rotate image

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Junaid
Junaid 2012-3-2
Dear all,
Let say I have patch P and I want to rotate it in the direction of angle T (in degrees). Rotation should be similar to This rather This.
Rotation should be in plane, not like
imrotate(P, T)

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回答（2 个）

Jan
Jan 2012-3-2
What is the difference between the two shown picture sets? Are you looking for the 'crop' method?
B = imrotate(P, T, 'nearest', 'crop')
See: help imrotate.
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Junaid
Junaid 2012-3-4
Hi Jan Simon,
Thanks for your reply. Actually I want to rotate the patch in the direction of dominant gradient (similar to SIFT). As when it is rotated in the direction of 45 degree then we see many blank part. But in image when image is rotated such that there is no blank space. Either it is in plane rotation or pixel by pixel rotation. How could I rotate like that ?
Jan
Jan 2012-3-4
I do not understand. It is still not clear, what you want to achieve and what is the difference between the two posted pictures. Why is the result of "imrotate('crop')" not satisfying?

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Image Analyst
Image Analyst 2012-3-2
Junaid, there is additional information that is not being shown. Even the 0 degree image was cropped out of a larger image. How do I know that? Well look at the "good" 45 degree rotation. Do you see that black and white "ball" structure in the upper left corner? Well, it was not there at all in the zero degree image. That means it "got rotated in" from some region unseen (i.e. outside) the zero degree image. To get this "good" image, you'll have to start with the full image.
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Junaid
Junaid 2012-3-4
Hi Image Analyst,
I mean to rotate a small patch in image such that there is no blank space when image is rotate. As using imrotate function there remains blank space as shown in Figures.
or there is any other way to rotate patch in dominant gradient (similarly like SIFT).
Image Analyst
Image Analyst 2012-3-4
That's impossible. As you rotate a rectangle, if it's going to be on a rectangular canvass, then there will be some area that was previously not shown. Something has to be there, usually a uniform gray level such as black. The only other option would be to crop such that no black appears but you'd be cutting off some of your image. Like I said the way that your web site did it was to rotate a larger image and then crop down.

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