# How to rotate a line about center point??

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Heera Bhadrecha on 20 Oct 2014
Commented: Image Analyst on 22 Oct 2014
I have an image i want to rotate line between two point by center point .
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Image Analyst on 22 Oct 2014
It's not clear to me. Post an image (screenshot) showing the image, the "center point" and the line. Then explain if you just want to "rotate line" (rotate the line itself and not the image) like you said, or if you want to rotate the image . And what does "between two point" mean? Do you mean a line segment where the line is defined just as going between one point and another point rather than off to infinity in both directions? And that line rotates around the "center point"? And is that "center point" the center point of the whole image, or the center point of the line segment?

Mohammad Abouali on 21 Oct 2014
Let's say you want to rotate around and arbitrary points designated by (ro,co);
Here how you can do it:
% Top left corner as center of rotation
ro=1;
co=1;
[r,c,nB]=size(I);
I2=zeros(2*r,2*c,nB,'like', I);
I2(r-ro+1:2*r-ro,c-co+1:2*c-co,:)=I;
Irotated=imrotate(I2,45);

### More Answers (2)

michael scheinfeild on 20 Oct 2014
use imrotate or calculate the affine transform
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Heera Bhadrecha on 21 Oct 2014
but i have a center point ,left top and right top point.i want to line rotate a line between left top and right top.

Heera Bhadrecha on 21 Oct 2014
Thanks How to calculate the angle between two line when one line is rotating???
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Mohammad Abouali on 22 Oct 2014
use dot (inner) product