is there a bug in imregcorr-function for transformtype "rigid" ?

I have tried some examples where imregcorr does not give the wanted result for the transformtype "rigid" , for the same examples I obtain the correct result when using "similarity" .

Here is one example :

I1 = imread('...\cameraman.tif');

FIXED = im2double(I1);

MOVING = imrotate(I1,125);

fixedRefObj = imref2d(size(FIXED));

movingRefObj = imref2d(size(MOVING));

tform = imregcorr(MOVING,movingRefObj,FIXED,fixedRefObj,'transformtype','rigid','Window',true);

MOVINGREG.RegisteredImage = imwarp(MOVING, movingRefObj, tform, 'OutputView', fixedRefObj,'interp','cubic', 'SmoothEdges', true);

imshow(MOVINGREG.RegisteredImage) giving the following output image :

This is far away from the original cameraman image, which was rotated 125 degrees counterclockwise

[Eirik Kvernevik]

I have found problems for the "rigid" transformtype for a multiple og angles : a bunch of angles between 21 and 87 degrees , and a bunch between 133 and 239 degrees is what I have found so far.

there also seems to be a problem with the "similarity" type for 88, 89, 268 and 269 degrees . Would be interesting if anyone else have problems with this or if someone have a solution to this ?

Answer 1

[Steve Eddins]

As of R2024b, the function imregcorr uses a new algorithm called normalized gradient correlation. See my 16-Oct-2025 blog post for more information. The function can now register images successfully.

fixed_image = imread("cameraman.tif");
moving_image = imrotate(fixed_image, 125);
tiledlayout(1,2)
nexttile
imshow(fixed_image), title("fixed image")
nexttile
imshow(moving_image), title("moving image")

tform = imregcorr(moving_image, fixed_image)

tform = 
  simtform2d with properties:

    Dimensionality: 2
             Scale: 1.0001
     RotationAngle: 124.9967
       Translation: [377.8203 84.5295]
                 R: [2×2 double]

                 A: [-0.5736   -0.8193  377.8203
                      0.8193   -0.5736   84.5295
                           0         0    1.0000]

[moving_image_reg,moving_reg_ref] = imwarp(moving_image, imref2d(size(moving_image)), tform);
clf
imshowpair(fixed_image,imref2d(size(fixed_image)),moving_image_reg,moving_reg_ref)