26 July 2010
You can use the onion skin feature when creating frame-by-frame animations in Adobe Flash Professional to help you compare the previous and next frames and adjust the objects in the current frame.
When onion skinning is turned off (the default setting), one frame of the animation sequence appears on the Stage at a time. The frame displayed corresponds to the location of the playhead in the Timeline.
To help position and edit a frame-by-frame animation, you can view two or more frames on the Stage at once by enabling onion skinning. When it is enabled, the frame under the playhead appears in full color, while surrounding frames are dimmed, as though each frame were drawn on a sheet of translucent onionskin paper and the sheets were stacked on top of each other. Dimmed frames cannot be edited; they are merely displayed as a visual reference.
Click the Onion Skin button to view several frames of an animation on the Stage simultaneously. Drag the Start Onion Skin and End Onion Skin markers in the Timeline header to specify the number of frames to display. To display onion skinned frames as outlines, click the Onion Skin Outlines button.
Note: Locked layers are not displayed when onion skinning is turned on. To avoid a multitude of confusing images, lock or hide the layers you don't want to see while using the onion skin feature.
To learn more about using the onion skin feature, see the section titled Frame-by-frame animation in the Animation Learning Guide for Flash.