rotate[/qualifiers]
This routine properly rotates sparse arrays such as X-ray images. In order to preserve the poissonian nature of the background a Monte Carlo redistribution of some events is carried out. The total number of photons is strictly conserved. This operation is however irreversible, that is, a rotation of +x degrees, followed by a rotation of -x degrees will produce an image that although closely resembles the original one, it is not identical. For this reason it is advisable to keep to a minimum the number of rotations performed on one image.
This qualifier can be used to specify the roll angle at which to rotate the image. The default angle is -90 00 00, corresponding to North up and East to the left. Degrees, minutes and seconds must be separated by commas.
Examples:
rotate/roll_angle=-20.1 ! Rotates the current image to a roll
! angle of 20.1 degrees