x,y coordinate transformation when image is rotated by 90 degrees

[manit]

i have 512x512 image whose SIFT descriptors I had found.
Now i rotated image by 90 degree using
convert src.jpg -rotate 90 dest.jpg
what will be new coordinates of point x,y of src.jpg ?
I require this so that I can see SIFT descriptor change between correspondences in src.jpg and dest.jpg .

Thanks.

[snibgo]

If we rotate an image of height (h) 90 degrees clockwise, a pixel that was at (x,y) will be in new location (x',y') where:

x' = h - 1 - y
y' = x

[manit]

okay.
Thanks.

[manit]

verified it.
it works.