Fully trend preserving operators
The concept of fully trend preserving (ftp) operators on sequences was introduced to prove variation preservation on the outputs of LULU-separators. It turns out that this property is central in further analysis of compositions of LULU-smoothers, and other smoothers. Several important results follow, amongst them the co-idempotence of a large class of smoothers. This has been an unresolved problem up to now. © 2004 NISC Pty Ltd.