How to rotate an image by applying rotational matrix

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tabw
tabw on 12 Oct 2014
Commented: Matt J on 14 Oct 2014
I guess rotating 3D image is same as rotating 2D image,right? for example, I have a 240x 240 2D image
R = [0 -1;-1 0]; % rotate 90 degree
Image = imread('pout.tif') % built-in image
Image = Image (1:240,1:240);
Image = reshape(Image , (240*240)/2, 2) * R;
Processed_image = reshape (Image,240,240);
However, It did not work.
Anyone help me?

Answers (1)

Matt J
Matt J on 12 Oct 2014
Edited: Matt J on 12 Oct 2014
You can use imrotate to rotate a 2D image, or a 3D stack of 2D images slice-by-slice.
Multiplying the rotation matrix by the pixel values would not be appropriate. The matrix needs to be multiplied with pixel coordinates. Then you have to interpolate the pixel values at the rotated coordinates, as imrotate or imtransform do for you internally.
  4 Comments
Matt J
Matt J on 14 Oct 2014
As it says in the documentation, A must be either 4x3 or 4x4. What is the dimension of your A matrix?

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