treat an image as a collection of points in 5 dimensions. 3 are color, 2 are positions.
then rotate the whole thing in 5 dimensions.
i think i already tried this, I don't remember how it came out.

another idea:
sum the squares of each component of each pixel. that's the image's distance from 'center'. now rotate the image around an n-dimensional sphere or pick random spots on it. n is width*height*3 (or *1 for a monotone)