Input device configurations are described. The method includes receiving interaction with a user interface resulting in user selection of viewing attributes for a document, the viewing attributes including a zoom level and a position of the document on the user interface, the viewing attributes together defining a view of the document visible on the user interface. The invention in turn may reduce computational complexity of certain coding and decoding operations by two orders of magnitude or more for a given signal vector input. Systems and machine-readable media are also provided. It is whereby possible to flexibly accommodate changes in number of channels combined in a WDM system, and to adaptively minimize ASE light leaking into the photoreceptor of the optical receiver even in a CWDM system with wide channel spacing.