# Rotate image about a specified pixel coordinate

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Philip on 29 Sep 2011
Does anyone know of a way to rotate an image about a specified pixel coordinate? If I have the pixel coordinates (50,55) for example, I would like the end result to be centred around (50,55)... So the centre pixel of the rotated image is equivalent to these coordinates.
I have tried imrotate, but cannot get it to rotate on a specified coordinate.

Rick Rosson on 29 Sep 2011
I think you can accomplish what you want by following a two-step process. First, rotate the image through the desired angle. I believe this will rotate the image about the origin. Then, translate the image by the desired amount in both directions.
HTH.
Rick
Walter Roberson on 29 Sep 2011
Shouldn't it be three-step? Translate the image so that (50,55) gets centered over (0,0), then do the rotation, and then translate back ?

Julien GANCE on 20 Jan 2012
I tried to use the imtransform function to do that but the part of the picture that is cropped during the first translation is lost so that when I translate back the picture, I get a black area on the final one. Do you have an idea on the function to use ?
Thanks
Julien
Image Analyst on 20 Jan 2012
Of course. You're going to have to figure out how large you need to make your canvass (prior to rotation) if you don't want any part of your image to be cropped. In other words, use padarray() to put a large margin of black around your image before rotating it so that the "good" part of your image will always lie within the output image.