Images and rotation angles

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Lluis Roca
Lluis Roca on 20 Apr 2013
Hola,
I have a theoretical question as I'm looking for ideas how to solve my current image analysis problem (a field which I am not an expert).
The problem is: I have 40 images of different types of drinking bottles in various rotation angles. Therefore, I am looking for a way how to automate the rotation process so all of them will have the same angle (neck up, base down), any idea how to solve it?
Thank you.

Accepted Answer

Image Analyst
Image Analyst on 20 Apr 2013
Basically you first need to find the bottle, by thresholding or whatever. Then you need to run regionprops and look for the orientation - that will tell you the angle - and the Centroid and MajorAxisLength. It will fit an ellipse to the bottle. Look at the location of the midpoint of the MajorAxis. It will be closer to one end (thick or thin - I'm not sure) of the bottle than the Centroid will be. So, knowing that you'll be able to rotate it so the thick end is down.
Please upload some of your images, including the binary images showing the detected bottle mask.
  4 Comments
Lluis Roca
Lluis Roca on 25 Apr 2013
Hola,
Thanks for the script. I will look in to it.
Gracias
Alex Taylor
Alex Taylor on 25 Apr 2013
Lluis,
Anyway you can post a few of the original, non-segmented images that you are interested in?
Thanks,
Alex.

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More Answers (1)

Anand
Anand on 21 Apr 2013
Another option is to register the images using imregister. If you know that the only deformation between the images is the rotation, you can use the 'rigid' transformation type. If there is a scale change involved, you should use the 'similarity' transformation type.
Here's a small example of how to use this:
% read in a test image
im = imread('cameraman.tif');
% rotate it to create another test image
imRot = imrotate(im,45);
figure; imshowpair(im,imRot,'montage');title('before registration');
% setup intensity-based image registration
[optimizer,metric] = imregconfig('monomodal');
% register imRot with im so that cameraman is upright
imReg = imregister(imRot, im, 'rigid', optimizer, metric);
figure; imshowpair(im,imReg,'montage');title('after registration');

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