www.pudn.com > 2D_phasc_unwrapping_algorithms.zip > PhaseResidues.m, change:2008-12-22,size:1938b


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
% PhaseResidues.m calculates the phase residues for a given wrapped phase 
% image. Note that by convention the positions of the phase residues are  
% marked on the top left corner of the 2 by 2 regions. 
% 
%   active---res4---right 
%      |              | 
%     res1           res3 
%      |              | 
%   below---res2---belowright 
% Phase residues with integer multiples of 2*pi are not accounted for, but  
% these rarely occur. 
% Created by B.S. Spottiswoode on 07/10/2004 
% Last modified on 08/10/2004 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
function residue_charge=PhaseResidues(IM_phase, IM_mask); 
 
[rows, cols]=size(IM_phase); 
 
%The code below is simply a vectorised representation of operations on 2 by 2 
%blocks in the matrix 
IM_active=IM_phase; 
IM_below=zeros(rows,cols); 
IM_below(1:rows-1,:)=IM_phase(2:rows,:); 
IM_right=zeros(rows,cols); 
IM_right(:,1:cols-1)=IM_phase(:,2:cols); 
IM_belowright=zeros(rows,cols); 
IM_belowright(1:rows-1,1:cols-1)=IM_phase(2:rows,2:cols); 
 
res1=mod(IM_active - IM_below + pi, 2*pi) - pi;          %Wrap the phase differences as we loop around the 2 by 2 blocks 
res2=mod(IM_below - IM_belowright + pi, 2*pi) - pi; 
res3=mod(IM_belowright - IM_right + pi, 2*pi) - pi; 
res4=mod(IM_right - IM_active + pi, 2*pi) - pi; 
 
temp_residues=res1+res2+res3+res4;              %Sum the phase differences. Positive residues appear as 2*pi, negative as -2*pi. 
residues=(temp_residues>=6);                    %Assign 1 to positive residue (which should equal 2*pi) 
residues=residues - (temp_residues<=-6);        %Assign -1 to negative residues (which should equal -2*pi) 
residues(:,cols)=0; residues(rows,:)=0;         %Zero pad the border residues 
residues(:,1)=0; residues(1,:)=0;  
residue_charge=residues; 
 
residue_sum=sum(sum(abs(residues)));