The region parameter defines the rectangular portion of the
full image to be returned. Region can be specified by pixel coordinates,
percentage or by the value “full”, which specifies that the entire image
should be returned.
The rotation parameter specifies mirroring and rotation. A leading exclamation mark (“!”) indicates that the image should be mirrored by reflection on the vertical axis before any rotation is applied. The numerical value represents the number of degrees of clockwise rotation, and may be any floating point number from 0 to 360.