What is the significance of rotating an image?

[hot_ice]

Image rotation???

what is the significance of rotating an image??? how can it be done???
i know there is a built-in function ('imrotate()') in MATLAB... but
i'm not interested in doing it using built-in function... is it possible
to rotate an image uisng Fourier transform??? if yes, how??? or r there
any other possible ways to accopmlish the desired task???

 

[sjjg]

Image rotation???

hi,
You can use "edit imrotate" in matlab, then you can see the algorithm of rotate.
is it possible
to rotate an image uisng Fourier transform? i don't
think so.

 

[eternal_nan]

Image rotation???

Using an FFT to rotate an image would certainly be a huge waist of resources. Rotating an image is really easy. Imagine the image is represented by a 2d array image[][], rotating the image would basically amount to:

for (i=0;i<horiz_size;i++) {
for(j=0;j<vert_size;j++) {
rotated_image[j] = image[j];
}
}

 

[saeid5977]

Image rotation???

hi
use from rotation matrix and multiply it in all pixels of picture.
x2=x1*cos(a)+y1*sin(a)
y2=y1*cos(a)-x1*sin(a)

if u want to reach beter results u can use from interpolation for pixel color calculation.

Added after 35 seconds:

http://kwon3d.com/theory/transform/rot.html

Added after 7 minutes:

and for interpolation see:
http://www.cambridgeincolour.com/tutorials/image-interpolation.htm