ANIMATED MASKS, as we’ve seen, can provide an interesting dimension to your animation. It really doesn’t take much effort to create various visual effects using an animated mask, such as this spotlight effect for a client’s logo.
1The first thing you need is some text or other image to “shine” a spotlight on to. Convert it to a symbol. The background should be dark if not completely black. In order to show light, we first need to create darkness. This technique wouldn’t have the same effect if the background was very light.
2Create a new layer above your image layer and convert it to a mask layer. The image layer will automatically be linked to it as a “masked” layer. Draw a shape using the Oval tool 
while holding down the 
key to constrain its proportions. Convert it to a symbol.
3 Add a keyframe further down the timeline and position the mask shape to the opposite side of the image. Apply a motion tween so that the mask shape passes across the image.
4The key to making this technique convincing is to copy and paste in place the image to a new layer below the original layer. Make sure it is a normal layer (not masked). Select the symbol and tint it to a dark color. This layer will not be affected by the mask .
5Test your movie to see your animated mask pass over the original image layer while the darker instance remains unmasked and visible throughout the animation.
Hot Tip
Don’t be afraid to add more keyframes in your mask layer and position the mask symbol in various positions relative to the image it is revealing. You can also animate the mask getting larger and smaller by scaling it. Be creative and change the shape of the mask to say two circles side-by-side to suggest we are looking through binoculars.
