[<< wikibooks] Beginner's Guide to Adobe Flash/Filters and Blend Modes/Custom Easing
By default, the interpolation of any differences in filter settings from the first keyframe to the 
last keyframe will match the interpolation of the motion tween - that is, the filters will 
change at the same rate as any other characteristics of the item that have been modified to 
create animation in the tween. General Easing settings (adjusted in the Property inspector) 
will be applied equally to all changes in the characteristics of an item. As we described in the 
previous chapter, if you need more precise control over the interpolation of different aspects 
of a tween, you can use Custom Easing to set unique curves for Position, Rotation, Scale, 
Color, and/or Filters. To access Custom Easing controls, select the first keyframe in the 
motion tween, then click the Edit button to the right of the Easing controls in the Property 
inspector. The easing Property menu at the top of the dialog box 
enables you to load a unique interpolation curve for each of the various properties that can. 
be animated in a tween. You can set a unique curve to apply to all properties, or set unique 
curves for selected properties, leaving the default curve for others.