------------------- 3[V|C=u0 if nargin==5 && ischar(nflag) @F,HyCSN isnorm = strcmpi(nflag,'norm'); 'kh%^_FH7 if ~isnorm L\-T[w),z7 error('zernfun:normalization','Unrecognized normalization flag.') Qy6Avw/$ end #Jm_~k else CS"p[-0 isnorm = false; ^2mXXAQf7^ end QGLm4 Wl9 Z&.FJZUP "\>3mVOb %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% x &9I2" % Compute the Zernike Polynomials &rNXn?>b %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% $iP#8La:Y *g=*}2 Q]|+Y0y}X % Determine the required powers of r: y!v $5wi % ----------------------------------- mB1)! m_abs = abs(m); MiSFT5$v6 rpowers = []; 9s7B1Pf for j = 1:length(n) \DQ; v rpowers = [rpowers m_abs(j):2:n(j)]; tXp)o>" end KX9ZwsC0 rpowers = unique(rpowers); |/<iydP Wc]Fg9E \\/X+4|o' % Pre-compute the values of r raised to the required powers, gf3/ kll9 % and compile them in a matrix: 1i>)@{P&BN % ----------------------------- S((8DSt* if rpowers(1)==0 ?&X6VNbU rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); pixI&iQ rpowern = cat(2,rpowern{:}); "^trHh8= rpowern = [ones(length_r,1) rpowern]; HFDg@@ else nB:Bw8U"Q rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); b#y}VY)? rpowern = cat(2,rpowern{:}); qh&K{r*T end ~cZ1=,P []Fy[G.)H R-h7c!ko % Compute the values of the polynomials: 3 $kZu % -------------------------------------- 'rF TtT
y = zeros(length_r,length(n)); L`Ic0}|lzy for j = 1:length(n) A5/h*`Q\\ s = 0:(n(j)-m_abs(j))/2; -!}1{ pows = n(j):-2:m_abs(j); <y'ttxeS for k = length(s):-1:1 |aVv Lz p = (1-2*mod(s(k),2))* ... u(~s$ENl prod(2:(n(j)-s(k)))/ ... Ec[:6} prod(2:s(k))/ ... xp&I~YPH prod(2:((n(j)-m_abs(j))/2-s(k)))/ ... xj~6,;83xR prod(2:((n(j)+m_abs(j))/2-s(k))); qMUqd}=P idx = (pows(k)==rpowers); w%ip"GT, y(:,j) = y(:,j) + p*rpowern(:,idx); B#gmT2L end "*T)L<G },"g* if isnorm 1rKR=To y(:,j) = y(:,j)*sqrt((1+(m(j)~=0))*(n(j)+1)/pi); asJYGqdF end e-s@@k
end NKGCz|-
9 % END: Compute the Zernike Polynomials Hv=coS>g: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% vd;wQ 81n%2G %sq=lW5R{b % Compute the Zernike functions: K)14v;@ % ------------------------------ 4-"wFp idx_pos = m>0; [L\w]6 idx_neg = m<0; O]Hg4">f '|cuVxcE55 BNByaC z = y; ^g0 Ig2' if any(idx_pos) ysa"f+/ z(:,idx_pos) = y(:,idx_pos).*sin(theta*m(idx_pos)'); u)V*o end }E=kfMu if any(idx_neg) J\%:jg( m z(:,idx_neg) = y(:,idx_neg).*cos(theta*m(idx_neg)'); e,x@?L* end 0N}5sF sDF J h}oQr0"c % EOF zernfun ::R^ w"
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