image - find the angle between two very similar pictures in matlab -

hi find angle between 2 similar(but not same) pictures ?

used

hvideosrc = vision.videofilereader(filename, 'imagecolorspace', 'intensity');  imga = step(hvideosrc); % read first frame imga imgb = step(hvideosrc); % read second frame imgb      figure; imshowpair(imga, imgb, 'montage');     title(['frame a', repmat(' ',[1 70]), 'frame b']); figure; imshowpair(imga,imgb,'colorchannels','red-cyan'); title('color composite (frame = red, frame b = cyan)'); 

from http://www.mathworks.com/help/vision/examples/video-stabilization-using-point-feature-matching.html not have idia

i'd recommend doing sort of feature detection using find homography matrix. might overkill @ least you'll able not find rotation 1 image respect another, shearing or translation well.

check feature detection module part of computer vision toolbox detecting keypoints: http://www.mathworks.com/help/vision/feature-detection-extraction-and-matching.html

once find pairs of corresponding points, take @ rebuilding homography matrix required morph 1 image another. these slides awesome: http://www.comp.nus.edu.sg/~cs4243/lecture/camera.pdf . @ slides 29 - 35.

once find homography matrix can determine angle of rotation examining coefficients , applying inverse trigonometric operation.

edit (april 7th, 2014): couldn't find actual matlab example, link dima (thanks!) shows worked out matlab example through mathworks (http://www.mathworks.com/help/vision/examples/find-image-rotation-and-scale-using-automated-feature-matching.html).