I would like to find the point that are "not interpolated" when I rotate an image with e.g. Matlab's imrotate() by an angle which require interpolation e.g. 6 degrees, i.e. not a multiple of 90 degrees.
In other words, I would like to perform rotation by an arbitrary angle but WITHOUT any interpolation. (i.e., I expect to find "holes'' where the fractional coordinates are computed by the multiplication with the rotation matrix.)
The idea I had was to use the points which would be mapped to an integer coordinate after rotation by the rotation matrix [cos(t) -sin(t);sin(t) cos(t)] but that does not seem to work since there is always some approximation error in a numerical analysis oriented language like Matlab, but in computers in general of course.