Flash CS3 Tutorial
How to Animate Object Brightness in Flash
Brightness Tweening works great to fade-in objects over a black or white background.
If you are fading in an object with a multi color background you might consider an Alpha Tween. For more information, see topic Transparency (Alpha) Tween.
Add an oval shape to the stage using the Oval tool (o key).
With the oval shape selected, convert it to a Movie Symbol (F8)(Modify > Convert to Symbol).
Click frame 20 of and press F6 (Insert > Timeline > Keyframe).
Right-click the timeline between your keyframes and choose Create Motion Tween from the pull-down menu.
Click the keyframe at frame one, then click the oval object.
From the Properties panel (Cmd/F3 (PC-Ctrl/F3)), select Brightness from the Color menu.
Set Brightness to 100% if you have a white background or 0% for a black background.
To render your swf file, press Cmd/Return (PC-Ctrl/Enter).