光学干涉成像是一种无透镜成像技术,它利用光波的干涉特性来重建被测物体的图像。与传统的透镜成像技术相比,光学干涉成像具有许多优点,例如成像分辨率高、成像速度快、成像成本低等。然而,光学干涉成像也存在一些挑战,例如成像过程中的相位噪声和散斑噪声等。
为了解决这些挑战,近年来,非凸优化方法在光学干涉成像领域得到了广泛的应用。非凸优化方法能够有效地处理相位噪声和散斑噪声,从而提高光学干涉成像的图像质量。
非凸优化方法在光学干涉成像中的应用主要体现在以下几个方面:
function [M_s, M_s_conj, M_s_zero, M_s_large, M1, M2, M3, M_p,count] = ... create_mask_freq_selection_power_bi(Ti,n,m,M_b,u_lf,seed,c)% c : vector position of 0 freq% u_lf : low frequency proprotion in bispectrumcount = 0;Ti = Ti(1:end-1,:) ;[mask_ind,M_p] = generate_idx_mask(n,m, unique(Ti(:)) ) ;mask = zeros(n*m,1) ;mask(mask_ind) = 1 ;M_s_large = reshape(mask,n,m) ;% figure, imagesc(M_s_large)M_s = zeros(n,m) ;M_s(:, 1:m/2) = M_s_large(:, 1:m/2) ;M_s(1:n/2+1, m/2+1) = M_s_large(1:n/2+1, m/2+1) ;% % % figure, imagesc(M_s)M_s_conj = zeros(n,m) ;M_s_conj(:, m/2+2:end) = M_s_large(:, m/2+2:end) ;M_s_conj(n/2+1:end, m/2+1) = M_s_large(n/2+1:end, m/2+1) ;% % % figure, imagesc(M_s_conj)M_s_large(n/2+1, m/2+1) = 1 ;M_s_zero = zeros(n,m) ;M_s_zero(n/2+1, m/2+1) = 1 ;M_s = logical(M_s) ;M_s_conj = logical(M_s_conj) ;M_s_zero = logical(M_s_zero) ;% select bispectra -------------------------------------------------------T = zeros(M_b,3) ;i0 = 1 ;% select bispectra from low freq.M_hf = floor(u_lf*n*m) ;if M_hf < 2*M_p[ ~, Tib ] = mask_1D_select_freq( n,m,u_lf, 1/20, seed, c ) ;Tib = Tib(1:end-1,:) ;mask_ind_hf = generate_idx_mask(n,m, unique(Tib(:)) ) ;mask_ind_hf = intersect(mask_ind_hf, mask_ind) ;mask_hf = zeros(n*m,1) ;mask_hf(mask_ind_hf) = 1 ;M_hf = max(size(mask_ind_hf)) ;while 1Idx = randperm(M_hf) ;for j =1:length(Idx)-2idx = Idx(j:j+2) ;idx = sort(mask_ind_hf(idx))' ;if idx(1)~=c && idx(2)~=c && idx(3)~=cif sum(ismember(idx,T,'rows')) == 0 if ~(nnz(find(idx(1) == T)) && nnz(find(idx(2) == T)) && nnz(find(idx(3) == T))) count = count + 1;endT(i0,:) = idx ;i0 = i0+1 ;endendif i0>floor(0.9*M_b) breakendendif i0>floor(0.9*M_b) breakendendend% select remaining bispectrafor i = i0:M_bidx = [c,c,c] ;while idx(1)==c || idx(2)==c || idx(3)==cwhile 1idx = sort(randperm(M_p*2,3)) ;idx = mask_ind(idx)' ;if sum(ismember(idx,T,'rows')) == 0 breakendendendif ~(nnz(find(idx(1) == T)) && nnz(find(idx(2) == T)) && nnz(find(idx(3) == T))) count = count + 1;endT(i,:) = idx ;end% build vectors of indices for bispectrum ---------------------------------M1 = 0*T(:,1) ;M2 = 0*T(:,2) ;M3 = 0*T(:,3) ;for i =1:M_bM1(i) = sum(mask(1:T(i,1))) ;M2(i) = sum(mask(1:T(i,2))) ;M3(i) = sum(mask(1:T(i,3))) ;endendfunction [mask_ind,M_p] = generate_idx_mask(n,m, mask_ind_inf )% frequency space sampling: symmetrymask = zeros(n*m,1) ;mask(mask_ind_inf) = 1 ;mask = reshape(mask,n,m) ;Mask = zeros(n+1,m+1) ;Mask(1:end-1,1:end-1) = mask ;Mask = fliplr(flipud(Mask)) ;mask = Mask(1:end-1,1:end-1) ;% % % figure, imagesc(mask)mask = mask(:) ;mask_ind_sup = find(mask==1) ;% frequency space samplingmask_ind = [mask_ind_inf;mask_ind_sup] ;% number of powerspectraM_p = length(mask_ind_inf) ;end
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非凸优化方法在光学干涉成像中的应用也面临着一些挑战,例如:
非凸优化方法在光学干涉成像领域得到了广泛的应用,并且取得了很好的效果。然而,非凸优化方法在实际应用中也面临着一些挑战。随着研究的深入,这些挑战有望得到解决,从而进一步提高光学干涉成像的图像质量。
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