Most filters let you select which properties and regions you want to filter. You can also apply filters to entire function curves.
If you want to define a filtering region, enter a value in the Start and Stop fields of the Filters window, or drag in the Start and Stop fields to modify a value. You can also Spacebar-drag in the FCurves pane to select a region. The start and end frames automatically display in the Start and Stop fields when a selection is made.
To apply a filter to an entire function curve, click Reset in the Start and Stop areas, or double-click an empty space in the FCurve or Optical panes to remove the current selection.
When both the Start and Stop fields are empty, applying a filter affects the entire function curve in the FCurve or Optical panes.