Using imregister and imregtform to stitch overlapping images

I'm trying to stich together two tiled images that have 15% overlap. Using imregister on the overlap sections, I get a good registration of those overlap sections, but when I multiply the whole image by the tform from imregtform, I don't get a translation.

In figure 3, I'm showing the pair of images before registration, figure 5 after registration, and then in figure 8, I'm using the tform I get from imregtform to 'warp' (in this case translate) the image. I can't figure out why in my figure 8, the image isn't registering properly. It also doesn't register if I multiply the overlap region from the moving image by the tform.

If anyone has any ideas, I'm sure it's something easy that I've been dancing around.

Thanks!

[optimizer, metric] = imregconfig('monomodal')

tform = imregtform(moving, fixed, 'translation', optimizer, metric);

movingRegistered = imregister(moving, fixed, 'translation', optimizer, metric);
moved = imwarp(moving, tform); %make the moved image

big_moved = imwarp(scaled_f2, tform);
%%

figure(3)
imshowpair(fixed, moving,'Scaling','joint')

figure(5)
imshowpair(fixed, movingRegistered)

figure(8)
imshowpair(fixed, big_moved)

[Andrea Jacobson]

Hi! Did you ever figure out what your problem was with the image registeration? If so, can you share some of your scripts for this? I am trying to do some 3D image stiching and need help.

[Todd Fallesen]

Hi Andrea, in the end I pulled the x and y distances out of the matrix, here's a function I made for it. Keep in mind, this is an old copy I have on my laptop, and you probably don't want to do what I did here and put in hard coded limits for images :-)

function [translate_distance] = Find_Translation_distance(image_1, image_2, direction, x_dim_tile, y_dim_tile, overlap)

switch direction

case 'x'

leeway = overlap*0.1*x_dim_tile; %the amount we let it move max

overlap_coord = round(x_dim_tile*overlap); %define the nominal overlap section in x

%generate the overlap sections to align

fixed = image_1(:,end-overlap_coord:end);

moving = image_2(:,1:overlap_coord); %move the second image over the first

[optimizer, metric] = imregconfig('monomodal');

tform = imregtform(moving, fixed, 'translation', optimizer, metric); %set up the image translation metric

tform.T;

x_trans = [1 0 1]*tform.T; %matrix multiplication to pull out the transformation matrix

x_trans = overlap_coord - x_trans(1);

if x_trans < 1

x_trans = 1; %how many pixels we're moving in x

end

if x_trans > 249.5235 || x_trans < 182.9617

x_trans = 216.2426; %give a hard set on the max number of pixels we can move.

disp('Hit offset max');

end

translate_distance = x_trans;

x_disp = strcat('x translate distance is: ',num2str(translate_distance));

disp(x_disp);

case 'y'

leeway = overlap*0.1*y_dim_tile; %the amount we let it move max

overlap_coord = (y_dim_tile*overlap); %define the nominal overlap section in y

%generate the overlap sections to align

fixed = image_1(end-overlap_coord:end,:);

moving = image_2(1:overlap_coord,:); %move the second image over the first

[optimizer, metric] = imregconfig('monomodal');

tform = imregtform(moving, fixed, 'translation', optimizer, metric); %set up the image translation metric

tform.T;

y_trans = [0 1 1]*tform.T;

y_trans = overlap_coord - y_trans(1); %how many pixels we're moving in y

if y_trans > 249.5235 || y_trans < 182.9617

y_trans = 216.2426; %give a hard set on the max number of pixels we can move.

disp('Hit offset max');

end

translate_distance = y_trans;

y_disp = strcat('y translate distance is: ',num2str(translate_distance));

disp(y_disp);

end

end