Looking for "animate draw on video" effect

Question

I need to supply a client with an animated drawing effect on video.
Actually it's a still frame- so hopefully that makes it easier.
(He wants me to animate glasses and a moustache being drawn on a face)
The effect seems fairly common.
Is this something that is done in photoshop or after effects or
is there a key frame, plug in for FCP?

Answer 1

You could do this pretty easily in AE or Motion. This will describe how to do it in Motion:
1.) Bring the frame in question into a "drawing" program: Illustrator or Photoshop. Draw your elements on top of your frame.
2.) Import your background frame & the new drawing into Motion. Put them into their own individual groups.
3.) Make a new group and use the "Bezier Tool" to draw lines (that Motion will call "Shapes") that hide your drawings. The lines should have no Fill & their outlines should be large enough to completely hide your drawings. You should 1 "shape" for every "stroke" of the drawing that needs to get revealed. This group probably needs to be on the top of your stack to see that you're hiding the drawing.
4.) Apply the Behavior, Shape > Write On to each of your shapes. This is going to cause your strokes to grow into place. Play with timing to suit yourself.
5.) Select the Group with your drawing: 'stache & glasses and go to the menu: Object > Add Image Mask. Make the top group, your written-on strokes, the mask for this drawing layer.
Your drawing should now draw itself on. You may need to make your drawing with individual layers for the strokes to make the write-on process cleaner. I'll post some screen shots in a minute to better illustrate this all. It's actually much easier than all the verbiage may make it sound...