complement — Return the complement of a region.
complement determines the complement of the input region(s).
If the system flag 'clip_region' is 'true', which is the default, the difference of the largest image processed so far (see reset_obj_db) and the input region is returned.
If the system flag 'clip_region' is 'false' (see set_system), the resluting region would be infinitely large. To avoid this, the complement is done only virtually by setting the complement flag of Region to TRUE. For succeeding operations the de Morgan laws are applied while calculating results. Using complement with 'clip_region' set to 'false' makes sense only to avoid fringe effects, e.g., if the area of interest is bigger or smaller than the image. For the latter case, the clipping would be set explicitly. If there is no reason to use the operator with 'clip_region'='false' but you need the flag for other operations of your program, it is recommended to temporarilly set the system flag to'true' and change it back to 'false' after applying complement. Otherwise, negative regions may result from succeeding operations.
Number of elements: RegionComplement == Region
complement always returns the value 2 (H_MSG_TRUE). The behavior in case of empty input (no regions given) can be set via set_system('no_object_result',<Result>) and the behavior in case of an empty input region via set_system('empty_region_result',<Result>). If necessary, an exception is raised.
threshold, connection, regiongrowing, pouring, class_ndim_norm
difference, union1, union2, intersection, reset_obj_db, set_system