warpprojective2.m

图像配准的源程序

function result = warpProjective2(im,A)
%
% function result = warpProjective2(im,A)
%
% im: input image
% A: 2x3 affine transform matrix or a 3x3 matrix with [0 0 1]
% for the last row.
% if a transformed point is outside of the volume, NaN is used
%
% result: output image, same size as im
%

% if (size(A,1)>2)
%   A=A(1:2,:);
% end

% Compute coordinates corresponding to input 
% and transformed coordinates for result
[x,y]=meshgrid(1:size(im,2),1:size(im,1));
coords=[x(:)'; y(:)'];
homogeneousCoords=[coords; ones(1,prod(size(im)))];
warpedCoords=A*homogeneousCoords;
xprime=warpedCoords(1,:)./warpedCoords(3,:);
yprime=warpedCoords(2,:)./warpedCoords(3,:);

result = interp2(x,y,im,xprime,yprime, 'linear');
result = reshape(result,size(im));

return;