...rotated.
Even when the data are sufficiently sampled, the conventional rotation algorithms implemented in the standard astronomical image processing packages are generally inadequate, since they are not faithful to the data. An algorithm is called ``faithful'' here if it preserves the information content (in particular, the high spatial frequency spectrum) of the data. Every faithful operator has an inverse operator.

...values
This simple and efficient heuristic algorithm can be (and has been) criticized for violating the first principle of data analysis ``Don't modify the data.'' However, this criticism can be rebutted, because bad pixels never attain the same status as good ones.

rlw@sundog.stsci.edu
Fri Apr 15 15:48:04 EDT 1994